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bh=iakRaPjlZHRAhoFV1mLNcawbsCOENmNXEShIiIe3GoI=; b=KZHvSkpLanZv7HnlhZXLIiHcjW2OuyIm0cFjkm+K8V/42XElGLJJ3ciy53d18BP9xN7lOd WuX4DmYTWrNNREcjXyhmbyl1NhPXKMhV5ECzDzdwjruRL/9xs9PCLMGRRqpSzyB4RplCMv lReabBGZRItt4ajeZspfwSZjVpjBDFk= X-MC-Unique: PlNzUGmTMkKPnwiocxq8Ow-1 From: Stefan Hajnoczi To: qemu-devel@nongnu.org Cc: qemu-block@nongnu.org, Hanna Reitz , Kevin Wolf , Stefan Hajnoczi Subject: [PATCH 3/3] block-ram-registrar: reset when the graph changes Date: Wed, 4 Jan 2023 17:06:31 -0500 Message-Id: <20230104220631.110321-4-stefanha@redhat.com> In-Reply-To: <20230104220631.110321-1-stefanha@redhat.com> References: <20230104220631.110321-1-stefanha@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.6 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.129.124; envelope-from=stefanha@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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1672871048228100003 Content-Type: text/plain; charset="utf-8" The BDRV_REQ_REGISTERED_BUF flag can be set on I/O requests to indicate that I/O buffers were previously registered using bdrv_register_buf(). block-ram-registrar automatically registers guest RAM so that emulated storage controllers can set BDRV_REQ_REGISTERED_BUF without having to worry about registering buffers themselves. Kevin Wolf pointed out that block-ram-registrar does not handle graph changes. This means buffers aren't unregistered when a node is removed from the graph and buffer registrations aren't replayed when a new node is inserted in the graph. Therefore BDRV_REQ_REGISTERED_BUF may be set but the buffer wasn't previously registered with the new node. Fix this by monitoring graph changes and replaying buffer registration. Note that the ram_block_notifier_add() API enumerates all RAM blocks so we don't need to manually replay them. Signed-off-by: Stefan Hajnoczi --- block/block-ram-registrar.c | 40 ++++++++++++++++++++++++++++++++----- 1 file changed, 35 insertions(+), 5 deletions(-) diff --git a/block/block-ram-registrar.c b/block/block-ram-registrar.c index 25dbafa789..1a111ac124 100644 --- a/block/block-ram-registrar.c +++ b/block/block-ram-registrar.c @@ -33,6 +33,35 @@ static void ram_block_removed(RAMBlockNotifier *n, void = *host, size_t size, blk_unregister_buf(r->blk, host, max_size); } =20 +static void remove_ram_block_notifier(BlockRAMRegistrar *r) +{ + if (r->ok) { + ram_block_notifier_remove(&r->notifier); + } +} + +static void add_ram_block_notifier(BlockRAMRegistrar *r) +{ + r->ok =3D true; /* reset flag in case it was false */ + ram_block_notifier_add(&r->notifier); +} + +static void graph_change_pre_detach(BlockBackend *blk, void *opaque) +{ + BlockRAMRegistrar *r =3D opaque; + + /* Unregisters all buffers from all BDSes */ + remove_ram_block_notifier(r); +} + +static void graph_change_post_attach(BlockBackend *blk, void *opaque) +{ + BlockRAMRegistrar *r =3D opaque; + + /* Re-registers all buffers with all BDSes */ + add_ram_block_notifier(r); +} + void blk_ram_registrar_init(BlockRAMRegistrar *r, BlockBackend *blk) { r->blk =3D blk; @@ -45,14 +74,15 @@ void blk_ram_registrar_init(BlockRAMRegistrar *r, Block= Backend *blk) * value that does not change across resize. */ }; - r->ok =3D true; =20 - ram_block_notifier_add(&r->notifier); + blk_add_graph_change_notifier(blk, graph_change_pre_detach, + graph_change_post_attach, r); + add_ram_block_notifier(r); } =20 void blk_ram_registrar_destroy(BlockRAMRegistrar *r) { - if (r->ok) { - ram_block_notifier_remove(&r->notifier); - } + remove_ram_block_notifier(r); + blk_remove_graph_change_notifier(r->blk, graph_change_pre_detach, + graph_change_post_attach, r); } --=20 2.39.0