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