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

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Message-ID: <b8487793-d7b8-0557-a4c2-b62754e14830@redhat.com>
Date:   Mon, 7 Nov 2022 22:10:06 +0100
From:   Eric Auger <eric.auger@...hat.com>
To:     "Michael S. Tsirkin" <mst@...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()

Hi Michael,
On 11/7/22 21:42, Michael S. Tsirkin wrote:
> 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?
Isn't the msg processing stopped at the moment this function is called
(VHOST_SET_FEATURES)?

Thanks

Eric
>
>
>> -- 
>> 2.37.3