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