On Wed, Mar 30, 2022 at 2:33 PM Si-Wei Liu <si-wei....@oracle.com> wrote:
>
> With MQ enabled vdpa device and non-MQ supporting guest e.g.
> booting vdpa with mq=on over OVMF of single vqp, below assert
> failure is seen:
>
> ../hw/virtio/vhost-vdpa.c:560: vhost_vdpa_get_vq_index: Assertion `idx >=
> dev->vq_index && idx < dev->vq_index + dev->nvqs' failed.
>
> 0 0x00007f8ce3ff3387 in raise () at /lib64/libc.so.6
> 1 0x00007f8ce3ff4a78 in abort () at /lib64/libc.so.6
> 2 0x00007f8ce3fec1a6 in __assert_fail_base () at /lib64/libc.so.6
> 3 0x00007f8ce3fec252 in () at /lib64/libc.so.6
> 4 0x0000558f52d79421 in vhost_vdpa_get_vq_index (dev=<optimized out>,
> idx=<optimized out>) at ../hw/virtio/vhost-vdpa.c:563
> 5 0x0000558f52d79421 in vhost_vdpa_get_vq_index (dev=<optimized out>,
> idx=<optimized out>) at ../hw/virtio/vhost-vdpa.c:558
> 6 0x0000558f52d7329a in vhost_virtqueue_mask (hdev=0x558f55c01800,
> vdev=0x558f568f91f0, n=2, mask=<optimized out>) at ../hw/virtio/vhost.c:1557
> 7 0x0000558f52c6b89a in virtio_pci_set_guest_notifier
> (d=d@entry=0x558f568f0f60, n=n@entry=2, assign=assign@entry=true,
> with_irqfd=with_irqfd@entry=false)
> at ../hw/virtio/virtio-pci.c:974
> 8 0x0000558f52c6c0d8 in virtio_pci_set_guest_notifiers (d=0x558f568f0f60,
> nvqs=3, assign=true) at ../hw/virtio/virtio-pci.c:1019
> 9 0x0000558f52bf091d in vhost_net_start (dev=dev@entry=0x558f568f91f0,
> ncs=0x558f56937cd0, data_queue_pairs=data_queue_pairs@entry=1,
> cvq=cvq@entry=1)
> at ../hw/net/vhost_net.c:361
> 10 0x0000558f52d4e5e7 in virtio_net_set_status (status=<optimized out>,
> n=0x558f568f91f0) at ../hw/net/virtio-net.c:289
> 11 0x0000558f52d4e5e7 in virtio_net_set_status (vdev=0x558f568f91f0,
> status=15 '\017') at ../hw/net/virtio-net.c:370
> 12 0x0000558f52d6c4b2 in virtio_set_status (vdev=vdev@entry=0x558f568f91f0,
> val=val@entry=15 '\017') at ../hw/virtio/virtio.c:1945
> 13 0x0000558f52c69eff in virtio_pci_common_write (opaque=0x558f568f0f60,
> addr=<optimized out>, val=<optimized out>, size=<optimized out>) at
> ../hw/virtio/virtio-pci.c:1292
> 14 0x0000558f52d15d6e in memory_region_write_accessor (mr=0x558f568f19d0,
> addr=20, value=<optimized out>, size=1, shift=<optimized out>,
> mask=<optimized out>, attrs=...)
> at ../softmmu/memory.c:492
> 15 0x0000558f52d127de in access_with_adjusted_size (addr=addr@entry=20,
> value=value@entry=0x7f8cdbffe748, size=size@entry=1,
> access_size_min=<optimized out>, access_size_max=<optimized out>,
> access_fn=0x558f52d15cf0 <memory_region_write_accessor>, mr=0x558f568f19d0,
> attrs=...) at ../softmmu/memory.c:554
> 16 0x0000558f52d157ef in memory_region_dispatch_write
> (mr=mr@entry=0x558f568f19d0, addr=20, data=<optimized out>, op=<optimized
> out>, attrs=attrs@entry=...)
> at ../softmmu/memory.c:1504
> 17 0x0000558f52d078e7 in flatview_write_continue (fv=fv@entry=0x7f8accbc3b90,
> addr=addr@entry=103079215124, attrs=..., ptr=ptr@entry=0x7f8ce6300028,
> len=len@entry=1, addr1=<optimized out>, l=<optimized out>, mr=0x558f568f19d0)
> at /home/opc/qemu-upstream/include/qemu/host-utils.h:165
> 18 0x0000558f52d07b06 in flatview_write (fv=0x7f8accbc3b90,
> addr=103079215124, attrs=..., buf=0x7f8ce6300028, len=1) at
> ../softmmu/physmem.c:2822
> 19 0x0000558f52d0b36b in address_space_write (as=<optimized out>,
> addr=<optimized out>, attrs=..., buf=buf@entry=0x7f8ce6300028, len=<optimized
> out>)
> at ../softmmu/physmem.c:2914
> 20 0x0000558f52d0b3da in address_space_rw (as=<optimized out>,
> addr=<optimized out>, attrs=...,
> attrs@entry=..., buf=buf@entry=0x7f8ce6300028, len=<optimized out>,
> is_write=<optimized out>) at ../softmmu/physmem.c:2924
> 21 0x0000558f52dced09 in kvm_cpu_exec (cpu=cpu@entry=0x558f55c2da60) at
> ../accel/kvm/kvm-all.c:2903
> 22 0x0000558f52dcfabd in kvm_vcpu_thread_fn (arg=arg@entry=0x558f55c2da60) at
> ../accel/kvm/kvm-accel-ops.c:49
> 23 0x0000558f52f9f04a in qemu_thread_start (args=<optimized out>) at
> ../util/qemu-thread-posix.c:556
> 24 0x00007f8ce4392ea5 in start_thread () at /lib64/libpthread.so.0
> 25 0x00007f8ce40bb9fd in clone () at /lib64/libc.so.6
>
> The cause for the assert failure is due to that the vhost_dev index
> for the ctrl vq was not aligned with actual one in use by the guest.
> Upon multiqueue feature negotiation in virtio_net_set_multiqueue(),
> if guest doesn't support multiqueue, the guest vq layout would shrink
> to a single queue pair, consisting of 3 vqs in total (rx, tx and ctrl).
> This results in ctrl_vq taking a different vhost_dev group index than
> the default. We can map vq to the correct vhost_dev group by checking
> if MQ is supported by guest and successfully negotiated. Since the
> MQ feature is only present along with CTRL_VQ, we make sure the index
> 2 is only meant for the control vq while MQ is not supported by guest.
>
> Be noted if QEMU or guest doesn't support control vq, there's no bother
> exposing vhost_dev and guest notifier for the control vq. Since
> vhost_net_start/stop implies DRIVER_OK is set in device status, feature
> negotiation should be completed when reaching virtio_net_vhost_status().
>
> Fixes: 22288fe ("virtio-net: vhost control virtqueue support")
> Suggested-by: Jason Wang <jasow...@redhat.com>
> Signed-off-by: Si-Wei Liu <si-wei....@oracle.com>
> ---
> hw/net/virtio-net.c | 19 ++++++++++++++++---
> 1 file changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index 1067e72..484b215 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -245,7 +245,8 @@ static void virtio_net_vhost_status(VirtIONet *n, uint8_t
> status)
> VirtIODevice *vdev = VIRTIO_DEVICE(n);
> NetClientState *nc = qemu_get_queue(n->nic);
> int queue_pairs = n->multiqueue ? n->max_queue_pairs : 1;
> - int cvq = n->max_ncs - n->max_queue_pairs;
> + int cvq = virtio_vdev_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ) ?
> + n->max_ncs - n->max_queue_pairs : 0;
Let's use a separate patch for this.
>
> if (!get_vhost_net(nc->peer)) {
> return;
> @@ -3170,8 +3171,14 @@ static NetClientInfo net_virtio_info = {
> static bool virtio_net_guest_notifier_pending(VirtIODevice *vdev, int idx)
> {
> VirtIONet *n = VIRTIO_NET(vdev);
> - NetClientState *nc = qemu_get_subqueue(n->nic, vq2q(idx));
> + NetClientState *nc;
> assert(n->vhost_started);
> + if (!virtio_vdev_has_feature(vdev, VIRTIO_NET_F_MQ) && idx == 2) {
> + assert(virtio_vdev_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ));
This assert seems guest trigger-able. If yes, I would remove this or
replace it with log_guest_error.
> + nc = qemu_get_subqueue(n->nic, n->max_queue_pairs);
> + } else {
> + nc = qemu_get_subqueue(n->nic, vq2q(idx));
> + }
> return vhost_net_virtqueue_pending(get_vhost_net(nc->peer), idx);
> }
>
> @@ -3179,8 +3186,14 @@ static void
> virtio_net_guest_notifier_mask(VirtIODevice *vdev, int idx,
> bool mask)
> {
> VirtIONet *n = VIRTIO_NET(vdev);
> - NetClientState *nc = qemu_get_subqueue(n->nic, vq2q(idx));
> + NetClientState *nc;
> assert(n->vhost_started);
> + if (!virtio_vdev_has_feature(vdev, VIRTIO_NET_F_MQ) && idx == 2) {
> + assert(virtio_vdev_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ));
And this.
Thanks
> + nc = qemu_get_subqueue(n->nic, n->max_queue_pairs);
> + } else {
> + nc = qemu_get_subqueue(n->nic, vq2q(idx));
> + }
> vhost_net_virtqueue_mask(get_vhost_net(nc->peer),
> vdev, idx, mask);
> }
> --
> 1.8.3.1
>
