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 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
decode_hsr(struct kvm_vcpu * vcpu,bool * is_write,int * len)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_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
io_mem_abort(struct kvm_vcpu * vcpu,struct kvm_run * run,phys_addr_t fault_ipa)155 int 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 }
218
