Hi Maxime,
> -----Original Message-----
> From: Maxime Coquelin <maxime.coque...@redhat.com>
> Sent: Tuesday, October 20, 2020 1:34 AM
> To: dev@dpdk.org; Xia, Chenbo <chenbo....@intel.com>; amore...@redhat.com
> Cc: Maxime Coquelin <maxime.coque...@redhat.com>; sta...@dpdk.org
> Subject: [PATCH 1/7] vhost: fix virtqueues metadata allocation
>
> The Vhost-user backend implementation assumes there will be
> no holes in the device's array of virtqueues metadata
> pointers.
>
> It can happen though, and would cause segmentation faults,
> memory leaks or undefined behaviour.
Could I ask when will this happen?
When QEMU does not configure all virtqueues? I'm not very sure.
Could you point that out for me?
Thanks!
Chenbo
>
> This patch keep the assumption that there is no holes in this
> array, and allocate all uninitialized virtqueues metadata up
> to requested index.
>
> Fixes: 160cbc815b41 ("vhost: remove a hack on queue allocation")
> Cc: sta...@dpdk.org
>
> Suggested-by: Adrian Moreno <amore...@redhat.com>
> Signed-off-by: Maxime Coquelin <maxime.coque...@redhat.com>
> ---
> lib/librte_vhost/vhost.c | 33 ++++++++++++++++++++-------------
> 1 file changed, 20 insertions(+), 13 deletions(-)
>
> diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c
> index 6068c38ec6..0c9ba3b3af 100644
> --- a/lib/librte_vhost/vhost.c
> +++ b/lib/librte_vhost/vhost.c
> @@ -579,22 +579,29 @@ int
> alloc_vring_queue(struct virtio_net *dev, uint32_t vring_idx)
> {
> struct vhost_virtqueue *vq;
> + uint32_t i;
>
> - vq = rte_malloc(NULL, sizeof(struct vhost_virtqueue), 0);
> - if (vq == NULL) {
> - VHOST_LOG_CONFIG(ERR,
> - "Failed to allocate memory for vring:%u.\n", vring_idx);
> - return -1;
> - }
> + /* Also allocate holes, if any, up to requested vring index. */
> + for (i = 0; i <= vring_idx; i++) {
> + if (dev->virtqueue[i])
> + continue;
>
> - dev->virtqueue[vring_idx] = vq;
> - init_vring_queue(dev, vring_idx);
> - rte_spinlock_init(&vq->access_lock);
> - vq->avail_wrap_counter = 1;
> - vq->used_wrap_counter = 1;
> - vq->signalled_used_valid = false;
> + vq = rte_malloc(NULL, sizeof(struct vhost_virtqueue), 0);
> + if (vq == NULL) {
> + VHOST_LOG_CONFIG(ERR,
> + "Failed to allocate memory for vring:%u.\n", i);
> + return -1;
> + }
> +
> + dev->virtqueue[i] = vq;
> + init_vring_queue(dev, vring_idx);
> + rte_spinlock_init(&vq->access_lock);
> + vq->avail_wrap_counter = 1;
> + vq->used_wrap_counter = 1;
> + vq->signalled_used_valid = false;
> + }
>
> - dev->nr_vring += 1;
> + dev->nr_vring = RTE_MAX(dev->nr_vring, vring_idx + 1);
>
> return 0;
> }
> --
> 2.26.2
