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[174.95.215.133]) by smtp.gmail.com with ESMTPSA id p187sm2089145qkf.70.2020.10.21.14.27.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 21 Oct 2020 14:27:22 -0700 (PDT) From: Peter Xu To: qemu-devel@nongnu.org Subject: [PATCH v6 0/6] migration/postcopy: Sync faulted addresses after network recovered Date: Wed, 21 Oct 2020 17:27:15 -0400 Message-Id: <20201021212721.440373-1-peterx@redhat.com> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=peterx@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=216.205.24.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/21 02:16:02 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] 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_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: Peter Maydell , Thomas Huth , "Dr . David Alan Gilbert" , peterx@redhat.com, Juan Quintela Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" v6: - fix page mask to use ramblock psize [Dave] v5: - added one test patch for easier debugging for migration-test - added one fix patch [1] for another postcopy race - fixed a bug that could trigger when host/guest page size differs v4: - use "void */ulong" instead of "uint64_t" where proper in patch 3/4 [Dave] v3: - fix build on 32bit hosts & rebase - remove r-bs for the last 2 patches for Dave due to the changes v2: - add r-bs for Dave - add patch "migration: Properly destroy variables on incoming side" as patch 1 - destroy page_request_mutex in migration_incoming_state_destroy() too [Dave] - use WITH_QEMU_LOCK_GUARD in two places where we can [Dave] We've seen conditional guest hangs on destination VM after postcopy recovered. However the hang will resolve itself after a few minutes. The problem is: after a postcopy recovery, the prioritized postcopy queue on the source VM is actually missing. So all the faulted threads before the postcopy recovery happened will keep halted until (accidentally) the page got copied by the background precopy migration stream. The solution is to also refresh this information after postcopy recovery. To achieve this, we need to maintain a list of faulted addresses on the destination node, so that we can resend the list when necessary. This work is done via patch 2-5. With that, the last thing we need to do is to send this extra information to source VM after recovered. Very luckily, this synchronization can be "emulated" by sending a bunch of page requests (although these pages have been sent previously!) to source VM just like when we've got a page fault. Even in the 1st version of the postcopy code we'll handle duplicated pages well. So this fix does not even need a new capability bit and it'll work smoothly on old QEMUs when we migrate from them to the new QEMUs. Please review, thanks. Peter Xu (6): migration: Pass incoming state into qemu_ufd_copy_ioctl() migration: Introduce migrate_send_rp_message_req_pages() migration: Maintain postcopy faulted addresses migration: Sync requested pages after postcopy recovery migration/postcopy: Release fd before going into 'postcopy-pause' migration-test: Only hide error if !QTEST_LOG migration/migration.c | 55 ++++++++++++++++++++++++++++++---- migration/migration.h | 21 ++++++++++++- migration/postcopy-ram.c | 25 ++++++++++++---- migration/savevm.c | 57 ++++++++++++++++++++++++++++++++++++ migration/trace-events | 3 ++ tests/qtest/migration-test.c | 6 +++- 6 files changed, 154 insertions(+), 13 deletions(-) -- 2.26.2 Reviewed-by: Thomas Huth Reviewed-by: Dr. David Alan Gilbert