On Wed, 2018-10-03 at 13:47 +0200, Paolo Bonzini wrote:
> Commit b5861e5cf2fcf83031ea3e26b0a69d887adf7d21 introduced a check on
> the interrupt-window and NMI-window CPU execution controls in order to
> inject an external interrupt vmexit before the first guest instruction
> executes. However, when APIC virtualization is enabled the host does not
> need a vmexit in order to inject an interrupt at the next interrupt window;
> instead, it just places the interrupt vector in RVI and the processor will
> inject it as soon as possible. Therefore, on machines with APICv it is
> not enough to check the CPU execution controls: the same scenario can also
> happen if RVI>0.
>
> Fixes: b5861e5cf2fcf83031ea3e26b0a69d887adf7d21
> Cc: Nikita Leshchenko <nikita.leshchenko@xxxxxxxxxx>
> Cc: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> Cc: Liran Alon <liran.alon@xxxxxxxxxx>
> Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx>
> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> ---
> arch/x86/kvm/vmx.c | 16 +++++++++++-----
> 1 file changed, 11 insertions(+), 5 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 6ef2d5b139b9..c0c7689f0049 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -10280,6 +10280,11 @@ static void vmx_hwapic_isr_update(struct kvm_vcpu *vcpu, int max_isr)
> }
> }
>
> +static u8 vmx_get_rvi(void)
> +{
> + return vmcs_read16(GUEST_INTR_STATUS) & 0xff;
> +}
> +
> static void vmx_set_rvi(int vector)
> {
> u16 status;
> @@ -12593,10 +12598,13 @@ static int enter_vmx_non_root_mode(struct kvm_vcpu *vcpu, u32 *exit_qual)
> struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
> bool from_vmentry = !!exit_qual;
> u32 dummy_exit_qual;
> - u32 vmcs01_cpu_exec_ctrl;
> + bool evaluate_pending_interrupts;
> int r = 0;
>
> - vmcs01_cpu_exec_ctrl = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
> + evaluate_pending_interrupts = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL) &
> + (CPU_BASED_VIRTUAL_INTR_PENDING | CPU_BASED_VIRTUAL_NMI_PENDING);
> + if (enable_apicv && kvm_vcpu_apicv_active(vcpu))
> + evaluate_pending_interrupts |= vmx_get_rvi() > 0;
You should check for RVI > VPPR, similarly to how it is done in
vmx_guest_apic_has_interrupt().
Also, now that you introduced vmx_get_rvi(), it could be nice to use it
in vmx_guest_apic_has_interrupt() as well.
Apart from that, looks good.
Reviewed-by: Nikita Leshenko <nikita.leshchenko@xxxxxxxxxx>
Thanks,
Nikita
>
> enter_guest_mode(vcpu);
>
> @@ -12650,10 +12658,8 @@ static int enter_vmx_non_root_mode(struct kvm_vcpu *vcpu, u32 *exit_qual)
> * instead. Thus, we force L0 to perform pending event
> * evaluation by requesting a KVM_REQ_EVENT.
> */
> - if (vmcs01_cpu_exec_ctrl &
> - (CPU_BASED_VIRTUAL_INTR_PENDING | CPU_BASED_VIRTUAL_NMI_PENDING)) {
> + if (evaluate_pending_interrupts)
> kvm_make_request(KVM_REQ_EVENT, vcpu);
> - }
>
> /*
> * Note no nested_vmx_succeed or nested_vmx_fail here. At this point
