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[2003:cb:c705:2200:178b:7244:2a1f:b5d8]) by smtp.gmail.com with ESMTPSA id 7-20020a05600c028700b0038cc9bfe6a4sm3954985wmk.37.2022.03.30.01.42.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 30 Mar 2022 01:42:28 -0700 (PDT) Message-ID: <50b39fbd-c5f4-d080-3cc1-f6e4c27985fd@redhat.com> Date: Wed, 30 Mar 2022 10:42:26 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.6.2 Subject: Re: [RFC 2/8] numa: call ->ram_block_removed() in ram_block_notifer_remove() To: Stefan Hajnoczi , qemu-devel@nongnu.org References: <20220323111727.1100209-1-stefanha@redhat.com> <20220323111727.1100209-3-stefanha@redhat.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20220323111727.1100209-3-stefanha@redhat.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=david@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=david@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, 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_H5=0.001, RCVD_IN_MSPIKE_WL=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: , Cc: Laurent Vivier , Kevin Wolf , Thomas Huth , Vladimir Sementsov-Ogievskiy , qemu-block@nongnu.org, "Michael S. Tsirkin" , John Snow , =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , Alberto Faria , Markus Armbruster , Yanan Wang , Eduardo Habkost , Hanna Reitz , Paolo Bonzini , Fam Zheng , Eric Blake , sgarzare@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 23.03.22 12:17, Stefan Hajnoczi wrote: > When a RAMBlockNotifier is added, ->ram_block_added() is called with all > existing RAMBlocks. There is no equivalent ->ram_block_removed() call > when a RAMBlockNotifier is removed. > > The util/vfio-helpers.c code (the sole user of RAMBlockNotifier) is fine > with this asymmetry because it does not rely on RAMBlockNotifier for > cleanup. It walks its internal list of DMA mappings and unmaps them by > itself. > > Future users of RAMBlockNotifier may not have an internal data structure > that records added RAMBlocks so they will need ->ram_block_removed() > callbacks. > > This patch makes ram_block_notifier_remove() symmetric with respect to > callbacks. Now util/vfio-helpers.c needs to unmap remaining DMA mappings > after ram_block_notifier_remove() has been called. This is necessary > since users like block/nvme.c may create additional DMA mappings that do > not originate from the RAMBlockNotifier. > > Cc: David Hildenbrand > Signed-off-by: Stefan Hajnoczi Reviewed-by: David Hildenbrand -- Thanks, David / dhildenb