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. Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx> --- arch/x86/kvm/vmx.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 051dab74e4e9..c8a8391e95e5 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -6231,15 +6231,15 @@ static int handle_io(struct kvm_vcpu *vcpu) exit_qualification = vmcs_readl(EXIT_QUALIFICATION); string = (exit_qualification & 16) != 0; - in = (exit_qualification & 8) != 0; ++vcpu->stat.io_exits; - if (string || in) + if (string) return emulate_instruction(vcpu, 0) == EMULATE_DONE; port = exit_qualification >> 16; size = (exit_qualification & 7) + 1; + in = (exit_qualification & 8) != 0; ret = kvm_skip_emulated_instruction(vcpu); @@ -6247,7 +6247,10 @@ static int handle_io(struct kvm_vcpu *vcpu) * TODO: we might be squashing a KVM_GUESTDBG_SINGLESTEP-triggered * KVM_EXIT_DEBUG here. */ - return kvm_fast_pio_out(vcpu, size, port) && ret; + if (in) + return kvm_fast_pio_in(vcpu, size, port) && ret; + else + return kvm_fast_pio_out(vcpu, size, port) && ret; } static void -- 2.16.2
