Re: [PATCH v9 9/9] KVM: VMX: enable IPI virtualization

[Paolo Bonzini]

On 4/19/22 17:45, Zeng Guang wrote:
> +static bool vmx_can_use_pi_wakeup(struct kvm_vcpu *vcpu)
> +{
> +	/*
> +	 * If a blocked vCPU can be the target of posted interrupts,
> +	 * switching notification vector is needed so that kernel can
> +	 * be informed when an interrupt is posted and get the chance
> +	 * to wake up the blocked vCPU. For now, using posted interrupt
> +	 * for vCPU wakeup when IPI virtualization or VT-d PI can be
> +	 * enabled.
> +	 */
> +	return vmx_can_use_ipiv(vcpu) || vmx_can_use_vtd_pi(vcpu->kvm);
> +}

Slightly more accurate name and comment:

static bool vmx_needs_pi_wakeup(struct kvm_vcpu *vcpu)
{
        /*
         * The default posted interrupt vector does nothing when
         * invoked outside guest mode.   Return whether a blocked vCPU
         * can be the target of posted interrupts, as is the case when
         * using either IPI virtualization or VT-d PI, so that the
         * notification vector is switched to the one that calls
         * back to the pi_wakeup_handler() function.
         */
        return vmx_can_use_ipiv(vcpu) || vmx_can_use_vtd_pi(vcpu->kvm);
}


Paolo