Re: [patch 4/4] KVM: VMX: update vcpu posted-interrupt descriptor when assigning device

[Paolo Bonzini <pbonzini@redhat.com>]

On 10/05/21 19:26, Marcelo Tosatti wrote:
> +void vmx_pi_start_assignment(struct kvm *kvm)
> +{
> +	struct kvm_vcpu *vcpu;
> +	int i;
> +
> +	if (!irq_remapping_cap(IRQ_POSTING_CAP))
> +		return;
> +
> +	/*
> +	 * Wakeup will cause the vCPU to bail out of kvm_vcpu_block() and
> +	 * go back through vcpu_block().
> +	 */
> +	kvm_for_each_vcpu(i, vcpu, kvm) {
> +		if (!kvm_vcpu_apicv_active(vcpu))
> +			continue;
> +
> +		kvm_vcpu_wake_up(vcpu);

Would you still need the check_block callback, if you also added a 
kvm_make_request(KVM_REQ_EVENT)?

In fact, since this is entirely not a hot path, can you just do 
kvm_make_all_cpus_request(kvm, KVM_REQ_EVENT) instead of this loop?

Thanks,

Paolo

> +	}
> +}
>   
>   /*
>    * pi_update_irte - set IRTE for Posted-Interrupts
> Index: kvm/arch/x86/kvm/vmx/posted_intr.h
> ===================================================================
> --- kvm.orig/arch/x86/kvm/vmx/posted_intr.h
> +++ kvm/arch/x86/kvm/vmx/posted_intr.h
> @@ -95,5 +95,7 @@ void __init pi_init_cpu(int cpu);
>   bool pi_has_pending_interrupt(struct kvm_vcpu *vcpu);
>   int pi_update_irte(struct kvm *kvm, unsigned int host_irq, uint32_t guest_irq,
>   		   bool set);
> +void vmx_pi_start_assignment(struct kvm *kvm);
> +int vmx_vcpu_check_block(struct kvm_vcpu *vcpu);
>   
>   #endif /* __KVM_X86_VMX_POSTED_INTR_H */
> Index: kvm/arch/x86/kvm/vmx/vmx.c
> ===================================================================
> --- kvm.orig/arch/x86/kvm/vmx/vmx.c
> +++ kvm/arch/x86/kvm/vmx/vmx.c
> @@ -7727,13 +7727,13 @@ static struct kvm_x86_ops vmx_x86_ops __
>   
>   	.pre_block = vmx_pre_block,
>   	.post_block = vmx_post_block,
> -	.vcpu_check_block = NULL,
> +	.vcpu_check_block = vmx_vcpu_check_block,
>   
>   	.pmu_ops = &intel_pmu_ops,
>   	.nested_ops = &vmx_nested_ops,
>   
>   	.update_pi_irte = pi_update_irte,
> -	.start_assignment = NULL,
> +	.start_assignment = vmx_pi_start_assignment,
>   
>   #ifdef CONFIG_X86_64
>   	.set_hv_timer = vmx_set_hv_timer,
> 
>