arch/mips/kvm/dyntrans.c

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * KVM/MIPS: Binary Patching for privileged instructions, reduces traps.
   7  *
   8  * Copyright (C) 2012  MIPS Technologies, Inc.  All rights reserved.
   9  * Authors: Sanjay Lal <sanjayl@kymasys.com>
  10  */
  11
  12 #include <linux/errno.h>
  13 #include <linux/err.h>
  14 #include <linux/kvm_host.h>
  15 #include <linux/module.h>
  16 #include <linux/vmalloc.h>
  17 #include <linux/fs.h>
  18 #include <linux/bootmem.h>
  19 #include <asm/cacheflush.h>
  20
  21 #include "commpage.h"
  22
  23 #define SYNCI_TEMPLATE  0x041f0000
  24 #define SYNCI_BASE(x)   (((x) >> 21) & 0x1f)
  25 #define SYNCI_OFFSET    ((x) & 0xffff)
  26
  27 #define LW_TEMPLATE     0x8c000000
  28 #define CLEAR_TEMPLATE  0x00000020
  29 #define SW_TEMPLATE     0xac000000
  30
  31 int kvm_mips_trans_cache_index(uint32_t inst, uint32_t *opc,
  32                                struct kvm_vcpu *vcpu)
  33 {
  34         int result = 0;
  35         unsigned long kseg0_opc;
  36         uint32_t synci_inst = 0x0;
  37
  38         /* Replace the CACHE instruction, with a NOP */
  39         kseg0_opc =
  40             CKSEG0ADDR(kvm_mips_translate_guest_kseg0_to_hpa
  41                        (vcpu, (unsigned long) opc));
  42         memcpy((void *)kseg0_opc, (void *)&synci_inst, sizeof(uint32_t));
  43         local_flush_icache_range(kseg0_opc, kseg0_opc + 32);
  44
  45         return result;
  46 }
  47
  48 /*
  49  * Address based CACHE instructions are transformed into synci(s). A little
  50  * heavy for just D-cache invalidates, but avoids an expensive trap
  51  */
  52 int kvm_mips_trans_cache_va(uint32_t inst, uint32_t *opc,
  53                             struct kvm_vcpu *vcpu)
  54 {
  55         int result = 0;
  56         unsigned long kseg0_opc;
  57         uint32_t synci_inst = SYNCI_TEMPLATE, base, offset;
  58
  59         base = (inst >> 21) & 0x1f;
  60         offset = inst & 0xffff;
  61         synci_inst |= (base << 21);
  62         synci_inst |= offset;
  63
  64         kseg0_opc =
  65             CKSEG0ADDR(kvm_mips_translate_guest_kseg0_to_hpa
  66                        (vcpu, (unsigned long) opc));
  67         memcpy((void *)kseg0_opc, (void *)&synci_inst, sizeof(uint32_t));
  68         local_flush_icache_range(kseg0_opc, kseg0_opc + 32);
  69
  70         return result;
  71 }
  72
  73 int kvm_mips_trans_mfc0(uint32_t inst, uint32_t *opc, struct kvm_vcpu *vcpu)
  74 {
  75         int32_t rt, rd, sel;
  76         uint32_t mfc0_inst;
  77         unsigned long kseg0_opc, flags;
  78
  79         rt = (inst >> 16) & 0x1f;
  80         rd = (inst >> 11) & 0x1f;
  81         sel = inst & 0x7;
  82
  83         if ((rd == MIPS_CP0_ERRCTL) && (sel == 0)) {
  84                 mfc0_inst = CLEAR_TEMPLATE;
  85                 mfc0_inst |= ((rt & 0x1f) << 16);
  86         } else {
  87                 mfc0_inst = LW_TEMPLATE;
  88                 mfc0_inst |= ((rt & 0x1f) << 16);
  89                 mfc0_inst |= offsetof(struct kvm_mips_commpage,
  90                                       cop0.reg[rd][sel]);
  91         }
  92
  93         if (KVM_GUEST_KSEGX(opc) == KVM_GUEST_KSEG0) {
  94                 kseg0_opc =
  95                     CKSEG0ADDR(kvm_mips_translate_guest_kseg0_to_hpa
  96                                (vcpu, (unsigned long) opc));
  97                 memcpy((void *)kseg0_opc, (void *)&mfc0_inst, sizeof(uint32_t));
  98                 local_flush_icache_range(kseg0_opc, kseg0_opc + 32);
  99         } else if (KVM_GUEST_KSEGX((unsigned long) opc) == KVM_GUEST_KSEG23) {
 100                 local_irq_save(flags);
 101                 memcpy((void *)opc, (void *)&mfc0_inst, sizeof(uint32_t));
 102                 local_flush_icache_range((unsigned long)opc,
 103                                          (unsigned long)opc + 32);
 104                 local_irq_restore(flags);
 105         } else {
 106                 kvm_err("%s: Invalid address: %p\n", __func__, opc);
 107                 return -EFAULT;
 108         }
 109
 110         return 0;
 111 }
 112
 113 int kvm_mips_trans_mtc0(uint32_t inst, uint32_t *opc, struct kvm_vcpu *vcpu)
 114 {
 115         int32_t rt, rd, sel;
 116         uint32_t mtc0_inst = SW_TEMPLATE;
 117         unsigned long kseg0_opc, flags;
 118
 119         rt = (inst >> 16) & 0x1f;
 120         rd = (inst >> 11) & 0x1f;
 121         sel = inst & 0x7;
 122
 123         mtc0_inst |= ((rt & 0x1f) << 16);
 124         mtc0_inst |= offsetof(struct kvm_mips_commpage, cop0.reg[rd][sel]);
 125
 126         if (KVM_GUEST_KSEGX(opc) == KVM_GUEST_KSEG0) {
 127                 kseg0_opc =
 128                     CKSEG0ADDR(kvm_mips_translate_guest_kseg0_to_hpa
 129                                (vcpu, (unsigned long) opc));
 130                 memcpy((void *)kseg0_opc, (void *)&mtc0_inst, sizeof(uint32_t));
 131                 local_flush_icache_range(kseg0_opc, kseg0_opc + 32);
 132         } else if (KVM_GUEST_KSEGX((unsigned long) opc) == KVM_GUEST_KSEG23) {
 133                 local_irq_save(flags);
 134                 memcpy((void *)opc, (void *)&mtc0_inst, sizeof(uint32_t));
 135                 local_flush_icache_range((unsigned long)opc,
 136                                          (unsigned long)opc + 32);
 137                 local_irq_restore(flags);
 138         } else {
 139                 kvm_err("%s: Invalid address: %p\n", __func__, opc);
 140                 return -EFAULT;
 141         }
 142
 143         return 0;
 144 }