Re: [PATCH] vhost: fix madvise IOTLB entries pages overlap check

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 3/15/23 12:31, Maxime Coquelin wrote:
> At removal time, when testing whether the IOTLB entry has
> shared pages with the previous and next entries in the
> cache, it checks whether the start address of the entry to
> be removed is on the same page as the start address of the
> next entry in the cache.
> 
> This is not correct, as an entry could cover several page
> so the end address of the entry to be remove should be
> used. This patch address this issue.
> 
> Fixes: dea092d0addb ("vhost: fix madvise arguments alignment")
> 
> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> ---
>   lib/vhost/iotlb.c | 8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/lib/vhost/iotlb.c b/lib/vhost/iotlb.c
> index 11785392ac..bfa04a0439 100644
> --- a/lib/vhost/iotlb.c
> +++ b/lib/vhost/iotlb.c
> @@ -182,8 +182,8 @@ vhost_user_iotlb_cache_random_evict(struct virtio_net *dev, struct vhost_virtque
>   					(node->uaddr & mask) != (prev_node->uaddr & mask)) {
>   				next_node = RTE_TAILQ_NEXT(node, next);
>   				/* Don't disable coredump if the next node is in the same page */
> -				if (next_node == NULL ||
> -						(node->uaddr & mask) != (next_node->uaddr & mask))
> +				if (next_node == NULL || ((node->uaddr + node->size) & mask) !=

Oups, forgot to amend a change before generating the patch.
It should be (node->uaddr + node->size - 1) as we want the end address
of the entry.

> +						(next_node->uaddr & mask))
>   					mem_set_dump((void *)(uintptr_t)node->uaddr, node->size,
>   							false, alignment);
>   			}
> @@ -287,8 +287,8 @@ vhost_user_iotlb_cache_remove(struct virtio_net *dev, struct vhost_virtqueue *vq
>   					(node->uaddr & mask) != (prev_node->uaddr & mask)) {
>   				next_node = RTE_TAILQ_NEXT(node, next);
>   				/* Don't disable coredump if the next node is in the same page */
> -				if (next_node == NULL ||
> -						(node->uaddr & mask) != (next_node->uaddr & mask))
> +				if (next_node == NULL || ((node->uaddr + node->size) & mask) !=

Same here.

> +						(next_node->uaddr & mask))
>   					mem_set_dump((void *)(uintptr_t)node->uaddr, node->size,
>   							false, alignment);
>   			}

Sending v2.