linux-kernel - Re: [RFC] vhost: Clear the pending messages on vhost_init_device

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Message-ID: <20221107153924-mutt-send-email-mst@kernel.org>
Date:   Mon, 7 Nov 2022 15:42:03 -0500
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Eric Auger <eric.auger@...hat.com>
Cc:     eric.auger.pro@...il.com, jasowang@...hat.com, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, peterx@...hat.com
Subject: Re: [RFC] vhost: Clear the pending messages on
 vhost_init_device_iotlb()

On Mon, Nov 07, 2022 at 09:34:31PM +0100, Eric Auger wrote:
> When the vhost iotlb is used along with a guest virtual iommu
> and the guest gets rebooted, some MISS messages may have been
> recorded just before the reboot and spuriously executed by
> the virtual iommu after the reboot. Despite the device iotlb gets
> re-initialized, the messages are not cleared. Fix that by calling
> vhost_clear_msg() at the end of vhost_init_device_iotlb().
> 
> Signed-off-by: Eric Auger <eric.auger@...hat.com>
> ---
>  drivers/vhost/vhost.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index 40097826cff0..422a1fdee0ca 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -1751,6 +1751,7 @@ int vhost_init_device_iotlb(struct vhost_dev *d, bool enabled)
>  	}
>  
>  	vhost_iotlb_free(oiotlb);
> +	vhost_clear_msg(d);
>  
>  	return 0;
>  }

Hmm.  Can't messages meanwhile get processes and affect the
new iotlb?


> -- 
> 2.37.3