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	if (is_write)
210		memcpy(run->mmio.data, data_buf, len);
211
212	if (!ret) {
213		/* We handled the access successfully in the kernel. */
214		vcpu->stat.mmio_exit_kernel++;
215		kvm_handle_mmio_return(vcpu, run);
216		return 1;
217	} else {
218		vcpu->stat.mmio_exit_user++;
219	}
220
221	run->exit_reason	= KVM_EXIT_MMIO;
222	return 0;
223}