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c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1757505315; 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=EV38TEjNyp5jDyAaZO+zz46tsIIZHTAxtiHGBnFQTsg=; b=eVJz8ZOJ1ElpjsIhJ+mzkdKbv5LZlRoWsAXUPCrudV76LoQ2BhICJzIQE/7azQPprUMoEV K8Fi9tis6HWADFjiUVm78ppfmGWn7vIMzVmy6XFd3mYdQ2halRzOgKFMYUayyNed/vzIsg ZfjXRZJ9KicX+SCNl4aIi4icBrw3xlA= X-MC-Unique: J2c29AW_M2q8obK6oCxG3Q-1 X-Mimecast-MFC-AGG-ID: J2c29AW_M2q8obK6oCxG3Q_1757505310 From: Albert Esteve To: qemu-devel@nongnu.org Cc: stevensd@chromium.org, dbassey@redhat.com, Laurent Vivier , Paolo Bonzini , mst@redhat.com, slp@redhat.com, hi@alyssa.is, stefanha@redhat.com, Fabiano Rosas , Stefano Garzarella , jasowang@redhat.com, david@redhat.com, =?UTF-8?q?Alex=20Benn=C3=A9e?= , Albert Esteve Subject: [PATCH v8 7/7] vhost-user-device: Add shared memory BAR Date: Wed, 10 Sep 2025 13:54:20 +0200 Message-ID: <20250910115420.1012191-8-aesteve@redhat.com> In-Reply-To: <20250910115420.1012191-1-aesteve@redhat.com> References: <20250910115420.1012191-1-aesteve@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 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" Add shared memory BAR support to vhost-user-device-pci to enable direct file mapping for VIRTIO Shared Memory Regions. The implementation creates a consolidated shared memory BAR that contains all VIRTIO Shared Memory Regions as subregions. Each region is configured with its proper shmid, size, and offset within the BAR. The number and size of regions are retrieved via VHOST_USER_GET_SHMEM_CONFIG message sent by vhost-user-base during realization after virtio_init(). Specifiically, it uses BAR 3 to avoid conflicts, as it is currently unused. The shared memory BAR is only created when the backend supports VHOST_USER_PROTOCOL_F_SHMEM and has configured shared memory regions. This maintains backward compatibility with backends that do not support shared memory functionality. Signed-off-by: Albert Esteve --- hw/virtio/vhost-user-base.c | 47 +++++++++++++++++++++++++++++-- hw/virtio/vhost-user-device-pci.c | 34 ++++++++++++++++++++-- 2 files changed, 76 insertions(+), 5 deletions(-) diff --git a/hw/virtio/vhost-user-base.c b/hw/virtio/vhost-user-base.c index ff67a020b4..82f49500e4 100644 --- a/hw/virtio/vhost-user-base.c +++ b/hw/virtio/vhost-user-base.c @@ -16,6 +16,7 @@ #include "hw/virtio/virtio-bus.h" #include "hw/virtio/vhost-user-base.h" #include "qemu/error-report.h" +#include "migration/blocker.h" =20 static void vub_start(VirtIODevice *vdev) { @@ -276,7 +277,9 @@ static void vub_device_realize(DeviceState *dev, Error = **errp) { VirtIODevice *vdev =3D VIRTIO_DEVICE(dev); VHostUserBase *vub =3D VHOST_USER_BASE(dev); - int ret; + uint64_t memory_sizes[VIRTIO_MAX_SHMEM_REGIONS]; + g_autofree char *name =3D NULL; + int i, ret, nregions, regions_processed =3D 0; =20 if (!vub->chardev.chr) { error_setg(errp, "vhost-user-base: missing chardev"); @@ -319,7 +322,7 @@ static void vub_device_realize(DeviceState *dev, Error = **errp) =20 /* Allocate queues */ vub->vqs =3D g_ptr_array_sized_new(vub->num_vqs); - for (int i =3D 0; i < vub->num_vqs; i++) { + for (i =3D 0; i < vub->num_vqs; i++) { g_ptr_array_add(vub->vqs, virtio_add_queue(vdev, vub->vq_size, vub_handle_output)); @@ -333,11 +336,49 @@ static void vub_device_realize(DeviceState *dev, Erro= r **errp) VHOST_BACKEND_TYPE_USER, 0, errp); =20 if (ret < 0) { - do_vhost_user_cleanup(vdev, vub); + goto err; + } + + ret =3D vub->vhost_dev.vhost_ops->vhost_get_shmem_config(&vub->vhost_d= ev, + &nregions, + memory_sizes, + errp); + + if (ret < 0) { + goto err; + } + + for (i =3D 0; i < VIRTIO_MAX_SHMEM_REGIONS && regions_processed < nreg= ions; i++) { + if (memory_sizes[i]) { + regions_processed++; + if (vub->vhost_dev.migration_blocker =3D=3D NULL) { + error_setg(&vub->vhost_dev.migration_blocker, + "Migration disabled: devices with VIRTIO Shared Mem= ory " + "Regions do not support migration yet."); + ret =3D migrate_add_blocker_normal( + &vub->vhost_dev.migration_blocker, + errp); + + if (ret < 0) { + goto err; + } + } + + if (memory_sizes[i] % qemu_real_host_page_size() !=3D 0) { + error_setg(errp, "Shared memory %d size must be a power of= 2 " + "no smaller than the page size", i); + goto err; + } + + virtio_new_shmem_region(vdev, i, memory_sizes[i]); + } } =20 qemu_chr_fe_set_handlers(&vub->chardev, NULL, NULL, vub_event, NULL, dev, NULL, true); + return; +err: + do_vhost_user_cleanup(vdev, vub); } =20 static void vub_device_unrealize(DeviceState *dev) diff --git a/hw/virtio/vhost-user-device-pci.c b/hw/virtio/vhost-user-devic= e-pci.c index f10bac874e..bac99e7c60 100644 --- a/hw/virtio/vhost-user-device-pci.c +++ b/hw/virtio/vhost-user-device-pci.c @@ -8,14 +8,18 @@ */ =20 #include "qemu/osdep.h" +#include "qapi/error.h" #include "hw/qdev-properties.h" #include "hw/virtio/vhost-user-base.h" #include "hw/virtio/virtio-pci.h" =20 +#define VIRTIO_DEVICE_PCI_SHMEM_BAR 3 + struct VHostUserDevicePCI { VirtIOPCIProxy parent_obj; =20 VHostUserBase vub; + MemoryRegion shmembar; }; =20 #define TYPE_VHOST_USER_DEVICE_PCI "vhost-user-device-pci-base" @@ -25,10 +29,36 @@ OBJECT_DECLARE_SIMPLE_TYPE(VHostUserDevicePCI, VHOST_US= ER_DEVICE_PCI) static void vhost_user_device_pci_realize(VirtIOPCIProxy *vpci_dev, Error = **errp) { VHostUserDevicePCI *dev =3D VHOST_USER_DEVICE_PCI(vpci_dev); - DeviceState *vdev =3D DEVICE(&dev->vub); + DeviceState *dev_state =3D DEVICE(&dev->vub); + VirtIODevice *vdev =3D VIRTIO_DEVICE(dev_state); + VirtioSharedMemory *shmem, *next; + uint64_t offset =3D 0, shmem_size =3D 0; =20 vpci_dev->nvectors =3D 1; - qdev_realize(vdev, BUS(&vpci_dev->bus), errp); + qdev_realize(dev_state, BUS(&vpci_dev->bus), errp); + + QSIMPLEQ_FOREACH_SAFE(shmem, &vdev->shmem_list, entry, next) { + if (shmem->mr.size > UINT64_MAX - shmem_size) { + error_setg(errp, "Total shared memory required overflow"); + return; + } + shmem_size =3D shmem_size + shmem->mr.size; + } + if (shmem_size) { + memory_region_init(&dev->shmembar, OBJECT(vpci_dev), + "vhost-device-pci-shmembar", shmem_size); + QSIMPLEQ_FOREACH_SAFE(shmem, &vdev->shmem_list, entry, next) { + memory_region_add_subregion(&dev->shmembar, offset, &shmem->mr= ); + virtio_pci_add_shm_cap(vpci_dev, VIRTIO_DEVICE_PCI_SHMEM_BAR, + offset, shmem->mr.size, shmem->shmid); + offset =3D offset + shmem->mr.size; + } + pci_register_bar(&vpci_dev->pci_dev, VIRTIO_DEVICE_PCI_SHMEM_BAR, + PCI_BASE_ADDRESS_SPACE_MEMORY | + PCI_BASE_ADDRESS_MEM_PREFETCH | + PCI_BASE_ADDRESS_MEM_TYPE_64, + &dev->shmembar); + } } =20 static void vhost_user_device_pci_class_init(ObjectClass *klass, --=20 2.49.0