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_mmio.h>
  9#include <asm/kvm_emulate.h>
 10#include <trace/events/kvm.h>
 11
 12#include "trace.h"
 13
 14void kvm_mmio_write_buf(void *buf, unsigned int len, unsigned long data)
 15{
 16	void *datap = NULL;
 17	union {
 18		u8	byte;
 19		u16	hword;
 20		u32	word;
 21		u64	dword;
 22	} tmp;
 23
 24	switch (len) {
 25	case 1:
 26		tmp.byte	= data;
 27		datap		= &tmp.byte;
 28		break;
 29	case 2:
 30		tmp.hword	= data;
 31		datap		= &tmp.hword;
 32		break;
 33	case 4:
 34		tmp.word	= data;
 35		datap		= &tmp.word;
 36		break;
 37	case 8:
 38		tmp.dword	= data;
 39		datap		= &tmp.dword;
 40		break;
 41	}
 42
 43	memcpy(buf, datap, len);
 44}
 45
 46unsigned long kvm_mmio_read_buf(const void *buf, unsigned int len)
 47{
 48	unsigned long data = 0;
 49	union {
 50		u16	hword;
 51		u32	word;
 52		u64	dword;
 53	} tmp;
 54
 55	switch (len) {
 56	case 1:
 57		data = *(u8 *)buf;
 58		break;
 59	case 2:
 60		memcpy(&tmp.hword, buf, len);
 61		data = tmp.hword;
 62		break;
 63	case 4:
 64		memcpy(&tmp.word, buf, len);
 65		data = tmp.word;
 66		break;
 67	case 8:
 68		memcpy(&tmp.dword, buf, len);
 69		data = tmp.dword;
 70		break;
 71	}
 72
 73	return data;
 74}
 75
 76/**
 77 * kvm_handle_mmio_return -- Handle MMIO loads after user space emulation
 78 *			     or in-kernel IO emulation
 79 *
 80 * @vcpu: The VCPU pointer
 81 * @run:  The VCPU run struct containing the mmio data
 82 */
 83int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run)
 84{
 85	unsigned long data;
 86	unsigned int len;
 87	int mask;
 88
 89	/* Detect an already handled MMIO return */
 90	if (unlikely(!vcpu->mmio_needed))
 91		return 0;
 92
 93	vcpu->mmio_needed = 0;
 94
 95	if (!run->mmio.is_write) {
 96		len = run->mmio.len;
 97		if (len > sizeof(unsigned long))
 98			return -EINVAL;
 99
100		data = kvm_mmio_read_buf(run->mmio.data, len);
101
102		if (vcpu->arch.mmio_decode.sign_extend &&
103		    len < sizeof(unsigned long)) {
104			mask = 1U << ((len * 8) - 1);
105			data = (data ^ mask) - mask;
106		}
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, vcpu->arch.mmio_decode.rt, data);
112	}
113
114	/*
115	 * The MMIO instruction is emulated and should not be re-executed
116	 * in the guest.
117	 */
118	kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
119
120	return 0;
121}
122
123static int decode_hsr(struct kvm_vcpu *vcpu, bool *is_write, int *len)
124{
125	unsigned long rt;
126	int access_size;
127	bool sign_extend;
128
129	if (kvm_vcpu_dabt_iss1tw(vcpu)) {
130		/* page table accesses IO mem: tell guest to fix its TTBR */
131		kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
132		return 1;
133	}
134
135	access_size = kvm_vcpu_dabt_get_as(vcpu);
136	if (unlikely(access_size < 0))
137		return access_size;
138
139	*is_write = kvm_vcpu_dabt_iswrite(vcpu);
140	sign_extend = kvm_vcpu_dabt_issext(vcpu);
141	rt = kvm_vcpu_dabt_get_rd(vcpu);
142
143	*len = access_size;
144	vcpu->arch.mmio_decode.sign_extend = sign_extend;
145	vcpu->arch.mmio_decode.rt = rt;
146
147	return 0;
148}
149
150int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
151		 phys_addr_t fault_ipa)
152{
153	unsigned long data;
154	unsigned long rt;
155	int ret;
156	bool is_write;
157	int len;
158	u8 data_buf[8];
159
160	/*
161	 * Prepare MMIO operation. First decode the syndrome data we get
162	 * from the CPU. Then try if some in-kernel emulation feels
163	 * responsible, otherwise let user space do its magic.
164	 */
165	if (kvm_vcpu_dabt_isvalid(vcpu)) {
166		ret = decode_hsr(vcpu, &is_write, &len);
167		if (ret)
168			return ret;
169	} else {
170		kvm_err("load/store instruction decoding not implemented\n");
171		return -ENOSYS;
172	}
173
174	rt = vcpu->arch.mmio_decode.rt;
175
176	if (is_write) {
177		data = vcpu_data_guest_to_host(vcpu, vcpu_get_reg(vcpu, rt),
178					       len);
179
180		trace_kvm_mmio(KVM_TRACE_MMIO_WRITE, len, fault_ipa, &data);
181		kvm_mmio_write_buf(data_buf, len, data);
182
183		ret = kvm_io_bus_write(vcpu, KVM_MMIO_BUS, fault_ipa, len,
184				       data_buf);
185	} else {
186		trace_kvm_mmio(KVM_TRACE_MMIO_READ_UNSATISFIED, len,
187			       fault_ipa, NULL);
188
189		ret = kvm_io_bus_read(vcpu, KVM_MMIO_BUS, fault_ipa, len,
190				      data_buf);
191	}
192
193	/* Now prepare kvm_run for the potential return to userland. */
194	run->mmio.is_write	= is_write;
195	run->mmio.phys_addr	= fault_ipa;
196	run->mmio.len		= len;
197	vcpu->mmio_needed	= 1;
198
199	if (!ret) {
200		/* We handled the access successfully in the kernel. */
201		if (!is_write)
202			memcpy(run->mmio.data, data_buf, len);
203		vcpu->stat.mmio_exit_kernel++;
204		kvm_handle_mmio_return(vcpu, run);
205		return 1;
206	}
207
208	if (is_write)
209		memcpy(run->mmio.data, data_buf, len);
210	vcpu->stat.mmio_exit_user++;
211	run->exit_reason	= KVM_EXIT_MMIO;
212	return 0;
213}