144 lines
4.0 KiB
C
144 lines
4.0 KiB
C
/*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* KVM/MIPS: Binary Patching for privileged instructions, reduces traps.
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*
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* Copyright (C) 2012 MIPS Technologies, Inc. All rights reserved.
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* Authors: Sanjay Lal <sanjayl@kymasys.com>
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*/
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#include <linux/errno.h>
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#include <linux/err.h>
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#include <linux/highmem.h>
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#include <linux/kvm_host.h>
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#include <linux/uaccess.h>
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#include <linux/vmalloc.h>
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#include <linux/fs.h>
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#include <linux/memblock.h>
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#include <asm/cacheflush.h>
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#include "commpage.h"
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/**
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* kvm_mips_trans_replace() - Replace trapping instruction in guest memory.
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* @vcpu: Virtual CPU.
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* @opc: PC of instruction to replace.
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* @replace: Instruction to write
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*/
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static int kvm_mips_trans_replace(struct kvm_vcpu *vcpu, u32 *opc,
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union mips_instruction replace)
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{
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unsigned long vaddr = (unsigned long)opc;
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int err;
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retry:
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/* The GVA page table is still active so use the Linux TLB handlers */
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kvm_trap_emul_gva_lockless_begin(vcpu);
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err = put_user(replace.word, opc);
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kvm_trap_emul_gva_lockless_end(vcpu);
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if (unlikely(err)) {
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/*
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* We write protect clean pages in GVA page table so normal
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* Linux TLB mod handler doesn't silently dirty the page.
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* Its also possible we raced with a GVA invalidation.
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* Try to force the page to become dirty.
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*/
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err = kvm_trap_emul_gva_fault(vcpu, vaddr, true);
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if (unlikely(err)) {
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kvm_info("%s: Address unwriteable: %p\n",
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__func__, opc);
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return -EFAULT;
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}
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/*
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* Try again. This will likely trigger a TLB refill, which will
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* fetch the new dirty entry from the GVA page table, which
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* should then succeed.
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*/
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goto retry;
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}
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__local_flush_icache_user_range(vaddr, vaddr + 4);
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return 0;
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}
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int kvm_mips_trans_cache_index(union mips_instruction inst, u32 *opc,
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struct kvm_vcpu *vcpu)
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{
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union mips_instruction nop_inst = { 0 };
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/* Replace the CACHE instruction, with a NOP */
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return kvm_mips_trans_replace(vcpu, opc, nop_inst);
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}
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/*
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* Address based CACHE instructions are transformed into synci(s). A little
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* heavy for just D-cache invalidates, but avoids an expensive trap
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*/
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int kvm_mips_trans_cache_va(union mips_instruction inst, u32 *opc,
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struct kvm_vcpu *vcpu)
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{
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union mips_instruction synci_inst = { 0 };
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synci_inst.i_format.opcode = bcond_op;
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synci_inst.i_format.rs = inst.i_format.rs;
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synci_inst.i_format.rt = synci_op;
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if (cpu_has_mips_r6)
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synci_inst.i_format.simmediate = inst.spec3_format.simmediate;
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else
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synci_inst.i_format.simmediate = inst.i_format.simmediate;
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return kvm_mips_trans_replace(vcpu, opc, synci_inst);
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}
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int kvm_mips_trans_mfc0(union mips_instruction inst, u32 *opc,
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struct kvm_vcpu *vcpu)
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{
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union mips_instruction mfc0_inst = { 0 };
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u32 rd, sel;
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rd = inst.c0r_format.rd;
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sel = inst.c0r_format.sel;
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if (rd == MIPS_CP0_ERRCTL && sel == 0) {
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mfc0_inst.r_format.opcode = spec_op;
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mfc0_inst.r_format.rd = inst.c0r_format.rt;
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mfc0_inst.r_format.func = add_op;
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} else {
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mfc0_inst.i_format.opcode = lw_op;
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mfc0_inst.i_format.rt = inst.c0r_format.rt;
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mfc0_inst.i_format.simmediate = KVM_GUEST_COMMPAGE_ADDR |
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offsetof(struct kvm_mips_commpage, cop0.reg[rd][sel]);
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#ifdef CONFIG_CPU_BIG_ENDIAN
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if (sizeof(vcpu->arch.cop0->reg[0][0]) == 8)
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mfc0_inst.i_format.simmediate |= 4;
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#endif
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}
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return kvm_mips_trans_replace(vcpu, opc, mfc0_inst);
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}
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int kvm_mips_trans_mtc0(union mips_instruction inst, u32 *opc,
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struct kvm_vcpu *vcpu)
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{
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union mips_instruction mtc0_inst = { 0 };
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u32 rd, sel;
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rd = inst.c0r_format.rd;
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sel = inst.c0r_format.sel;
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mtc0_inst.i_format.opcode = sw_op;
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mtc0_inst.i_format.rt = inst.c0r_format.rt;
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mtc0_inst.i_format.simmediate = KVM_GUEST_COMMPAGE_ADDR |
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offsetof(struct kvm_mips_commpage, cop0.reg[rd][sel]);
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#ifdef CONFIG_CPU_BIG_ENDIAN
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if (sizeof(vcpu->arch.cop0->reg[0][0]) == 8)
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mtc0_inst.i_format.simmediate |= 4;
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#endif
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return kvm_mips_trans_replace(vcpu, opc, mtc0_inst);
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}
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