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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* KVM/MIPS: Binary Patching for privileged instructions, reduces traps.
*
* Copyright (C) 2012 MIPS Technologies, Inc. All rights reserved.
* Authors: Sanjay Lal <sanjayl@kymasys.com>
*/
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/kvm_host.h>
#include <linux/module.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include <linux/bootmem.h>
#include <asm/cacheflush.h>
#include "commpage.h"
/**
* kvm_mips_trans_replace() - Replace trapping instruction in guest memory.
* @vcpu: Virtual CPU.
* @opc: PC of instruction to replace.
* @replace: Instruction to write
*/
static int kvm_mips_trans_replace(struct kvm_vcpu *vcpu, u32 *opc,
union mips_instruction replace)
{
unsigned long kseg0_opc, flags;
if (KVM_GUEST_KSEGX(opc) == KVM_GUEST_KSEG0) {
kseg0_opc =
CKSEG0ADDR(kvm_mips_translate_guest_kseg0_to_hpa
(vcpu, (unsigned long) opc));
memcpy((void *)kseg0_opc, (void *)&replace, sizeof(u32));
local_flush_icache_range(kseg0_opc, kseg0_opc + 32);
} else if (KVM_GUEST_KSEGX((unsigned long) opc) == KVM_GUEST_KSEG23) {
local_irq_save(flags);
memcpy((void *)opc, (void *)&replace, sizeof(u32));
local_flush_icache_range((unsigned long)opc,
(unsigned long)opc + 32);
local_irq_restore(flags);
} else {
kvm_err("%s: Invalid address: %p\n", __func__, opc);
return -EFAULT;
}
return 0;
}
int kvm_mips_trans_cache_index(union mips_instruction inst, u32 *opc,
struct kvm_vcpu *vcpu)
{
union mips_instruction nop_inst = { 0 };
/* Replace the CACHE instruction, with a NOP */
return kvm_mips_trans_replace(vcpu, opc, nop_inst);
}
/*
* Address based CACHE instructions are transformed into synci(s). A little
* heavy for just D-cache invalidates, but avoids an expensive trap
*/
int kvm_mips_trans_cache_va(union mips_instruction inst, u32 *opc,
struct kvm_vcpu *vcpu)
{
union mips_instruction synci_inst = { 0 };
synci_inst.i_format.opcode = bcond_op;
synci_inst.i_format.rs = inst.i_format.rs;
synci_inst.i_format.rt = synci_op;
synci_inst.i_format.simmediate = inst.i_format.simmediate;
return kvm_mips_trans_replace(vcpu, opc, synci_inst);
}
int kvm_mips_trans_mfc0(union mips_instruction inst, u32 *opc,
struct kvm_vcpu *vcpu)
{
union mips_instruction mfc0_inst = { 0 };
u32 rd, sel;
rd = inst.c0r_format.rd;
sel = inst.c0r_format.sel;
if (rd == MIPS_CP0_ERRCTL && sel == 0) {
mfc0_inst.r_format.opcode = spec_op;
mfc0_inst.r_format.rd = inst.c0r_format.rt;
mfc0_inst.r_format.func = add_op;
} else {
mfc0_inst.i_format.opcode = lw_op;
mfc0_inst.i_format.rt = inst.c0r_format.rt;
mfc0_inst.i_format.simmediate = KVM_GUEST_COMMPAGE_ADDR |
offsetof(struct kvm_mips_commpage, cop0.reg[rd][sel]);
}
return kvm_mips_trans_replace(vcpu, opc, mfc0_inst);
}
int kvm_mips_trans_mtc0(union mips_instruction inst, u32 *opc,
struct kvm_vcpu *vcpu)
{
union mips_instruction mtc0_inst = { 0 };
u32 rd, sel;
rd = inst.c0r_format.rd;
sel = inst.c0r_format.sel;
mtc0_inst.i_format.opcode = sw_op;
mtc0_inst.i_format.rt = inst.c0r_format.rt;
mtc0_inst.i_format.simmediate = KVM_GUEST_COMMPAGE_ADDR |
offsetof(struct kvm_mips_commpage, cop0.reg[rd][sel]);
return kvm_mips_trans_replace(vcpu, opc, mtc0_inst);
}
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