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
kvm_mmio_write_buf(void * buf,unsigned int len,unsigned long data)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
kvm_mmio_read_buf(const void * buf,unsigned int len)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 */
kvm_handle_mmio_return(struct kvm_vcpu * vcpu,struct kvm_run * run)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 if (!vcpu->arch.mmio_decode.sixty_four)
121 data = data & 0xffffffff;
122
123 trace_kvm_mmio(KVM_TRACE_MMIO_READ, len, run->mmio.phys_addr,
124 &data);
125 data = vcpu_data_host_to_guest(vcpu, data, len);
126 vcpu_set_reg(vcpu, vcpu->arch.mmio_decode.rt, data);
127 }
128
129 /*
130 * The MMIO instruction is emulated and should not be re-executed
131 * in the guest.
132 */
133 kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
134
135 return 0;
136 }
137
decode_hsr(struct kvm_vcpu * vcpu,bool * is_write,int * len)138 static int decode_hsr(struct kvm_vcpu *vcpu, bool *is_write, int *len)
139 {
140 unsigned long rt;
141 int access_size;
142 bool sign_extend;
143 bool sixty_four;
144
145 if (kvm_vcpu_abt_iss1tw(vcpu)) {
146 /* page table accesses IO mem: tell guest to fix its TTBR */
147 kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
148 return 1;
149 }
150
151 access_size = kvm_vcpu_dabt_get_as(vcpu);
152 if (unlikely(access_size < 0))
153 return access_size;
154
155 *is_write = kvm_vcpu_dabt_iswrite(vcpu);
156 sign_extend = kvm_vcpu_dabt_issext(vcpu);
157 sixty_four = kvm_vcpu_dabt_issf(vcpu);
158 rt = kvm_vcpu_dabt_get_rd(vcpu);
159
160 *len = access_size;
161 vcpu->arch.mmio_decode.sign_extend = sign_extend;
162 vcpu->arch.mmio_decode.rt = rt;
163 vcpu->arch.mmio_decode.sixty_four = sixty_four;
164
165 return 0;
166 }
167
io_mem_abort(struct kvm_vcpu * vcpu,struct kvm_run * run,phys_addr_t fault_ipa)168 int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
169 phys_addr_t fault_ipa)
170 {
171 unsigned long data;
172 unsigned long rt;
173 int ret;
174 bool is_write;
175 int len;
176 u8 data_buf[8];
177
178 /*
179 * Prepare MMIO operation. First decode the syndrome data we get
180 * from the CPU. Then try if some in-kernel emulation feels
181 * responsible, otherwise let user space do its magic.
182 */
183 if (kvm_vcpu_dabt_isvalid(vcpu)) {
184 ret = decode_hsr(vcpu, &is_write, &len);
185 if (ret)
186 return ret;
187 } else {
188 kvm_err("load/store instruction decoding not implemented\n");
189 return -ENOSYS;
190 }
191
192 rt = vcpu->arch.mmio_decode.rt;
193
194 if (is_write) {
195 data = vcpu_data_guest_to_host(vcpu, vcpu_get_reg(vcpu, rt),
196 len);
197
198 trace_kvm_mmio(KVM_TRACE_MMIO_WRITE, len, fault_ipa, &data);
199 kvm_mmio_write_buf(data_buf, len, data);
200
201 ret = kvm_io_bus_write(vcpu, KVM_MMIO_BUS, fault_ipa, len,
202 data_buf);
203 } else {
204 trace_kvm_mmio(KVM_TRACE_MMIO_READ_UNSATISFIED, len,
205 fault_ipa, NULL);
206
207 ret = kvm_io_bus_read(vcpu, KVM_MMIO_BUS, fault_ipa, len,
208 data_buf);
209 }
210
211 /* Now prepare kvm_run for the potential return to userland. */
212 run->mmio.is_write = is_write;
213 run->mmio.phys_addr = fault_ipa;
214 run->mmio.len = len;
215 vcpu->mmio_needed = 1;
216
217 if (!ret) {
218 /* We handled the access successfully in the kernel. */
219 if (!is_write)
220 memcpy(run->mmio.data, data_buf, len);
221 vcpu->stat.mmio_exit_kernel++;
222 kvm_handle_mmio_return(vcpu, run);
223 return 1;
224 }
225
226 if (is_write)
227 memcpy(run->mmio.data, data_buf, len);
228 vcpu->stat.mmio_exit_user++;
229 run->exit_reason = KVM_EXIT_MMIO;
230 return 0;
231 }
232