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 * @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 */
kvm_handle_mmio_return(struct kvm_vcpu * vcpu,struct kvm_run * run)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_set_reg(vcpu, vcpu->arch.mmio_decode.rt, data);
119 }
120
121 return 0;
122 }
123
decode_hsr(struct kvm_vcpu * vcpu,bool * is_write,int * len)124 static int decode_hsr(struct kvm_vcpu *vcpu, bool *is_write, int *len)
125 {
126 unsigned long rt;
127 int access_size;
128 bool sign_extend;
129
130 if (kvm_vcpu_dabt_isextabt(vcpu)) {
131 /* cache operation on I/O addr, tell guest unsupported */
132 kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
133 return 1;
134 }
135
136 if (kvm_vcpu_dabt_iss1tw(vcpu)) {
137 /* page table accesses IO mem: tell guest to fix its TTBR */
138 kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
139 return 1;
140 }
141
142 access_size = kvm_vcpu_dabt_get_as(vcpu);
143 if (unlikely(access_size < 0))
144 return access_size;
145
146 *is_write = kvm_vcpu_dabt_iswrite(vcpu);
147 sign_extend = kvm_vcpu_dabt_issext(vcpu);
148 rt = kvm_vcpu_dabt_get_rd(vcpu);
149
150 *len = access_size;
151 vcpu->arch.mmio_decode.sign_extend = sign_extend;
152 vcpu->arch.mmio_decode.rt = rt;
153
154 /*
155 * The MMIO instruction is emulated and should not be re-executed
156 * in the guest.
157 */
158 kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
159 return 0;
160 }
161
io_mem_abort(struct kvm_vcpu * vcpu,struct kvm_run * run,phys_addr_t fault_ipa)162 int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
163 phys_addr_t fault_ipa)
164 {
165 unsigned long data;
166 unsigned long rt;
167 int ret;
168 bool is_write;
169 int len;
170 u8 data_buf[8];
171
172 /*
173 * Prepare MMIO operation. First decode the syndrome data we get
174 * from the CPU. Then try if some in-kernel emulation feels
175 * responsible, otherwise let user space do its magic.
176 */
177 if (kvm_vcpu_dabt_isvalid(vcpu)) {
178 ret = decode_hsr(vcpu, &is_write, &len);
179 if (ret)
180 return ret;
181 } else {
182 kvm_err("load/store instruction decoding not implemented\n");
183 return -ENOSYS;
184 }
185
186 rt = vcpu->arch.mmio_decode.rt;
187
188 if (is_write) {
189 data = vcpu_data_guest_to_host(vcpu, vcpu_get_reg(vcpu, rt),
190 len);
191
192 trace_kvm_mmio(KVM_TRACE_MMIO_WRITE, len, fault_ipa, data);
193 mmio_write_buf(data_buf, len, data);
194
195 ret = kvm_io_bus_write(vcpu, KVM_MMIO_BUS, fault_ipa, len,
196 data_buf);
197 } else {
198 trace_kvm_mmio(KVM_TRACE_MMIO_READ_UNSATISFIED, len,
199 fault_ipa, 0);
200
201 ret = kvm_io_bus_read(vcpu, KVM_MMIO_BUS, fault_ipa, len,
202 data_buf);
203 }
204
205 /* Now prepare kvm_run for the potential return to userland. */
206 run->mmio.is_write = is_write;
207 run->mmio.phys_addr = fault_ipa;
208 run->mmio.len = len;
209 memcpy(run->mmio.data, data_buf, len);
210
211 if (!ret) {
212 /* We handled the access successfully in the kernel. */
213 kvm_handle_mmio_return(vcpu, run);
214 return 1;
215 }
216
217 run->exit_reason = KVM_EXIT_MMIO;
218 return 0;
219 }
220