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Linux/arch/arm/kvm/mmio.c

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  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  * @vcpu: The VCPU pointer
 91  * @run:  The VCPU run struct containing the mmio data
 92  *
 93  * This should only be called after returning from userspace for MMIO load
 94  * emulation.
 95  */
 96 int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run)
 97 {
 98         unsigned long data;
 99         unsigned int len;
100         int mask;
101 
102         if (!run->mmio.is_write) {
103                 len = run->mmio.len;
104                 if (len > sizeof(unsigned long))
105                         return -EINVAL;
106 
107                 data = mmio_read_buf(run->mmio.data, len);
108 
109                 if (vcpu->arch.mmio_decode.sign_extend &&
110                     len < sizeof(unsigned long)) {
111                         mask = 1U << ((len * 8) - 1);
112                         data = (data ^ mask) - mask;
113                 }
114 
115                 trace_kvm_mmio(KVM_TRACE_MMIO_READ, len, run->mmio.phys_addr,
116                                data);
117                 data = vcpu_data_host_to_guest(vcpu, data, len);
118                 *vcpu_reg(vcpu, vcpu->arch.mmio_decode.rt) = data;
119         }
120 
121         return 0;
122 }
123 
124 static int decode_hsr(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
125                       struct kvm_exit_mmio *mmio)
126 {
127         unsigned long rt;
128         int len;
129         bool is_write, sign_extend;
130 
131         if (kvm_vcpu_dabt_isextabt(vcpu)) {
132                 /* cache operation on I/O addr, tell guest unsupported */
133                 kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
134                 return 1;
135         }
136 
137         if (kvm_vcpu_dabt_iss1tw(vcpu)) {
138                 /* page table accesses IO mem: tell guest to fix its TTBR */
139                 kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
140                 return 1;
141         }
142 
143         len = kvm_vcpu_dabt_get_as(vcpu);
144         if (unlikely(len < 0))
145                 return len;
146 
147         is_write = kvm_vcpu_dabt_iswrite(vcpu);
148         sign_extend = kvm_vcpu_dabt_issext(vcpu);
149         rt = kvm_vcpu_dabt_get_rd(vcpu);
150 
151         mmio->is_write = is_write;
152         mmio->phys_addr = fault_ipa;
153         mmio->len = len;
154         vcpu->arch.mmio_decode.sign_extend = sign_extend;
155         vcpu->arch.mmio_decode.rt = rt;
156 
157         /*
158          * The MMIO instruction is emulated and should not be re-executed
159          * in the guest.
160          */
161         kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
162         return 0;
163 }
164 
165 int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
166                  phys_addr_t fault_ipa)
167 {
168         struct kvm_exit_mmio mmio;
169         unsigned long data;
170         unsigned long rt;
171         int ret;
172 
173         /*
174          * Prepare MMIO operation. First stash it in a private
175          * structure that we can use for in-kernel emulation. If the
176          * kernel can't handle it, copy it into run->mmio and let user
177          * space do its magic.
178          */
179 
180         if (kvm_vcpu_dabt_isvalid(vcpu)) {
181                 ret = decode_hsr(vcpu, fault_ipa, &mmio);
182                 if (ret)
183                         return ret;
184         } else {
185                 kvm_err("load/store instruction decoding not implemented\n");
186                 return -ENOSYS;
187         }
188 
189         rt = vcpu->arch.mmio_decode.rt;
190         data = vcpu_data_guest_to_host(vcpu, *vcpu_reg(vcpu, rt), mmio.len);
191 
192         trace_kvm_mmio((mmio.is_write) ? KVM_TRACE_MMIO_WRITE :
193                                          KVM_TRACE_MMIO_READ_UNSATISFIED,
194                         mmio.len, fault_ipa,
195                         (mmio.is_write) ? data : 0);
196 
197         if (mmio.is_write)
198                 mmio_write_buf(mmio.data, mmio.len, data);
199 
200         if (vgic_handle_mmio(vcpu, run, &mmio))
201                 return 1;
202 
203         kvm_prepare_mmio(run, &mmio);
204         return 0;
205 }
206 

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