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
mmio_write_buf(char * buf,unsigned int len,unsigned long data)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
mmio_read_buf(char * buf,unsigned int len)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 */
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 = 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 trace_kvm_mmio(KVM_TRACE_MMIO_READ, len, run->mmio.phys_addr,
121 &data);
122 data = vcpu_data_host_to_guest(vcpu, data, len);
123 vcpu_set_reg(vcpu, vcpu->arch.mmio_decode.rt, data);
124 }
125
126 /*
127 * The MMIO instruction is emulated and should not be re-executed
128 * in the guest.
129 */
130 kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
131
132 return 0;
133 }
134
decode_hsr(struct kvm_vcpu * vcpu,bool * is_write,int * len)135 static int decode_hsr(struct kvm_vcpu *vcpu, bool *is_write, int *len)
136 {
137 unsigned long rt;
138 int access_size;
139 bool sign_extend;
140
141 if (kvm_vcpu_dabt_isextabt(vcpu)) {
142 /* cache operation on I/O addr, tell guest unsupported */
143 kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
144 return 1;
145 }
146
147 if (kvm_vcpu_dabt_iss1tw(vcpu)) {
148 /* page table accesses IO mem: tell guest to fix its TTBR */
149 kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
150 return 1;
151 }
152
153 access_size = kvm_vcpu_dabt_get_as(vcpu);
154 if (unlikely(access_size < 0))
155 return access_size;
156
157 *is_write = kvm_vcpu_dabt_iswrite(vcpu);
158 sign_extend = kvm_vcpu_dabt_issext(vcpu);
159 rt = kvm_vcpu_dabt_get_rd(vcpu);
160
161 *len = access_size;
162 vcpu->arch.mmio_decode.sign_extend = sign_extend;
163 vcpu->arch.mmio_decode.rt = rt;
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 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 kvm_handle_mmio_return(vcpu, run);
222 return 1;
223 }
224
225 if (is_write)
226 memcpy(run->mmio.data, data_buf, len);
227 run->exit_reason = KVM_EXIT_MMIO;
228 return 0;
229 }
230