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Tsirkin" , Stefan Hajnoczi , sgarzare@redhat.com, Parav Pandit , akpm@linux-foundation.org, Randy Dunlap , Matthew Wilcox , viro@zeniv.linux.org.uk, axboe@kernel.dk, bcrl@kvack.org, corbet@lwn.net, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, kvm@vger.kernel.org, linux-aio@kvack.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org References: <20201222145221.711-1-xieyongji@bytedance.com> <20201222145221.711-10-xieyongji@bytedance.com> <6818a214-d587-4f0b-7de6-13c4e7e94ab6@redhat.com> From: Jason Wang Message-ID: <595fe7d6-7876-26e4-0b7c-1d63ca6d7a97@redhat.com> Date: Thu, 24 Dec 2020 10:41:25 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2020/12/23 =E4=B8=8B=E5=8D=888:14, Yongji Xie wrote: > On Wed, Dec 23, 2020 at 5:05 PM Jason Wang wrote: >> >> On 2020/12/22 =E4=B8=8B=E5=8D=8810:52, Xie Yongji wrote: >>> To support vhost-vdpa bus driver, we need a way to share the >>> vhost-vdpa backend process's memory with the userspace VDUSE process. >>> >>> This patch tries to make use of the vhost iotlb message to achieve >>> that. We will get the shm file from the iotlb message and pass it >>> to the userspace VDUSE process. >>> >>> Signed-off-by: Xie Yongji >>> --- >>> Documentation/driver-api/vduse.rst | 15 +++- >>> drivers/vdpa/vdpa_user/vduse_dev.c | 147 +++++++++++++++++++++++++= +++++++++++- >>> include/uapi/linux/vduse.h | 11 +++ >>> 3 files changed, 171 insertions(+), 2 deletions(-) >>> >>> diff --git a/Documentation/driver-api/vduse.rst b/Documentation/drive= r-api/vduse.rst >>> index 623f7b040ccf..48e4b1ba353f 100644 >>> --- a/Documentation/driver-api/vduse.rst >>> +++ b/Documentation/driver-api/vduse.rst >>> @@ -46,13 +46,26 @@ The following types of messages are provided by t= he VDUSE framework now: >>> >>> - VDUSE_GET_CONFIG: Read from device specific configuration space >>> >>> +- VDUSE_UPDATE_IOTLB: Update the memory mapping in device IOTLB >>> + >>> +- VDUSE_INVALIDATE_IOTLB: Invalidate the memory mapping in device IO= TLB >>> + >>> Please see include/linux/vdpa.h for details. >>> >>> -In the data path, VDUSE framework implements a MMU-based on-chip IOM= MU >>> +The data path of userspace vDPA device is implemented in different w= ays >>> +depending on the vdpa bus to which it is attached. >>> + >>> +In virtio-vdpa case, VDUSE framework implements a MMU-based on-chip = IOMMU >>> driver which supports mapping the kernel dma buffer to a userspace= iova >>> region dynamically. The userspace iova region can be created by pa= ssing >>> the userspace vDPA device fd to mmap(2). >>> >>> +In vhost-vdpa case, the dma buffer is reside in a userspace memory r= egion >>> +which will be shared to the VDUSE userspace processs via the file >>> +descriptor in VDUSE_UPDATE_IOTLB message. And the corresponding addr= ess >>> +mapping (IOVA of dma buffer <-> VA of the memory region) is also inc= luded >>> +in this message. >>> + >>> Besides, the eventfd mechanism is used to trigger interrupt callba= cks and >>> receive virtqueue kicks in userspace. The following ioctls on the = userspace >>> vDPA device fd are provided to support that: >>> diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_u= ser/vduse_dev.c >>> index b974333ed4e9..d24aaacb6008 100644 >>> --- a/drivers/vdpa/vdpa_user/vduse_dev.c >>> +++ b/drivers/vdpa/vdpa_user/vduse_dev.c >>> @@ -34,6 +34,7 @@ >>> >>> struct vduse_dev_msg { >>> struct vduse_dev_request req; >>> + struct file *iotlb_file; >>> struct vduse_dev_response resp; >>> struct list_head list; >>> wait_queue_head_t waitq; >>> @@ -325,12 +326,80 @@ static int vduse_dev_set_vq_state(struct vduse_= dev *dev, >>> return ret; >>> } >>> >>> +static int vduse_dev_update_iotlb(struct vduse_dev *dev, struct file= *file, >>> + u64 offset, u64 iova, u64 size, u8 perm= ) >>> +{ >>> + struct vduse_dev_msg *msg; >>> + int ret; >>> + >>> + if (!size) >>> + return -EINVAL; >>> + >>> + msg =3D vduse_dev_new_msg(dev, VDUSE_UPDATE_IOTLB); >>> + msg->req.size =3D sizeof(struct vduse_iotlb); >>> + msg->req.iotlb.offset =3D offset; >>> + msg->req.iotlb.iova =3D iova; >>> + msg->req.iotlb.size =3D size; >>> + msg->req.iotlb.perm =3D perm; >>> + msg->req.iotlb.fd =3D -1; >>> + msg->iotlb_file =3D get_file(file); >>> + >>> + ret =3D vduse_dev_msg_sync(dev, msg); >> >> My feeling is that we should provide consistent API for the userspace >> device to use. >> >> E.g we'd better carry the IOTLB message for both virtio/vhost drivers. >> >> It looks to me for virtio drivers we can still use UPDAT_IOTLB message >> by using VDUSE file as msg->iotlb_file here. >> > It's OK for me. One problem is when to transfer the UPDATE_IOTLB > message in virtio cases. Instead of generating IOTLB messages for userspace. How about record the mappings (which is a common case for device have=20 on-chip IOMMU e.g mlx5e and vdpa simlator), then we can introduce ioctl=20 for userspace to query? Thanks > >>> + vduse_dev_msg_put(msg); >>> + fput(file); >>> + >>> + return ret; >>> +} >>> + >>> +static int vduse_dev_invalidate_iotlb(struct vduse_dev *dev, >>> + u64 iova, u64 size) >>> +{ >>> + struct vduse_dev_msg *msg; >>> + int ret; >>> + >>> + if (!size) >>> + return -EINVAL; >>> + >>> + msg =3D vduse_dev_new_msg(dev, VDUSE_INVALIDATE_IOTLB); >>> + msg->req.size =3D sizeof(struct vduse_iotlb); >>> + msg->req.iotlb.iova =3D iova; >>> + msg->req.iotlb.size =3D size; >>> + >>> + ret =3D vduse_dev_msg_sync(dev, msg); >>> + vduse_dev_msg_put(msg); >>> + >>> + return ret; >>> +} >>> + >>> +static unsigned int perm_to_file_flags(u8 perm) >>> +{ >>> + unsigned int flags =3D 0; >>> + >>> + switch (perm) { >>> + case VHOST_ACCESS_WO: >>> + flags |=3D O_WRONLY; >>> + break; >>> + case VHOST_ACCESS_RO: >>> + flags |=3D O_RDONLY; >>> + break; >>> + case VHOST_ACCESS_RW: >>> + flags |=3D O_RDWR; >>> + break; >>> + default: >>> + WARN(1, "invalidate vhost IOTLB permission\n"); >>> + break; >>> + } >>> + >>> + return flags; >>> +} >>> + >>> static ssize_t vduse_dev_read_iter(struct kiocb *iocb, struct iov_= iter *to) >>> { >>> struct file *file =3D iocb->ki_filp; >>> struct vduse_dev *dev =3D file->private_data; >>> struct vduse_dev_msg *msg; >>> - int size =3D sizeof(struct vduse_dev_request); >>> + unsigned int flags; >>> + int fd, size =3D sizeof(struct vduse_dev_request); >>> ssize_t ret =3D 0; >>> >>> if (iov_iter_count(to) < size) >>> @@ -349,6 +418,18 @@ static ssize_t vduse_dev_read_iter(struct kiocb = *iocb, struct iov_iter *to) >>> if (ret) >>> return ret; >>> } >>> + >>> + if (msg->req.type =3D=3D VDUSE_UPDATE_IOTLB && msg->req.iotlb.f= d =3D=3D -1) { >>> + flags =3D perm_to_file_flags(msg->req.iotlb.perm); >>> + fd =3D get_unused_fd_flags(flags); >>> + if (fd < 0) { >>> + vduse_dev_enqueue_msg(dev, msg, &dev->send_list= ); >>> + return fd; >>> + } >>> + fd_install(fd, get_file(msg->iotlb_file)); >>> + msg->req.iotlb.fd =3D fd; >>> + } >>> + >>> ret =3D copy_to_iter(&msg->req, size, to); >>> if (ret !=3D size) { >>> vduse_dev_enqueue_msg(dev, msg, &dev->send_list); >>> @@ -565,6 +646,69 @@ static void vduse_vdpa_set_config(struct vdpa_de= vice *vdpa, unsigned int offset, >>> vduse_dev_set_config(dev, offset, buf, len); >>> } >>> >>> +static void vduse_vdpa_invalidate_iotlb(struct vduse_dev *dev, >>> + struct vhost_iotlb_msg *msg) >>> +{ >>> + vduse_dev_invalidate_iotlb(dev, msg->iova, msg->size); >>> +} >>> + >>> +static int vduse_vdpa_update_iotlb(struct vduse_dev *dev, >>> + struct vhost_iotlb_msg *msg) >>> +{ >>> + u64 uaddr =3D msg->uaddr; >>> + u64 iova =3D msg->iova; >>> + u64 size =3D msg->size; >>> + u64 offset; >>> + struct vm_area_struct *vma; >>> + int ret; >>> + >>> + while (uaddr < msg->uaddr + msg->size) { >>> + vma =3D find_vma(current->mm, uaddr); >>> + ret =3D -EINVAL; >>> + if (!vma) >>> + goto err; >>> + >>> + size =3D min(msg->size, vma->vm_end - uaddr); >>> + offset =3D (vma->vm_pgoff << PAGE_SHIFT) + uaddr - vma-= >vm_start; >>> + if (vma->vm_file && (vma->vm_flags & VM_SHARED)) { >>> + ret =3D vduse_dev_update_iotlb(dev, vma->vm_fil= e, offset, >>> + iova, size, msg= ->perm); >>> + if (ret) >>> + goto err; >> >> My understanding is that vma is something that should not be known by = a >> device. So I suggest to move the above processing to vhost-vdpa.c. >> > Will do it. > > Thanks, > Yongji >