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[81.97.203.96]) by smtp.gmail.com with ESMTPSA id f6-20020a7bc8c6000000b003e215a796fasm3408520wml.34.2023.03.14.11.03.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Mar 2023 11:03:36 -0700 (PDT) Date: Tue, 14 Mar 2023 18:03:34 +0000 From: "Dr. David Alan Gilbert" To: Peter Xu Cc: qemu-devel@nongnu.org, quintela@redhat.com, lizhijian@cn.fujitsu.com, jdenemar@redhat.com Subject: Re: [PATCH] migration/rdma: Fix return-path case Message-ID: References: <20230314171558.75941-1-dgilbert@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/2.2.9 (2022-11-12) Received-SPF: pass client-ip=170.10.129.124; envelope-from=dgilbert@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 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 * Peter Xu (peterx@redhat.com) wrote: > On Tue, Mar 14, 2023 at 05:15:58PM +0000, Dr. David Alan Gilbert (git) wrote: > > From: "Dr. David Alan Gilbert" > > > > The RDMA code has return-path handling code, but it's only enabled > > if postcopy is enabled; if the 'return-path' migration capability > > is enabled, the return path is NOT setup but the core migration > > code still tries to use it and breaks. > > > > Enable the RDMA return path if either postcopy or the return-path > > capability is enabled. > > > > bz: https://bugzilla.redhat.com/show_bug.cgi?id=2063615 > > > > Signed-off-by: Dr. David Alan Gilbert > > Acked-by: Peter Xu > > > @@ -3373,7 +3373,8 @@ static int qemu_rdma_accept(RDMAContext *rdma) > > * initialize the RDMAContext for return path for postcopy after first > > * connection request reached. > > */ > > - if (migrate_postcopy() && !rdma->is_return_path) { > > + if ((migrate_postcopy() || migrate_use_return_path()) > > + && !rdma->is_return_path) { > > rdma_return_path = qemu_rdma_data_init(rdma->host_port, NULL); > > if (rdma_return_path == NULL) { > > rdma_ack_cm_event(cm_event); > > It's not extremely clear to me yet on when we should use migrate_postcopy() > and when to use migrate_postcopy_ram(). I think it's because I don't know > enough on the dirty-bitmaps capability. Do we have some good documentation > somewhere? Hmm that's probably a good point. > Not much I get from the qapi doc.. > > # @dirty-bitmaps: If enabled, QEMU will migrate named dirty bitmaps. > # (since 2.12) I don't know of any good docs; I think this is a blocks mechanism; I'm not even sure if it needs the return path. Dave > Thanks, > > -- > Peter Xu > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK