arch/arm64/kvm/mmio.c

   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_emulate.h>
   9 #include <trace/events/kvm.h>
  10
  11 #include "trace.h"
  12
  13 void kvm_mmio_write_buf(void *buf, unsigned int len, unsigned long data)
  14 {
  15         void *datap = NULL;
  16         union {
  17                 u8      byte;
  18                 u16     hword;
  19                 u32     word;
  20                 u64     dword;
  21         } tmp;
  22
  23         switch (len) {
  24         case 1:
  25                 tmp.byte        = data;
  26                 datap           = &tmp.byte;
  27                 break;
  28         case 2:
  29                 tmp.hword       = data;
  30                 datap           = &tmp.hword;
  31                 break;
  32         case 4:
  33                 tmp.word        = data;
  34                 datap           = &tmp.word;
  35                 break;
  36         case 8:
  37                 tmp.dword       = data;
  38                 datap           = &tmp.dword;
  39                 break;
  40         }
  41
  42         memcpy(buf, datap, len);
  43 }
  44
  45 unsigned long kvm_mmio_read_buf(const void *buf, unsigned int len)
  46 {
  47         unsigned long data = 0;
  48         union {
  49                 u16     hword;
  50                 u32     word;
  51                 u64     dword;
  52         } tmp;
  53
  54         switch (len) {
  55         case 1:
  56                 data = *(u8 *)buf;
  57                 break;
  58         case 2:
  59                 memcpy(&tmp.hword, buf, len);
  60                 data = tmp.hword;
  61                 break;
  62         case 4:
  63                 memcpy(&tmp.word, buf, len);
  64                 data = tmp.word;
  65                 break;
  66         case 8:
  67                 memcpy(&tmp.dword, buf, len);
  68                 data = tmp.dword;
  69                 break;
  70         }
  71
  72         return data;
  73 }
  74
  75 /**
  76  * kvm_handle_mmio_return -- Handle MMIO loads after user space emulation
  77  *                           or in-kernel IO emulation
  78  *
  79  * @vcpu: The VCPU pointer
  80  * @run:  The VCPU run struct containing the mmio data
  81  */
  82 int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run)
  83 {
  84         unsigned long data;
  85         unsigned int len;
  86         int mask;
  87
  88         /* Detect an already handled MMIO return */
  89         if (unlikely(!vcpu->mmio_needed))
  90                 return 0;
  91
  92         vcpu->mmio_needed = 0;
  93
  94         if (!kvm_vcpu_dabt_iswrite(vcpu)) {
  95                 len = kvm_vcpu_dabt_get_as(vcpu);
  96                 data = kvm_mmio_read_buf(run->mmio.data, len);
  97
  98                 if (kvm_vcpu_dabt_issext(vcpu) &&
  99                     len < sizeof(unsigned long)) {
 100                         mask = 1U << ((len * 8) - 1);
 101                         data = (data ^ mask) - mask;
 102                 }
 103
 104                 if (!kvm_vcpu_dabt_issf(vcpu))
 105                         data = data & 0xffffffff;
 106
 107                 trace_kvm_mmio(KVM_TRACE_MMIO_READ, len, run->mmio.phys_addr,
 108                                &data);
 109                 data = vcpu_data_host_to_guest(vcpu, data, len);
 110                 vcpu_set_reg(vcpu, kvm_vcpu_dabt_get_rd(vcpu), data);
 111         }
 112
 113         /*
 114          * The MMIO instruction is emulated and should not be re-executed
 115          * in the guest.
 116          */
 117         kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
 118
 119         return 0;
 120 }
 121
 122 int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
 123                  phys_addr_t fault_ipa)
 124 {
 125         unsigned long data;
 126         unsigned long rt;
 127         int ret;
 128         bool is_write;
 129         int len;
 130         u8 data_buf[8];
 131
 132         /*
 133          * No valid syndrome? Ask userspace for help if it has
 134          * volunteered to do so, and bail out otherwise.
 135          */
 136         if (!kvm_vcpu_dabt_isvalid(vcpu)) {
 137                 if (vcpu->kvm->arch.return_nisv_io_abort_to_user) {
 138                         run->exit_reason = KVM_EXIT_ARM_NISV;
 139                         run->arm_nisv.esr_iss = kvm_vcpu_dabt_iss_nisv_sanitized(vcpu);
 140                         run->arm_nisv.fault_ipa = fault_ipa;
 141                         return 0;
 142                 }
 143
 144                 kvm_pr_unimpl("Data abort outside memslots with no valid syndrome info\n");
 145                 return -ENOSYS;
 146         }
 147
 148         /* Page table accesses IO mem: tell guest to fix its TTBR */
 149         if (kvm_vcpu_dabt_iss1tw(vcpu)) {
 150                 kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
 151                 return 1;
 152         }
 153
 154         /*
 155          * Prepare MMIO operation. First decode the syndrome data we get
 156          * from the CPU. Then try if some in-kernel emulation feels
 157          * responsible, otherwise let user space do its magic.
 158          */
 159         is_write = kvm_vcpu_dabt_iswrite(vcpu);
 160         len = kvm_vcpu_dabt_get_as(vcpu);
 161         rt = kvm_vcpu_dabt_get_rd(vcpu);
 162
 163         if (is_write) {
 164                 data = vcpu_data_guest_to_host(vcpu, vcpu_get_reg(vcpu, rt),
 165                                                len);
 166
 167                 trace_kvm_mmio(KVM_TRACE_MMIO_WRITE, len, fault_ipa, &data);
 168                 kvm_mmio_write_buf(data_buf, len, data);
 169
 170                 ret = kvm_io_bus_write(vcpu, KVM_MMIO_BUS, fault_ipa, len,
 171                                        data_buf);
 172         } else {
 173                 trace_kvm_mmio(KVM_TRACE_MMIO_READ_UNSATISFIED, len,
 174                                fault_ipa, NULL);
 175
 176                 ret = kvm_io_bus_read(vcpu, KVM_MMIO_BUS, fault_ipa, len,
 177                                       data_buf);
 178         }
 179
 180         /* Now prepare kvm_run for the potential return to userland. */
 181         run->mmio.is_write      = is_write;
 182         run->mmio.phys_addr     = fault_ipa;
 183         run->mmio.len           = len;
 184         vcpu->mmio_needed       = 1;
 185
 186         if (!ret) {
 187                 /* We handled the access successfully in the kernel. */
 188                 if (!is_write)
 189                         memcpy(run->mmio.data, data_buf, len);
 190                 vcpu->stat.mmio_exit_kernel++;
 191                 kvm_handle_mmio_return(vcpu, run);
 192                 return 1;
 193         }
 194
 195         if (is_write)
 196                 memcpy(run->mmio.data, data_buf, len);
 197         vcpu->stat.mmio_exit_user++;
 198         run->exit_reason        = KVM_EXIT_MMIO;
 199         return 0;
 200 }