Re: [RFC] vhost: Clear the pending messages on vhost_init_device_iotlb()

From: "Michael S. Tsirkin" <mst@redhat.com>
To: Eric Auger <eric.auger@redhat.com>
Cc: kvm@vger.kernel.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	eric.auger.pro@gmail.com
Subject: Re: [RFC] vhost: Clear the pending messages on vhost_init_device_iotlb()
Date: Mon, 7 Nov 2022 15:42:03 -0500	[thread overview]
Message-ID: <20221107153924-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20221107203431.368306-1-eric.auger@redhat.com>

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@redhat.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

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