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[70.24.86.62]) by smtp.gmail.com with ESMTPSA id r11-20020ac85e8b000000b003f6be76a5c1sm237809qtx.6.2023.05.23.06.40.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 23 May 2023 06:40:49 -0700 (PDT) Date: Tue, 23 May 2023 09:40:48 -0400 From: Peter Xu To: "Wang, Wei W" Cc: "quintela@redhat.com" , "Wang, Lei4" , "berrange@redhat.com" , "qemu-devel@nongnu.org" Subject: Re: [PATCH v1] migration: fail the cap check if it requires the use of deferred incoming Message-ID: References: <20230518160026.57414-1-wei.w.wang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Received-SPF: pass client-ip=170.10.133.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Tue, May 23, 2023 at 01:44:03AM +0000, Wang, Wei W wrote: > On Tuesday, May 23, 2023 7:36 AM, Peter Xu wrote: > > > > We may also want to trap the channel setups on num: > > > > > > > > migrate_params_test_apply(): > > > > > > > > if (params->has_multifd_channels) { > > > > dest->multifd_channels = params->multifd_channels; > > > > } > > > > > > Didn’t get this one. What do you want to add to above? > > > > I meant after listen() is called with an explicit number in this case, should we > > disallow changing of multifd number of channels? > > Got you, thanks. That seems unnecessary to me, as the cap setting is required > for the use of multifd and patching there already achieves below what we want: > - users get the error message when deferred -incoming isn’t used; > - fail the cap setting for multifd, meaning that multifd won't be used (i.e. > no place that will care about multifd_channels). It's about whether we want to protect e.g. below steps: 1. start dest qemu with -incoming defer 2. "migrate-set-capabilities" to enable multifd 3. "migrate-incoming xxx" to setup the sockets 4. "migrate-set-parameters" to setup the num of multifd <--- will be invalid here Would that still be a problem that falls into the same category of what this patch wants to protect qemu from? Thanks, -- Peter Xu