The idea is from Avi: | tag instructions that are typically used to modify the page tables, and drop | shadow if any other instruction is used | The list would include, I'd guess, and, or, bts, btc, mov, xchg, cmpxchg, and | cmpxchg8b
This patch is used to tag the instructions and in the later path, shadow page is dropped if it is written by other instructions Signed-off-by: Xiao Guangrong <[email protected]> --- arch/x86/include/asm/kvm_emulate.h | 1 + arch/x86/kvm/emulate.c | 8 ++++++++ arch/x86/kvm/x86.c | 1 + arch/x86/kvm/x86.h | 5 +++++ 4 files changed, 15 insertions(+), 0 deletions(-) diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h index 6040d11..049a6f5 100644 --- a/arch/x86/include/asm/kvm_emulate.h +++ b/arch/x86/include/asm/kvm_emulate.h @@ -244,6 +244,7 @@ struct x86_emulate_ctxt { bool guest_mode; /* guest running a nested guest */ bool perm_ok; /* do not check permissions if true */ bool only_vendor_specific_insn; + bool page_table_written_insn; bool have_exception; struct x86_exception exception; diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 0453c07..3c027ac 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -2516,6 +2516,7 @@ static int em_add(struct x86_emulate_ctxt *ctxt) static int em_or(struct x86_emulate_ctxt *ctxt) { emulate_2op_SrcV("or", ctxt->src, ctxt->dst, ctxt->eflags); + tag_page_table_written_insn(ctxt); return X86EMUL_CONTINUE; } @@ -2534,6 +2535,7 @@ static int em_sbb(struct x86_emulate_ctxt *ctxt) static int em_and(struct x86_emulate_ctxt *ctxt) { emulate_2op_SrcV("and", ctxt->src, ctxt->dst, ctxt->eflags); + tag_page_table_written_insn(ctxt); return X86EMUL_CONTINUE; } @@ -2572,6 +2574,7 @@ static int em_xchg(struct x86_emulate_ctxt *ctxt) /* Write back the memory destination with implicit LOCK prefix. */ ctxt->dst.val = ctxt->src.orig_val; ctxt->lock_prefix = 1; + tag_page_table_written_insn(ctxt); return X86EMUL_CONTINUE; } @@ -2610,6 +2613,7 @@ static int em_rdtsc(struct x86_emulate_ctxt *ctxt) static int em_mov(struct x86_emulate_ctxt *ctxt) { ctxt->dst.val = ctxt->src.val; + tag_page_table_written_insn(ctxt); return X86EMUL_CONTINUE; } @@ -4135,6 +4139,7 @@ twobyte_insn: break; case 0xab: bts: /* bts */ + tag_page_table_written_insn(ctxt); emulate_2op_SrcV_nobyte("bts", ctxt->src, ctxt->dst, ctxt->eflags); break; case 0xac: /* shrd imm8, r, r/m */ @@ -4148,6 +4153,7 @@ twobyte_insn: * Save real source value, then compare EAX against * destination. */ + tag_page_table_written_insn(ctxt); ctxt->src.orig_val = ctxt->src.val; ctxt->src.val = ctxt->regs[VCPU_REGS_RAX]; emulate_2op_SrcV("cmp", ctxt->src, ctxt->dst, ctxt->eflags); @@ -4192,6 +4198,7 @@ twobyte_insn: break; case 0xbb: btc: /* btc */ + tag_page_table_written_insn(ctxt); emulate_2op_SrcV_nobyte("btc", ctxt->src, ctxt->dst, ctxt->eflags); break; case 0xbc: { /* bsf */ @@ -4235,6 +4242,7 @@ twobyte_insn: (u64) ctxt->src.val; break; case 0xc7: /* Grp9 (cmpxchg8b) */ + tag_page_table_written_insn(ctxt); rc = em_grp9(ctxt); break; default: diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index ea8f9f0..cf6fb29 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4831,6 +4831,7 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, ctxt->interruptibility = 0; ctxt->have_exception = false; ctxt->perm_ok = false; + ctxt->page_table_written_insn = false; ctxt->only_vendor_specific_insn = emulation_type & EMULTYPE_TRAP_UD; diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index d36fe23..b6e868f 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -111,6 +111,11 @@ static inline bool vcpu_match_mmio_gpa(struct kvm_vcpu *vcpu, gpa_t gpa) return false; } +static inline void tag_page_table_written_insn(struct x86_emulate_ctxt *ctxt) +{ + ctxt->page_table_written_insn = true; +} + void kvm_before_handle_nmi(struct kvm_vcpu *vcpu); void kvm_after_handle_nmi(struct kvm_vcpu *vcpu); int kvm_inject_realmode_interrupt(struct kvm_vcpu *vcpu, int irq, int inc_eip); -- 1.7.5.4 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
