On Tue, Dec 2, 2025 at 8:50 PM Michael S. Tsirkin <[email protected]> wrote: > > On Tue, Nov 11, 2025 at 10:10:51AM +0100, Albert Esteve wrote: > > Hi all, > > > > v10->v11 > > - Rebase to grab commit fde5930cc37175cfcd0f03a089e26f4458a52311 > > and explicitly unset reply_ack on the SHMEM_MAP/UNMAP msg. > > - Mention mapping cleanup on device reset in the spec. > > v9->v10 > > - Fix transaction_commit invoked without transaction_begin > > on vhost_user_backend_handle_shmem_map() early errors > > - Removed fd tracking on VirtioSharedMemoryMapping, it > > is handled by the RAMBlock > > - Reject invalid BAR configurations when VIRTIO Shared Memory > > Regions are in use by vhost-user-test-device > > v8->v9 > > - Fixed vhost-user new handlers to ensure that they always > > reply > > - Made MMAP request flags field u64 everywhere > > - Fixed double memory_region_del_subregion() on UNMAP > > - Add mappings cleaning on virtio_reset() > > - Some small typos and fixes > > - Fixed virtio pci bar mapping for vhost-user-test-device > > v7->v8 > > - Unified VhostUserShmemObject and VirtioSharedMemoryMapping > > - Refined shmem_obj lifecycle by transferring ownership > > - Other small improvements > > > > This patch series implements dynamic fd-backed memory mapping support > > for vhost-user backends, enabling backends to dynamically request memory > > mappings and unmappings during runtime through the new > > VHOST_USER_BACKEND_SHMEM_MAP/UNMAP protocol messages. > > > > This feature benefits various VIRTIO devices that require dynamic shared > > memory management, including virtiofs (for DAX mappings), virtio-gpu > > (for resource sharing), and the recently standardized virtio-media. > > > > The implementation introduces a QOM-based architecture for managing > > shared memory lifecycle: > > > > - VirtioSharedMemoryMapping: an intermediate object that manages > > individual memory mappings by acting as generic container for regions > > declared in any vhost-user device type > > - Dynamic Mapping: backends can request mappings via SHMEM_MAP messages, > > with the frontend creating MemoryRegions from the provided file > > descriptors and adding them as subregions > > > > When a SHMEM_MAP request is received, the frontend: > > 1. Creates VirtioSharedMemoryMapping to manage the mapping lifecycle > > 2. Maps the provided fd with memory_region_init_ram_from_fd() > > 3. Creates a MemoryRegion backed by the mapped memory > > 4. Adds it as a subregion of the appropiate VIRTIO Shared Memory Region > > > > The QOM reference counting ensures automatic cleanup when mappings are > > removed or the device is destroyed. > > > > This patch also includes: > > - VHOST_USER_GET_SHMEM_CONFIG: a new frontend request allowing generic > > vhost-user devices to query shared memory configuration from backends > > at device initialization, enabling the generic vhost-user-device > > frontend to work with any backend regardless of specific shared memory > > requirements. > > Looks good, we are in freeze so will merge after 10.2. > If it's not too much trouble, pls ping me after the release > to help make sure it's not forgotten.
Release happened already iianm? Sending the ping. > > > > The implementation has been tested with rust-vmm based backends. > > > > Albert Esteve (7): > > vhost-user: Add VirtIO Shared Memory map request > > vhost_user.rst: Align VhostUserMsg excerpt members > > vhost_user.rst: Add SHMEM_MAP/_UNMAP to spec > > vhost_user: Add frontend get_shmem_config command > > vhost_user.rst: Add GET_SHMEM_CONFIG message > > qmp: add shmem feature map > > vhost-user-device: Add shared memory BAR > > > > docs/interop/vhost-user.rst | 102 ++++++++ > > hw/virtio/vhost-user-base.c | 47 +++- > > hw/virtio/vhost-user-test-device-pci.c | 39 +++- > > hw/virtio/vhost-user.c | 269 ++++++++++++++++++++++ > > hw/virtio/virtio-qmp.c | 3 + > > hw/virtio/virtio.c | 199 ++++++++++++++++ > > include/hw/virtio/vhost-backend.h | 10 + > > include/hw/virtio/vhost-user.h | 1 + > > include/hw/virtio/virtio.h | 137 +++++++++++ > > subprojects/libvhost-user/libvhost-user.c | 70 ++++++ > > subprojects/libvhost-user/libvhost-user.h | 54 +++++ > > 11 files changed, 926 insertions(+), 5 deletions(-) > > > > -- > > 2.49.0 >
