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[83.51.215.31]) by smtp.gmail.com with ESMTPSA id v12sm355890wru.73.2021.05.13.02.43.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 13 May 2021 02:43:26 -0700 (PDT) Subject: Re: [vhost-user] Expectations around reconnection To: "Boeuf, Sebastien" , "qemu-devel@nongnu.org" References: From: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= Message-ID: <6eded3ad-ea69-3d07-65ee-01d4ac7cf067@redhat.com> Date: Thu, 13 May 2021 11:43:25 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=philmd@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=philmd@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.7, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: =?UTF-8?Q?Marc-Andr=c3=a9_Lureau?= , Stefan Hajnoczi , "Michael S. Tsirkin" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Cc'ing few developers On 5/11/21 3:33 PM, Boeuf, Sebastien wrote: > Hi All, > > In the context of vhost-user, I was wondering how a reconnection should > be handled from the VMM perspective? > > In particular, I'm looking at the OVS-DPDK use case using the client > mode (meaning QEMU acts as the server), and I'd like to understand what > QEMU does to handle this. Upon disconnection from the backend, does QEMU > reset the virtio device (meaning the guest > is notified about it)? And upon the new connection from the backend, > does QEMU go through the whole vhost-user initialization once again > (feature acknowledgement, setup of vrings, etc...), or does it simply > assume the backend will have saved all these information? > > Thanks for your time, > Sebastien