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Tsirkin" To: qemu-devel@nongnu.org Subject: [PULL 01/35] vhost-vdpa: Do not send empty IOTLB update batches Message-ID: <20210904213506.486886-2-mst@redhat.com> References: <20210904213506.486886-1-mst@redhat.com> MIME-Version: 1.0 In-Reply-To: <20210904213506.486886-1-mst@redhat.com> X-Mailer: git-send-email 2.27.0.106.g8ac3dc51b1 X-Mutt-Fcc: =sent Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mst@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=mst@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.391, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, 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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Jason Wang , Eugenio =?utf-8?B?UMOpcmV6?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: Eugenio Pérez With the introduction of the batch hinting, meaningless batches can be created with no IOTLB updates if the memory region was skipped by vhost_vdpa_listener_skipped_section. This is the case of host notifiers memory regions, device un/realize, and others. This causes the vdpa device to receive dma mapping settings with no changes, a possibly expensive operation for nothing. To avoid that, VHOST_IOTLB_BATCH_BEGIN hint is delayed until we have a meaningful (not skipped section) mapping or unmapping operation, and VHOST_IOTLB_BATCH_END is not written unless at least one of _UPDATE / _INVALIDATE has been issued. v3: * Use a bool instead of a counter avoiding potential number wrapping * Fix bad check on _commit * Move VHOST_BACKEND_F_IOTLB_BATCH check to vhost_vdpa_iotlb_batch_begin_once v2 (from RFC): * Rename misleading name * Abstract start batching function for listener_add/del Signed-off-by: Eugenio Pérez Message-Id: <20210812140933.226288-1-eperezma@redhat.com> Acked-by: Jason Wang Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- include/hw/virtio/vhost-vdpa.h | 1 + hw/virtio/vhost-vdpa.c | 35 ++++++++++++++++++++++------------ 2 files changed, 24 insertions(+), 12 deletions(-) diff --git a/include/hw/virtio/vhost-vdpa.h b/include/hw/virtio/vhost-vdpa.h index 9188226d8b..a8963da2d9 100644 --- a/include/hw/virtio/vhost-vdpa.h +++ b/include/hw/virtio/vhost-vdpa.h @@ -22,6 +22,7 @@ typedef struct VhostVDPAHostNotifier { typedef struct vhost_vdpa { int device_fd; uint32_t msg_type; + bool iotlb_batch_begin_sent; MemoryListener listener; struct vhost_dev *dev; VhostVDPAHostNotifier notifier[VIRTIO_QUEUE_MAX]; diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c index 4fa414feea..ca1227e5dc 100644 --- a/hw/virtio/vhost-vdpa.c +++ b/hw/virtio/vhost-vdpa.c @@ -89,19 +89,13 @@ static int vhost_vdpa_dma_unmap(struct vhost_vdpa *v, hwaddr iova, return ret; } -static void vhost_vdpa_listener_begin(MemoryListener *listener) +static void vhost_vdpa_listener_begin_batch(struct vhost_vdpa *v) { - struct vhost_vdpa *v = container_of(listener, struct vhost_vdpa, listener); - struct vhost_dev *dev = v->dev; - struct vhost_msg_v2 msg = {}; int fd = v->device_fd; - - if (!(dev->backend_cap & (0x1ULL << VHOST_BACKEND_F_IOTLB_BATCH))) { - return; - } - - msg.type = v->msg_type; - msg.iotlb.type = VHOST_IOTLB_BATCH_BEGIN; + struct vhost_msg_v2 msg = { + .type = v->msg_type, + .iotlb.type = VHOST_IOTLB_BATCH_BEGIN, + }; if (write(fd, &msg, sizeof(msg)) != sizeof(msg)) { error_report("failed to write, fd=%d, errno=%d (%s)", @@ -109,6 +103,16 @@ static void vhost_vdpa_listener_begin(MemoryListener *listener) } } +static void vhost_vdpa_iotlb_batch_begin_once(struct vhost_vdpa *v) +{ + if (v->dev->backend_cap & (0x1ULL << VHOST_BACKEND_F_IOTLB_BATCH) && + !v->iotlb_batch_begin_sent) { + vhost_vdpa_listener_begin_batch(v); + } + + v->iotlb_batch_begin_sent = true; +} + static void vhost_vdpa_listener_commit(MemoryListener *listener) { struct vhost_vdpa *v = container_of(listener, struct vhost_vdpa, listener); @@ -120,6 +124,10 @@ static void vhost_vdpa_listener_commit(MemoryListener *listener) return; } + if (!v->iotlb_batch_begin_sent) { + return; + } + msg.type = v->msg_type; msg.iotlb.type = VHOST_IOTLB_BATCH_END; @@ -127,6 +135,8 @@ static void vhost_vdpa_listener_commit(MemoryListener *listener) error_report("failed to write, fd=%d, errno=%d (%s)", fd, errno, strerror(errno)); } + + v->iotlb_batch_begin_sent = false; } static void vhost_vdpa_listener_region_add(MemoryListener *listener, @@ -170,6 +180,7 @@ static void vhost_vdpa_listener_region_add(MemoryListener *listener, llsize = int128_sub(llend, int128_make64(iova)); + vhost_vdpa_iotlb_batch_begin_once(v); ret = vhost_vdpa_dma_map(v, iova, int128_get64(llsize), vaddr, section->readonly); if (ret) { @@ -221,6 +232,7 @@ static void vhost_vdpa_listener_region_del(MemoryListener *listener, llsize = int128_sub(llend, int128_make64(iova)); + vhost_vdpa_iotlb_batch_begin_once(v); ret = vhost_vdpa_dma_unmap(v, iova, int128_get64(llsize)); if (ret) { error_report("vhost_vdpa dma unmap error!"); @@ -234,7 +246,6 @@ static void vhost_vdpa_listener_region_del(MemoryListener *listener, * depends on the addnop(). */ static const MemoryListener vhost_vdpa_memory_listener = { - .begin = vhost_vdpa_listener_begin, .commit = vhost_vdpa_listener_commit, .region_add = vhost_vdpa_listener_region_add, .region_del = vhost_vdpa_listener_region_del, -- MST