Re: [PATCH v5 21/26] KVM: arm/arm64: GICv4: Hook vPE scheduling into vgic flush/sync

[Auger Eric <eric.auger@redhat.com>]

Hi Marc,

On 27/10/2017 16:28, Marc Zyngier wrote:
> The redistributor needs to be told which vPE is about to be run,
> and tells us whether there is any pending VLPI on exit.
> 
> Let's add the scheduling calls to the vgic flush/sync functions,
> allowing the VLPIs to be delivered to the guest.
> 
> Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> ---
>  virt/kvm/arm/vgic/vgic-v4.c | 39 +++++++++++++++++++++++++++++++++++++++
>  virt/kvm/arm/vgic/vgic.c    |  4 ++++
>  virt/kvm/arm/vgic/vgic.h    |  2 ++
>  3 files changed, 45 insertions(+)
> 
> diff --git a/virt/kvm/arm/vgic/vgic-v4.c b/virt/kvm/arm/vgic/vgic-v4.c
> index 1a2f2fcdfa67..d7fe610bb1f5 100644
> --- a/virt/kvm/arm/vgic/vgic-v4.c
> +++ b/virt/kvm/arm/vgic/vgic-v4.c
> @@ -131,6 +131,45 @@ void vgic_v4_teardown(struct kvm *kvm)
>  	its_vm->vpes = NULL;
>  }
>  
> +int vgic_v4_sync_hwstate(struct kvm_vcpu *vcpu)
> +{
> +	if (!vgic_supports_direct_msis(vcpu->kvm))
> +		return 0;
> +
> +	return its_schedule_vpe(&vcpu->arch.vgic_cpu.vgic_v3.its_vpe, false);
> +}
> +
> +int vgic_v4_flush_hwstate(struct kvm_vcpu *vcpu)
> +{
> +	int irq = vcpu->arch.vgic_cpu.vgic_v3.its_vpe.irq;
> +	int err;
> +
> +	if (!vgic_supports_direct_msis(vcpu->kvm))
> +		return 0;
> +
> +	/*
> +	 * Before making the VPE resident, make sure the redistributor
> +	 * corresponding to our current CPU expects us here. See the
> +	 * doc in drivers/irqchip/irq-gic-v4.c to understand how this
> +	 * turns into a VMOVP command at the ITS level.
> +	 */
I don't get the above comment. Don't you set the affinity of the
doorbell irq below?

Thanks

Eric
> +	err = irq_set_affinity(irq, cpumask_of(smp_processor_id()));
> +	if (err)
> +		return err;
> +
> +	err = its_schedule_vpe(&vcpu->arch.vgic_cpu.vgic_v3.its_vpe, true);
> +	if (err)
> +		return err;
> +
> +	/*
> +	 * Now that the VPE is resident, let's get rid of a potential
> +	 * doorbell interrupt that would still be pending.
> +	 */
> +	err = irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING, false);
> +
> +	return err;
> +}
> +
>  static struct vgic_its *vgic_get_its(struct kvm *kvm,
>  				     struct kvm_kernel_irq_routing_entry *irq_entry)
>  {
> diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
> index 0691a2250949..71ca0ff1b35a 100644
> --- a/virt/kvm/arm/vgic/vgic.c
> +++ b/virt/kvm/arm/vgic/vgic.c
> @@ -709,6 +709,8 @@ void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu)
>  {
>  	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
>  
> +	WARN_ON(vgic_v4_sync_hwstate(vcpu));
> +
>  	/* An empty ap_list_head implies used_lrs == 0 */
>  	if (list_empty(&vcpu->arch.vgic_cpu.ap_list_head))
>  		return;
> @@ -721,6 +723,8 @@ void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu)
>  /* Flush our emulation state into the GIC hardware before entering the guest. */
>  void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu)
>  {
> +	WARN_ON(vgic_v4_flush_hwstate(vcpu));
> +
>  	/*
>  	 * If there are no virtual interrupts active or pending for this
>  	 * VCPU, then there is no work to do and we can bail out without
> diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
> index c4105f613f57..9cafb61b79af 100644
> --- a/virt/kvm/arm/vgic/vgic.h
> +++ b/virt/kvm/arm/vgic/vgic.h
> @@ -243,5 +243,7 @@ struct vgic_its *vgic_msi_to_its(struct kvm *kvm, struct kvm_msi *msi);
>  bool vgic_supports_direct_msis(struct kvm *kvm);
>  int vgic_v4_init(struct kvm *kvm);
>  void vgic_v4_teardown(struct kvm *kvm);
> +int vgic_v4_sync_hwstate(struct kvm_vcpu *vcpu);
> +int vgic_v4_flush_hwstate(struct kvm_vcpu *vcpu);
>  
>  #endif
>