On Fri, Jan 18, 2019 at 02:34:00PM +0800, Luwei Kang wrote:
> Some Posted-Interrupts from passthrough devices may be lost or
> overwritten when the vCPU is in runnable state.
>
> The SN (Suppress Notification) of PID (Posted Interrupt Descriptor) will
> be set when the vCPU is preempted (vCPU in KVM_MP_STATE_RUNNABLE state
> but not running on physical CPU). If a posted interrupt coming at this
> time, the irq remmaping facility will set the bit of PIR (Posted
> Interrupt Requests) but ON (Outstanding Notification).
s/but ON/and ON is set too/?
> So this interrupt can't be sync to APIC virtualization register and
> will not be handled by Guest because ON is zero.
>
> Signed-off-by: Luwei Kang <luwei.kang@xxxxxxxxx>
> ---
> arch/x86/kvm/vmx/vmx.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index f6915f1..820a03b 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -6048,7 +6048,7 @@ static int vmx_sync_pir_to_irr(struct kvm_vcpu *vcpu)
> bool max_irr_updated;
>
> WARN_ON(!vcpu->arch.apicv_active);
> - if (pi_test_on(&vmx->pi_desc)) {
> + if (!bitmap_empty((unsigned long *)vmx->pi_desc.pir, NR_VECTORS)) {
> pi_clear_on(&vmx->pi_desc);
> /*
> * IOMMU can write to PIR.ON, so the barrier matters even on UP.
