1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2012 - Virtual Open Systems and Columbia University
4 * Author: Christoffer Dall <c.dall@virtualopensystems.com>
5 */
6
7#include <linux/kvm_host.h>
8#include <asm/kvm_emulate.h>
9#include <trace/events/kvm.h>
10
11#include "trace.h"
12
13void kvm_mmio_write_buf(void *buf, unsigned int len, unsigned long data)
14{
15	void *datap = NULL;
16	union {
17		u8	byte;
18		u16	hword;
19		u32	word;
20		u64	dword;
21	} tmp;
22
23	switch (len) {
24	case 1:
25		tmp.byte	= data;
26		datap		= &tmp.byte;
27		break;
28	case 2:
29		tmp.hword	= data;
30		datap		= &tmp.hword;
31		break;
32	case 4:
33		tmp.word	= data;
34		datap		= &tmp.word;
35		break;
36	case 8:
37		tmp.dword	= data;
38		datap		= &tmp.dword;
39		break;
40	}
41
42	memcpy(buf, datap, len);
43}
44
45unsigned long kvm_mmio_read_buf(const void *buf, unsigned int len)
46{
47	unsigned long data = 0;
48	union {
49		u16	hword;
50		u32	word;
51		u64	dword;
52	} tmp;
53
54	switch (len) {
55	case 1:
56		data = *(u8 *)buf;
57		break;
58	case 2:
59		memcpy(&tmp.hword, buf, len);
60		data = tmp.hword;
61		break;
62	case 4:
63		memcpy(&tmp.word, buf, len);
64		data = tmp.word;
65		break;
66	case 8:
67		memcpy(&tmp.dword, buf, len);
68		data = tmp.dword;
69		break;
70	}
71
72	return data;
73}
74
75/**
76 * kvm_handle_mmio_return -- Handle MMIO loads after user space emulation
77 *			     or in-kernel IO emulation
78 *
79 * @vcpu: The VCPU pointer
80 */
81int kvm_handle_mmio_return(struct kvm_vcpu *vcpu)
82{
83	unsigned long data;
84	unsigned int len;
85	int mask;
86
87	/* Detect an already handled MMIO return */
88	if (unlikely(!vcpu->mmio_needed))
89		return 0;
90
91	vcpu->mmio_needed = 0;
92
93	if (!kvm_vcpu_dabt_iswrite(vcpu)) {
94		struct kvm_run *run = vcpu->run;
95
96		len = kvm_vcpu_dabt_get_as(vcpu);
97		data = kvm_mmio_read_buf(run->mmio.data, len);
98
99		if (kvm_vcpu_dabt_issext(vcpu) &&
100		    len < sizeof(unsigned long)) {
101			mask = 1U << ((len * 8) - 1);
102			data = (data ^ mask) - mask;
103		}
104
105		if (!kvm_vcpu_dabt_issf(vcpu))
106			data = data & 0xffffffff;
107
108		trace_kvm_mmio(KVM_TRACE_MMIO_READ, len, run->mmio.phys_addr,
109			       &data);
110		data = vcpu_data_host_to_guest(vcpu, data, len);
111		vcpu_set_reg(vcpu, kvm_vcpu_dabt_get_rd(vcpu), data);
112	}
113
114	/*
115	 * The MMIO instruction is emulated and should not be re-executed
116	 * in the guest.
117	 */
118	kvm_incr_pc(vcpu);
119
120	return 0;
121}
122
123int io_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa)
124{
125	struct kvm_run *run = vcpu->run;
126	unsigned long data;
127	unsigned long rt;
128	int ret;
129	bool is_write;
130	int len;
131	u8 data_buf[8];
132
133	/*
134	 * No valid syndrome? Ask userspace for help if it has
135	 * volunteered to do so, and bail out otherwise.
136	 */
137	if (!kvm_vcpu_dabt_isvalid(vcpu)) {
138		trace_kvm_mmio_nisv(*vcpu_pc(vcpu), kvm_vcpu_get_esr(vcpu),
139				    kvm_vcpu_get_hfar(vcpu), fault_ipa);
140
141		if (test_bit(KVM_ARCH_FLAG_RETURN_NISV_IO_ABORT_TO_USER,
142			     &vcpu->kvm->arch.flags)) {
143			run->exit_reason = KVM_EXIT_ARM_NISV;
144			run->arm_nisv.esr_iss = kvm_vcpu_dabt_iss_nisv_sanitized(vcpu);
145			run->arm_nisv.fault_ipa = fault_ipa;
146			return 0;
147		}
148
149		return -ENOSYS;
150	}
151
152	/*
153	 * Prepare MMIO operation. First decode the syndrome data we get
154	 * from the CPU. Then try if some in-kernel emulation feels
155	 * responsible, otherwise let user space do its magic.
156	 */
157	is_write = kvm_vcpu_dabt_iswrite(vcpu);
158	len = kvm_vcpu_dabt_get_as(vcpu);
159	rt = kvm_vcpu_dabt_get_rd(vcpu);
160
161	if (is_write) {
162		data = vcpu_data_guest_to_host(vcpu, vcpu_get_reg(vcpu, rt),
163					       len);
164
165		trace_kvm_mmio(KVM_TRACE_MMIO_WRITE, len, fault_ipa, &data);
166		kvm_mmio_write_buf(data_buf, len, data);
167
168		ret = kvm_io_bus_write(vcpu, KVM_MMIO_BUS, fault_ipa, len,
169				       data_buf);
170	} else {
171		trace_kvm_mmio(KVM_TRACE_MMIO_READ_UNSATISFIED, len,
172			       fault_ipa, NULL);
173
174		ret = kvm_io_bus_read(vcpu, KVM_MMIO_BUS, fault_ipa, len,
175				      data_buf);
176	}
177
178	/* Now prepare kvm_run for the potential return to userland. */
179	run->mmio.is_write	= is_write;
180	run->mmio.phys_addr	= fault_ipa;
181	run->mmio.len		= len;
182	vcpu->mmio_needed	= 1;
183
184	if (!ret) {
185		/* We handled the access successfully in the kernel. */
186		if (!is_write)
187			memcpy(run->mmio.data, data_buf, len);
188		vcpu->stat.mmio_exit_kernel++;
189		kvm_handle_mmio_return(vcpu);
190		return 1;
191	}
192
193	if (is_write)
194		memcpy(run->mmio.data, data_buf, len);
195	vcpu->stat.mmio_exit_user++;
196	run->exit_reason	= KVM_EXIT_MMIO;
197	return 0;
198}
199