linux-kernel - Re: [PATCH] rpmsg: virtio: Fix broken rpmsg

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Date:   Thu, 30 Jun 2022 15:16:41 -0400
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Anup Patel <apatel@...tanamicro.com>
Cc:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Atish Patra <atishp@...shpatra.org>,
        Alistair Francis <Alistair.Francis@....com>,
        Anup Patel <anup@...infault.org>,
        linux-remoteproc@...r.kernel.org, kvm-riscv@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] rpmsg: virtio: Fix broken rpmsg_probe()

On Wed, Jun 08, 2022 at 10:43:34PM +0530, Anup Patel wrote:
> The rpmsg_probe() is broken at the moment because virtqueue_add_inbuf()
> fails due to both virtqueues (Rx and Tx) marked as broken by the
> __vring_new_virtqueue() function. To solve this, virtio_device_ready()
> (which unbreaks queues) should be called before virtqueue_add_inbuf().
> 
> Fixes: 8b4ec69d7e09 ("virtio: harden vring IRQ")
> Signed-off-by: Anup Patel <apatel@...tanamicro.com>


Yea, I've more or less reverted that. (There's VIRTIO_HARDEN_NOTIFICATION
that we'll use to try and develop this to something more reasonable).

> ---
>  drivers/rpmsg/virtio_rpmsg_bus.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c
> index 905ac7910c98..71a64d2c7644 100644
> --- a/drivers/rpmsg/virtio_rpmsg_bus.c
> +++ b/drivers/rpmsg/virtio_rpmsg_bus.c
> @@ -929,6 +929,9 @@ static int rpmsg_probe(struct virtio_device *vdev)
>  	/* and half is dedicated for TX */
>  	vrp->sbufs = bufs_va + total_buf_space / 2;
>  
> +	/* From this point on, we can notify and get callbacks. */
> +	virtio_device_ready(vdev);
> +
>  	/* set up the receive buffers */
>  	for (i = 0; i < vrp->num_bufs / 2; i++) {
>  		struct scatterlist sg;
> @@ -983,9 +986,6 @@ static int rpmsg_probe(struct virtio_device *vdev)
>  	 */
>  	notify = virtqueue_kick_prepare(vrp->rvq);
>  
> -	/* From this point on, we can notify and get callbacks. */
> -	virtio_device_ready(vdev);
> -
>  	/* tell the remote processor it can start sending messages */
>  	/*
>  	 * this might be concurrent with callbacks, but we are only
> -- 
> 2.34.1
> 
>