Re: [PATCH v2 4/9] KVM: arm/arm64: vgic-its: Invalidate MSI-LPI translation cache on specific commands

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Hi Marc,

On 6/11/19 7:03 PM, Marc Zyngier wrote:
> The LPI translation cache needs to be discarded when an ITS command
> may affect the translation of an LPI (DISCARD and MAPD with V=0) or
> the routing of an LPI to a redistributor with disabled LPIs (MOVI,
> MOVALL).
> 
> We decide to perform a full invalidation of the cache, irrespective
> of the LPI that is affected. Commands are supposed to be rare enough
> that it doesn't matter.
> 
> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
> ---
>  virt/kvm/arm/vgic/vgic-its.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
> index 9b6b66204b97..5254bb762e1b 100644
> --- a/virt/kvm/arm/vgic/vgic-its.c
> +++ b/virt/kvm/arm/vgic/vgic-its.c
> @@ -733,6 +733,8 @@ static int vgic_its_cmd_handle_discard(struct kvm *kvm, struct vgic_its *its,
>  		 * don't bother here since we clear the ITTE anyway and the
>  		 * pending state is a property of the ITTE struct.
>  		 */
> +		vgic_its_invalidate_cache(kvm);
> +
>  		its_free_ite(kvm, ite);
>  		return 0;
>  	}
> @@ -768,6 +770,8 @@ static int vgic_its_cmd_handle_movi(struct kvm *kvm, struct vgic_its *its,
>  	ite->collection = collection;
>  	vcpu = kvm_get_vcpu(kvm, collection->target_addr);
>  
> +	vgic_its_invalidate_cache(kvm);
> +
>  	return update_affinity(ite->irq, vcpu);
>  }
>  
> @@ -996,6 +1000,8 @@ static void vgic_its_free_device(struct kvm *kvm, struct its_device *device)
>  	list_for_each_entry_safe(ite, temp, &device->itt_head, ite_list)
>  		its_free_ite(kvm, ite);
>  
> +	vgic_its_invalidate_cache(kvm);
> +
>  	list_del(&device->dev_list);
>  	kfree(device);
>  }
> @@ -1249,6 +1255,8 @@ static int vgic_its_cmd_handle_movall(struct kvm *kvm, struct vgic_its *its,
>  		vgic_put_irq(kvm, irq);
>  	}
>  
> +	vgic_its_invalidate_cache(kvm);
All the commands are executed with the its_lock held. Now we don't take
it anymore on the fast cache injection path. Don't we have a window
where the move has been applied at table level and the cache is not yet
invalidated? Same question for vgic_its_free_device().

Thanks

Eric


> +
>  	kfree(intids);
>  	return 0;
>  }
> 
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