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c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1771506254; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=gWQU8N3M/VEPlBfsThD0/ZfMnUZYv5eJfQvM3AaTjpw=; b=Fi6A7zIlyiIQ5xkAcpt/pNeiplv7QFpwTLntP/87Q+DrSrYQzvnNwW8bXHFscfoL9GWfJs dBhlqiDAdvcZ5O2Kf0mRlp3sk7NqzeWmquBQHmvPwarg/DuJ6J20JaptSWFsP/KI9ENELz ZaN9QV7/u6F/keZweBRhpByzBwmmeqc= X-MC-Unique: Ej4-2qOpPWOR-8Sxi3XpaQ-1 X-Mimecast-MFC-AGG-ID: Ej4-2qOpPWOR-8Sxi3XpaQ_1771506249 From: Albert Esteve To: qemu-devel@nongnu.org Cc: Peter Xu , Pierrick Bouvier , mst@redhat.com, dbassey@redhat.com, =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , =?UTF-8?q?Alex=20Benn=C3=A9e?= , Paolo Bonzini , Fabiano Rosas , stefanha@redhat.com, manos.pitsidianakis@linaro.org, Stefano Garzarella , jasowang@redhat.com, Laurent Vivier , slp@redhat.com, hi@alyssa.is, stevensd@chromium.org Subject: [PATCH v13 4/7] vhost_user: Add frontend get_shmem_config command Date: Thu, 19 Feb 2026 14:03:31 +0100 Message-ID: <20260219130334.787858-5-aesteve@redhat.com> In-Reply-To: <20260219130334.787858-1-aesteve@redhat.com> References: <20260219130334.787858-1-aesteve@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; 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charset="utf-8" The frontend can use this command to retrieve VirtIO Shared Memory Regions configuration from the backend. The response contains the number of shared memory regions, their size, and shmid. This is useful when the frontend is unaware of specific backend type and configuration, for example, in the `vhost-user-device` case. Reviewed-by: Stefan Hajnoczi Signed-off-by: Albert Esteve Reviewed-by: Stefano Garzarella --- include/hw/virtio/vhost-backend.h | 10 ++++++++++ include/hw/virtio/vhost-user.h | 1 + include/hw/virtio/virtio.h | 2 ++ 3 files changed, 13 insertions(+) diff --git a/include/hw/virtio/vhost-backend.h b/include/hw/virtio/vhost-ba= ckend.h index ff94fa1734..ce58b4d2d6 100644 --- a/include/hw/virtio/vhost-backend.h +++ b/include/hw/virtio/vhost-backend.h @@ -163,6 +163,15 @@ typedef int (*vhost_set_device_state_fd_op)(struct vho= st_dev *dev, int *reply_fd, Error **errp); typedef int (*vhost_check_device_state_op)(struct vhost_dev *dev, Error **= errp); +/* + * Max regions is VIRTIO_MAX_SHMEM_REGIONS, so that is the maximum + * number of memory_sizes that will be accepted. + */ +typedef int (*vhost_get_shmem_config_op)(struct vhost_dev *dev, + int *nregions, + uint64_t *memory_sizes, + Error **errp); + =20 typedef struct VhostOps { VhostBackendType backend_type; @@ -220,6 +229,7 @@ typedef struct VhostOps { vhost_supports_device_state_op vhost_supports_device_state; vhost_set_device_state_fd_op vhost_set_device_state_fd; vhost_check_device_state_op vhost_check_device_state; + vhost_get_shmem_config_op vhost_get_shmem_config; } VhostOps; =20 int vhost_backend_update_device_iotlb(struct vhost_dev *dev, diff --git a/include/hw/virtio/vhost-user.h b/include/hw/virtio/vhost-user.h index 55d5725ef8..8ac2120cfd 100644 --- a/include/hw/virtio/vhost-user.h +++ b/include/hw/virtio/vhost-user.h @@ -32,6 +32,7 @@ enum VhostUserProtocolFeature { /* Feature 17 reserved for VHOST_USER_PROTOCOL_F_XEN_MMAP. */ VHOST_USER_PROTOCOL_F_SHARED_OBJECT =3D 18, VHOST_USER_PROTOCOL_F_DEVICE_STATE =3D 19, + VHOST_USER_PROTOCOL_F_SHMEM =3D 20, VHOST_USER_PROTOCOL_F_MAX }; =20 diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h index 40d881ca09..9aef913af0 100644 --- a/include/hw/virtio/virtio.h +++ b/include/hw/virtio/virtio.h @@ -82,6 +82,8 @@ typedef struct VirtQueueElement =20 #define VIRTIO_NO_VECTOR 0xffff =20 +#define VIRTIO_MAX_SHMEM_REGIONS 256 + /* special index value used internally for config irqs */ #define VIRTIO_CONFIG_IRQ_IDX -1 =20 --=20 2.52.0