Commit 4fc40f07 authored by Gleb Natapov's avatar Gleb Natapov Committed by Avi Kivity
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KVM: x86 emulator: check io permissions only once for string pio 



Do not recheck io permission on every iteration.

Signed-off-by: default avatarGleb Natapov <gleb@redhat.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 9928ff60

arch/x86/include/asm/kvm_emulate.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */

arch/x86/kvm/emulate.c

+6 −0
Original line number Diff line number Diff line
@@ -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;

}

arch/x86/kvm/x86.c

+1 −0
Original line number Diff line number Diff line
@@ -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);

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