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
 26void kvm_mmio_write_buf(void *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
 58unsigned long kvm_mmio_read_buf(const void *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 = *(u8 *)buf;
 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 *			     or in-kernel IO emulation
 91 *
 92 * @vcpu: The VCPU pointer
 93 * @run:  The VCPU run struct containing the mmio data
 94 */
 95int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run)
 96{
 97	unsigned long data;
 98	unsigned int len;
 99	int mask;
100
101	if (!run->mmio.is_write) {
102		len = run->mmio.len;
103		if (len > sizeof(unsigned long))
104			return -EINVAL;
105
106		data = kvm_mmio_read_buf(run->mmio.data, len);
107
108		if (vcpu->arch.mmio_decode.sign_extend &&
109		    len < sizeof(unsigned long)) {
110			mask = 1U << ((len * 8) - 1);
111			data = (data ^ mask) - mask;
112		}
113
114		trace_kvm_mmio(KVM_TRACE_MMIO_READ, len, run->mmio.phys_addr,
115			       data);
116		data = vcpu_data_host_to_guest(vcpu, data, len);
117		vcpu_set_reg(vcpu, vcpu->arch.mmio_decode.rt, data);
118	}
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	/*
148	 * The MMIO instruction is emulated and should not be re-executed
149	 * in the guest.
150	 */
151	kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
152	return 0;
153}
154
155int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
156		 phys_addr_t fault_ipa)
157{
158	unsigned long data;
159	unsigned long rt;
160	int ret;
161	bool is_write;
162	int len;
163	u8 data_buf[8];
164
165	/*
166	 * Prepare MMIO operation. First decode the syndrome data we get
167	 * from the CPU. Then try if some in-kernel emulation feels
168	 * responsible, otherwise let user space do its magic.
169	 */
170	if (kvm_vcpu_dabt_isvalid(vcpu)) {
171		ret = decode_hsr(vcpu, &is_write, &len);
172		if (ret)
173			return ret;
174	} else {
175		kvm_err("load/store instruction decoding not implemented\n");
176		return -ENOSYS;
177	}
178
179	rt = vcpu->arch.mmio_decode.rt;
180
181	if (is_write) {
182		data = vcpu_data_guest_to_host(vcpu, vcpu_get_reg(vcpu, rt),
183					       len);
184
185		trace_kvm_mmio(KVM_TRACE_MMIO_WRITE, len, fault_ipa, data);
186		kvm_mmio_write_buf(data_buf, len, data);
187
188		ret = kvm_io_bus_write(vcpu, KVM_MMIO_BUS, fault_ipa, len,
189				       data_buf);
190	} else {
191		trace_kvm_mmio(KVM_TRACE_MMIO_READ_UNSATISFIED, len,
192			       fault_ipa, 0);
193
194		ret = kvm_io_bus_read(vcpu, KVM_MMIO_BUS, fault_ipa, len,
195				      data_buf);
196	}
197
198	/* Now prepare kvm_run for the potential return to userland. */
199	run->mmio.is_write	= is_write;
200	run->mmio.phys_addr	= fault_ipa;
201	run->mmio.len		= len;
202
203	if (!ret) {
204		/* We handled the access successfully in the kernel. */
205		if (!is_write)
206			memcpy(run->mmio.data, data_buf, len);
207		vcpu->stat.mmio_exit_kernel++;
208		kvm_handle_mmio_return(vcpu, run);
209		return 1;
210	}
211
212	if (is_write)
213		memcpy(run->mmio.data, data_buf, len);
214	vcpu->stat.mmio_exit_user++;
215	run->exit_reason	= KVM_EXIT_MMIO;
216	return 0;
217}