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         /* Detect an already handled MMIO return */
 102         if (unlikely(!vcpu->mmio_needed))
 103                 return 0;
 104
 105         vcpu->mmio_needed = 0;
 106
 107         if (!run->mmio.is_write) {
 108                 len = run->mmio.len;
 109                 if (len > sizeof(unsigned long))
 110                         return -EINVAL;
 111
 112                 data = kvm_mmio_read_buf(run->mmio.data, len);
 113
 114                 if (vcpu->arch.mmio_decode.sign_extend &&
 115                     len < sizeof(unsigned long)) {
 116                         mask = 1U << ((len * 8) - 1);
 117                         data = (data ^ mask) - mask;
 118                 }
 119
 120                 trace_kvm_mmio(KVM_TRACE_MMIO_READ, len, run->mmio.phys_addr,
 121                                &data);
 122                 data = vcpu_data_host_to_guest(vcpu, data, len);
 123                 vcpu_set_reg(vcpu, vcpu->arch.mmio_decode.rt, data);
 124         }
 125
 126         /*
 127          * The MMIO instruction is emulated and should not be re-executed
 128          * in the guest.
 129          */
 130         kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
 131
 132         return 0;
 133 }
 134
 135 static int decode_hsr(struct kvm_vcpu *vcpu, bool *is_write, int *len)
 136 {
 137         unsigned long rt;
 138         int access_size;
 139         bool sign_extend;
 140
 141         if (kvm_vcpu_dabt_iss1tw(vcpu)) {
 142                 /* page table accesses IO mem: tell guest to fix its TTBR */
 143                 kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
 144                 return 1;
 145         }
 146
 147         access_size = kvm_vcpu_dabt_get_as(vcpu);
 148         if (unlikely(access_size < 0))
 149                 return access_size;
 150
 151         *is_write = kvm_vcpu_dabt_iswrite(vcpu);
 152         sign_extend = kvm_vcpu_dabt_issext(vcpu);
 153         rt = kvm_vcpu_dabt_get_rd(vcpu);
 154
 155         *len = access_size;
 156         vcpu->arch.mmio_decode.sign_extend = sign_extend;
 157         vcpu->arch.mmio_decode.rt = rt;
 158
 159         return 0;
 160 }
 161
 162 int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
 163                  phys_addr_t fault_ipa)
 164 {
 165         unsigned long data;
 166         unsigned long rt;
 167         int ret;
 168         bool is_write;
 169         int len;
 170         u8 data_buf[8];
 171
 172         /*
 173          * Prepare MMIO operation. First decode the syndrome data we get
 174          * from the CPU. Then try if some in-kernel emulation feels
 175          * responsible, otherwise let user space do its magic.
 176          */
 177         if (kvm_vcpu_dabt_isvalid(vcpu)) {
 178                 ret = decode_hsr(vcpu, &is_write, &len);
 179                 if (ret)
 180                         return ret;
 181         } else {
 182                 kvm_err("load/store instruction decoding not implemented\n");
 183                 return -ENOSYS;
 184         }
 185
 186         rt = vcpu->arch.mmio_decode.rt;
 187
 188         if (is_write) {
 189                 data = vcpu_data_guest_to_host(vcpu, vcpu_get_reg(vcpu, rt),
 190                                                len);
 191
 192                 trace_kvm_mmio(KVM_TRACE_MMIO_WRITE, len, fault_ipa, &data);
 193                 kvm_mmio_write_buf(data_buf, len, data);
 194
 195                 ret = kvm_io_bus_write(vcpu, KVM_MMIO_BUS, fault_ipa, len,
 196                                        data_buf);
 197         } else {
 198                 trace_kvm_mmio(KVM_TRACE_MMIO_READ_UNSATISFIED, len,
 199                                fault_ipa, NULL);
 200
 201                 ret = kvm_io_bus_read(vcpu, KVM_MMIO_BUS, fault_ipa, len,
 202                                       data_buf);
 203         }
 204
 205         /* Now prepare kvm_run for the potential return to userland. */
 206         run->mmio.is_write      = is_write;
 207         run->mmio.phys_addr     = fault_ipa;
 208         run->mmio.len           = len;
 209         vcpu->mmio_needed       = 1;
 210
 211         if (!ret) {
 212                 /* We handled the access successfully in the kernel. */
 213                 if (!is_write)
 214                         memcpy(run->mmio.data, data_buf, len);
 215                 vcpu->stat.mmio_exit_kernel++;
 216                 kvm_handle_mmio_return(vcpu, run);
 217                 return 1;
 218         }
 219
 220         if (is_write)
 221                 memcpy(run->mmio.data, data_buf, len);
 222         vcpu->stat.mmio_exit_user++;
 223         run->exit_reason        = KVM_EXIT_MMIO;
 224         return 0;
 225 }