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
26static 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
58static 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 */
96int 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
124static 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
162int 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