On Sun, Oct 08, 2023 at 05:38:41PM +0800, Xuan Zhuo wrote:
> Now, the function vp_modern_map_capability() takes the size parameter,
> which corresponds to the size of virtio_pci_common_cfg. As a result,
> this indicates the size of memory area to map.
>
> However, if the _F_RING_RESET is negotiated, the extra items will be
> used. Therefore, we need to use the size of virtio_pci_modern_common_cfg
> to map more space.
>
> Meanwhile, this patch removes the feature(_F_RING_ERSET and
typo
> _F_NOTIFICATION_DATA) when the common cfg size does not match
> the corresponding feature.
>
> Fixes: 0b50cece0b78 ("virtio_pci: introduce helper to get/set queue reset")
> Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
> ---
> drivers/virtio/virtio_pci_modern.c | 20 +++++++++++++++++++-
> drivers/virtio/virtio_pci_modern_dev.c | 4 ++--
> include/linux/virtio_pci_modern.h | 1 +
> 3 files changed, 22 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
> index d6bb68ba84e5..c0b9d2363ddb 100644
> --- a/drivers/virtio/virtio_pci_modern.c
> +++ b/drivers/virtio/virtio_pci_modern.c
> @@ -22,8 +22,26 @@
> static u64 vp_get_features(struct virtio_device *vdev)
> {
> struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> + u64 features = vp_modern_get_features(&vp_dev->mdev);
> +
> +#define check_feature(feature, field) \
> + do { \
> + if (features & BIT_ULL(feature)) { \
> + u32 offset = offsetofend(struct virtio_pci_modern_common_cfg, field); \
> + if (unlikely(vp_dev->mdev.common_len < offset)) \
> + features &= ~BIT_ULL(feature); \
> + } \
> + } while (0)
> +
> + /* For buggy devices, if the common len does not match the feature, we
> + * remove the feature.
I don't like doing this in vp_get_features. userspace won't be able
to see the actual device features at all.
Also, we should print an info message at least.
I am still debating with myself whether clearing feature bits
or just failing finalize_features (and thus, probe) is best.
> + */
> + check_feature(VIRTIO_F_NOTIFICATION_DATA, queue_notify_data);
> + check_feature(VIRTIO_F_RING_RESET, queue_reset);
> +
> +#undef check_feature
this macro's too scary. just pass offset and feature bit as
parameters to an inline function.
>
> - return vp_modern_get_features(&vp_dev->mdev);
> + return features;
> }
>
> static void vp_transport_features(struct virtio_device *vdev, u64 features)
> diff --git a/drivers/virtio/virtio_pci_modern_dev.c b/drivers/virtio/virtio_pci_modern_dev.c
> index aad7d9296e77..33f319da1558 100644
> --- a/drivers/virtio/virtio_pci_modern_dev.c
> +++ b/drivers/virtio/virtio_pci_modern_dev.c
> @@ -291,8 +291,8 @@ int vp_modern_probe(struct virtio_pci_modern_device *mdev)
> err = -EINVAL;
> mdev->common = vp_modern_map_capability(mdev, common,
> sizeof(struct virtio_pci_common_cfg), 4,
> - 0, sizeof(struct virtio_pci_common_cfg),
> - NULL, NULL);
> + 0, sizeof(struct virtio_pci_modern_common_cfg),
> + &mdev->common_len, NULL);
> if (!mdev->common)
> goto err_map_common;
> mdev->isr = vp_modern_map_capability(mdev, isr, sizeof(u8), 1,
> diff --git a/include/linux/virtio_pci_modern.h b/include/linux/virtio_pci_modern.h
> index 067ac1d789bc..edf62bae0474 100644
> --- a/include/linux/virtio_pci_modern.h
> +++ b/include/linux/virtio_pci_modern.h
> @@ -28,6 +28,7 @@ struct virtio_pci_modern_device {
> /* So we can sanity-check accesses. */
> size_t notify_len;
> size_t device_len;
> + size_t common_len;
>
> /* Capability for when we need to map notifications per-vq. */
> int notify_map_cap;
> --
> 2.32.0.3.g01195cf9f
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