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