Re: [PATCH v2 9/9] KVM: arm/arm64: vgic-irqfd: Implement kvm_arch_set_irq_inatomic

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

Hi Marc,

On 6/11/19 7:03 PM, Marc Zyngier wrote:
> Now that we have a cache of MSI->LPI translations, it is pretty
> easy to implement kvm_arch_set_irq_inatomic (this cache can be
> parsed without sleeping).
> 
> Hopefully, this will improve some LPI-heavy workloads.
> 
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> ---
>  virt/kvm/arm/vgic/vgic-irqfd.c | 36 ++++++++++++++++++++++++++++------
>  1 file changed, 30 insertions(+), 6 deletions(-)
> 
> diff --git a/virt/kvm/arm/vgic/vgic-irqfd.c b/virt/kvm/arm/vgic/vgic-irqfd.c
> index 99e026d2dade..9f203ed8c8f3 100644
> --- a/virt/kvm/arm/vgic/vgic-irqfd.c
> +++ b/virt/kvm/arm/vgic/vgic-irqfd.c
> @@ -77,6 +77,15 @@ int kvm_set_routing_entry(struct kvm *kvm,
>  	return r;
>  }
>  
> +static void kvm_populate_msi(struct kvm_kernel_irq_routing_entry *e,
> +			     struct kvm_msi *msi)
> +{
> +	msi->address_lo = e->msi.address_lo;
> +	msi->address_hi = e->msi.address_hi;
> +	msi->data = e->msi.data;
> +	msi->flags = e->msi.flags;
> +	msi->devid = e->msi.devid;
> +}
>  /**
>   * kvm_set_msi: inject the MSI corresponding to the
s/:/ -
>   * MSI routing entry
> @@ -90,21 +99,36 @@ int kvm_set_msi(struct kvm_kernel_irq_routing_entry *e,
>  {
>  	struct kvm_msi msi;
>  
> -	msi.address_lo = e->msi.address_lo;
> -	msi.address_hi = e->msi.address_hi;
> -	msi.data = e->msi.data;
> -	msi.flags = e->msi.flags;
> -	msi.devid = e->msi.devid;
> -
>  	if (!vgic_has_its(kvm))
>  		return -ENODEV;
>  
>  	if (!level)
>  		return -1;
>  
> +	kvm_populate_msi(e, &msi);
>  	return vgic_its_inject_msi(kvm, &msi);
>  }
>  
> +/**
> + * kvm_arch_set_irq_inatomic: fast-path for irqfd injection
s/:/ -
> + *
> + * Currently only direct MSI injecton is supported.
injection
> + */
> +int kvm_arch_set_irq_inatomic(struct kvm_kernel_irq_routing_entry *e,
> +			      struct kvm *kvm, int irq_source_id, int level,
> +			      bool line_status)
> +{
> +	if (e->type == KVM_IRQ_ROUTING_MSI && vgic_has_its(kvm) && level) {
> +		struct kvm_msi msi;
> +
> +		kvm_populate_msi(e, &msi);
> +		if (!vgic_its_inject_cached_translation(kvm, &msi))
> +			return 0;
if this fails since its->enabled is false we will re-attempt the
injection though the normal injection path but that's not a big deal.
> +	}
> +
> +	return -EWOULDBLOCK;
> +}
> +
>  int kvm_vgic_setup_default_irq_routing(struct kvm *kvm)
>  {
>  	struct kvm_irq_routing_entry *entries;
> 
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Thanks

Eric
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