arch/arm/kvm/mmio.c

   1 /*
   2  * Copyright (C) 2012 - Virtual Open Systems and Columbia University
   3  * Author: Christoffer Dall <c.dall@virtualopensystems.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License, version 2, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  17  */
  18
  19 #include <linux/kvm_host.h>
  20 #include <asm/kvm_mmio.h>
  21 #include <asm/kvm_emulate.h>
  22 #include <trace/events/kvm.h>
  23
  24 #include "trace.h"
  25
  26 /**
  27  * kvm_handle_mmio_return -- Handle MMIO loads after user space emulation
  28  * @vcpu: The VCPU pointer
  29  * @run:  The VCPU run struct containing the mmio data
  30  *
  31  * This should only be called after returning from userspace for MMIO load
  32  * emulation.
  33  */
  34 int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run)
  35 {
  36         unsigned long *dest;
  37         unsigned int len;
  38         int mask;
  39
  40         if (!run->mmio.is_write) {
  41                 dest = vcpu_reg(vcpu, vcpu->arch.mmio_decode.rt);
  42                 *dest = 0;
  43
  44                 len = run->mmio.len;
  45                 if (len > sizeof(unsigned long))
  46                         return -EINVAL;
  47
  48                 memcpy(dest, run->mmio.data, len);
  49
  50                 trace_kvm_mmio(KVM_TRACE_MMIO_READ, len, run->mmio.phys_addr,
  51                                 *((u64 *)run->mmio.data));
  52
  53                 if (vcpu->arch.mmio_decode.sign_extend &&
  54                     len < sizeof(unsigned long)) {
  55                         mask = 1U << ((len * 8) - 1);
  56                         *dest = (*dest ^ mask) - mask;
  57                 }
  58         }
  59
  60         return 0;
  61 }
  62
  63 static int decode_hsr(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
  64                       struct kvm_exit_mmio *mmio)
  65 {
  66         unsigned long rt, len;
  67         bool is_write, sign_extend;
  68
  69         if (kvm_vcpu_dabt_isextabt(vcpu)) {
  70                 /* cache operation on I/O addr, tell guest unsupported */
  71                 kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
  72                 return 1;
  73         }
  74
  75         if (kvm_vcpu_dabt_iss1tw(vcpu)) {
  76                 /* page table accesses IO mem: tell guest to fix its TTBR */
  77                 kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
  78                 return 1;
  79         }
  80
  81         len = kvm_vcpu_dabt_get_as(vcpu);
  82         if (unlikely(len < 0))
  83                 return len;
  84
  85         is_write = kvm_vcpu_dabt_iswrite(vcpu);
  86         sign_extend = kvm_vcpu_dabt_issext(vcpu);
  87         rt = kvm_vcpu_dabt_get_rd(vcpu);
  88
  89         mmio->is_write = is_write;
  90         mmio->phys_addr = fault_ipa;
  91         mmio->len = len;
  92         vcpu->arch.mmio_decode.sign_extend = sign_extend;
  93         vcpu->arch.mmio_decode.rt = rt;
  94
  95         /*
  96          * The MMIO instruction is emulated and should not be re-executed
  97          * in the guest.
  98          */
  99         kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
 100         return 0;
 101 }
 102
 103 int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
 104                  phys_addr_t fault_ipa)
 105 {
 106         struct kvm_exit_mmio mmio;
 107         unsigned long rt;
 108         int ret;
 109
 110         /*
 111          * Prepare MMIO operation. First stash it in a private
 112          * structure that we can use for in-kernel emulation. If the
 113          * kernel can't handle it, copy it into run->mmio and let user
 114          * space do its magic.
 115          */
 116
 117         if (kvm_vcpu_dabt_isvalid(vcpu)) {
 118                 ret = decode_hsr(vcpu, fault_ipa, &mmio);
 119                 if (ret)
 120                         return ret;
 121         } else {
 122                 kvm_err("load/store instruction decoding not implemented\n");
 123                 return -ENOSYS;
 124         }
 125
 126         rt = vcpu->arch.mmio_decode.rt;
 127         trace_kvm_mmio((mmio.is_write) ? KVM_TRACE_MMIO_WRITE :
 128                                          KVM_TRACE_MMIO_READ_UNSATISFIED,
 129                         mmio.len, fault_ipa,
 130                         (mmio.is_write) ? *vcpu_reg(vcpu, rt) : 0);
 131
 132         if (mmio.is_write)
 133                 memcpy(mmio.data, vcpu_reg(vcpu, rt), mmio.len);
 134
 135         if (vgic_handle_mmio(vcpu, run, &mmio))
 136                 return 1;
 137
 138         kvm_prepare_mmio(run, &mmio);
 139         return 0;
 140 }