[RFC 03/27] vhost: fix IOTLB entries overlap check with previous entry

[Xia, Chenbo]

> -----Original Message-----
> From: Maxime Coquelin <maxime.coquelin at redhat.com>
> Sent: Friday, March 31, 2023 11:43 PM
> To: dev at dpdk.org; david.marchand at redhat.com; Xia, Chenbo
> <chenbo.xia at intel.com>; mkp at redhat.com; fbl at redhat.com;
> jasowang at redhat.com; Liang, Cunming <cunming.liang at intel.com>; Xie, Yongji
> <xieyongji at bytedance.com>; echaudro at redhat.com; eperezma at redhat.com;
> amorenoz at redhat.com
> Cc: Maxime Coquelin <maxime.coquelin at redhat.com>; stable at dpdk.org
> Subject: [RFC 03/27] vhost: fix IOTLB entries overlap check with previous
> entry
> 
> Commit 22b6d0ac691a ("vhost: fix madvise IOTLB entries pages overlap
> check")
> fixed the check to ensure the entry to be removed does not
> overlap with the next one in the IOTLB cache before marking
> it as DONTDUMP with madvise(). This is not enough, because
> the same issue is present when comparing with the previous
> entry in the cache, where the end address of the previous
> entry should be used, not the start one.
> 
> Fixes: dea092d0addb ("vhost: fix madvise arguments alignment")
> Cc: stable at dpdk.org
> 
> Signed-off-by: Maxime Coquelin <maxime.coquelin at 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 3f45bc6061..870c8acb88 100644
> --- a/lib/vhost/iotlb.c
> +++ b/lib/vhost/iotlb.c
> @@ -178,8 +178,8 @@ vhost_user_iotlb_cache_random_evict(struct virtio_net
> *dev, struct vhost_virtque
>  			mask = ~(alignment - 1);
> 
>  			/* Don't disable coredump if the previous node is in the
> same page */
> -			if (prev_node == NULL ||
> -					(node->uaddr & mask) != (prev_node->uaddr &
> mask)) {
> +			if (prev_node == NULL || (node->uaddr & mask) !=
> +					((prev_node->uaddr + prev_node->size - 1) &
> 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 + node-
> >size - 1) & mask) !=
> @@ -283,8 +283,8 @@ vhost_user_iotlb_cache_remove(struct virtio_net *dev,
> struct vhost_virtqueue *vq
>  			mask = ~(alignment-1);
> 
>  			/* Don't disable coredump if the previous node is in the
> same page */
> -			if (prev_node == NULL ||
> -					(node->uaddr & mask) != (prev_node->uaddr &
> mask)) {
> +			if (prev_node == NULL || (node->uaddr & mask) !=
> +					((prev_node->uaddr + prev_node->size - 1) &
> 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 + node-
> >size - 1) & mask) !=
> --
> 2.39.2

Reviewed-by: Chenbo Xia <chenbo.xia at intel.com>