Commit 432baf60 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: VMX: use kvm_fast_pio_in for handling IN I/O 



Fast emulation of processor I/O for IN was disabled on x86 (both VMX
and SVM) some years ago due to a buggy implementation.  The addition
of kvm_fast_pio_in(), used by SVM, re-introduced (functional!) fast
emulation of IN.  Piggyback SVM's work and use kvm_fast_pio_in() on
VMX instead of performing full emulation of IN.

Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 2bb8cafe

arch/x86/kvm/vmx.c

+6 −3
Original line number Original line Diff line number Diff line
@@ -6270,15 +6270,15 @@ static int handle_io(struct kvm_vcpu *vcpu) 




	exit_qualification = vmcs_readl(EXIT_QUALIFICATION);

	exit_qualification = vmcs_readl(EXIT_QUALIFICATION);

	string = (exit_qualification & 16) != 0;

	string = (exit_qualification & 16) != 0;

	in = (exit_qualification & 8) != 0;





	++vcpu->stat.io_exits;

	++vcpu->stat.io_exits;





	if (string || in)

	if (string)

		return emulate_instruction(vcpu, 0) == EMULATE_DONE;

		return emulate_instruction(vcpu, 0) == EMULATE_DONE;





	port = exit_qualification >> 16;

	port = exit_qualification >> 16;

	size = (exit_qualification & 7) + 1;

	size = (exit_qualification & 7) + 1;

	in = (exit_qualification & 8) != 0;





	ret = kvm_skip_emulated_instruction(vcpu);

	ret = kvm_skip_emulated_instruction(vcpu);
@@ -6286,6 +6286,9 @@ static int handle_io(struct kvm_vcpu *vcpu) 
	 * TODO: we might be squashing a KVM_GUESTDBG_SINGLESTEP-triggered

	 * TODO: we might be squashing a KVM_GUESTDBG_SINGLESTEP-triggered

	 * KVM_EXIT_DEBUG here.

	 * KVM_EXIT_DEBUG here.

	 */

	 */

	if (in)

		return kvm_fast_pio_in(vcpu, size, port) && ret;

	else

		return kvm_fast_pio_out(vcpu, size, port) && ret;

		return kvm_fast_pio_out(vcpu, size, port) && ret;

}

}

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