From 4fc40f076f4fa289dd546990b597351c9cdad985 Mon Sep 17 00:00:00 2001 From: Gleb Natapov Date: Mon, 2 Aug 2010 12:47:51 +0300 Subject: [PATCH] KVM: x86 emulator: check io permissions only once for string pio Do not recheck io permission on every iteration. Signed-off-by: Gleb Natapov Signed-off-by: Avi Kivity --- arch/x86/include/asm/kvm_emulate.h | 1 + arch/x86/kvm/emulate.c | 6 ++++++ arch/x86/kvm/x86.c | 1 + 3 files changed, 8 insertions(+) diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h index 0f901c1..8762411 100644 --- a/arch/x86/include/asm/kvm_emulate.h +++ b/arch/x86/include/asm/kvm_emulate.h @@ -224,6 +224,7 @@ struct x86_emulate_ctxt { int interruptibility; bool restart; /* restart string instruction after writeback */ + bool perm_ok; /* do not check permissions if true */ int exception; /* exception that happens during emulation or -1 */ u32 error_code; /* error code for exception */ diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 4d49514..760e2b0 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -1621,9 +1621,15 @@ static bool emulator_io_permited(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops, u16 port, u16 len) { + if (ctxt->perm_ok) + return true; + if (emulator_bad_iopl(ctxt, ops)) if (!emulator_io_port_access_allowed(ctxt, ops, port, len)) return false; + + ctxt->perm_ok = true; + return true; } diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 3cbe803..35c0f4e 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3997,6 +3997,7 @@ int emulate_instruction(struct kvm_vcpu *vcpu, memcpy(c->regs, vcpu->arch.regs, sizeof c->regs); vcpu->arch.emulate_ctxt.interruptibility = 0; vcpu->arch.emulate_ctxt.exception = -1; + vcpu->arch.emulate_ctxt.perm_ok = false; r = x86_decode_insn(&vcpu->arch.emulate_ctxt); trace_kvm_emulate_insn_start(vcpu); -- 2.7.4