virt/kvm/arm/mmio.c

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This source file includes following definitions.
kvm_mmio_write_buf
kvm_mmio_read_buf
kvm_handle_mmio_return
decode_hsr
io_mem_abort
   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2012 - Virtual Open Systems and Columbia University
   4  * Author: Christoffer Dall <c.dall@virtualopensystems.com>
   5  */
   6 
   7 #include <linux/kvm_host.h>
   8 #include <asm/kvm_mmio.h>
   9 #include <asm/kvm_emulate.h>
  10 #include <trace/events/kvm.h>
  11 
  12 #include "trace.h"
  13 
  14 void kvm_mmio_write_buf(void *buf, unsigned int len, unsigned long data)
  15 {
  16         void *datap = NULL;
  17         union {
  18                 u8      byte;
  19                 u16     hword;
  20                 u32     word;
  21                 u64     dword;
  22         } tmp;
  23 
  24         switch (len) {
  25         case 1:
  26                 tmp.byte        = data;
  27                 datap           = &tmp.byte;
  28                 break;
  29         case 2:
  30                 tmp.hword       = data;
  31                 datap           = &tmp.hword;
  32                 break;
  33         case 4:
  34                 tmp.word        = data;
  35                 datap           = &tmp.word;
  36                 break;
  37         case 8:
  38                 tmp.dword       = data;
  39                 datap           = &tmp.dword;
  40                 break;
  41         }
  42 
  43         memcpy(buf, datap, len);
  44 }
  45 
  46 unsigned long kvm_mmio_read_buf(const void *buf, unsigned int len)
  47 {
  48         unsigned long data = 0;
  49         union {
  50                 u16     hword;
  51                 u32     word;
  52                 u64     dword;
  53         } tmp;
  54 
  55         switch (len) {
  56         case 1:
  57                 data = *(u8 *)buf;
  58                 break;
  59         case 2:
  60                 memcpy(&tmp.hword, buf, len);
  61                 data = tmp.hword;
  62                 break;
  63         case 4:
  64                 memcpy(&tmp.word, buf, len);
  65                 data = tmp.word;
  66                 break;
  67         case 8:
  68                 memcpy(&tmp.dword, buf, len);
  69                 data = tmp.dword;
  70                 break;
  71         }
  72 
  73         return data;
  74 }
  75 
  76 /**
  77  * kvm_handle_mmio_return -- Handle MMIO loads after user space emulation
  78  *                           or in-kernel IO emulation
  79  *
  80  * @vcpu: The VCPU pointer
  81  * @run:  The VCPU run struct containing the mmio data
  82  */
  83 int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run)
  84 {
  85         unsigned long data;
  86         unsigned int len;
  87         int mask;
  88 
  89         /* Detect an already handled MMIO return */
  90         if (unlikely(!vcpu->mmio_needed))
  91                 return 0;
  92 
  93         vcpu->mmio_needed = 0;
  94 
  95         if (!run->mmio.is_write) {
  96                 len = run->mmio.len;
  97                 if (len > sizeof(unsigned long))
  98                         return -EINVAL;
  99 
 100                 data = kvm_mmio_read_buf(run->mmio.data, len);
 101 
 102                 if (vcpu->arch.mmio_decode.sign_extend &&
 103                     len < sizeof(unsigned long)) {
 104                         mask = 1U << ((len * 8) - 1);
 105                         data = (data ^ mask) - mask;
 106                 }
 107 
 108                 if (!vcpu->arch.mmio_decode.sixty_four)
 109                         data = data & 0xffffffff;
 110 
 111                 trace_kvm_mmio(KVM_TRACE_MMIO_READ, len, run->mmio.phys_addr,
 112                                &data);
 113                 data = vcpu_data_host_to_guest(vcpu, data, len);
 114                 vcpu_set_reg(vcpu, vcpu->arch.mmio_decode.rt, data);
 115         }
 116 
 117         /*
 118          * The MMIO instruction is emulated and should not be re-executed
 119          * in the guest.
 120          */
 121         kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
 122 
 123         return 0;
 124 }
 125 
 126 static int decode_hsr(struct kvm_vcpu *vcpu, bool *is_write, int *len)
 127 {
 128         unsigned long rt;
 129         int access_size;
 130         bool sign_extend;
 131         bool sixty_four;
 132 
 133         if (kvm_vcpu_dabt_iss1tw(vcpu)) {
 134                 /* page table accesses IO mem: tell guest to fix its TTBR */
 135                 kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
 136                 return 1;
 137         }
 138 
 139         access_size = kvm_vcpu_dabt_get_as(vcpu);
 140         if (unlikely(access_size < 0))
 141                 return access_size;
 142 
 143         *is_write = kvm_vcpu_dabt_iswrite(vcpu);
 144         sign_extend = kvm_vcpu_dabt_issext(vcpu);
 145         sixty_four = kvm_vcpu_dabt_issf(vcpu);
 146         rt = kvm_vcpu_dabt_get_rd(vcpu);
 147 
 148         *len = access_size;
 149         vcpu->arch.mmio_decode.sign_extend = sign_extend;
 150         vcpu->arch.mmio_decode.rt = rt;
 151         vcpu->arch.mmio_decode.sixty_four = sixty_four;
 152 
 153         return 0;
 154 }
 155 
 156 int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
 157                  phys_addr_t fault_ipa)
 158 {
 159         unsigned long data;
 160         unsigned long rt;
 161         int ret;
 162         bool is_write;
 163         int len;
 164         u8 data_buf[8];
 165 
 166         /*
 167          * Prepare MMIO operation. First decode the syndrome data we get
 168          * from the CPU. Then try if some in-kernel emulation feels
 169          * responsible, otherwise let user space do its magic.
 170          */
 171         if (kvm_vcpu_dabt_isvalid(vcpu)) {
 172                 ret = decode_hsr(vcpu, &is_write, &len);
 173                 if (ret)
 174                         return ret;
 175         } else {
 176                 kvm_err("load/store instruction decoding not implemented\n");
 177                 return -ENOSYS;
 178         }
 179 
 180         rt = vcpu->arch.mmio_decode.rt;
 181 
 182         if (is_write) {
 183                 data = vcpu_data_guest_to_host(vcpu, vcpu_get_reg(vcpu, rt),
 184                                                len);
 185 
 186                 trace_kvm_mmio(KVM_TRACE_MMIO_WRITE, len, fault_ipa, &data);
 187                 kvm_mmio_write_buf(data_buf, len, data);
 188 
 189                 ret = kvm_io_bus_write(vcpu, KVM_MMIO_BUS, fault_ipa, len,
 190                                        data_buf);
 191         } else {
 192                 trace_kvm_mmio(KVM_TRACE_MMIO_READ_UNSATISFIED, len,
 193                                fault_ipa, NULL);
 194 
 195                 ret = kvm_io_bus_read(vcpu, KVM_MMIO_BUS, fault_ipa, len,
 196                                       data_buf);
 197         }
 198 
 199         /* Now prepare kvm_run for the potential return to userland. */
 200         run->mmio.is_write      = is_write;
 201         run->mmio.phys_addr     = fault_ipa;
 202         run->mmio.len           = len;
 203         vcpu->mmio_needed       = 1;
 204 
 205         if (!ret) {
 206                 /* We handled the access successfully in the kernel. */
 207                 if (!is_write)
 208                         memcpy(run->mmio.data, data_buf, len);
 209                 vcpu->stat.mmio_exit_kernel++;
 210                 kvm_handle_mmio_return(vcpu, run);
 211                 return 1;
 212         }
 213 
 214         if (is_write)
 215                 memcpy(run->mmio.data, data_buf, len);
 216         vcpu->stat.mmio_exit_user++;
 217         run->exit_reason        = KVM_EXIT_MMIO;
 218         return 0;
 219 }
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root/virt/kvm/arm/mmio.c

DEFINITIONS
