Re: [PATCH] IOMMU and ATS not supported by vhost-user filesystem.

[Dr. David Alan Gilbert]

* lagarcia@linux.ibm.com (lagarcia@linux.ibm.com) wrote:
> From: Leonardo Garcia <lagarcia@br.ibm.com>
> 
> Currently, as IOMMU and ATS are not supported, if a user mistakenly set
> any of them and tries to mount the vhost-user filesystem inside the
> guest, whenever the user tries to access the mount point, the system
> will hang forever.
> 
> Signed-off-by: Leonardo Garcia <lagarcia@br.ibm.com>
> ---
>  hw/virtio/vhost-user-fs-pci.c | 7 +++++++
>  hw/virtio/vhost-user-fs.c     | 5 +++++
>  2 files changed, 12 insertions(+)
> 
> diff --git a/hw/virtio/vhost-user-fs-pci.c b/hw/virtio/vhost-user-fs-pci.c
> index 2ed8492b3f..564d1fd108 100644
> --- a/hw/virtio/vhost-user-fs-pci.c
> +++ b/hw/virtio/vhost-user-fs-pci.c
> @@ -11,6 +11,8 @@
>   * top-level directory.
>   */
>  
> +#include "qemu/osdep.h"
> +#include "qapi/error.h"
>  #include "qemu/osdep.h"
>  #include "hw/qdev-properties.h"
>  #include "hw/virtio/vhost-user-fs.h"
> @@ -45,6 +47,11 @@ static void vhost_user_fs_pci_realize(VirtIOPCIProxy 
> *vpci_dev, Error **errp)
>          vpci_dev->nvectors = dev->vdev.conf.num_request_queues + 2;
>      }
>  
> +    if (vpci_dev->flags & VIRTIO_PCI_FLAG_ATS) {
> +        error_setg(errp, "ATS is currently not supported with 
> vhost-user-fs-pci");
> +        return;
> +    }
> +
>      qdev_realize(vdev, BUS(&vpci_dev->bus), errp);
>  }
>  
> diff --git a/hw/virtio/vhost-user-fs.c b/hw/virtio/vhost-user-fs.c
> index ac4fc34b36..914d68b3ee 100644
> --- a/hw/virtio/vhost-user-fs.c
> +++ b/hw/virtio/vhost-user-fs.c
> @@ -203,6 +203,11 @@ static void vuf_device_realize(DeviceState *dev, Error 
> **errp)
>          return;
>      }
>  
> +    if (virtio_host_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM)) {
> +        error_setg(errp, "IOMMU is currently not supported with 
> vhost-user-fs");
> +        return;
> +    }

Yes, I've seen this problem - however, I'm a little confused; isn't the
negotiation of features on virtio supposed to happen automatically?
If so, how come it's managing to set VIRTIO_F_IOMMU_PLATFORM?

Dave

>      if (!vhost_user_init(&fs->vhost_user, &fs->conf.chardev, errp)) {
>          return;
>      }
> -- 
> 2.29.2
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK