Hi Leo,
Please use my personal gr...@kaod.org address for upstream matters.
On Wed, 17 Feb 2021 16:55:12 -0300
lagar...@linux.ibm.com wrote:
> From: Leonardo Garcia <lagar...@br.ibm.com>
>
> Currently, as IOMMU is not supported, if a user mistakenly set it and
> tries to mount the vhost-user filesystem (or use any other vhost-user
> based device) inside the guest, whenever the user tries to access the
> device, the system will hang forever (because virtiofsd will not be
> running anymore).
>
> Signed-off-by: Leonardo Garcia <lagar...@br.ibm.com>
> ---
> hw/virtio/vhost-user-fs.c | 5 +++++
> hw/virtio/vhost-user.c | 7 +++++++
> hw/virtio/vhost.c | 1 -
> 3 files changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/hw/virtio/vhost-user-fs.c b/hw/virtio/vhost-user-fs.c
> index ac4fc34b36..059b0d2ef9 100644
> --- a/hw/virtio/vhost-user-fs.c
> +++ b/hw/virtio/vhost-user-fs.c
> @@ -222,6 +222,11 @@ static void vuf_device_realize(DeviceState *dev, Error
> **errp)
> /* 1 high prio queue, plus the number configured */
> fs->vhost_dev.nvqs = 1 + fs->conf.num_request_queues;
> fs->vhost_dev.vqs = g_new0(struct vhost_virtqueue, fs->vhost_dev.nvqs);
> + /*
> + * vhost_user_backend_init does additional checks if VirtIODevice is
> defined
> + * in vhost_dev
> + */
> + fs->vhost_dev.vdev = vdev;
This looks a bit like a software boundary violation to me.
Only places where ->vdev is modified are all in hw/vhost/vhost.c :
- vhost_dev_init() = NULL
- vhost_dev_start() = vdev
- vhost_dev_stop() = NULL
- vhost_dev_prepare_inflight() = vdev
The last one is interesting because it seems to be doing something
vaguely similar to what you're trying to achieve, i.e. setting ->vdev
before vhost_dev_start() is called for some reason.
commit 1b0063b3048af65dfaae6422a572c87db8575a92
Author: Jin Yu <jin...@intel.com>
Date: Tue Nov 3 20:36:17 2020 +0800
vhost-blk: set features before setting inflight feature
> ret = vhost_dev_init(&fs->vhost_dev, &fs->vhost_user,
> VHOST_BACKEND_TYPE_USER, 0);
> if (ret < 0) {
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index 2fdd5daf74..6ab760364b 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -1849,6 +1849,13 @@ static int vhost_user_backend_init(struct vhost_dev
> *dev, void *opaque)
> }
> }
>
> + if ((dev->vdev != NULL) &&
> + virtio_host_has_feature(dev->vdev, VIRTIO_F_IOMMU_PLATFORM) &&
> + !(features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))) {
> + error_report("IOMMU is currently not supported with vhost-user");
> + return -1;
> + }
> +
> if (virtio_has_feature(features, VIRTIO_F_IOMMU_PLATFORM) &&
> !(virtio_has_feature(dev->protocol_features,
> VHOST_USER_PROTOCOL_F_SLAVE_REQ) &&
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index 6e17d631f7..78e58d2148 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -1293,7 +1293,6 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
> int i, r, n_initialized_vqs = 0;
> Error *local_err = NULL;
>
> - hdev->vdev = NULL;
With this change, vhost_dev_init() no longer offers the guarantee
that ->vdev is valid, which might cause problems for any device
that doesn't set ->vdev itself like this patch does for vhost-user-fs.
I suggest you to turn vhost_dev_init() into a vhost_dev_init_vdev()
with an extra vdev argument and use it for all vhost-user devices.
Introduce a vhost_dev_init() inline that does vhost_dev_init_vdev(NULL)
and call it everywhere else.
> hdev->migration_blocker = NULL;
>
> r = vhost_set_backend_type(hdev, backend_type);
