diff options
Diffstat (limited to 'arch/mips/kvm/dyntrans.c')
| -rw-r--r-- | arch/mips/kvm/dyntrans.c | 143 |
1 files changed, 143 insertions, 0 deletions
diff --git a/arch/mips/kvm/dyntrans.c b/arch/mips/kvm/dyntrans.c new file mode 100644 index 000000000..f8e772564 --- /dev/null +++ b/arch/mips/kvm/dyntrans.c @@ -0,0 +1,143 @@ +/* + * 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/highmem.h> +#include <linux/kvm_host.h> +#include <linux/uaccess.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 vaddr = (unsigned long)opc; + int err; + +retry: + /* The GVA page table is still active so use the Linux TLB handlers */ + kvm_trap_emul_gva_lockless_begin(vcpu); + err = put_user(replace.word, opc); + kvm_trap_emul_gva_lockless_end(vcpu); + + if (unlikely(err)) { + /* + * We write protect clean pages in GVA page table so normal + * Linux TLB mod handler doesn't silently dirty the page. + * Its also possible we raced with a GVA invalidation. + * Try to force the page to become dirty. + */ + err = kvm_trap_emul_gva_fault(vcpu, vaddr, true); + if (unlikely(err)) { + kvm_info("%s: Address unwriteable: %p\n", + __func__, opc); + return -EFAULT; + } + + /* + * Try again. This will likely trigger a TLB refill, which will + * fetch the new dirty entry from the GVA page table, which + * should then succeed. + */ + goto retry; + } + __local_flush_icache_user_range(vaddr, vaddr + 4); + + 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; + if (cpu_has_mips_r6) + synci_inst.i_format.simmediate = inst.spec3_format.simmediate; + else + 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]); +#ifdef CONFIG_CPU_BIG_ENDIAN + if (sizeof(vcpu->arch.cop0->reg[0][0]) == 8) + mfc0_inst.i_format.simmediate |= 4; +#endif + } + + 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]); +#ifdef CONFIG_CPU_BIG_ENDIAN + if (sizeof(vcpu->arch.cop0->reg[0][0]) == 8) + mtc0_inst.i_format.simmediate |= 4; +#endif + + return kvm_mips_trans_replace(vcpu, opc, mtc0_inst); +} |