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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_reg(vcpu, vcpu->arch.mmio_decode.rt) = data;
119 	}
120 
121 	return 0;
122 }
123 
decode_hsr(struct kvm_vcpu * vcpu,phys_addr_t fault_ipa,struct kvm_exit_mmio * mmio)124 static int decode_hsr(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
125 		      struct kvm_exit_mmio *mmio)
126 {
127 	unsigned long rt;
128 	int len;
129 	bool is_write, sign_extend;
130 
131 	if (kvm_vcpu_dabt_isextabt(vcpu)) {
132 		/* cache operation on I/O addr, tell guest unsupported */
133 		kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
134 		return 1;
135 	}
136 
137 	if (kvm_vcpu_dabt_iss1tw(vcpu)) {
138 		/* page table accesses IO mem: tell guest to fix its TTBR */
139 		kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
140 		return 1;
141 	}
142 
143 	len = kvm_vcpu_dabt_get_as(vcpu);
144 	if (unlikely(len < 0))
145 		return len;
146 
147 	is_write = kvm_vcpu_dabt_iswrite(vcpu);
148 	sign_extend = kvm_vcpu_dabt_issext(vcpu);
149 	rt = kvm_vcpu_dabt_get_rd(vcpu);
150 
151 	mmio->is_write = is_write;
152 	mmio->phys_addr = fault_ipa;
153 	mmio->len = len;
154 	vcpu->arch.mmio_decode.sign_extend = sign_extend;
155 	vcpu->arch.mmio_decode.rt = rt;
156 
157 	/*
158 	 * The MMIO instruction is emulated and should not be re-executed
159 	 * in the guest.
160 	 */
161 	kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
162 	return 0;
163 }
164 
io_mem_abort(struct kvm_vcpu * vcpu,struct kvm_run * run,phys_addr_t fault_ipa)165 int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
166 		 phys_addr_t fault_ipa)
167 {
168 	struct kvm_exit_mmio mmio;
169 	unsigned long data;
170 	unsigned long rt;
171 	int ret;
172 
173 	/*
174 	 * Prepare MMIO operation. First stash it in a private
175 	 * structure that we can use for in-kernel emulation. If the
176 	 * kernel can't handle it, copy it into run->mmio and let user
177 	 * space do its magic.
178 	 */
179 
180 	if (kvm_vcpu_dabt_isvalid(vcpu)) {
181 		ret = decode_hsr(vcpu, fault_ipa, &mmio);
182 		if (ret)
183 			return ret;
184 	} else {
185 		kvm_err("load/store instruction decoding not implemented\n");
186 		return -ENOSYS;
187 	}
188 
189 	rt = vcpu->arch.mmio_decode.rt;
190 	data = vcpu_data_guest_to_host(vcpu, *vcpu_reg(vcpu, rt), mmio.len);
191 
192 	trace_kvm_mmio((mmio.is_write) ? KVM_TRACE_MMIO_WRITE :
193 					 KVM_TRACE_MMIO_READ_UNSATISFIED,
194 			mmio.len, fault_ipa,
195 			(mmio.is_write) ? data : 0);
196 
197 	if (mmio.is_write)
198 		mmio_write_buf(mmio.data, mmio.len, data);
199 
200 	if (vgic_handle_mmio(vcpu, run, &mmio))
201 		return 1;
202 
203 	kvm_prepare_mmio(run, &mmio);
204 	return 0;
205 }
206