From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 6E802C021AA for ; Tue, 18 Feb 2025 10:34:48 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tkKvb-0001vL-1I; Tue, 18 Feb 2025 05:34:11 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tkKvZ-0001up-9e for qemu-devel@nongnu.org; Tue, 18 Feb 2025 05:34:09 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tkKvW-0000rH-AP for qemu-devel@nongnu.org; Tue, 18 Feb 2025 05:34:09 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1739874845; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=As1jmVgerOf5bCVudJmfe3lgYa94RDnfAYwNaRuYs3g=; b=VGz8hgdimrsH4vQ8HIGNOQtD6XK+UDUbE7wGFlRCMuTljzuzV8yoR9u/Psfw6A/oR/TCam tCQoAEQ4dYgz8QbwCO9rgumAsO2AUyXBH3GHs5UKe3hEJI9i8klJ6fRDBBvQzWux/X+6I5 KeKPRcpMsmClWZA7HMCMs1IDzccu7Pw= Received: from mail-pj1-f70.google.com (mail-pj1-f70.google.com [209.85.216.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-439-1Mtv3SenO_eotlUqVgBgkw-1; Tue, 18 Feb 2025 05:34:03 -0500 X-MC-Unique: 1Mtv3SenO_eotlUqVgBgkw-1 X-Mimecast-MFC-AGG-ID: 1Mtv3SenO_eotlUqVgBgkw_1739874842 Received: by mail-pj1-f70.google.com with SMTP id 98e67ed59e1d1-2fc518f0564so5229228a91.2 for ; Tue, 18 Feb 2025 02:34:02 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1739874842; x=1740479642; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=As1jmVgerOf5bCVudJmfe3lgYa94RDnfAYwNaRuYs3g=; b=ESzI9o0Dx77nROQvsClpD7xnjv5xG9VwtTyat/oJZ0sOPlIEpGiwdSSxnQpklfMey2 z8QGGMs5av7FZSLvI0QIkAF7fQRus0uzguw10sg/Zti5rjSveYTqBsUWK7/OkJ4F6EPr zJ5erpfZteZNjF0oRkKApQXNgpOwj6Fn1KQGEr1Sw5M/bNTgFQLFmlIxG4s0fx9I6kXr nao+GXczuk9Z/2Afr872YDP3a9A7SQ9PFtHrn0SgAA1h+eD1FyFuGIuR5srs1mL1Am8Z AgyoIpW/x+3L3Uq48wdJrIXhOIXZK9SmAHJE1xwr/o3AmoDO5uvTXMNdUTjqn/eNTwWU 7NdQ== X-Gm-Message-State: AOJu0Yz+nqYdVR321v/defePhJb1bbt8jQek0KUBw3nMZFVsoa/k8jNZ iFwIlPC4nWuVnKqO3Xm+w+mmQrlx658w7Au/YwLoMlJ/RRS3Q0OqvgpJK5t/whhWxt+uRzN+yBd Xj079cQ3iB1jBqaV85bXy7miQCfI3J7p34sv0zSpxt1FdeGKgJEMF85Iw6ZKyCBqJeZlzfVfetG Ppmp1VXSt2HwZkLj+rds5oUz6Q7zY= X-Gm-Gg: ASbGncuypSdzqw8cWWFVTM83dtilWZnPEv4KnpPwCZfca22gQNgRqV6N5/H7hwADrqO lCmPbNeUaXgInUm6kdAaypG7PFnp9YuwCveD1CAl3Z31fhp3Jo+1+wPiqoo1tOJjP X-Received: by 2002:a17:90b:4cc3:b0:2ee:af31:a7bd with SMTP id 98e67ed59e1d1-2fc40d13e11mr19633239a91.5.1739874841817; Tue, 18 Feb 2025 02:34:01 -0800 (PST) X-Google-Smtp-Source: AGHT+IFRnUshNfFuhUA/kyewhvi/9HVf7fy7fIaFgq7fYWywABlOu2s6vU4vEUDBfbBmLWZFdME2r+PoXU/NJhONqfM= X-Received: by 2002:a17:90b:4cc3:b0:2ee:af31:a7bd with SMTP id 98e67ed59e1d1-2fc40d13e11mr19633203a91.5.1739874841358; Tue, 18 Feb 2025 02:34:01 -0800 (PST) MIME-Version: 1.0 References: <20250217164012.246727-1-aesteve@redhat.com> <20250217164012.246727-2-aesteve@redhat.com> <20250218064321.GE10767@fedora> In-Reply-To: <20250218064321.GE10767@fedora> From: Albert Esteve Date: Tue, 18 Feb 2025 11:33:49 +0100 X-Gm-Features: AWEUYZkIggR26dmotMSVrDoq26iPNpSzI_judq9mRqI86fEIukpHKhx1qJ5mW_I Message-ID: Subject: Re: [PATCH v4 1/9] vhost-user: Add VirtIO Shared Memory map request To: Stefan Hajnoczi Cc: qemu-devel@nongnu.org, slp@redhat.com, stevensd@chromium.org, =?UTF-8?B?QWxleCBCZW5uw6ll?= , Stefano Garzarella , david@redhat.com, hi@alyssa.is, mst@redhat.com, jasowang@redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=170.10.129.124; envelope-from=aesteve@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Tue, Feb 18, 2025 at 7:43=E2=80=AFAM Stefan Hajnoczi wrote: > > On Mon, Feb 17, 2025 at 05:40:04PM +0100, Albert Esteve wrote: > > Add SHMEM_MAP/UNMAP requests to vhost-user to > > handle VIRTIO Shared Memory mappings. > > > > This request allows backends to dynamically map > > fds into a VIRTIO Shared Memory Region indentified > > by its `shmid`. The map is performed by calling > > `memory_region_init_ram_from_fd` and adding the > > new region as a subregion of the shmem container > > MR. Then, the fd memory is advertised to the > > driver as a base addres + offset, so it can be > > read/written (depending on the mmap flags > > requested) while it is valid. > > > > The backend can unmap the memory range > > in a given VIRTIO Shared Memory Region (again, > > identified by its `shmid`), to free it. > > Upon receiving this message, the front-end > > must delete the MR as a subregion of > > the shmem container region and free its > > resources. > > > > Note that commit all these operations need > > to be delayed to after we respond the request > > to the backend to avoid deadlocks. > > > > The device model needs to create VirtSharedMemory > > instances for the VirtIO Shared Memory Regions > > and add them to the `VirtIODevice` instance. > > > > Signed-off-by: Albert Esteve > > --- > > hw/virtio/vhost-user.c | 134 ++++++++++++++++++++++ > > hw/virtio/virtio.c | 81 +++++++++++++ > > include/hw/virtio/virtio.h | 27 +++++ > > subprojects/libvhost-user/libvhost-user.c | 70 +++++++++++ > > subprojects/libvhost-user/libvhost-user.h | 55 +++++++++ > > 5 files changed, 367 insertions(+) > > > > diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c > > index 267b612587..d88e6f8c3c 100644 > > --- a/hw/virtio/vhost-user.c > > +++ b/hw/virtio/vhost-user.c > > @@ -115,6 +115,8 @@ typedef enum VhostUserBackendRequest { > > VHOST_USER_BACKEND_SHARED_OBJECT_ADD =3D 6, > > VHOST_USER_BACKEND_SHARED_OBJECT_REMOVE =3D 7, > > VHOST_USER_BACKEND_SHARED_OBJECT_LOOKUP =3D 8, > > + VHOST_USER_BACKEND_SHMEM_MAP =3D 9, > > + VHOST_USER_BACKEND_SHMEM_UNMAP =3D 10, > > VHOST_USER_BACKEND_MAX > > } VhostUserBackendRequest; > > > > @@ -192,6 +194,24 @@ typedef struct VhostUserShared { > > unsigned char uuid[16]; > > } VhostUserShared; > > > > +/* For the flags field of VhostUserMMap */ > > +#define VHOST_USER_FLAG_MAP_R (1u << 0) > > +#define VHOST_USER_FLAG_MAP_W (1u << 1) > > + > > +typedef struct { > > + /* VIRTIO Shared Memory Region ID */ > > + uint8_t shmid; > > + uint8_t padding[7]; > > + /* File offset */ > > + uint64_t fd_offset; > > + /* Offset within the VIRTIO Shared Memory Region */ > > + uint64_t shm_offset; > > + /* Size of the mapping */ > > + uint64_t len; > > + /* Flags for the mmap operation, from VHOST_USER_FLAG_* */ > > + uint64_t flags; > > +} VhostUserMMap; > > + > > typedef struct { > > VhostUserRequest request; > > > > @@ -224,6 +244,7 @@ typedef union { > > VhostUserInflight inflight; > > VhostUserShared object; > > VhostUserTransferDeviceState transfer_state; > > + VhostUserMMap mmap; > > } VhostUserPayload; > > > > typedef struct VhostUserMsg { > > @@ -1770,6 +1791,111 @@ vhost_user_backend_handle_shared_object_lookup(= struct vhost_user *u, > > return 0; > > } > > > > +static int > > +vhost_user_backend_handle_shmem_map(struct vhost_dev *dev, > > + QIOChannel *ioc, > > + VhostUserHeader *hdr, > > + VhostUserPayload *payload, > > + int fd, Error **errp) > > +{ > > + VirtSharedMemory *shmem =3D NULL; > > + VhostUserMMap *vu_mmap =3D &payload->mmap; > > + g_autoptr(GString) shm_name =3D g_string_new(NULL); > > + > > + if (fd < 0) { > > + error_report("Bad fd for map"); > > + return -EBADF; > > + } > > + > > + if (!dev->vdev->shmem_list || > > + dev->vdev->n_shmem_regions <=3D vu_mmap->shmid) { > > + error_report("Device only has %d VIRTIO Shared Memory Regions.= " > > + "Requested ID: %d", > > + dev->vdev->n_shmem_regions, vu_mmap->shmid); > > + return -EFAULT; > > + } > > + > > + shmem =3D &dev->vdev->shmem_list[vu_mmap->shmid]; > > + > > + if (!shmem) { > > + error_report("VIRTIO Shared Memory Region at " > > + "ID %d unitialized", vu_mmap->shmid); > > + return -EFAULT; > > + } > > + > > + if ((vu_mmap->shm_offset + vu_mmap->len) < vu_mmap->len || > > + (vu_mmap->shm_offset + vu_mmap->len) > shmem->mr->size) { > > + error_report("Bad offset/len for mmap %" PRIx64 "+%" PRIx64, > > + vu_mmap->shm_offset, vu_mmap->len); > > + return -EFAULT; > > + } > > + > > + g_string_printf(shm_name, "virtio-shm%i-%lu", > > + vu_mmap->shmid, vu_mmap->shm_offset); > > + > > + memory_region_transaction_begin(); > > + virtio_add_shmem_map(shmem, shm_name->str, vu_mmap->shm_offset, > > + vu_mmap->fd_offset, vu_mmap->len, fd, errp); > > Error handling is missing. In particular, if virtio_add_shmem_map() sets > errp due to an error, then vhost_user_send_resp() will crash if it also > needs to set the error. An Error object can only be filled in once. > > > + > > + hdr->size =3D sizeof(payload->u64); > > + vhost_user_send_resp(ioc, hdr, payload, errp); > > payload->u64 has not been initialized. It contains the contents of > payload->mmap, which is not the u64 return value that must be sent here. > I think something like the following is necessary: > payload->u64 =3D 0; > > > + memory_region_transaction_commit(); > > + > > + return 0; > > +} > > + > > +static int > > +vhost_user_backend_handle_shmem_unmap(struct vhost_dev *dev, > > + QIOChannel *ioc, > > + VhostUserHeader *hdr, > > + VhostUserPayload *payload, > > + Error **errp) > > +{ > > + VirtSharedMemory *shmem =3D NULL; > > + MappedMemoryRegion *mmap =3D NULL; > > + VhostUserMMap *vu_mmap =3D &payload->mmap; > > + > > + if (!dev->vdev->shmem_list || > > + dev->vdev->n_shmem_regions <=3D vu_mmap->shmid) { > > + error_report("Device only has %d VIRTIO Shared Memory Regions.= " > > + "Requested ID: %d", > > + dev->vdev->n_shmem_regions, vu_mmap->shmid); > > + return -EFAULT; > > + } > > + > > + shmem =3D &dev->vdev->shmem_list[vu_mmap->shmid]; > > + > > + if (!shmem) { > > + error_report("VIRTIO Shared Memory Region at " > > + "ID %d unitialized", vu_mmap->shmid); > > + return -EFAULT; > > + } > > + > > + if ((vu_mmap->shm_offset + vu_mmap->len) < vu_mmap->len || > > + (vu_mmap->shm_offset + vu_mmap->len) > shmem->mr->size) { > > + error_report("Bad offset/len for unmmap %" PRIx64 "+%" PRIx64, > > + vu_mmap->shm_offset, vu_mmap->len); > > + return -EFAULT; > > + } > > + > > + mmap =3D virtio_find_shmem_map(shmem, vu_mmap->shm_offset, vu_mmap= ->len); > > + if (!mmap) { > > + return -EFAULT; > > + } > > + > > + memory_region_transaction_begin(); > > + memory_region_del_subregion(shmem->mr, mmap->mem); > > + > > + hdr->size =3D sizeof(payload->u64); > > + vhost_user_send_resp(ioc, hdr, payload, errp); > > Same uninitialized payload->u64 issue here. > > > + memory_region_transaction_commit(); > > + > > + /* Free the MemoryRegion only after vhost_commit */ > > + virtio_del_shmem_map(shmem, vu_mmap->shm_offset, vu_mmap->len); > > + > > + return 0; > > +} > > + > > static void close_backend_channel(struct vhost_user *u) > > { > > g_source_destroy(u->backend_src); > > @@ -1837,6 +1963,14 @@ static gboolean backend_read(QIOChannel *ioc, GI= OCondition condition, > > case VHOST_USER_BACKEND_SHARED_OBJECT_LOOKUP: > > ret =3D vhost_user_backend_handle_shared_object_lookup(dev->op= aque, ioc, > > &hdr, &pa= yload); > > + case VHOST_USER_BACKEND_SHMEM_MAP: > > + ret =3D vhost_user_backend_handle_shmem_map(dev, ioc, &hdr, &p= ayload, > > + fd ? fd[0] : -1, &lo= cal_err); > > + break; > > + case VHOST_USER_BACKEND_SHMEM_UNMAP: > > + ret =3D vhost_user_backend_handle_shmem_unmap(dev, ioc, &hdr, = &payload, > > + &local_err); > > + break; > > break; > > default: > > error_report("Received unexpected msg type: %d.", hdr.request)= ; > > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c > > index 85110bce37..47d0ddb820 100644 > > --- a/hw/virtio/virtio.c > > +++ b/hw/virtio/virtio.c > > @@ -3063,6 +3063,75 @@ int virtio_save(VirtIODevice *vdev, QEMUFile *f) > > return vmstate_save_state(f, &vmstate_virtio, vdev, NULL); > > } > > > > +VirtSharedMemory *virtio_new_shmem_region(VirtIODevice *vdev) > > +{ > > + ++vdev->n_shmem_regions; > > + vdev->shmem_list =3D g_renew(VirtSharedMemory, vdev->shmem_list, > > + vdev->n_shmem_regions); > > + vdev->shmem_list[vdev->n_shmem_regions - 1].mr =3D g_new0(MemoryRe= gion, 1); > > + QTAILQ_INIT(&vdev->shmem_list[vdev->n_shmem_regions - 1].mmaps); > > QTAILQ cannot be used inside a struct that is reallocated using > g_renew() because a dangling tql_prev pointer will be left after > reallocation. From QTAILQ_INIT(): > (head)->tqh_circ.tql_prev =3D &(head)->tqh_circ; <--- not realloc-safe > > Instead of using g_renew() on an array, consider using a list from > "qemu/queue.h". Lookup by shmid becomes O(n) instead of O(1), but it > doesn't matter in practice since existing devices have a small number of > VIRTIO Shared Memory Regions. > > > + return &vdev->shmem_list[vdev->n_shmem_regions - 1]; > > +} > > + > > +void virtio_add_shmem_map(VirtSharedMemory *shmem, const char *shm_nam= e, > > + hwaddr shm_offset, hwaddr fd_offset, uint64_= t size, > > + int fd, Error **errp) > > +{ > > + MappedMemoryRegion *mmap; > > + fd =3D dup(fd); > > + if (fd < 0) { > > + error_setg_errno(errp, errno, "Failed to duplicate fd"); > > + return; > > + } > > + > > + if (shm_offset + size > shmem->mr->size) { > > + error_setg(errp, "Memory exceeds the shared memory boundaries"= ); > > + return; > > fd is leaked here. > > > + } > > + > > + mmap =3D g_new0(MappedMemoryRegion, 1); > > + mmap->mem =3D g_new0(MemoryRegion, 1); > > + mmap->offset =3D shm_offset; > > + if (!memory_region_init_ram_from_fd(mmap->mem, > > + OBJECT(shmem->mr), > > + shm_name, size, RAM_SHARED, > > + fd, fd_offset, errp)) { > > + error_setg(errp, "Failed to mmap region %s", shm_name); > > + close(fd); > > + g_free(mmap->mem); > > + g_free(mmap); > > + return; > > + } > > + memory_region_add_subregion(shmem->mr, shm_offset, mmap->mem); > > + > > + QTAILQ_INSERT_TAIL(&shmem->mmaps, mmap, link); > > +} > > + > > +MappedMemoryRegion *virtio_find_shmem_map(VirtSharedMemory *shmem, > > + hwaddr offset, uint64_t size= ) > > +{ > > + MappedMemoryRegion *mmap; > > + QTAILQ_FOREACH(mmap, &shmem->mmaps, link) { > > + if (mmap->offset =3D=3D offset && mmap->mem->size =3D=3D size)= { > > + return mmap; > > + } > > + } > > + return NULL; > > +} > > + > > +void virtio_del_shmem_map(VirtSharedMemory *shmem, hwaddr offset, > > + uint64_t size) > > +{ > > + MappedMemoryRegion *mmap =3D virtio_find_shmem_map(shmem, offset, = size); > > + if (mmap =3D=3D NULL) { > > + return; > > + } > > + > > + object_unparent(OBJECT(mmap->mem)); > > + QTAILQ_REMOVE(&shmem->mmaps, mmap, link); > > + g_free(mmap); > > +} > > + > > /* A wrapper for use as a VMState .put function */ > > static int virtio_device_put(QEMUFile *f, void *opaque, size_t size, > > const VMStateField *field, JSONWriter *v= mdesc) > > @@ -3492,6 +3561,8 @@ void virtio_init(VirtIODevice *vdev, uint16_t dev= ice_id, size_t config_size) > > virtio_vmstate_change, vdev); > > vdev->device_endian =3D virtio_default_endian(); > > vdev->use_guest_notifier_mask =3D true; > > + vdev->shmem_list =3D NULL; > > + vdev->n_shmem_regions =3D 0; > > } > > > > /* > > @@ -4005,11 +4076,21 @@ static void virtio_device_free_virtqueues(VirtI= ODevice *vdev) > > static void virtio_device_instance_finalize(Object *obj) > > { > > VirtIODevice *vdev =3D VIRTIO_DEVICE(obj); > > + VirtSharedMemory *shmem =3D NULL; > > + int i; > > > > virtio_device_free_virtqueues(vdev); > > > > g_free(vdev->config); > > g_free(vdev->vector_queues); > > + for (i =3D 0; i< vdev->n_shmem_regions; i++) { > > + shmem =3D &vdev->shmem_list[i]; > > + while (!QTAILQ_EMPTY(&shmem->mmaps)) { > > + MappedMemoryRegion *mmap_reg =3D QTAILQ_FIRST(&shmem->mmap= s); > > + QTAILQ_REMOVE(&shmem->mmaps, mmap_reg, link); > > + g_free(mmap_reg); > > Is it possible to reuse virtio_del_shmem_map() to avoid code duplication > and inconsistencies? > > while (!QTAILQ_EMPTY(&shmem->mmaps)) { > MappedMemoryRegion *mmap_reg =3D QTAILQ_FIRST(&shmem->mmaps); > virtio_del_shmem_map(shmem, mmap_reg->offset, mmap_reg->mem->size); > } Yes that is a good idea, thanks. Maybe I could change the function signature to receive the mmap_reg as parameter instead of the offset and size combo. > > > + } > > + } > > Missing g_free(vdev->shmem_list). > > > } > > > > static const Property virtio_properties[] =3D { > > diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h > > index 6386910280..a778547c79 100644 > > --- a/include/hw/virtio/virtio.h > > +++ b/include/hw/virtio/virtio.h > > @@ -98,6 +98,21 @@ enum virtio_device_endian { > > VIRTIO_DEVICE_ENDIAN_BIG, > > }; > > > > +struct MappedMemoryRegion { > > + MemoryRegion *mem; > > + hwaddr offset; > > + QTAILQ_ENTRY(MappedMemoryRegion) link; > > +}; > > + > > +typedef struct MappedMemoryRegion MappedMemoryRegion; > > + > > +struct VirtSharedMemory { > > + MemoryRegion *mr; > > + QTAILQ_HEAD(, MappedMemoryRegion) mmaps; > > +}; > > + > > +typedef struct VirtSharedMemory VirtSharedMemory; > > + > > /** > > * struct VirtIODevice - common VirtIO structure > > * @name: name of the device > > @@ -167,6 +182,9 @@ struct VirtIODevice > > */ > > EventNotifier config_notifier; > > bool device_iotlb_enabled; > > + /* Shared memory region for vhost-user mappings. */ > > This is core VIRTIO code and Shared Memory Regions are a VIRTIO concept. > It is possible that built-in (non-vhost) devices might also add their > shared memory regions with virtio_new_shmem_region(), so let's not talk > about vhost-user specifically. > > > + VirtSharedMemory *shmem_list; > > + int n_shmem_regions; > > }; > > > > struct VirtioDeviceClass { > > @@ -289,6 +307,15 @@ void virtio_notify(VirtIODevice *vdev, VirtQueue *= vq); > > > > int virtio_save(VirtIODevice *vdev, QEMUFile *f); > > > > +VirtSharedMemory *virtio_new_shmem_region(VirtIODevice *vdev); > > +void virtio_add_shmem_map(VirtSharedMemory *shmem, const char *shm_nam= e, > > + hwaddr shm_offset, hwaddr fd_offset, uint64_= t size, > > + int fd, Error **errp); > > +MappedMemoryRegion *virtio_find_shmem_map(VirtSharedMemory *shmem, hwa= ddr offset, > > + uint64_t size); > > +void virtio_del_shmem_map(VirtSharedMemory *shmem, hwaddr offset, > > + uint64_t size); > > + > > extern const VMStateInfo virtio_vmstate_info; > > > > #define VMSTATE_VIRTIO_DEVICE \ > > diff --git a/subprojects/libvhost-user/libvhost-user.c b/subprojects/li= bvhost-user/libvhost-user.c > > index 9c630c2170..034cbfdc3c 100644 > > --- a/subprojects/libvhost-user/libvhost-user.c > > +++ b/subprojects/libvhost-user/libvhost-user.c > > @@ -1592,6 +1592,76 @@ vu_rm_shared_object(VuDev *dev, unsigned char uu= id[UUID_LEN]) > > return vu_send_message(dev, &msg); > > } > > > > +bool > > +vu_shmem_map(VuDev *dev, uint8_t shmid, uint64_t fd_offset, > > + uint64_t shm_offset, uint64_t len, uint64_t flags, int fd= ) > > +{ > > + VhostUserMsg vmsg =3D { > > + .request =3D VHOST_USER_BACKEND_SHMEM_MAP, > > + .size =3D sizeof(vmsg.payload.mmap), > > + .flags =3D VHOST_USER_VERSION, > > + .payload.mmap =3D { > > + .shmid =3D shmid, > > + .fd_offset =3D fd_offset, > > + .shm_offset =3D shm_offset, > > + .len =3D len, > > + .flags =3D flags, > > + }, > > + .fd_num =3D 1, > > + .fds[0] =3D fd, > > + }; > > + > > + if (!vu_has_protocol_feature(dev, VHOST_USER_PROTOCOL_F_SHMEM)) { > > + return false; > > + } > > + > > + if (vu_has_protocol_feature(dev, VHOST_USER_PROTOCOL_F_REPLY_ACK))= { > > + vmsg.flags |=3D VHOST_USER_NEED_REPLY_MASK; > > + } > > Setting this flag is inconsistent with > vhost_user_backend_handle_shmem_map() and > vhost_user_backend_handle_shmem_unmap(). They call > vhost_user_send_resp() explicitly instead of relying on backend_read() > to send the return value when VHOST_USER_NEED_REPLY_MASK is set. This > inconsistency means that a successful return message will be sent twice > when VHOST_USER_NEED_REPLY_MASK is set. It is true that is inconsistent, I need to check for the field before sending the reponse in the handlers. But at least it will not respond twice as `vhost_user_send_resp()` unset the VHOST_USER_NEED_REPLY_MASK bit. > > Either these new vhost-user messages could be specified with a mandatory > reply payload or the patch could be updated to avoid the explicit > vhost_user_send_resp() calls. I think the latter is more commonly used > by other vhost-user messages, so it's probably best to do it the same > way. The explicit calls are necessary to be able to control that vhost_commit is called after the response is sent, or else it will cause a deadlock. What I need to do is to check for the VHOST_USER_NEED_REPLY_MASK bit before calling it. Then `vhost_user_send_resp()` will unset it to avoid double reponse. > > > + > > + pthread_mutex_lock(&dev->backend_mutex); > > + if (!vu_message_write(dev, dev->backend_fd, &vmsg)) { > > + pthread_mutex_unlock(&dev->backend_mutex); > > + return false; > > + } > > + > > + /* Also unlocks the backend_mutex */ > > + return vu_process_message_reply(dev, &vmsg); > > +} > > + > > +bool > > +vu_shmem_unmap(VuDev *dev, uint8_t shmid, uint64_t shm_offset, uint64_= t len) > > +{ > > + VhostUserMsg vmsg =3D { > > + .request =3D VHOST_USER_BACKEND_SHMEM_UNMAP, > > + .size =3D sizeof(vmsg.payload.mmap), > > + .flags =3D VHOST_USER_VERSION, > > + .payload.mmap =3D { > > + .shmid =3D shmid, > > + .fd_offset =3D 0, > > + .shm_offset =3D shm_offset, > > + .len =3D len, > > + }, > > + }; > > + > > + if (!vu_has_protocol_feature(dev, VHOST_USER_PROTOCOL_F_SHMEM)) { > > + return false; > > + } > > + > > + if (vu_has_protocol_feature(dev, VHOST_USER_PROTOCOL_F_REPLY_ACK))= { > > + vmsg.flags |=3D VHOST_USER_NEED_REPLY_MASK; > > + } > > + > > + pthread_mutex_lock(&dev->backend_mutex); > > + if (!vu_message_write(dev, dev->backend_fd, &vmsg)) { > > + pthread_mutex_unlock(&dev->backend_mutex); > > + return false; > > + } > > + > > + /* Also unlocks the backend_mutex */ > > + return vu_process_message_reply(dev, &vmsg); > > +} > > + > > static bool > > vu_set_vring_call_exec(VuDev *dev, VhostUserMsg *vmsg) > > { > > diff --git a/subprojects/libvhost-user/libvhost-user.h b/subprojects/li= bvhost-user/libvhost-user.h > > index 2ffc58c11b..e9adb836f0 100644 > > --- a/subprojects/libvhost-user/libvhost-user.h > > +++ b/subprojects/libvhost-user/libvhost-user.h > > @@ -69,6 +69,8 @@ enum VhostUserProtocolFeature { > > /* Feature 16 is reserved for VHOST_USER_PROTOCOL_F_STATUS. */ > > /* Feature 17 reserved for VHOST_USER_PROTOCOL_F_XEN_MMAP. */ > > VHOST_USER_PROTOCOL_F_SHARED_OBJECT =3D 18, > > + /* Feature 19 is reserved for VHOST_USER_PROTOCOL_F_DEVICE_STATE *= / > > + VHOST_USER_PROTOCOL_F_SHMEM =3D 20, > > VHOST_USER_PROTOCOL_F_MAX > > }; > > > > @@ -127,6 +129,8 @@ typedef enum VhostUserBackendRequest { > > VHOST_USER_BACKEND_SHARED_OBJECT_ADD =3D 6, > > VHOST_USER_BACKEND_SHARED_OBJECT_REMOVE =3D 7, > > VHOST_USER_BACKEND_SHARED_OBJECT_LOOKUP =3D 8, > > + VHOST_USER_BACKEND_SHMEM_MAP =3D 9, > > + VHOST_USER_BACKEND_SHMEM_UNMAP =3D 10, > > VHOST_USER_BACKEND_MAX > > } VhostUserBackendRequest; > > > > @@ -186,6 +190,24 @@ typedef struct VhostUserShared { > > unsigned char uuid[UUID_LEN]; > > } VhostUserShared; > > > > +/* For the flags field of VhostUserMMap */ > > +#define VHOST_USER_FLAG_MAP_R (1u << 0) > > +#define VHOST_USER_FLAG_MAP_W (1u << 1) > > + > > +typedef struct { > > + /* VIRTIO Shared Memory Region ID */ > > + uint8_t shmid; > > + uint8_t padding[7]; > > + /* File offset */ > > + uint64_t fd_offset; > > + /* Offset within the VIRTIO Shared Memory Region */ > > + uint64_t shm_offset; > > + /* Size of the mapping */ > > + uint64_t len; > > + /* Flags for the mmap operation, from VHOST_USER_FLAG_* */ > > + uint64_t flags; > > +} VhostUserMMap; > > + > > #define VU_PACKED __attribute__((packed)) > > > > typedef struct VhostUserMsg { > > @@ -210,6 +232,7 @@ typedef struct VhostUserMsg { > > VhostUserVringArea area; > > VhostUserInflight inflight; > > VhostUserShared object; > > + VhostUserMMap mmap; > > } payload; > > > > int fds[VHOST_MEMORY_BASELINE_NREGIONS]; > > @@ -593,6 +616,38 @@ bool vu_add_shared_object(VuDev *dev, unsigned cha= r uuid[UUID_LEN]); > > */ > > bool vu_rm_shared_object(VuDev *dev, unsigned char uuid[UUID_LEN]); > > > > +/** > > + * vu_shmem_map: > > + * @dev: a VuDev context > > + * @shmid: VIRTIO Shared Memory Region ID > > + * @fd_offset: File offset > > + * @shm_offset: Offset within the VIRTIO Shared Memory Region > > + * @len: Size of the mapping > > + * @flags: Flags for the mmap operation > > + * @fd: A file descriptor > > + * > > + * Advertises a new mapping to be made in a given VIRTIO Shared Memory= Region. > > + * > > + * Returns: TRUE on success, FALSE on failure. > > + */ > > +bool vu_shmem_map(VuDev *dev, uint8_t shmid, uint64_t fd_offset, > > + uint64_t shm_offset, uint64_t len, uint64_t flags, i= nt fd); > > + > > +/** > > + * vu_shmem_unmap: > > + * @dev: a VuDev context > > + * @shmid: VIRTIO Shared Memory Region ID > > + * @fd_offset: File offset > > + * @len: Size of the mapping > > + * > > + * The front-end un-mmaps a given range in the VIRTIO Shared Memory Re= gion > > + * with the requested `shmid`. > > + * > > + * Returns: TRUE on success, FALSE on failure. > > + */ > > +bool vu_shmem_unmap(VuDev *dev, uint8_t shmid, uint64_t shm_offset, > > + uint64_t len); > > + > > /** > > * vu_queue_set_notification: > > * @dev: a VuDev context > > -- > > 2.48.1 > >