1/*
  2 * This file is subject to the terms and conditions of the GNU General Public
  3 * License.  See the file "COPYING" in the main directory of this archive
  4 * for more details.
  5 *
  6 * KVM/MIPS: Binary Patching for privileged instructions, reduces traps.
  7 *
  8 * Copyright (C) 2012  MIPS Technologies, Inc.  All rights reserved.
  9 * Authors: Sanjay Lal <sanjayl@kymasys.com>
 10 */
 11
 12#include <linux/errno.h>
 13#include <linux/err.h>
 14#include <linux/kvm_host.h>
 15#include <linux/module.h>
 16#include <linux/vmalloc.h>
 17#include <linux/fs.h>
 18#include <linux/bootmem.h>
 19#include <asm/cacheflush.h>
 20
 21#include "commpage.h"
 22
 23#define SYNCI_TEMPLATE  0x041f0000
 24#define SYNCI_BASE(x)   (((x) >> 21) & 0x1f)
 25#define SYNCI_OFFSET    ((x) & 0xffff)
 26
 27#define LW_TEMPLATE     0x8c000000
 28#define CLEAR_TEMPLATE  0x00000020
 29#define SW_TEMPLATE     0xac000000
 30
 31int kvm_mips_trans_cache_index(uint32_t inst, uint32_t *opc,
 32			       struct kvm_vcpu *vcpu)
 33{
 34	int result = 0;
 35	unsigned long kseg0_opc;
 36	uint32_t synci_inst = 0x0;
 37
 38	/* Replace the CACHE instruction, with a NOP */
 39	kseg0_opc =
 40	    CKSEG0ADDR(kvm_mips_translate_guest_kseg0_to_hpa
 41		       (vcpu, (unsigned long) opc));
 42	memcpy((void *)kseg0_opc, (void *)&synci_inst, sizeof(uint32_t));
 43	local_flush_icache_range(kseg0_opc, kseg0_opc + 32);
 44
 45	return result;
 46}
 47
 48/*
 49 * Address based CACHE instructions are transformed into synci(s). A little
 50 * heavy for just D-cache invalidates, but avoids an expensive trap
 51 */
 52int kvm_mips_trans_cache_va(uint32_t inst, uint32_t *opc,
 53			    struct kvm_vcpu *vcpu)
 54{
 55	int result = 0;
 56	unsigned long kseg0_opc;
 57	uint32_t synci_inst = SYNCI_TEMPLATE, base, offset;
 58
 59	base = (inst >> 21) & 0x1f;
 60	offset = inst & 0xffff;
 61	synci_inst |= (base << 21);
 62	synci_inst |= offset;
 63
 64	kseg0_opc =
 65	    CKSEG0ADDR(kvm_mips_translate_guest_kseg0_to_hpa
 66		       (vcpu, (unsigned long) opc));
 67	memcpy((void *)kseg0_opc, (void *)&synci_inst, sizeof(uint32_t));
 68	local_flush_icache_range(kseg0_opc, kseg0_opc + 32);
 69
 70	return result;
 71}
 72
 73int kvm_mips_trans_mfc0(uint32_t inst, uint32_t *opc, struct kvm_vcpu *vcpu)
 74{
 75	int32_t rt, rd, sel;
 76	uint32_t mfc0_inst;
 77	unsigned long kseg0_opc, flags;
 78
 79	rt = (inst >> 16) & 0x1f;
 80	rd = (inst >> 11) & 0x1f;
 81	sel = inst & 0x7;
 82
 83	if ((rd == MIPS_CP0_ERRCTL) && (sel == 0)) {
 84		mfc0_inst = CLEAR_TEMPLATE;
 85		mfc0_inst |= ((rt & 0x1f) << 16);
 86	} else {
 87		mfc0_inst = LW_TEMPLATE;
 88		mfc0_inst |= ((rt & 0x1f) << 16);
 89		mfc0_inst |= offsetof(struct kvm_mips_commpage,
 90				      cop0.reg[rd][sel]);
 91	}
 92
 93	if (KVM_GUEST_KSEGX(opc) == KVM_GUEST_KSEG0) {
 94		kseg0_opc =
 95		    CKSEG0ADDR(kvm_mips_translate_guest_kseg0_to_hpa
 96			       (vcpu, (unsigned long) opc));
 97		memcpy((void *)kseg0_opc, (void *)&mfc0_inst, sizeof(uint32_t));
 98		local_flush_icache_range(kseg0_opc, kseg0_opc + 32);
 99	} else if (KVM_GUEST_KSEGX((unsigned long) opc) == KVM_GUEST_KSEG23) {
100		local_irq_save(flags);
101		memcpy((void *)opc, (void *)&mfc0_inst, sizeof(uint32_t));
102		local_flush_icache_range((unsigned long)opc,
103					 (unsigned long)opc + 32);
104		local_irq_restore(flags);
105	} else {
106		kvm_err("%s: Invalid address: %p\n", __func__, opc);
107		return -EFAULT;
108	}
109
110	return 0;
111}
112
113int kvm_mips_trans_mtc0(uint32_t inst, uint32_t *opc, struct kvm_vcpu *vcpu)
114{
115	int32_t rt, rd, sel;
116	uint32_t mtc0_inst = SW_TEMPLATE;
117	unsigned long kseg0_opc, flags;
118
119	rt = (inst >> 16) & 0x1f;
120	rd = (inst >> 11) & 0x1f;
121	sel = inst & 0x7;
122
123	mtc0_inst |= ((rt & 0x1f) << 16);
124	mtc0_inst |= offsetof(struct kvm_mips_commpage, cop0.reg[rd][sel]);
125
126	if (KVM_GUEST_KSEGX(opc) == KVM_GUEST_KSEG0) {
127		kseg0_opc =
128		    CKSEG0ADDR(kvm_mips_translate_guest_kseg0_to_hpa
129			       (vcpu, (unsigned long) opc));
130		memcpy((void *)kseg0_opc, (void *)&mtc0_inst, sizeof(uint32_t));
131		local_flush_icache_range(kseg0_opc, kseg0_opc + 32);
132	} else if (KVM_GUEST_KSEGX((unsigned long) opc) == KVM_GUEST_KSEG23) {
133		local_irq_save(flags);
134		memcpy((void *)opc, (void *)&mtc0_inst, sizeof(uint32_t));
135		local_flush_icache_range((unsigned long)opc,
136					 (unsigned long)opc + 32);
137		local_irq_restore(flags);
138	} else {
139		kvm_err("%s: Invalid address: %p\n", __func__, opc);
140		return -EFAULT;
141	}
142
143	return 0;
144}