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Mon, 17 Aug 2026 22:12:29 -0700 (PDT) From: Connor Kite Date: Mon, 17 Aug 2026 22:12:19 -0700 Subject: [PATCH RFC v2 04/13] hw/virtio/vhost-shadow-virtqueue: used callback Precedence: bulk X-Mailing-List: virtio-fs@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260817-vhost-user-isolated-memory-v2-4-948aae960abb@gmail.com> References: <20260817-vhost-user-isolated-memory-v2-0-948aae960abb@gmail.com> In-Reply-To: <20260817-vhost-user-isolated-memory-v2-0-948aae960abb@gmail.com> To: qemu-devel@nongnu.org Cc: "Michael S. Tsirkin" , Stefano Garzarella , =?utf-8?q?Alex_Benn=C3=A9e?= , Viresh Kumar , Gerd Hoffmann , Mathieu Poirier , Manos Pitsidianakis , Raphael Norwitz , Kevin Wolf , Hanna Reitz , =?utf-8?q?Marc-Andr=C3=A9_Lureau?= , Paolo Bonzini , Fam Zheng , Stefan Hajnoczi , Milan Zamazal , Akihiko Odaki , Dmitry Osipenko , qemu-block@nongnu.org, virtio-fs@lists.linux.dev, "Gonglei (Arei)" , zhenwei pi , =?utf-8?q?Daniel_P=2E_Berrang=C3=A9?= , Eric Blake , Markus Armbruster , Jason Wang , Peter Xu , =?utf-8?q?Eugenio_P=C3=A9rez?= , Alyssa Ross , Demi Marie Obenour , Connor Kite , 20260817233147.2867623-1-connorkite@gmail.com X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1787029936; l=2434; i=connorkite@gmail.com; s=20260723; h=from:subject:message-id; bh=HH0SlSvH+q+3nGir6vgptvnX9Dx9KLnOIY0C19/JvF0=; b=4pu5D0cnp4xmAOKz3RDWU/Xos+GwI2mPfbnmu6yDH3gb9L0MxXGupZxCloz5NW3k23uRSdoVi DOmLtpxDokJB5SnhdWlEtuB9sI0MvC9+Jv6t5oUtBm8+S/MOO015cy3 X-Developer-Key: i=connorkite@gmail.com; a=ed25519; pk=xg/3N8AntFCYogaIgN5NC/KkT7UlZB6ktPIRliJ3hv4= Adds a callback to shadow virtqueues in order to enable non-default processing of used vring elements from the device. Signed-off-by: Connor Kite --- hw/virtio/vhost-shadow-virtqueue.c | 9 +++++++++ hw/virtio/vhost-shadow-virtqueue.h | 16 ++++++++++++++++ 2 files changed, 25 insertions(+) diff --git a/hw/virtio/vhost-shadow-virtqueue.c b/hw/virtio/vhost-shadow-virtqueue.c index c8831d52be..496e7e58a3 100644 --- a/hw/virtio/vhost-shadow-virtqueue.c +++ b/hw/virtio/vhost-shadow-virtqueue.c @@ -675,6 +675,15 @@ static void vhost_svq_flush(VhostShadowVirtqueue *svq, break; } + if (svq->ops && svq->ops->used_callback) { + int r = svq->ops->used_callback(svq, elem, svq->ops_opaque); + + if (r < 0) { + /* VQ or handler is broken. Do not set guest notifier */ + return; + } + } + if (unlikely(i >= svq->vring.num)) { qemu_log_mask(LOG_GUEST_ERROR, "More than %u used buffers obtained in a %u size SVQ", diff --git a/hw/virtio/vhost-shadow-virtqueue.h b/hw/virtio/vhost-shadow-virtqueue.h index ec16a1e838..fd68319fb7 100644 --- a/hw/virtio/vhost-shadow-virtqueue.h +++ b/hw/virtio/vhost-shadow-virtqueue.h @@ -56,8 +56,24 @@ typedef int (*VirtQueueAvailCallback)(VhostShadowVirtqueue *svq, VirtQueueElement *elem, void *vq_callback_opaque); +/** + * Callback to handle a used buffer + * + * @svq: Shadow virtqueue + * @elem: Element placed in the queue by the device + * @vq_callback_opaque: Used to pass arguments to callback + * + * Returns 0 if the vq is running as expected. Returns a negative errno on + * failure. The callback should not add used elements to the vq shadowed + * by the svq as that is done separately after the callback returns. + */ +typedef int (*VirtQueueUsedCallback)(VhostShadowVirtqueue *svq, + VirtQueueElement *elem, + void *vq_callback_opaque); + typedef struct VhostShadowVirtqueueOps { VirtQueueAvailCallback avail_handler; + VirtQueueUsedCallback used_callback; } VhostShadowVirtqueueOps; /* Shadow virtqueue to relay notifications */ -- 2.43.0