Re: [PATCH v2 2/2] vhost: add reconnection support to VDUSE

[David Marchand <david.marchand@redhat.com>]

On Fri, Sep 20, 2024 at 11:09 AM Maxime Coquelin
<maxime.coquelin@redhat.com> wrote:
>
> This patch enables VDUSE reconnection support making use of
> the newly introduced reconnection mechanism in Vhost
> library.
>
> At DPDK VDUSE device creation time, there are two
> possibilities:
>  1. The Kernel VDUSE device does not exist:
>   a. A reconnection file named after the VUDSE device name

VDUSE*

>      is created in VDUSE tmpfs.
>   b. The file is truncated to 'struct vhost_reconnect_data'
>      size, and mmapped.
>   c. Negotiated features, Virtio status... are saved for
>      sanity checks at reconnect time.
>  2. The Kernel VDUSE device already exists:
>   a. Exit with failure if no reconnect file exists for
>      this device.
>   b. Open and mmap the reconnect file.
>   c. Perform sanity check to ensure features are compatible.
>   d. Restore virtqueues' available indexes at startup time.
>
> Then at runtime, the virtqueues' available index are logged by
> the Vhost reconnection mechanism.
>
> At DPDK VDUSE device destruction time, there are two
> possibilities:
>  1. The Kernel VDUSE device destruction succeed, which

succeeded*


>     means it is no more attached to the vDPA bus. The
>     reconnection file is unmapped and then removed.
>  2. The Kernel VDUSE device destruction failed, meaning it
>     is no more attached to the vDPA bus. The reconnection
>     file is unmapped but not removed to make possible later
>     reconnection.
>
> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Reviewed-by: David Marchand <david.marchand@redhat.com>


-- 
David Marchand