Merge remote-tracking branch 'lightnvm/for-next'

[deliverable/linux.git] / drivers / gpu / drm / i915 / intel_lrc.c

/*
 * Copyright © 2014 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 *
 * Authors:
 *    Ben Widawsky <ben@bwidawsk.net>
 *    Michel Thierry <michel.thierry@intel.com>
 *    Thomas Daniel <thomas.daniel@intel.com>
 *    Oscar Mateo <oscar.mateo@intel.com>
 *
 */

/**
 * DOC: Logical Rings, Logical Ring Contexts and Execlists
 *
 * Motivation:
 * GEN8 brings an expansion of the HW contexts: "Logical Ring Contexts".
 * These expanded contexts enable a number of new abilities, especially
 * "Execlists" (also implemented in this file).
 *
 * One of the main differences with the legacy HW contexts is that logical
 * ring contexts incorporate many more things to the context's state, like
 * PDPs or ringbuffer control registers:
 *
 * The reason why PDPs are included in the context is straightforward: as
 * PPGTTs (per-process GTTs) are actually per-context, having the PDPs
 * contained there mean you don't need to do a ppgtt->switch_mm yourself,
 * instead, the GPU will do it for you on the context switch.
 *
 * But, what about the ringbuffer control registers (head, tail, etc..)?
 * shouldn't we just need a set of those per engine command streamer? This is
 * where the name "Logical Rings" starts to make sense: by virtualizing the
 * rings, the engine cs shifts to a new "ring buffer" with every context
 * switch. When you want to submit a workload to the GPU you: A) choose your
 * context, B) find its appropriate virtualized ring, C) write commands to it
 * and then, finally, D) tell the GPU to switch to that context.
 *
 * Instead of the legacy MI_SET_CONTEXT, the way you tell the GPU to switch
 * to a contexts is via a context execution list, ergo "Execlists".
 *
 * LRC implementation:
 * Regarding the creation of contexts, we have:
 *
 * - One global default context.
 * - One local default context for each opened fd.
 * - One local extra context for each context create ioctl call.
 *
 * Now that ringbuffers belong per-context (and not per-engine, like before)
 * and that contexts are uniquely tied to a given engine (and not reusable,
 * like before) we need:
 *
 * - One ringbuffer per-engine inside each context.
 * - One backing object per-engine inside each context.
 *
 * The global default context starts its life with these new objects fully
 * allocated and populated. The local default context for each opened fd is
 * more complex, because we don't know at creation time which engine is going
 * to use them. To handle this, we have implemented a deferred creation of LR
 * contexts:
 *
 * The local context starts its life as a hollow or blank holder, that only
 * gets populated for a given engine once we receive an execbuffer. If later
 * on we receive another execbuffer ioctl for the same context but a different
 * engine, we allocate/populate a new ringbuffer and context backing object and
 * so on.
 *
 * Finally, regarding local contexts created using the ioctl call: as they are
 * only allowed with the render ring, we can allocate & populate them right
 * away (no need to defer anything, at least for now).
 *
 * Execlists implementation:
 * Execlists are the new method by which, on gen8+ hardware, workloads are
 * submitted for execution (as opposed to the legacy, ringbuffer-based, method).
 * This method works as follows:
 *
 * When a request is committed, its commands (the BB start and any leading or
 * trailing commands, like the seqno breadcrumbs) are placed in the ringbuffer
 * for the appropriate context. The tail pointer in the hardware context is not
 * updated at this time, but instead, kept by the driver in the ringbuffer
 * structure. A structure representing this request is added to a request queue
 * for the appropriate engine: this structure contains a copy of the context's
 * tail after the request was written to the ring buffer and a pointer to the
 * context itself.
 *
 * If the engine's request queue was empty before the request was added, the
 * queue is processed immediately. Otherwise the queue will be processed during
 * a context switch interrupt. In any case, elements on the queue will get sent
 * (in pairs) to the GPU's ExecLists Submit Port (ELSP, for short) with a
 * globally unique 20-bits submission ID.
 *
 * When execution of a request completes, the GPU updates the context status
 * buffer with a context complete event and generates a context switch interrupt.
 * During the interrupt handling, the driver examines the events in the buffer:
 * for each context complete event, if the announced ID matches that on the head
 * of the request queue, then that request is retired and removed from the queue.
 *
 * After processing, if any requests were retired and the queue is not empty
 * then a new execution list can be submitted. The two requests at the front of
 * the queue are next to be submitted but since a context may not occur twice in
 * an execution list, if subsequent requests have the same ID as the first then
 * the two requests must be combined. This is done simply by discarding requests
 * at the head of the queue until either only one requests is left (in which case
 * we use a NULL second context) or the first two requests have unique IDs.
 *
 * By always executing the first two requests in the queue the driver ensures
 * that the GPU is kept as busy as possible. In the case where a single context
 * completes but a second context is still executing, the request for this second
 * context will be at the head of the queue when we remove the first one. This
 * request will then be resubmitted along with a new request for a different context,
 * which will cause the hardware to continue executing the second request and queue
 * the new request (the GPU detects the condition of a context getting preempted
 * with the same context and optimizes the context switch flow by not doing
 * preemption, but just sampling the new tail pointer).
 *
 */
#include <linux/interrupt.h>

#include <drm/drmP.h>
#include <drm/i915_drm.h>
#include "i915_drv.h"
#include "intel_mocs.h"

#define GEN9_LR_CONTEXT_RENDER_SIZE (22 * PAGE_SIZE)
#define GEN8_LR_CONTEXT_RENDER_SIZE (20 * PAGE_SIZE)
#define GEN8_LR_CONTEXT_OTHER_SIZE (2 * PAGE_SIZE)

#define RING_EXECLIST_QFULL             (1 << 0x2)
#define RING_EXECLIST1_VALID            (1 << 0x3)
#define RING_EXECLIST0_VALID            (1 << 0x4)
#define RING_EXECLIST_ACTIVE_STATUS     (3 << 0xE)
#define RING_EXECLIST1_ACTIVE           (1 << 0x11)
#define RING_EXECLIST0_ACTIVE           (1 << 0x12)

#define GEN8_CTX_STATUS_IDLE_ACTIVE     (1 << 0)
#define GEN8_CTX_STATUS_PREEMPTED       (1 << 1)
#define GEN8_CTX_STATUS_ELEMENT_SWITCH  (1 << 2)
#define GEN8_CTX_STATUS_ACTIVE_IDLE     (1 << 3)
#define GEN8_CTX_STATUS_COMPLETE        (1 << 4)
#define GEN8_CTX_STATUS_LITE_RESTORE    (1 << 15)

#define GEN8_CTX_STATUS_COMPLETED_MASK \
         (GEN8_CTX_STATUS_ACTIVE_IDLE | \
          GEN8_CTX_STATUS_PREEMPTED | \
          GEN8_CTX_STATUS_ELEMENT_SWITCH)

#define CTX_LRI_HEADER_0                0x01
#define CTX_CONTEXT_CONTROL             0x02
#define CTX_RING_HEAD                   0x04
#define CTX_RING_TAIL                   0x06
#define CTX_RING_BUFFER_START           0x08
#define CTX_RING_BUFFER_CONTROL         0x0a
#define CTX_BB_HEAD_U                   0x0c
#define CTX_BB_HEAD_L                   0x0e
#define CTX_BB_STATE                    0x10
#define CTX_SECOND_BB_HEAD_U            0x12
#define CTX_SECOND_BB_HEAD_L            0x14
#define CTX_SECOND_BB_STATE             0x16
#define CTX_BB_PER_CTX_PTR              0x18
#define CTX_RCS_INDIRECT_CTX            0x1a
#define CTX_RCS_INDIRECT_CTX_OFFSET     0x1c
#define CTX_LRI_HEADER_1                0x21
#define CTX_CTX_TIMESTAMP               0x22
#define CTX_PDP3_UDW                    0x24
#define CTX_PDP3_LDW                    0x26
#define CTX_PDP2_UDW                    0x28
#define CTX_PDP2_LDW                    0x2a
#define CTX_PDP1_UDW                    0x2c
#define CTX_PDP1_LDW                    0x2e
#define CTX_PDP0_UDW                    0x30
#define CTX_PDP0_LDW                    0x32
#define CTX_LRI_HEADER_2                0x41
#define CTX_R_PWR_CLK_STATE             0x42
#define CTX_GPGPU_CSR_BASE_ADDRESS      0x44

#define GEN8_CTX_VALID (1<<0)
#define GEN8_CTX_FORCE_PD_RESTORE (1<<1)
#define GEN8_CTX_FORCE_RESTORE (1<<2)
#define GEN8_CTX_L3LLC_COHERENT (1<<5)
#define GEN8_CTX_PRIVILEGE (1<<8)

#define ASSIGN_CTX_REG(reg_state, pos, reg, val) do { \
        (reg_state)[(pos)+0] = i915_mmio_reg_offset(reg); \
        (reg_state)[(pos)+1] = (val); \
} while (0)

#define ASSIGN_CTX_PDP(ppgtt, reg_state, n) do {                \
        const u64 _addr = i915_page_dir_dma_addr((ppgtt), (n)); \
        reg_state[CTX_PDP ## n ## _UDW+1] = upper_32_bits(_addr); \
        reg_state[CTX_PDP ## n ## _LDW+1] = lower_32_bits(_addr); \
} while (0)

#define ASSIGN_CTX_PML4(ppgtt, reg_state) do { \
        reg_state[CTX_PDP0_UDW + 1] = upper_32_bits(px_dma(&ppgtt->pml4)); \
        reg_state[CTX_PDP0_LDW + 1] = lower_32_bits(px_dma(&ppgtt->pml4)); \
} while (0)

enum {
        FAULT_AND_HANG = 0,
        FAULT_AND_HALT, /* Debug only */
        FAULT_AND_STREAM,
        FAULT_AND_CONTINUE /* Unsupported */
};
#define GEN8_CTX_ID_SHIFT 32
#define GEN8_CTX_ID_WIDTH 21
#define GEN8_CTX_RCS_INDIRECT_CTX_OFFSET_DEFAULT        0x17
#define GEN9_CTX_RCS_INDIRECT_CTX_OFFSET_DEFAULT        0x26

/* Typical size of the average request (2 pipecontrols and a MI_BB) */
#define EXECLISTS_REQUEST_SIZE 64 /* bytes */

static int execlists_context_deferred_alloc(struct i915_gem_context *ctx,
                                            struct intel_engine_cs *engine);
static int intel_lr_context_pin(struct i915_gem_context *ctx,
                                struct intel_engine_cs *engine);

/**
 * intel_sanitize_enable_execlists() - sanitize i915.enable_execlists
 * @dev_priv: i915 device private
 * @enable_execlists: value of i915.enable_execlists module parameter.
 *
 * Only certain platforms support Execlists (the prerequisites being
 * support for Logical Ring Contexts and Aliasing PPGTT or better).
 *
 * Return: 1 if Execlists is supported and has to be enabled.
 */
int intel_sanitize_enable_execlists(struct drm_i915_private *dev_priv, int enable_execlists)
{
        /* On platforms with execlist available, vGPU will only
         * support execlist mode, no ring buffer mode.
         */
        if (HAS_LOGICAL_RING_CONTEXTS(dev_priv) && intel_vgpu_active(dev_priv))
                return 1;

        if (INTEL_GEN(dev_priv) >= 9)
                return 1;

        if (enable_execlists == 0)
                return 0;

        if (HAS_LOGICAL_RING_CONTEXTS(dev_priv) &&
            USES_PPGTT(dev_priv) &&
            i915.use_mmio_flip >= 0)
                return 1;

        return 0;
}

static void
logical_ring_init_platform_invariants(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        engine->disable_lite_restore_wa =
                (IS_SKL_REVID(dev_priv, 0, SKL_REVID_B0) ||
                 IS_BXT_REVID(dev_priv, 0, BXT_REVID_A1)) &&
                (engine->id == VCS || engine->id == VCS2);

        engine->ctx_desc_template = GEN8_CTX_VALID;
        if (IS_GEN8(dev_priv))
                engine->ctx_desc_template |= GEN8_CTX_L3LLC_COHERENT;
        engine->ctx_desc_template |= GEN8_CTX_PRIVILEGE;

        /* TODO: WaDisableLiteRestore when we start using semaphore
         * signalling between Command Streamers */
        /* ring->ctx_desc_template |= GEN8_CTX_FORCE_RESTORE; */

        /* WaEnableForceRestoreInCtxtDescForVCS:skl */
        /* WaEnableForceRestoreInCtxtDescForVCS:bxt */
        if (engine->disable_lite_restore_wa)
                engine->ctx_desc_template |= GEN8_CTX_FORCE_RESTORE;
}

/**
 * intel_lr_context_descriptor_update() - calculate & cache the descriptor
 *                                        descriptor for a pinned context
 * @ctx: Context to work on
 * @engine: Engine the descriptor will be used with
 *
 * The context descriptor encodes various attributes of a context,
 * including its GTT address and some flags. Because it's fairly
 * expensive to calculate, we'll just do it once and cache the result,
 * which remains valid until the context is unpinned.
 *
 * This is what a descriptor looks like, from LSB to MSB::
 *
 *      bits  0-11:    flags, GEN8_CTX_* (cached in ctx_desc_template)
 *      bits 12-31:    LRCA, GTT address of (the HWSP of) this context
 *      bits 32-52:    ctx ID, a globally unique tag
 *      bits 53-54:    mbz, reserved for use by hardware
 *      bits 55-63:    group ID, currently unused and set to 0
 */
static void
intel_lr_context_descriptor_update(struct i915_gem_context *ctx,
                                   struct intel_engine_cs *engine)
{
        struct intel_context *ce = &ctx->engine[engine->id];
        u64 desc;

        BUILD_BUG_ON(MAX_CONTEXT_HW_ID > (1<<GEN8_CTX_ID_WIDTH));

        desc = ctx->desc_template;                              /* bits  3-4  */
        desc |= engine->ctx_desc_template;                      /* bits  0-11 */
        desc |= i915_ggtt_offset(ce->state) + LRC_PPHWSP_PN * PAGE_SIZE;
                                                                /* bits 12-31 */
        desc |= (u64)ctx->hw_id << GEN8_CTX_ID_SHIFT;           /* bits 32-52 */

        ce->lrc_desc = desc;
}

uint64_t intel_lr_context_descriptor(struct i915_gem_context *ctx,
                                     struct intel_engine_cs *engine)
{
        return ctx->engine[engine->id].lrc_desc;
}

static inline void
execlists_context_status_change(struct drm_i915_gem_request *rq,
                                unsigned long status)
{
        /*
         * Only used when GVT-g is enabled now. When GVT-g is disabled,
         * The compiler should eliminate this function as dead-code.
         */
        if (!IS_ENABLED(CONFIG_DRM_I915_GVT))
                return;

        atomic_notifier_call_chain(&rq->ctx->status_notifier, status, rq);
}

static void
execlists_update_context_pdps(struct i915_hw_ppgtt *ppgtt, u32 *reg_state)
{
        ASSIGN_CTX_PDP(ppgtt, reg_state, 3);
        ASSIGN_CTX_PDP(ppgtt, reg_state, 2);
        ASSIGN_CTX_PDP(ppgtt, reg_state, 1);
        ASSIGN_CTX_PDP(ppgtt, reg_state, 0);
}

static u64 execlists_update_context(struct drm_i915_gem_request *rq)
{
        struct intel_context *ce = &rq->ctx->engine[rq->engine->id];
        struct i915_hw_ppgtt *ppgtt = rq->ctx->ppgtt;
        u32 *reg_state = ce->lrc_reg_state;

        reg_state[CTX_RING_TAIL+1] = intel_ring_offset(rq->ring, rq->tail);

        /* True 32b PPGTT with dynamic page allocation: update PDP
         * registers and point the unallocated PDPs to scratch page.
         * PML4 is allocated during ppgtt init, so this is not needed
         * in 48-bit mode.
         */
        if (ppgtt && !USES_FULL_48BIT_PPGTT(ppgtt->base.dev))
                execlists_update_context_pdps(ppgtt, reg_state);

        return ce->lrc_desc;
}

static void execlists_submit_ports(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;
        struct execlist_port *port = engine->execlist_port;
        u32 __iomem *elsp =
                dev_priv->regs + i915_mmio_reg_offset(RING_ELSP(engine));
        u64 desc[2];

        if (!port[0].count)
                execlists_context_status_change(port[0].request,
                                                INTEL_CONTEXT_SCHEDULE_IN);
        desc[0] = execlists_update_context(port[0].request);
        engine->preempt_wa = port[0].count++; /* bdw only? fixed on skl? */

        if (port[1].request) {
                GEM_BUG_ON(port[1].count);
                execlists_context_status_change(port[1].request,
                                                INTEL_CONTEXT_SCHEDULE_IN);
                desc[1] = execlists_update_context(port[1].request);
                port[1].count = 1;
        } else {
                desc[1] = 0;
        }
        GEM_BUG_ON(desc[0] == desc[1]);

        /* You must always write both descriptors in the order below. */
        writel(upper_32_bits(desc[1]), elsp);
        writel(lower_32_bits(desc[1]), elsp);

        writel(upper_32_bits(desc[0]), elsp);
        /* The context is automatically loaded after the following */
        writel(lower_32_bits(desc[0]), elsp);
}

static bool ctx_single_port_submission(const struct i915_gem_context *ctx)
{
        return (IS_ENABLED(CONFIG_DRM_I915_GVT) &&
                ctx->execlists_force_single_submission);
}

static bool can_merge_ctx(const struct i915_gem_context *prev,
                          const struct i915_gem_context *next)
{
        if (prev != next)
                return false;

        if (ctx_single_port_submission(prev))
                return false;

        return true;
}

static void execlists_dequeue(struct intel_engine_cs *engine)
{
        struct drm_i915_gem_request *cursor, *last;
        struct execlist_port *port = engine->execlist_port;
        bool submit = false;

        last = port->request;
        if (last)
                /* WaIdleLiteRestore:bdw,skl
                 * Apply the wa NOOPs to prevent ring:HEAD == req:TAIL
                 * as we resubmit the request. See gen8_emit_request()
                 * for where we prepare the padding after the end of the
                 * request.
                 */
                last->tail = last->wa_tail;

        GEM_BUG_ON(port[1].request);

        /* Hardware submission is through 2 ports. Conceptually each port
         * has a (RING_START, RING_HEAD, RING_TAIL) tuple. RING_START is
         * static for a context, and unique to each, so we only execute
         * requests belonging to a single context from each ring. RING_HEAD
         * is maintained by the CS in the context image, it marks the place
         * where it got up to last time, and through RING_TAIL we tell the CS
         * where we want to execute up to this time.
         *
         * In this list the requests are in order of execution. Consecutive
         * requests from the same context are adjacent in the ringbuffer. We
         * can combine these requests into a single RING_TAIL update:
         *
         *              RING_HEAD...req1...req2
         *                                    ^- RING_TAIL
         * since to execute req2 the CS must first execute req1.
         *
         * Our goal then is to point each port to the end of a consecutive
         * sequence of requests as being the most optimal (fewest wake ups
         * and context switches) submission.
         */

        spin_lock(&engine->execlist_lock);
        list_for_each_entry(cursor, &engine->execlist_queue, execlist_link) {
                /* Can we combine this request with the current port? It has to
                 * be the same context/ringbuffer and not have any exceptions
                 * (e.g. GVT saying never to combine contexts).
                 *
                 * If we can combine the requests, we can execute both by
                 * updating the RING_TAIL to point to the end of the second
                 * request, and so we never need to tell the hardware about
                 * the first.
                 */
                if (last && !can_merge_ctx(cursor->ctx, last->ctx)) {
                        /* If we are on the second port and cannot combine
                         * this request with the last, then we are done.
                         */
                        if (port != engine->execlist_port)
                                break;

                        /* If GVT overrides us we only ever submit port[0],
                         * leaving port[1] empty. Note that we also have
                         * to be careful that we don't queue the same
                         * context (even though a different request) to
                         * the second port.
                         */
                        if (ctx_single_port_submission(cursor->ctx))
                                break;

                        GEM_BUG_ON(last->ctx == cursor->ctx);

                        i915_gem_request_assign(&port->request, last);
                        port++;
                }
                last = cursor;
                submit = true;
        }
        if (submit) {
                /* Decouple all the requests submitted from the queue */
                engine->execlist_queue.next = &cursor->execlist_link;
                cursor->execlist_link.prev = &engine->execlist_queue;

                i915_gem_request_assign(&port->request, last);
        }
        spin_unlock(&engine->execlist_lock);

        if (submit)
                execlists_submit_ports(engine);
}

static bool execlists_elsp_idle(struct intel_engine_cs *engine)
{
        return !engine->execlist_port[0].request;
}

static bool execlists_elsp_ready(struct intel_engine_cs *engine)
{
        int port;

        port = 1; /* wait for a free slot */
        if (engine->disable_lite_restore_wa || engine->preempt_wa)
                port = 0; /* wait for GPU to be idle before continuing */

        return !engine->execlist_port[port].request;
}

/*
 * Check the unread Context Status Buffers and manage the submission of new
 * contexts to the ELSP accordingly.
 */
static void intel_lrc_irq_handler(unsigned long data)
{
        struct intel_engine_cs *engine = (struct intel_engine_cs *)data;
        struct execlist_port *port = engine->execlist_port;
        struct drm_i915_private *dev_priv = engine->i915;

        intel_uncore_forcewake_get(dev_priv, engine->fw_domains);

        if (!execlists_elsp_idle(engine)) {
                u32 __iomem *csb_mmio =
                        dev_priv->regs + i915_mmio_reg_offset(RING_CONTEXT_STATUS_PTR(engine));
                u32 __iomem *buf =
                        dev_priv->regs + i915_mmio_reg_offset(RING_CONTEXT_STATUS_BUF_LO(engine, 0));
                unsigned int csb, head, tail;

                csb = readl(csb_mmio);
                head = GEN8_CSB_READ_PTR(csb);
                tail = GEN8_CSB_WRITE_PTR(csb);
                if (tail < head)
                        tail += GEN8_CSB_ENTRIES;
                while (head < tail) {
                        unsigned int idx = ++head % GEN8_CSB_ENTRIES;
                        unsigned int status = readl(buf + 2 * idx);

                        if (!(status & GEN8_CTX_STATUS_COMPLETED_MASK))
                                continue;

                        GEM_BUG_ON(port[0].count == 0);
                        if (--port[0].count == 0) {
                                GEM_BUG_ON(status & GEN8_CTX_STATUS_PREEMPTED);
                                execlists_context_status_change(port[0].request,
                                                                INTEL_CONTEXT_SCHEDULE_OUT);

                                i915_gem_request_put(port[0].request);
                                port[0] = port[1];
                                memset(&port[1], 0, sizeof(port[1]));

                                engine->preempt_wa = false;
                        }

                        GEM_BUG_ON(port[0].count == 0 &&
                                   !(status & GEN8_CTX_STATUS_ACTIVE_IDLE));
                }

                writel(_MASKED_FIELD(GEN8_CSB_READ_PTR_MASK,
                                     GEN8_CSB_WRITE_PTR(csb) << 8),
                       csb_mmio);
        }

        if (execlists_elsp_ready(engine))
                execlists_dequeue(engine);

        intel_uncore_forcewake_put(dev_priv, engine->fw_domains);
}

static void execlists_submit_request(struct drm_i915_gem_request *request)
{
        struct intel_engine_cs *engine = request->engine;
        unsigned long flags;

        spin_lock_irqsave(&engine->execlist_lock, flags);

        list_add_tail(&request->execlist_link, &engine->execlist_queue);
        if (execlists_elsp_idle(engine))
                tasklet_hi_schedule(&engine->irq_tasklet);

        spin_unlock_irqrestore(&engine->execlist_lock, flags);
}

int intel_logical_ring_alloc_request_extras(struct drm_i915_gem_request *request)
{
        struct intel_engine_cs *engine = request->engine;
        struct intel_context *ce = &request->ctx->engine[engine->id];
        int ret;

        /* Flush enough space to reduce the likelihood of waiting after
         * we start building the request - in which case we will just
         * have to repeat work.
         */
        request->reserved_space += EXECLISTS_REQUEST_SIZE;

        if (!ce->state) {
                ret = execlists_context_deferred_alloc(request->ctx, engine);
                if (ret)
                        return ret;
        }

        request->ring = ce->ring;

        if (i915.enable_guc_submission) {
                /*
                 * Check that the GuC has space for the request before
                 * going any further, as the i915_add_request() call
                 * later on mustn't fail ...
                 */
                ret = i915_guc_wq_check_space(request);
                if (ret)
                        return ret;
        }

        ret = intel_lr_context_pin(request->ctx, engine);
        if (ret)
                return ret;

        ret = intel_ring_begin(request, 0);
        if (ret)
                goto err_unpin;

        if (!ce->initialised) {
                ret = engine->init_context(request);
                if (ret)
                        goto err_unpin;

                ce->initialised = true;
        }

        /* Note that after this point, we have committed to using
         * this request as it is being used to both track the
         * state of engine initialisation and liveness of the
         * golden renderstate above. Think twice before you try
         * to cancel/unwind this request now.
         */

        request->reserved_space -= EXECLISTS_REQUEST_SIZE;
        return 0;

err_unpin:
        intel_lr_context_unpin(request->ctx, engine);
        return ret;
}

/*
 * intel_logical_ring_advance() - advance the tail and prepare for submission
 * @request: Request to advance the logical ringbuffer of.
 *
 * The tail is updated in our logical ringbuffer struct, not in the actual context. What
 * really happens during submission is that the context and current tail will be placed
 * on a queue waiting for the ELSP to be ready to accept a new context submission. At that
 * point, the tail *inside* the context is updated and the ELSP written to.
 */
static int
intel_logical_ring_advance(struct drm_i915_gem_request *request)
{
        struct intel_ring *ring = request->ring;
        struct intel_engine_cs *engine = request->engine;

        intel_ring_advance(ring);
        request->tail = ring->tail;

        /*
         * Here we add two extra NOOPs as padding to avoid
         * lite restore of a context with HEAD==TAIL.
         *
         * Caller must reserve WA_TAIL_DWORDS for us!
         */
        intel_ring_emit(ring, MI_NOOP);
        intel_ring_emit(ring, MI_NOOP);
        intel_ring_advance(ring);
        request->wa_tail = ring->tail;

        /* We keep the previous context alive until we retire the following
         * request. This ensures that any the context object is still pinned
         * for any residual writes the HW makes into it on the context switch
         * into the next object following the breadcrumb. Otherwise, we may
         * retire the context too early.
         */
        request->previous_context = engine->last_context;
        engine->last_context = request->ctx;
        return 0;
}

static int intel_lr_context_pin(struct i915_gem_context *ctx,
                                struct intel_engine_cs *engine)
{
        struct intel_context *ce = &ctx->engine[engine->id];
        void *vaddr;
        u32 *lrc_reg_state;
        int ret;

        lockdep_assert_held(&ctx->i915->drm.struct_mutex);

        if (ce->pin_count++)
                return 0;

        ret = i915_vma_pin(ce->state, 0, GEN8_LR_CONTEXT_ALIGN,
                           PIN_OFFSET_BIAS | GUC_WOPCM_TOP | PIN_GLOBAL);
        if (ret)
                goto err;

        vaddr = i915_gem_object_pin_map(ce->state->obj, I915_MAP_WB);
        if (IS_ERR(vaddr)) {
                ret = PTR_ERR(vaddr);
                goto unpin_vma;
        }

        lrc_reg_state = vaddr + LRC_STATE_PN * PAGE_SIZE;

        ret = intel_ring_pin(ce->ring);
        if (ret)
                goto unpin_map;

        intel_lr_context_descriptor_update(ctx, engine);

        lrc_reg_state[CTX_RING_BUFFER_START+1] =
                i915_ggtt_offset(ce->ring->vma);
        ce->lrc_reg_state = lrc_reg_state;
        ce->state->obj->dirty = true;

        /* Invalidate GuC TLB. */
        if (i915.enable_guc_submission) {
                struct drm_i915_private *dev_priv = ctx->i915;
                I915_WRITE(GEN8_GTCR, GEN8_GTCR_INVALIDATE);
        }

        i915_gem_context_get(ctx);
        return 0;

unpin_map:
        i915_gem_object_unpin_map(ce->state->obj);
unpin_vma:
        __i915_vma_unpin(ce->state);
err:
        ce->pin_count = 0;
        return ret;
}

void intel_lr_context_unpin(struct i915_gem_context *ctx,
                            struct intel_engine_cs *engine)
{
        struct intel_context *ce = &ctx->engine[engine->id];

        lockdep_assert_held(&ctx->i915->drm.struct_mutex);
        GEM_BUG_ON(ce->pin_count == 0);

        if (--ce->pin_count)
                return;

        intel_ring_unpin(ce->ring);

        i915_gem_object_unpin_map(ce->state->obj);
        i915_vma_unpin(ce->state);

        i915_gem_context_put(ctx);
}

static int intel_logical_ring_workarounds_emit(struct drm_i915_gem_request *req)
{
        int ret, i;
        struct intel_ring *ring = req->ring;
        struct i915_workarounds *w = &req->i915->workarounds;

        if (w->count == 0)
                return 0;

        ret = req->engine->emit_flush(req, EMIT_BARRIER);
        if (ret)
                return ret;

        ret = intel_ring_begin(req, w->count * 2 + 2);
        if (ret)
                return ret;

        intel_ring_emit(ring, MI_LOAD_REGISTER_IMM(w->count));
        for (i = 0; i < w->count; i++) {
                intel_ring_emit_reg(ring, w->reg[i].addr);
                intel_ring_emit(ring, w->reg[i].value);
        }
        intel_ring_emit(ring, MI_NOOP);

        intel_ring_advance(ring);

        ret = req->engine->emit_flush(req, EMIT_BARRIER);
        if (ret)
                return ret;

        return 0;
}

#define wa_ctx_emit(batch, index, cmd)                                  \
        do {                                                            \
                int __index = (index)++;                                \
                if (WARN_ON(__index >= (PAGE_SIZE / sizeof(uint32_t)))) { \
                        return -ENOSPC;                                 \
                }                                                       \
                batch[__index] = (cmd);                                 \
        } while (0)

#define wa_ctx_emit_reg(batch, index, reg) \
        wa_ctx_emit((batch), (index), i915_mmio_reg_offset(reg))

/*
 * In this WA we need to set GEN8_L3SQCREG4[21:21] and reset it after
 * PIPE_CONTROL instruction. This is required for the flush to happen correctly
 * but there is a slight complication as this is applied in WA batch where the
 * values are only initialized once so we cannot take register value at the
 * beginning and reuse it further; hence we save its value to memory, upload a
 * constant value with bit21 set and then we restore it back with the saved value.
 * To simplify the WA, a constant value is formed by using the default value
 * of this register. This shouldn't be a problem because we are only modifying
 * it for a short period and this batch in non-premptible. We can ofcourse
 * use additional instructions that read the actual value of the register
 * at that time and set our bit of interest but it makes the WA complicated.
 *
 * This WA is also required for Gen9 so extracting as a function avoids
 * code duplication.
 */
static inline int gen8_emit_flush_coherentl3_wa(struct intel_engine_cs *engine,
                                                uint32_t *batch,
                                                uint32_t index)
{
        struct drm_i915_private *dev_priv = engine->i915;
        uint32_t l3sqc4_flush = (0x40400000 | GEN8_LQSC_FLUSH_COHERENT_LINES);

        /*
         * WaDisableLSQCROPERFforOCL:skl,kbl
         * This WA is implemented in skl_init_clock_gating() but since
         * this batch updates GEN8_L3SQCREG4 with default value we need to
         * set this bit here to retain the WA during flush.
         */
        if (IS_SKL_REVID(dev_priv, 0, SKL_REVID_E0) ||
            IS_KBL_REVID(dev_priv, 0, KBL_REVID_E0))
                l3sqc4_flush |= GEN8_LQSC_RO_PERF_DIS;

        wa_ctx_emit(batch, index, (MI_STORE_REGISTER_MEM_GEN8 |
                                   MI_SRM_LRM_GLOBAL_GTT));
        wa_ctx_emit_reg(batch, index, GEN8_L3SQCREG4);
        wa_ctx_emit(batch, index, i915_ggtt_offset(engine->scratch) + 256);
        wa_ctx_emit(batch, index, 0);

        wa_ctx_emit(batch, index, MI_LOAD_REGISTER_IMM(1));
        wa_ctx_emit_reg(batch, index, GEN8_L3SQCREG4);
        wa_ctx_emit(batch, index, l3sqc4_flush);

        wa_ctx_emit(batch, index, GFX_OP_PIPE_CONTROL(6));
        wa_ctx_emit(batch, index, (PIPE_CONTROL_CS_STALL |
                                   PIPE_CONTROL_DC_FLUSH_ENABLE));
        wa_ctx_emit(batch, index, 0);
        wa_ctx_emit(batch, index, 0);
        wa_ctx_emit(batch, index, 0);
        wa_ctx_emit(batch, index, 0);

        wa_ctx_emit(batch, index, (MI_LOAD_REGISTER_MEM_GEN8 |
                                   MI_SRM_LRM_GLOBAL_GTT));
        wa_ctx_emit_reg(batch, index, GEN8_L3SQCREG4);
        wa_ctx_emit(batch, index, i915_ggtt_offset(engine->scratch) + 256);
        wa_ctx_emit(batch, index, 0);

        return index;
}

static inline uint32_t wa_ctx_start(struct i915_wa_ctx_bb *wa_ctx,
                                    uint32_t offset,
                                    uint32_t start_alignment)
{
        return wa_ctx->offset = ALIGN(offset, start_alignment);
}

static inline int wa_ctx_end(struct i915_wa_ctx_bb *wa_ctx,
                             uint32_t offset,
                             uint32_t size_alignment)
{
        wa_ctx->size = offset - wa_ctx->offset;

        WARN(wa_ctx->size % size_alignment,
             "wa_ctx_bb failed sanity checks: size %d is not aligned to %d\n",
             wa_ctx->size, size_alignment);
        return 0;
}

/*
 * Typically we only have one indirect_ctx and per_ctx batch buffer which are
 * initialized at the beginning and shared across all contexts but this field
 * helps us to have multiple batches at different offsets and select them based
 * on a criteria. At the moment this batch always start at the beginning of the page
 * and at this point we don't have multiple wa_ctx batch buffers.
 *
 * The number of WA applied are not known at the beginning; we use this field
 * to return the no of DWORDS written.
 *
 * It is to be noted that this batch does not contain MI_BATCH_BUFFER_END
 * so it adds NOOPs as padding to make it cacheline aligned.
 * MI_BATCH_BUFFER_END will be added to perctx batch and both of them together
 * makes a complete batch buffer.
 */
static int gen8_init_indirectctx_bb(struct intel_engine_cs *engine,
                                    struct i915_wa_ctx_bb *wa_ctx,
                                    uint32_t *batch,
                                    uint32_t *offset)
{
        uint32_t scratch_addr;
        uint32_t index = wa_ctx_start(wa_ctx, *offset, CACHELINE_DWORDS);

        /* WaDisableCtxRestoreArbitration:bdw,chv */
        wa_ctx_emit(batch, index, MI_ARB_ON_OFF | MI_ARB_DISABLE);

        /* WaFlushCoherentL3CacheLinesAtContextSwitch:bdw */
        if (IS_BROADWELL(engine->i915)) {
                int rc = gen8_emit_flush_coherentl3_wa(engine, batch, index);
                if (rc < 0)
                        return rc;
                index = rc;
        }

        /* WaClearSlmSpaceAtContextSwitch:bdw,chv */
        /* Actual scratch location is at 128 bytes offset */
        scratch_addr = i915_ggtt_offset(engine->scratch) + 2 * CACHELINE_BYTES;

        wa_ctx_emit(batch, index, GFX_OP_PIPE_CONTROL(6));
        wa_ctx_emit(batch, index, (PIPE_CONTROL_FLUSH_L3 |
                                   PIPE_CONTROL_GLOBAL_GTT_IVB |
                                   PIPE_CONTROL_CS_STALL |
                                   PIPE_CONTROL_QW_WRITE));
        wa_ctx_emit(batch, index, scratch_addr);
        wa_ctx_emit(batch, index, 0);
        wa_ctx_emit(batch, index, 0);
        wa_ctx_emit(batch, index, 0);

        /* Pad to end of cacheline */
        while (index % CACHELINE_DWORDS)
                wa_ctx_emit(batch, index, MI_NOOP);

        /*
         * MI_BATCH_BUFFER_END is not required in Indirect ctx BB because
         * execution depends on the length specified in terms of cache lines
         * in the register CTX_RCS_INDIRECT_CTX
         */

        return wa_ctx_end(wa_ctx, *offset = index, CACHELINE_DWORDS);
}

/*
 *  This batch is started immediately after indirect_ctx batch. Since we ensure
 *  that indirect_ctx ends on a cacheline this batch is aligned automatically.
 *
 *  The number of DWORDS written are returned using this field.
 *
 *  This batch is terminated with MI_BATCH_BUFFER_END and so we need not add padding
 *  to align it with cacheline as padding after MI_BATCH_BUFFER_END is redundant.
 */
static int gen8_init_perctx_bb(struct intel_engine_cs *engine,
                               struct i915_wa_ctx_bb *wa_ctx,
                               uint32_t *batch,
                               uint32_t *offset)
{
        uint32_t index = wa_ctx_start(wa_ctx, *offset, CACHELINE_DWORDS);

        /* WaDisableCtxRestoreArbitration:bdw,chv */
        wa_ctx_emit(batch, index, MI_ARB_ON_OFF | MI_ARB_ENABLE);

        wa_ctx_emit(batch, index, MI_BATCH_BUFFER_END);

        return wa_ctx_end(wa_ctx, *offset = index, 1);
}

static int gen9_init_indirectctx_bb(struct intel_engine_cs *engine,
                                    struct i915_wa_ctx_bb *wa_ctx,
                                    uint32_t *batch,
                                    uint32_t *offset)
{
        int ret;
        struct drm_i915_private *dev_priv = engine->i915;
        uint32_t index = wa_ctx_start(wa_ctx, *offset, CACHELINE_DWORDS);

        /* WaDisableCtxRestoreArbitration:skl,bxt */
        if (IS_SKL_REVID(dev_priv, 0, SKL_REVID_D0) ||
            IS_BXT_REVID(dev_priv, 0, BXT_REVID_A1))
                wa_ctx_emit(batch, index, MI_ARB_ON_OFF | MI_ARB_DISABLE);

        /* WaFlushCoherentL3CacheLinesAtContextSwitch:skl,bxt */
        ret = gen8_emit_flush_coherentl3_wa(engine, batch, index);
        if (ret < 0)
                return ret;
        index = ret;

        /* WaDisableGatherAtSetShaderCommonSlice:skl,bxt,kbl */
        wa_ctx_emit(batch, index, MI_LOAD_REGISTER_IMM(1));
        wa_ctx_emit_reg(batch, index, COMMON_SLICE_CHICKEN2);
        wa_ctx_emit(batch, index, _MASKED_BIT_DISABLE(
                            GEN9_DISABLE_GATHER_AT_SET_SHADER_COMMON_SLICE));
        wa_ctx_emit(batch, index, MI_NOOP);

        /* WaClearSlmSpaceAtContextSwitch:kbl */
        /* Actual scratch location is at 128 bytes offset */
        if (IS_KBL_REVID(dev_priv, 0, KBL_REVID_A0)) {
                u32 scratch_addr =
                        i915_ggtt_offset(engine->scratch) + 2 * CACHELINE_BYTES;

                wa_ctx_emit(batch, index, GFX_OP_PIPE_CONTROL(6));
                wa_ctx_emit(batch, index, (PIPE_CONTROL_FLUSH_L3 |
                                           PIPE_CONTROL_GLOBAL_GTT_IVB |
                                           PIPE_CONTROL_CS_STALL |
                                           PIPE_CONTROL_QW_WRITE));
                wa_ctx_emit(batch, index, scratch_addr);
                wa_ctx_emit(batch, index, 0);
                wa_ctx_emit(batch, index, 0);
                wa_ctx_emit(batch, index, 0);
        }

        /* WaMediaPoolStateCmdInWABB:bxt */
        if (HAS_POOLED_EU(engine->i915)) {
                /*
                 * EU pool configuration is setup along with golden context
                 * during context initialization. This value depends on
                 * device type (2x6 or 3x6) and needs to be updated based
                 * on which subslice is disabled especially for 2x6
                 * devices, however it is safe to load default
                 * configuration of 3x6 device instead of masking off
                 * corresponding bits because HW ignores bits of a disabled
                 * subslice and drops down to appropriate config. Please
                 * see render_state_setup() in i915_gem_render_state.c for
                 * possible configurations, to avoid duplication they are
                 * not shown here again.
                 */
                u32 eu_pool_config = 0x00777000;
                wa_ctx_emit(batch, index, GEN9_MEDIA_POOL_STATE);
                wa_ctx_emit(batch, index, GEN9_MEDIA_POOL_ENABLE);
                wa_ctx_emit(batch, index, eu_pool_config);
                wa_ctx_emit(batch, index, 0);
                wa_ctx_emit(batch, index, 0);
                wa_ctx_emit(batch, index, 0);
        }

        /* Pad to end of cacheline */
        while (index % CACHELINE_DWORDS)
                wa_ctx_emit(batch, index, MI_NOOP);

        return wa_ctx_end(wa_ctx, *offset = index, CACHELINE_DWORDS);
}

static int gen9_init_perctx_bb(struct intel_engine_cs *engine,
                               struct i915_wa_ctx_bb *wa_ctx,
                               uint32_t *batch,
                               uint32_t *offset)
{
        uint32_t index = wa_ctx_start(wa_ctx, *offset, CACHELINE_DWORDS);

        /* WaSetDisablePixMaskCammingAndRhwoInCommonSliceChicken:skl,bxt */
        if (IS_SKL_REVID(engine->i915, 0, SKL_REVID_B0) ||
            IS_BXT_REVID(engine->i915, 0, BXT_REVID_A1)) {
                wa_ctx_emit(batch, index, MI_LOAD_REGISTER_IMM(1));
                wa_ctx_emit_reg(batch, index, GEN9_SLICE_COMMON_ECO_CHICKEN0);
                wa_ctx_emit(batch, index,
                            _MASKED_BIT_ENABLE(DISABLE_PIXEL_MASK_CAMMING));
                wa_ctx_emit(batch, index, MI_NOOP);
        }

        /* WaClearTdlStateAckDirtyBits:bxt */
        if (IS_BXT_REVID(engine->i915, 0, BXT_REVID_B0)) {
                wa_ctx_emit(batch, index, MI_LOAD_REGISTER_IMM(4));

                wa_ctx_emit_reg(batch, index, GEN8_STATE_ACK);
                wa_ctx_emit(batch, index, _MASKED_BIT_DISABLE(GEN9_SUBSLICE_TDL_ACK_BITS));

                wa_ctx_emit_reg(batch, index, GEN9_STATE_ACK_SLICE1);
                wa_ctx_emit(batch, index, _MASKED_BIT_DISABLE(GEN9_SUBSLICE_TDL_ACK_BITS));

                wa_ctx_emit_reg(batch, index, GEN9_STATE_ACK_SLICE2);
                wa_ctx_emit(batch, index, _MASKED_BIT_DISABLE(GEN9_SUBSLICE_TDL_ACK_BITS));

                wa_ctx_emit_reg(batch, index, GEN7_ROW_CHICKEN2);
                /* dummy write to CS, mask bits are 0 to ensure the register is not modified */
                wa_ctx_emit(batch, index, 0x0);
                wa_ctx_emit(batch, index, MI_NOOP);
        }

        /* WaDisableCtxRestoreArbitration:skl,bxt */
        if (IS_SKL_REVID(engine->i915, 0, SKL_REVID_D0) ||
            IS_BXT_REVID(engine->i915, 0, BXT_REVID_A1))
                wa_ctx_emit(batch, index, MI_ARB_ON_OFF | MI_ARB_ENABLE);

        wa_ctx_emit(batch, index, MI_BATCH_BUFFER_END);

        return wa_ctx_end(wa_ctx, *offset = index, 1);
}

static int lrc_setup_wa_ctx_obj(struct intel_engine_cs *engine, u32 size)
{
        struct drm_i915_gem_object *obj;
        struct i915_vma *vma;
        int err;

        obj = i915_gem_object_create(&engine->i915->drm, PAGE_ALIGN(size));
        if (IS_ERR(obj))
                return PTR_ERR(obj);

        vma = i915_vma_create(obj, &engine->i915->ggtt.base, NULL);
        if (IS_ERR(vma)) {
                err = PTR_ERR(vma);
                goto err;
        }

        err = i915_vma_pin(vma, 0, PAGE_SIZE, PIN_GLOBAL | PIN_HIGH);
        if (err)
                goto err;

        engine->wa_ctx.vma = vma;
        return 0;

err:
        i915_gem_object_put(obj);
        return err;
}

static void lrc_destroy_wa_ctx_obj(struct intel_engine_cs *engine)
{
        i915_vma_unpin_and_release(&engine->wa_ctx.vma);
}

static int intel_init_workaround_bb(struct intel_engine_cs *engine)
{
        struct i915_ctx_workarounds *wa_ctx = &engine->wa_ctx;
        uint32_t *batch;
        uint32_t offset;
        struct page *page;
        int ret;

        WARN_ON(engine->id != RCS);

        /* update this when WA for higher Gen are added */
        if (INTEL_GEN(engine->i915) > 9) {
                DRM_ERROR("WA batch buffer is not initialized for Gen%d\n",
                          INTEL_GEN(engine->i915));
                return 0;
        }

        /* some WA perform writes to scratch page, ensure it is valid */
        if (!engine->scratch) {
                DRM_ERROR("scratch page not allocated for %s\n", engine->name);
                return -EINVAL;
        }

        ret = lrc_setup_wa_ctx_obj(engine, PAGE_SIZE);
        if (ret) {
                DRM_DEBUG_DRIVER("Failed to setup context WA page: %d\n", ret);
                return ret;
        }

        page = i915_gem_object_get_dirty_page(wa_ctx->vma->obj, 0);
        batch = kmap_atomic(page);
        offset = 0;

        if (IS_GEN8(engine->i915)) {
                ret = gen8_init_indirectctx_bb(engine,
                                               &wa_ctx->indirect_ctx,
                                               batch,
                                               &offset);
                if (ret)
                        goto out;

                ret = gen8_init_perctx_bb(engine,
                                          &wa_ctx->per_ctx,
                                          batch,
                                          &offset);
                if (ret)
                        goto out;
        } else if (IS_GEN9(engine->i915)) {
                ret = gen9_init_indirectctx_bb(engine,
                                               &wa_ctx->indirect_ctx,
                                               batch,
                                               &offset);
                if (ret)
                        goto out;

                ret = gen9_init_perctx_bb(engine,
                                          &wa_ctx->per_ctx,
                                          batch,
                                          &offset);
                if (ret)
                        goto out;
        }

out:
        kunmap_atomic(batch);
        if (ret)
                lrc_destroy_wa_ctx_obj(engine);

        return ret;
}

static void lrc_init_hws(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        I915_WRITE(RING_HWS_PGA(engine->mmio_base),
                   engine->status_page.ggtt_offset);
        POSTING_READ(RING_HWS_PGA(engine->mmio_base));
}

static int gen8_init_common_ring(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;
        int ret;

        ret = intel_mocs_init_engine(engine);
        if (ret)
                return ret;

        lrc_init_hws(engine);

        intel_engine_reset_irq(engine);

        I915_WRITE(RING_HWSTAM(engine->mmio_base), 0xffffffff);

        I915_WRITE(RING_MODE_GEN7(engine),
                   _MASKED_BIT_DISABLE(GFX_REPLAY_MODE) |
                   _MASKED_BIT_ENABLE(GFX_RUN_LIST_ENABLE));

        DRM_DEBUG_DRIVER("Execlists enabled for %s\n", engine->name);

        intel_engine_init_hangcheck(engine);

        if (!execlists_elsp_idle(engine))
                execlists_submit_ports(engine);

        return 0;
}

static int gen8_init_render_ring(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;
        int ret;

        ret = gen8_init_common_ring(engine);
        if (ret)
                return ret;

        /* We need to disable the AsyncFlip performance optimisations in order
         * to use MI_WAIT_FOR_EVENT within the CS. It should already be
         * programmed to '1' on all products.
         *
         * WaDisableAsyncFlipPerfMode:snb,ivb,hsw,vlv,bdw,chv
         */
        I915_WRITE(MI_MODE, _MASKED_BIT_ENABLE(ASYNC_FLIP_PERF_DISABLE));

        I915_WRITE(INSTPM, _MASKED_BIT_ENABLE(INSTPM_FORCE_ORDERING));

        return init_workarounds_ring(engine);
}

static int gen9_init_render_ring(struct intel_engine_cs *engine)
{
        int ret;

        ret = gen8_init_common_ring(engine);
        if (ret)
                return ret;

        return init_workarounds_ring(engine);
}

static void reset_common_ring(struct intel_engine_cs *engine,
                              struct drm_i915_gem_request *request)
{
        struct drm_i915_private *dev_priv = engine->i915;
        struct execlist_port *port = engine->execlist_port;
        struct intel_context *ce = &request->ctx->engine[engine->id];

        /* Move the RING_HEAD onto the breadcrumb, past the hanging batch */
        ce->lrc_reg_state[CTX_RING_HEAD+1] = request->postfix;
        request->ring->head = request->postfix;
        request->ring->last_retired_head = -1;
        intel_ring_update_space(request->ring);

        if (i915.enable_guc_submission)
                return;

        /* Catch up with any missed context-switch interrupts */
        I915_WRITE(RING_CONTEXT_STATUS_PTR(engine), _MASKED_FIELD(0xffff, 0));
        if (request->ctx != port[0].request->ctx) {
                i915_gem_request_put(port[0].request);
                port[0] = port[1];
                memset(&port[1], 0, sizeof(port[1]));
        }

        /* CS is stopped, and we will resubmit both ports on resume */
        GEM_BUG_ON(request->ctx != port[0].request->ctx);
        port[0].count = 0;
        port[1].count = 0;
}

static int intel_logical_ring_emit_pdps(struct drm_i915_gem_request *req)
{
        struct i915_hw_ppgtt *ppgtt = req->ctx->ppgtt;
        struct intel_ring *ring = req->ring;
        struct intel_engine_cs *engine = req->engine;
        const int num_lri_cmds = GEN8_LEGACY_PDPES * 2;
        int i, ret;

        ret = intel_ring_begin(req, num_lri_cmds * 2 + 2);
        if (ret)
                return ret;

        intel_ring_emit(ring, MI_LOAD_REGISTER_IMM(num_lri_cmds));
        for (i = GEN8_LEGACY_PDPES - 1; i >= 0; i--) {
                const dma_addr_t pd_daddr = i915_page_dir_dma_addr(ppgtt, i);

                intel_ring_emit_reg(ring, GEN8_RING_PDP_UDW(engine, i));
                intel_ring_emit(ring, upper_32_bits(pd_daddr));
                intel_ring_emit_reg(ring, GEN8_RING_PDP_LDW(engine, i));
                intel_ring_emit(ring, lower_32_bits(pd_daddr));
        }

        intel_ring_emit(ring, MI_NOOP);
        intel_ring_advance(ring);

        return 0;
}

static int gen8_emit_bb_start(struct drm_i915_gem_request *req,
                              u64 offset, u32 len,
                              unsigned int dispatch_flags)
{
        struct intel_ring *ring = req->ring;
        bool ppgtt = !(dispatch_flags & I915_DISPATCH_SECURE);
        int ret;

        /* Don't rely in hw updating PDPs, specially in lite-restore.
         * Ideally, we should set Force PD Restore in ctx descriptor,
         * but we can't. Force Restore would be a second option, but
         * it is unsafe in case of lite-restore (because the ctx is
         * not idle). PML4 is allocated during ppgtt init so this is
         * not needed in 48-bit.*/
        if (req->ctx->ppgtt &&
            (intel_engine_flag(req->engine) & req->ctx->ppgtt->pd_dirty_rings)) {
                if (!USES_FULL_48BIT_PPGTT(req->i915) &&
                    !intel_vgpu_active(req->i915)) {
                        ret = intel_logical_ring_emit_pdps(req);
                        if (ret)
                                return ret;
                }

                req->ctx->ppgtt->pd_dirty_rings &= ~intel_engine_flag(req->engine);
        }

        ret = intel_ring_begin(req, 4);
        if (ret)
                return ret;

        /* FIXME(BDW): Address space and security selectors. */
        intel_ring_emit(ring, MI_BATCH_BUFFER_START_GEN8 |
                        (ppgtt<<8) |
                        (dispatch_flags & I915_DISPATCH_RS ?
                         MI_BATCH_RESOURCE_STREAMER : 0));
        intel_ring_emit(ring, lower_32_bits(offset));
        intel_ring_emit(ring, upper_32_bits(offset));
        intel_ring_emit(ring, MI_NOOP);
        intel_ring_advance(ring);

        return 0;
}

static void gen8_logical_ring_enable_irq(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;
        I915_WRITE_IMR(engine,
                       ~(engine->irq_enable_mask | engine->irq_keep_mask));
        POSTING_READ_FW(RING_IMR(engine->mmio_base));
}

static void gen8_logical_ring_disable_irq(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;
        I915_WRITE_IMR(engine, ~engine->irq_keep_mask);
}

static int gen8_emit_flush(struct drm_i915_gem_request *request, u32 mode)
{
        struct intel_ring *ring = request->ring;
        u32 cmd;
        int ret;

        ret = intel_ring_begin(request, 4);
        if (ret)
                return ret;

        cmd = MI_FLUSH_DW + 1;

        /* We always require a command barrier so that subsequent
         * commands, such as breadcrumb interrupts, are strictly ordered
         * wrt the contents of the write cache being flushed to memory
         * (and thus being coherent from the CPU).
         */
        cmd |= MI_FLUSH_DW_STORE_INDEX | MI_FLUSH_DW_OP_STOREDW;

        if (mode & EMIT_INVALIDATE) {
                cmd |= MI_INVALIDATE_TLB;
                if (request->engine->id == VCS)
                        cmd |= MI_INVALIDATE_BSD;
        }

        intel_ring_emit(ring, cmd);
        intel_ring_emit(ring,
                        I915_GEM_HWS_SCRATCH_ADDR |
                        MI_FLUSH_DW_USE_GTT);
        intel_ring_emit(ring, 0); /* upper addr */
        intel_ring_emit(ring, 0); /* value */
        intel_ring_advance(ring);

        return 0;
}

static int gen8_emit_flush_render(struct drm_i915_gem_request *request,
                                  u32 mode)
{
        struct intel_ring *ring = request->ring;
        struct intel_engine_cs *engine = request->engine;
        u32 scratch_addr =
                i915_ggtt_offset(engine->scratch) + 2 * CACHELINE_BYTES;
        bool vf_flush_wa = false, dc_flush_wa = false;
        u32 flags = 0;
        int ret;
        int len;

        flags |= PIPE_CONTROL_CS_STALL;

        if (mode & EMIT_FLUSH) {
                flags |= PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH;
                flags |= PIPE_CONTROL_DEPTH_CACHE_FLUSH;
                flags |= PIPE_CONTROL_DC_FLUSH_ENABLE;
                flags |= PIPE_CONTROL_FLUSH_ENABLE;
        }

        if (mode & EMIT_INVALIDATE) {
                flags |= PIPE_CONTROL_TLB_INVALIDATE;
                flags |= PIPE_CONTROL_INSTRUCTION_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_TEXTURE_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_VF_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_CONST_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_STATE_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_QW_WRITE;
                flags |= PIPE_CONTROL_GLOBAL_GTT_IVB;

                /*
                 * On GEN9: before VF_CACHE_INVALIDATE we need to emit a NULL
                 * pipe control.
                 */
                if (IS_GEN9(request->i915))
                        vf_flush_wa = true;

                /* WaForGAMHang:kbl */
                if (IS_KBL_REVID(request->i915, 0, KBL_REVID_B0))
                        dc_flush_wa = true;
        }

        len = 6;

        if (vf_flush_wa)
                len += 6;

        if (dc_flush_wa)
                len += 12;

        ret = intel_ring_begin(request, len);
        if (ret)
                return ret;

        if (vf_flush_wa) {
                intel_ring_emit(ring, GFX_OP_PIPE_CONTROL(6));
                intel_ring_emit(ring, 0);
                intel_ring_emit(ring, 0);
                intel_ring_emit(ring, 0);
                intel_ring_emit(ring, 0);
                intel_ring_emit(ring, 0);
        }

        if (dc_flush_wa) {
                intel_ring_emit(ring, GFX_OP_PIPE_CONTROL(6));
                intel_ring_emit(ring, PIPE_CONTROL_DC_FLUSH_ENABLE);
                intel_ring_emit(ring, 0);
                intel_ring_emit(ring, 0);
                intel_ring_emit(ring, 0);
                intel_ring_emit(ring, 0);
        }

        intel_ring_emit(ring, GFX_OP_PIPE_CONTROL(6));
        intel_ring_emit(ring, flags);
        intel_ring_emit(ring, scratch_addr);
        intel_ring_emit(ring, 0);
        intel_ring_emit(ring, 0);
        intel_ring_emit(ring, 0);

        if (dc_flush_wa) {
                intel_ring_emit(ring, GFX_OP_PIPE_CONTROL(6));
                intel_ring_emit(ring, PIPE_CONTROL_CS_STALL);
                intel_ring_emit(ring, 0);
                intel_ring_emit(ring, 0);
                intel_ring_emit(ring, 0);
                intel_ring_emit(ring, 0);
        }

        intel_ring_advance(ring);

        return 0;
}

static void bxt_a_seqno_barrier(struct intel_engine_cs *engine)
{
        /*
         * On BXT A steppings there is a HW coherency issue whereby the
         * MI_STORE_DATA_IMM storing the completed request's seqno
         * occasionally doesn't invalidate the CPU cache. Work around this by
         * clflushing the corresponding cacheline whenever the caller wants
         * the coherency to be guaranteed. Note that this cacheline is known
         * to be clean at this point, since we only write it in
         * bxt_a_set_seqno(), where we also do a clflush after the write. So
         * this clflush in practice becomes an invalidate operation.
         */
        intel_flush_status_page(engine, I915_GEM_HWS_INDEX);
}

/*
 * Reserve space for 2 NOOPs at the end of each request to be
 * used as a workaround for not being allowed to do lite
 * restore with HEAD==TAIL (WaIdleLiteRestore).
 */
#define WA_TAIL_DWORDS 2

static int gen8_emit_request(struct drm_i915_gem_request *request)
{
        struct intel_ring *ring = request->ring;
        int ret;

        ret = intel_ring_begin(request, 6 + WA_TAIL_DWORDS);
        if (ret)
                return ret;

        /* w/a: bit 5 needs to be zero for MI_FLUSH_DW address. */
        BUILD_BUG_ON(I915_GEM_HWS_INDEX_ADDR & (1 << 5));

        intel_ring_emit(ring, (MI_FLUSH_DW + 1) | MI_FLUSH_DW_OP_STOREDW);
        intel_ring_emit(ring,
                        intel_hws_seqno_address(request->engine) |
                        MI_FLUSH_DW_USE_GTT);
        intel_ring_emit(ring, 0);
        intel_ring_emit(ring, request->fence.seqno);
        intel_ring_emit(ring, MI_USER_INTERRUPT);
        intel_ring_emit(ring, MI_NOOP);
        return intel_logical_ring_advance(request);
}

static int gen8_emit_request_render(struct drm_i915_gem_request *request)
{
        struct intel_ring *ring = request->ring;
        int ret;

        ret = intel_ring_begin(request, 8 + WA_TAIL_DWORDS);
        if (ret)
                return ret;

        /* We're using qword write, seqno should be aligned to 8 bytes. */
        BUILD_BUG_ON(I915_GEM_HWS_INDEX & 1);

        /* w/a for post sync ops following a GPGPU operation we
         * need a prior CS_STALL, which is emitted by the flush
         * following the batch.
         */
        intel_ring_emit(ring, GFX_OP_PIPE_CONTROL(6));
        intel_ring_emit(ring,
                        (PIPE_CONTROL_GLOBAL_GTT_IVB |
                         PIPE_CONTROL_CS_STALL |
                         PIPE_CONTROL_QW_WRITE));
        intel_ring_emit(ring, intel_hws_seqno_address(request->engine));
        intel_ring_emit(ring, 0);
        intel_ring_emit(ring, i915_gem_request_get_seqno(request));
        /* We're thrashing one dword of HWS. */
        intel_ring_emit(ring, 0);
        intel_ring_emit(ring, MI_USER_INTERRUPT);
        intel_ring_emit(ring, MI_NOOP);
        return intel_logical_ring_advance(request);
}

static int gen8_init_rcs_context(struct drm_i915_gem_request *req)
{
        int ret;

        ret = intel_logical_ring_workarounds_emit(req);
        if (ret)
                return ret;

        ret = intel_rcs_context_init_mocs(req);
        /*
         * Failing to program the MOCS is non-fatal.The system will not
         * run at peak performance. So generate an error and carry on.
         */
        if (ret)
                DRM_ERROR("MOCS failed to program: expect performance issues.\n");

        return i915_gem_render_state_init(req);
}

/**
 * intel_logical_ring_cleanup() - deallocate the Engine Command Streamer
 * @engine: Engine Command Streamer.
 */
void intel_logical_ring_cleanup(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv;

        if (!intel_engine_initialized(engine))
                return;

        /*
         * Tasklet cannot be active at this point due intel_mark_active/idle
         * so this is just for documentation.
         */
        if (WARN_ON(test_bit(TASKLET_STATE_SCHED, &engine->irq_tasklet.state)))
                tasklet_kill(&engine->irq_tasklet);

        dev_priv = engine->i915;

        if (engine->buffer) {
                WARN_ON((I915_READ_MODE(engine) & MODE_IDLE) == 0);
        }

        if (engine->cleanup)
                engine->cleanup(engine);

        intel_engine_cleanup_common(engine);

        if (engine->status_page.vma) {
                i915_gem_object_unpin_map(engine->status_page.vma->obj);
                engine->status_page.vma = NULL;
        }
        intel_lr_context_unpin(dev_priv->kernel_context, engine);

        lrc_destroy_wa_ctx_obj(engine);
        engine->i915 = NULL;
}

void intel_execlists_enable_submission(struct drm_i915_private *dev_priv)
{
        struct intel_engine_cs *engine;

        for_each_engine(engine, dev_priv)
                engine->submit_request = execlists_submit_request;
}

static void
logical_ring_default_vfuncs(struct intel_engine_cs *engine)
{
        /* Default vfuncs which can be overriden by each engine. */
        engine->init_hw = gen8_init_common_ring;
        engine->reset_hw = reset_common_ring;
        engine->emit_flush = gen8_emit_flush;
        engine->emit_request = gen8_emit_request;
        engine->submit_request = execlists_submit_request;

        engine->irq_enable = gen8_logical_ring_enable_irq;
        engine->irq_disable = gen8_logical_ring_disable_irq;
        engine->emit_bb_start = gen8_emit_bb_start;
        if (IS_BXT_REVID(engine->i915, 0, BXT_REVID_A1))
                engine->irq_seqno_barrier = bxt_a_seqno_barrier;
}

static inline void
logical_ring_default_irqs(struct intel_engine_cs *engine)
{
        unsigned shift = engine->irq_shift;
        engine->irq_enable_mask = GT_RENDER_USER_INTERRUPT << shift;
        engine->irq_keep_mask = GT_CONTEXT_SWITCH_INTERRUPT << shift;
}

static int
lrc_setup_hws(struct intel_engine_cs *engine, struct i915_vma *vma)
{
        const int hws_offset = LRC_PPHWSP_PN * PAGE_SIZE;
        void *hws;

        /* The HWSP is part of the default context object in LRC mode. */
        hws = i915_gem_object_pin_map(vma->obj, I915_MAP_WB);
        if (IS_ERR(hws))
                return PTR_ERR(hws);

        engine->status_page.page_addr = hws + hws_offset;
        engine->status_page.ggtt_offset = i915_ggtt_offset(vma) + hws_offset;
        engine->status_page.vma = vma;

        return 0;
}

static void
logical_ring_setup(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;
        enum forcewake_domains fw_domains;

        intel_engine_setup_common(engine);

        /* Intentionally left blank. */
        engine->buffer = NULL;

        fw_domains = intel_uncore_forcewake_for_reg(dev_priv,
                                                    RING_ELSP(engine),
                                                    FW_REG_WRITE);

        fw_domains |= intel_uncore_forcewake_for_reg(dev_priv,
                                                     RING_CONTEXT_STATUS_PTR(engine),
                                                     FW_REG_READ | FW_REG_WRITE);

        fw_domains |= intel_uncore_forcewake_for_reg(dev_priv,
                                                     RING_CONTEXT_STATUS_BUF_BASE(engine),
                                                     FW_REG_READ);

        engine->fw_domains = fw_domains;

        tasklet_init(&engine->irq_tasklet,
                     intel_lrc_irq_handler, (unsigned long)engine);

        logical_ring_init_platform_invariants(engine);
        logical_ring_default_vfuncs(engine);
        logical_ring_default_irqs(engine);
}

static int
logical_ring_init(struct intel_engine_cs *engine)
{
        struct i915_gem_context *dctx = engine->i915->kernel_context;
        int ret;

        ret = intel_engine_init_common(engine);
        if (ret)
                goto error;

        ret = execlists_context_deferred_alloc(dctx, engine);
        if (ret)
                goto error;

        /* As this is the default context, always pin it */
        ret = intel_lr_context_pin(dctx, engine);
        if (ret) {
                DRM_ERROR("Failed to pin context for %s: %d\n",
                          engine->name, ret);
                goto error;
        }

        /* And setup the hardware status page. */
        ret = lrc_setup_hws(engine, dctx->engine[engine->id].state);
        if (ret) {
                DRM_ERROR("Failed to set up hws %s: %d\n", engine->name, ret);
                goto error;
        }

        return 0;

error:
        intel_logical_ring_cleanup(engine);
        return ret;
}

int logical_render_ring_init(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;
        int ret;

        logical_ring_setup(engine);

        if (HAS_L3_DPF(dev_priv))
                engine->irq_keep_mask |= GT_RENDER_L3_PARITY_ERROR_INTERRUPT;

        /* Override some for render ring. */
        if (INTEL_GEN(dev_priv) >= 9)
                engine->init_hw = gen9_init_render_ring;
        else
                engine->init_hw = gen8_init_render_ring;
        engine->init_context = gen8_init_rcs_context;
        engine->emit_flush = gen8_emit_flush_render;
        engine->emit_request = gen8_emit_request_render;

        ret = intel_engine_create_scratch(engine, 4096);
        if (ret)
                return ret;

        ret = intel_init_workaround_bb(engine);
        if (ret) {
                /*
                 * We continue even if we fail to initialize WA batch
                 * because we only expect rare glitches but nothing
                 * critical to prevent us from using GPU
                 */
                DRM_ERROR("WA batch buffer initialization failed: %d\n",
                          ret);
        }

        ret = logical_ring_init(engine);
        if (ret) {
                lrc_destroy_wa_ctx_obj(engine);
        }

        return ret;
}

int logical_xcs_ring_init(struct intel_engine_cs *engine)
{
        logical_ring_setup(engine);

        return logical_ring_init(engine);
}

static u32
make_rpcs(struct drm_i915_private *dev_priv)
{
        u32 rpcs = 0;

        /*
         * No explicit RPCS request is needed to ensure full
         * slice/subslice/EU enablement prior to Gen9.
        */
        if (INTEL_GEN(dev_priv) < 9)
                return 0;

        /*
         * Starting in Gen9, render power gating can leave
         * slice/subslice/EU in a partially enabled state. We
         * must make an explicit request through RPCS for full
         * enablement.
        */
        if (INTEL_INFO(dev_priv)->sseu.has_slice_pg) {
                rpcs |= GEN8_RPCS_S_CNT_ENABLE;
                rpcs |= hweight8(INTEL_INFO(dev_priv)->sseu.slice_mask) <<
                        GEN8_RPCS_S_CNT_SHIFT;
                rpcs |= GEN8_RPCS_ENABLE;
        }

        if (INTEL_INFO(dev_priv)->sseu.has_subslice_pg) {
                rpcs |= GEN8_RPCS_SS_CNT_ENABLE;
                rpcs |= hweight8(INTEL_INFO(dev_priv)->sseu.subslice_mask) <<
                        GEN8_RPCS_SS_CNT_SHIFT;
                rpcs |= GEN8_RPCS_ENABLE;
        }

        if (INTEL_INFO(dev_priv)->sseu.has_eu_pg) {
                rpcs |= INTEL_INFO(dev_priv)->sseu.eu_per_subslice <<
                        GEN8_RPCS_EU_MIN_SHIFT;
                rpcs |= INTEL_INFO(dev_priv)->sseu.eu_per_subslice <<
                        GEN8_RPCS_EU_MAX_SHIFT;
                rpcs |= GEN8_RPCS_ENABLE;
        }

        return rpcs;
}

static u32 intel_lr_indirect_ctx_offset(struct intel_engine_cs *engine)
{
        u32 indirect_ctx_offset;

        switch (INTEL_GEN(engine->i915)) {
        default:
                MISSING_CASE(INTEL_GEN(engine->i915));
                /* fall through */
        case 9:
                indirect_ctx_offset =
                        GEN9_CTX_RCS_INDIRECT_CTX_OFFSET_DEFAULT;
                break;
        case 8:
                indirect_ctx_offset =
                        GEN8_CTX_RCS_INDIRECT_CTX_OFFSET_DEFAULT;
                break;
        }

        return indirect_ctx_offset;
}

static int
populate_lr_context(struct i915_gem_context *ctx,
                    struct drm_i915_gem_object *ctx_obj,
                    struct intel_engine_cs *engine,
                    struct intel_ring *ring)
{
        struct drm_i915_private *dev_priv = ctx->i915;
        struct i915_hw_ppgtt *ppgtt = ctx->ppgtt;
        void *vaddr;
        u32 *reg_state;
        int ret;

        if (!ppgtt)
                ppgtt = dev_priv->mm.aliasing_ppgtt;

        ret = i915_gem_object_set_to_cpu_domain(ctx_obj, true);
        if (ret) {
                DRM_DEBUG_DRIVER("Could not set to CPU domain\n");
                return ret;
        }

        vaddr = i915_gem_object_pin_map(ctx_obj, I915_MAP_WB);
        if (IS_ERR(vaddr)) {
                ret = PTR_ERR(vaddr);
                DRM_DEBUG_DRIVER("Could not map object pages! (%d)\n", ret);
                return ret;
        }
        ctx_obj->dirty = true;

        /* The second page of the context object contains some fields which must
         * be set up prior to the first execution. */
        reg_state = vaddr + LRC_STATE_PN * PAGE_SIZE;

        /* A context is actually a big batch buffer with several MI_LOAD_REGISTER_IMM
         * commands followed by (reg, value) pairs. The values we are setting here are
         * only for the first context restore: on a subsequent save, the GPU will
         * recreate this batchbuffer with new values (including all the missing
         * MI_LOAD_REGISTER_IMM commands that we are not initializing here). */
        reg_state[CTX_LRI_HEADER_0] =
                MI_LOAD_REGISTER_IMM(engine->id == RCS ? 14 : 11) | MI_LRI_FORCE_POSTED;
        ASSIGN_CTX_REG(reg_state, CTX_CONTEXT_CONTROL,
                       RING_CONTEXT_CONTROL(engine),
                       _MASKED_BIT_ENABLE(CTX_CTRL_INHIBIT_SYN_CTX_SWITCH |
                                          CTX_CTRL_ENGINE_CTX_RESTORE_INHIBIT |
                                          (HAS_RESOURCE_STREAMER(dev_priv) ?
                                            CTX_CTRL_RS_CTX_ENABLE : 0)));
        ASSIGN_CTX_REG(reg_state, CTX_RING_HEAD, RING_HEAD(engine->mmio_base),
                       0);
        ASSIGN_CTX_REG(reg_state, CTX_RING_TAIL, RING_TAIL(engine->mmio_base),
                       0);
        /* Ring buffer start address is not known until the buffer is pinned.
         * It is written to the context image in execlists_update_context()
         */
        ASSIGN_CTX_REG(reg_state, CTX_RING_BUFFER_START,
                       RING_START(engine->mmio_base), 0);
        ASSIGN_CTX_REG(reg_state, CTX_RING_BUFFER_CONTROL,
                       RING_CTL(engine->mmio_base),
                       ((ring->size - PAGE_SIZE) & RING_NR_PAGES) | RING_VALID);
        ASSIGN_CTX_REG(reg_state, CTX_BB_HEAD_U,
                       RING_BBADDR_UDW(engine->mmio_base), 0);
        ASSIGN_CTX_REG(reg_state, CTX_BB_HEAD_L,
                       RING_BBADDR(engine->mmio_base), 0);
        ASSIGN_CTX_REG(reg_state, CTX_BB_STATE,
                       RING_BBSTATE(engine->mmio_base),
                       RING_BB_PPGTT);
        ASSIGN_CTX_REG(reg_state, CTX_SECOND_BB_HEAD_U,
                       RING_SBBADDR_UDW(engine->mmio_base), 0);
        ASSIGN_CTX_REG(reg_state, CTX_SECOND_BB_HEAD_L,
                       RING_SBBADDR(engine->mmio_base), 0);
        ASSIGN_CTX_REG(reg_state, CTX_SECOND_BB_STATE,
                       RING_SBBSTATE(engine->mmio_base), 0);
        if (engine->id == RCS) {
                ASSIGN_CTX_REG(reg_state, CTX_BB_PER_CTX_PTR,
                               RING_BB_PER_CTX_PTR(engine->mmio_base), 0);
                ASSIGN_CTX_REG(reg_state, CTX_RCS_INDIRECT_CTX,
                               RING_INDIRECT_CTX(engine->mmio_base), 0);
                ASSIGN_CTX_REG(reg_state, CTX_RCS_INDIRECT_CTX_OFFSET,
                               RING_INDIRECT_CTX_OFFSET(engine->mmio_base), 0);
                if (engine->wa_ctx.vma) {
                        struct i915_ctx_workarounds *wa_ctx = &engine->wa_ctx;
                        u32 ggtt_offset = i915_ggtt_offset(wa_ctx->vma);

                        reg_state[CTX_RCS_INDIRECT_CTX+1] =
                                (ggtt_offset + wa_ctx->indirect_ctx.offset * sizeof(uint32_t)) |
                                (wa_ctx->indirect_ctx.size / CACHELINE_DWORDS);

                        reg_state[CTX_RCS_INDIRECT_CTX_OFFSET+1] =
                                intel_lr_indirect_ctx_offset(engine) << 6;

                        reg_state[CTX_BB_PER_CTX_PTR+1] =
                                (ggtt_offset + wa_ctx->per_ctx.offset * sizeof(uint32_t)) |
                                0x01;
                }
        }
        reg_state[CTX_LRI_HEADER_1] = MI_LOAD_REGISTER_IMM(9) | MI_LRI_FORCE_POSTED;
        ASSIGN_CTX_REG(reg_state, CTX_CTX_TIMESTAMP,
                       RING_CTX_TIMESTAMP(engine->mmio_base), 0);
        /* PDP values well be assigned later if needed */
        ASSIGN_CTX_REG(reg_state, CTX_PDP3_UDW, GEN8_RING_PDP_UDW(engine, 3),
                       0);
        ASSIGN_CTX_REG(reg_state, CTX_PDP3_LDW, GEN8_RING_PDP_LDW(engine, 3),
                       0);
        ASSIGN_CTX_REG(reg_state, CTX_PDP2_UDW, GEN8_RING_PDP_UDW(engine, 2),
                       0);
        ASSIGN_CTX_REG(reg_state, CTX_PDP2_LDW, GEN8_RING_PDP_LDW(engine, 2),
                       0);
        ASSIGN_CTX_REG(reg_state, CTX_PDP1_UDW, GEN8_RING_PDP_UDW(engine, 1),
                       0);
        ASSIGN_CTX_REG(reg_state, CTX_PDP1_LDW, GEN8_RING_PDP_LDW(engine, 1),
                       0);
        ASSIGN_CTX_REG(reg_state, CTX_PDP0_UDW, GEN8_RING_PDP_UDW(engine, 0),
                       0);
        ASSIGN_CTX_REG(reg_state, CTX_PDP0_LDW, GEN8_RING_PDP_LDW(engine, 0),
                       0);

        if (USES_FULL_48BIT_PPGTT(ppgtt->base.dev)) {
                /* 64b PPGTT (48bit canonical)
                 * PDP0_DESCRIPTOR contains the base address to PML4 and
                 * other PDP Descriptors are ignored.
                 */
                ASSIGN_CTX_PML4(ppgtt, reg_state);
        } else {
                /* 32b PPGTT
                 * PDP*_DESCRIPTOR contains the base address of space supported.
                 * With dynamic page allocation, PDPs may not be allocated at
                 * this point. Point the unallocated PDPs to the scratch page
                 */
                execlists_update_context_pdps(ppgtt, reg_state);
        }

        if (engine->id == RCS) {
                reg_state[CTX_LRI_HEADER_2] = MI_LOAD_REGISTER_IMM(1);
                ASSIGN_CTX_REG(reg_state, CTX_R_PWR_CLK_STATE, GEN8_R_PWR_CLK_STATE,
                               make_rpcs(dev_priv));
        }

        i915_gem_object_unpin_map(ctx_obj);

        return 0;
}

/**
 * intel_lr_context_size() - return the size of the context for an engine
 * @engine: which engine to find the context size for
 *
 * Each engine may require a different amount of space for a context image,
 * so when allocating (or copying) an image, this function can be used to
 * find the right size for the specific engine.
 *
 * Return: size (in bytes) of an engine-specific context image
 *
 * Note: this size includes the HWSP, which is part of the context image
 * in LRC mode, but does not include the "shared data page" used with
 * GuC submission. The caller should account for this if using the GuC.
 */
uint32_t intel_lr_context_size(struct intel_engine_cs *engine)
{
        int ret = 0;

        WARN_ON(INTEL_GEN(engine->i915) < 8);

        switch (engine->id) {
        case RCS:
                if (INTEL_GEN(engine->i915) >= 9)
                        ret = GEN9_LR_CONTEXT_RENDER_SIZE;
                else
                        ret = GEN8_LR_CONTEXT_RENDER_SIZE;
                break;
        case VCS:
        case BCS:
        case VECS:
        case VCS2:
                ret = GEN8_LR_CONTEXT_OTHER_SIZE;
                break;
        }

        return ret;
}

static int execlists_context_deferred_alloc(struct i915_gem_context *ctx,
                                            struct intel_engine_cs *engine)
{
        struct drm_i915_gem_object *ctx_obj;
        struct intel_context *ce = &ctx->engine[engine->id];
        struct i915_vma *vma;
        uint32_t context_size;
        struct intel_ring *ring;
        int ret;

        WARN_ON(ce->state);

        context_size = round_up(intel_lr_context_size(engine), 4096);

        /* One extra page as the sharing data between driver and GuC */
        context_size += PAGE_SIZE * LRC_PPHWSP_PN;

        ctx_obj = i915_gem_object_create(&ctx->i915->drm, context_size);
        if (IS_ERR(ctx_obj)) {
                DRM_DEBUG_DRIVER("Alloc LRC backing obj failed.\n");
                return PTR_ERR(ctx_obj);
        }

        vma = i915_vma_create(ctx_obj, &ctx->i915->ggtt.base, NULL);
        if (IS_ERR(vma)) {
                ret = PTR_ERR(vma);
                goto error_deref_obj;
        }

        ring = intel_engine_create_ring(engine, ctx->ring_size);
        if (IS_ERR(ring)) {
                ret = PTR_ERR(ring);
                goto error_deref_obj;
        }

        ret = populate_lr_context(ctx, ctx_obj, engine, ring);
        if (ret) {
                DRM_DEBUG_DRIVER("Failed to populate LRC: %d\n", ret);
                goto error_ring_free;
        }

        ce->ring = ring;
        ce->state = vma;
        ce->initialised = engine->init_context == NULL;

        return 0;

error_ring_free:
        intel_ring_free(ring);
error_deref_obj:
        i915_gem_object_put(ctx_obj);
        return ret;
}

void intel_lr_context_resume(struct drm_i915_private *dev_priv)
{
        struct i915_gem_context *ctx = dev_priv->kernel_context;
        struct intel_engine_cs *engine;

        for_each_engine(engine, dev_priv) {
                struct intel_context *ce = &ctx->engine[engine->id];
                void *vaddr;
                uint32_t *reg_state;

                if (!ce->state)
                        continue;

                vaddr = i915_gem_object_pin_map(ce->state->obj, I915_MAP_WB);
                if (WARN_ON(IS_ERR(vaddr)))
                        continue;

                reg_state = vaddr + LRC_STATE_PN * PAGE_SIZE;

                reg_state[CTX_RING_HEAD+1] = 0;
                reg_state[CTX_RING_TAIL+1] = 0;

                ce->state->obj->dirty = true;
                i915_gem_object_unpin_map(ce->state->obj);

                ce->ring->head = 0;
                ce->ring->tail = 0;
        }
}