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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2012 - Virtual Open Systems and Columbia University
4 * Author: Christoffer Dall <c.dall@virtualopensystems.com>
5 */
6
7#include <linux/kvm_host.h>
8#include <asm/kvm_mmio.h>
9#include <asm/kvm_emulate.h>
10#include <trace/events/kvm.h>
11
12#include "trace.h"
13
14void kvm_mmio_write_buf(void *buf, unsigned int len, unsigned long data)
15{
16 void *datap = NULL;
17 union {
18 u8 byte;
19 u16 hword;
20 u32 word;
21 u64 dword;
22 } tmp;
23
24 switch (len) {
25 case 1:
26 tmp.byte = data;
27 datap = &tmp.byte;
28 break;
29 case 2:
30 tmp.hword = data;
31 datap = &tmp.hword;
32 break;
33 case 4:
34 tmp.word = data;
35 datap = &tmp.word;
36 break;
37 case 8:
38 tmp.dword = data;
39 datap = &tmp.dword;
40 break;
41 }
42
43 memcpy(buf, datap, len);
44}
45
46unsigned long kvm_mmio_read_buf(const void *buf, unsigned int len)
47{
48 unsigned long data = 0;
49 union {
50 u16 hword;
51 u32 word;
52 u64 dword;
53 } tmp;
54
55 switch (len) {
56 case 1:
57 data = *(u8 *)buf;
58 break;
59 case 2:
60 memcpy(&tmp.hword, buf, len);
61 data = tmp.hword;
62 break;
63 case 4:
64 memcpy(&tmp.word, buf, len);
65 data = tmp.word;
66 break;
67 case 8:
68 memcpy(&tmp.dword, buf, len);
69 data = tmp.dword;
70 break;
71 }
72
73 return data;
74}
75
76/**
77 * kvm_handle_mmio_return -- Handle MMIO loads after user space emulation
78 * or in-kernel IO emulation
79 *
80 * @vcpu: The VCPU pointer
81 * @run: The VCPU run struct containing the mmio data
82 */
83int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run)
84{
85 unsigned long data;
86 unsigned int len;
87 int mask;
88
89 /* Detect an already handled MMIO return */
90 if (unlikely(!vcpu->mmio_needed))
91 return 0;
92
93 vcpu->mmio_needed = 0;
94
95 if (!run->mmio.is_write) {
96 len = run->mmio.len;
97 if (len > sizeof(unsigned long))
98 return -EINVAL;
99
100 data = kvm_mmio_read_buf(run->mmio.data, len);
101
102 if (vcpu->arch.mmio_decode.sign_extend &&
103 len < sizeof(unsigned long)) {
104 mask = 1U << ((len * 8) - 1);
105 data = (data ^ mask) - mask;
106 }
107
108 trace_kvm_mmio(KVM_TRACE_MMIO_READ, len, run->mmio.phys_addr,
109 &data);
110 data = vcpu_data_host_to_guest(vcpu, data, len);
111 vcpu_set_reg(vcpu, vcpu->arch.mmio_decode.rt, data);
112 }
113
114 /*
115 * The MMIO instruction is emulated and should not be re-executed
116 * in the guest.
117 */
118 kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
119
120 return 0;
121}
122
123static 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 return 0;
148}
149
150int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
151 phys_addr_t fault_ipa)
152{
153 unsigned long data;
154 unsigned long rt;
155 int ret;
156 bool is_write;
157 int len;
158 u8 data_buf[8];
159
160 /*
161 * Prepare MMIO operation. First decode the syndrome data we get
162 * from the CPU. Then try if some in-kernel emulation feels
163 * responsible, otherwise let user space do its magic.
164 */
165 if (kvm_vcpu_dabt_isvalid(vcpu)) {
166 ret = decode_hsr(vcpu, &is_write, &len);
167 if (ret)
168 return ret;
169 } else {
170 kvm_err("load/store instruction decoding not implemented\n");
171 return -ENOSYS;
172 }
173
174 rt = vcpu->arch.mmio_decode.rt;
175
176 if (is_write) {
177 data = vcpu_data_guest_to_host(vcpu, vcpu_get_reg(vcpu, rt),
178 len);
179
180 trace_kvm_mmio(KVM_TRACE_MMIO_WRITE, len, fault_ipa, &data);
181 kvm_mmio_write_buf(data_buf, len, data);
182
183 ret = kvm_io_bus_write(vcpu, KVM_MMIO_BUS, fault_ipa, len,
184 data_buf);
185 } else {
186 trace_kvm_mmio(KVM_TRACE_MMIO_READ_UNSATISFIED, len,
187 fault_ipa, NULL);
188
189 ret = kvm_io_bus_read(vcpu, KVM_MMIO_BUS, fault_ipa, len,
190 data_buf);
191 }
192
193 /* Now prepare kvm_run for the potential return to userland. */
194 run->mmio.is_write = is_write;
195 run->mmio.phys_addr = fault_ipa;
196 run->mmio.len = len;
197 vcpu->mmio_needed = 1;
198
199 if (!ret) {
200 /* We handled the access successfully in the kernel. */
201 if (!is_write)
202 memcpy(run->mmio.data, data_buf, len);
203 vcpu->stat.mmio_exit_kernel++;
204 kvm_handle_mmio_return(vcpu, run);
205 return 1;
206 }
207
208 if (is_write)
209 memcpy(run->mmio.data, data_buf, len);
210 vcpu->stat.mmio_exit_user++;
211 run->exit_reason = KVM_EXIT_MMIO;
212 return 0;
213}
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
26void 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
58unsigned 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 */
95int 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
123static 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
155int 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, NULL);
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}