Virtualization - Oct 2023 - [PATCH 1/2] virtio_pci: Don't make an extra copy of cpu affinity mask

Since commit 19e226e8cc5d ("virtio: Make vp_set_vq_affinity() take a
mask.") it is actually not needed to have a local copy of the cpu mask.

Pass the cpu mask we got as argument to set the irq affinity hint.

Cc: Caleb Raitto <caraitto at google.com>
Signed-off-by: Jakub Sitnicki <jakub at cloudflare.com>
---
 drivers/virtio/virtio_pci_common.c | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/drivers/virtio/virtio_pci_common.c
b/drivers/virtio/virtio_pci_common.c
index c2524a7207cf..8927bc338f06 100644
--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -433,21 +433,14 @@ int vp_set_vq_affinity(struct virtqueue *vq, const struct
cpumask *cpu_mask)
 	struct virtio_device *vdev = vq->vdev;
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 	struct virtio_pci_vq_info *info = vp_dev->vqs[vq->index];
-	struct cpumask *mask;
 	unsigned int irq;
 
 	if (!vq->callback)
 		return -EINVAL;
 
 	if (vp_dev->msix_enabled) {
-		mask = vp_dev->msix_affinity_masks[info->msix_vector];
 		irq = pci_irq_vector(vp_dev->pci_dev, info->msix_vector);
-		if (!cpu_mask)
-			irq_set_affinity_hint(irq, NULL);
-		else {
-			cpumask_copy(mask, cpu_mask);
-			irq_set_affinity_hint(irq, mask);
-		}
+		irq_set_affinity_hint(irq, cpu_mask);
 	}
 	return 0;
 }
-- 
2.41.0

Since commit 65c7cdedeb30 ("genirq: Provide new interfaces for affinity
hints") irq_set_affinity_hint is being phased out.

Switch to new interfaces for setting and applying irq affinity hints.

Signed-off-by: Jakub Sitnicki <jakub at cloudflare.com>
---
 drivers/virtio/virtio_pci_common.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/virtio/virtio_pci_common.c
b/drivers/virtio/virtio_pci_common.c
index 8927bc338f06..9fab99b540f1 100644
--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -242,7 +242,7 @@ void vp_del_vqs(struct virtio_device *vdev)
 			if (v != VIRTIO_MSI_NO_VECTOR) {
 				int irq = pci_irq_vector(vp_dev->pci_dev, v);
 
-				irq_set_affinity_hint(irq, NULL);
+				irq_update_affinity_hint(irq, NULL);
 				free_irq(irq, vq);
 			}
 		}
@@ -440,7 +440,7 @@ int vp_set_vq_affinity(struct virtqueue *vq, const struct
cpumask *cpu_mask)
 
 	if (vp_dev->msix_enabled) {
 		irq = pci_irq_vector(vp_dev->pci_dev, info->msix_vector);
-		irq_set_affinity_hint(irq, cpu_mask);
+		irq_set_affinity_and_hint(irq, cpu_mask);
 	}
 	return 0;
 }
-- 
2.41.0

On Thu, 19 Oct 2023 12:16:24 +0200, Jakub Sitnicki <jakub at
cloudflare.com> wrote:
> Since commit 19e226e8cc5d ("virtio: Make vp_set_vq_affinity() take a
> mask.") it is actually not needed to have a local copy of the cpu
mask.

Could you give more info to prove this?

If you are right, I think you should delete all code about msix_affinity_masks?

Thanks.
>
> Pass the cpu mask we got as argument to set the irq affinity hint.
>
> Cc: Caleb Raitto <caraitto at google.com>
> Signed-off-by: Jakub Sitnicki <jakub at cloudflare.com>
> ---
>  drivers/virtio/virtio_pci_common.c | 9 +--------
>  1 file changed, 1 insertion(+), 8 deletions(-)
>
> diff --git a/drivers/virtio/virtio_pci_common.c
b/drivers/virtio/virtio_pci_common.c
> index c2524a7207cf..8927bc338f06 100644
> --- a/drivers/virtio/virtio_pci_common.c
> +++ b/drivers/virtio/virtio_pci_common.c
> @@ -433,21 +433,14 @@ int vp_set_vq_affinity(struct virtqueue *vq, const
struct cpumask *cpu_mask)
>  	struct virtio_device *vdev = vq->vdev;
>  	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
>  	struct virtio_pci_vq_info *info = vp_dev->vqs[vq->index];
> -	struct cpumask *mask;
>  	unsigned int irq;
>
>  	if (!vq->callback)
>  		return -EINVAL;
>
>  	if (vp_dev->msix_enabled) {
> -		mask = vp_dev->msix_affinity_masks[info->msix_vector];
>  		irq = pci_irq_vector(vp_dev->pci_dev, info->msix_vector);
> -		if (!cpu_mask)
> -			irq_set_affinity_hint(irq, NULL);
> -		else {
> -			cpumask_copy(mask, cpu_mask);
> -			irq_set_affinity_hint(irq, mask);
> -		}
> +		irq_set_affinity_hint(irq, cpu_mask);
>  	}
>  	return 0;
>  }
> --
> 2.41.0
>