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Tsirkin" To: Xie Yongji Cc: jasowang@redhat.com, xiaodong.liu@intel.com, maxime.coquelin@redhat.com, stefanha@redhat.com, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 5/6] vduse: Support registering userspace memory for IOTLB Message-ID: <20220629043539-mutt-send-email-mst@kernel.org> References: <20220629082541.118-1-xieyongji@bytedance.com> <20220629082541.118-6-xieyongji@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220629082541.118-6-xieyongji@bytedance.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 29, 2022 at 04:25:40PM +0800, Xie Yongji wrote: > Introduce two ioctls: VDUSE_IOTLB_REG_UMEM and > VDUSE_IOTLB_DEREG_UMEM to support registering > and de-registering userspace memory for IOTLB > in virtio-vdpa case. > > Now it only supports registering userspace memory > for IOTLB as bounce buffer. > > Signed-off-by: Xie Yongji > --- > drivers/vdpa/vdpa_user/vduse_dev.c | 138 +++++++++++++++++++++++++++++ > include/uapi/linux/vduse.h | 28 ++++++ > 2 files changed, 166 insertions(+) > > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c > index c47a5d9765cf..7b2ea7612da9 100644 > --- a/drivers/vdpa/vdpa_user/vduse_dev.c > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c > @@ -21,6 +21,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -64,6 +65,13 @@ struct vduse_vdpa { > struct vduse_dev *dev; > }; > > +struct vduse_iotlb_mem { > + unsigned long iova; > + unsigned long npages; > + struct page **pages; > + struct mm_struct *mm; > +}; > + > struct vduse_dev { > struct vduse_vdpa *vdev; > struct device *dev; > @@ -95,6 +103,8 @@ struct vduse_dev { > u8 status; > u32 vq_num; > u32 vq_align; > + struct vduse_iotlb_mem *iotlb_mem; > + struct mutex mem_lock; > }; > > struct vduse_dev_msg { > @@ -917,6 +927,100 @@ static int vduse_dev_queue_irq_work(struct vduse_dev *dev, > return ret; > } > > +static int vduse_dev_dereg_iotlb_mem(struct vduse_dev *dev, > + u64 iova, u64 size) > +{ > + int ret; > + > + mutex_lock(&dev->mem_lock); > + ret = -ENOENT; > + if (!dev->iotlb_mem) > + goto unlock; > + > + ret = -EINVAL; > + if (dev->iotlb_mem->iova != iova || size != dev->domain->bounce_size) > + goto unlock; > + > + vduse_domain_remove_user_bounce_pages(dev->domain); > + unpin_user_pages(dev->iotlb_mem->pages, dev->iotlb_mem->npages); I notice you don't mark the pages dirty. This is going to be a problem. > + atomic64_sub(dev->iotlb_mem->npages, &dev->iotlb_mem->mm->pinned_vm); > + mmdrop(dev->iotlb_mem->mm); > + vfree(dev->iotlb_mem->pages); > + kfree(dev->iotlb_mem); > + dev->iotlb_mem = NULL; > + ret = 0; > +unlock: > + mutex_unlock(&dev->mem_lock); > + return ret; > +} > + > +static int vduse_dev_reg_iotlb_mem(struct vduse_dev *dev, > + u64 iova, u64 uaddr, u64 size) > +{ > + struct page **page_list = NULL; > + struct vduse_iotlb_mem *mem = NULL; > + long pinned = 0; > + unsigned long npages, lock_limit; > + int ret; > + > + if (size != dev->domain->bounce_size || > + iova != 0 || uaddr & ~PAGE_MASK) > + return -EINVAL; > + > + mutex_lock(&dev->mem_lock); > + ret = -EEXIST; > + if (dev->iotlb_mem) > + goto unlock; > + > + ret = -ENOMEM; > + npages = size >> PAGE_SHIFT; > + page_list = vmalloc(array_size(npages, > + sizeof(struct page *))); Is this basically trying to do a vmalloc with userspace-controlled size? That's an easy DOS vector. > + mem = kzalloc(sizeof(*mem), GFP_KERNEL); > + if (!page_list || !mem) > + goto unlock; > + > + mmap_read_lock(current->mm); > + > + lock_limit = PFN_DOWN(rlimit(RLIMIT_MEMLOCK)); > + if (npages + atomic64_read(¤t->mm->pinned_vm) > lock_limit) > + goto out; > + > + pinned = pin_user_pages(uaddr, npages, FOLL_LONGTERM | FOLL_WRITE, > + page_list, NULL); > + if (pinned != npages) { > + ret = pinned < 0 ? pinned : -ENOMEM; > + goto out; > + } This is a popular approach but it's problematic if multiple devices try to pin the same page. Can this happen here? > + > + ret = vduse_domain_add_user_bounce_pages(dev->domain, > + page_list, pinned); > + if (ret) > + goto out; > + > + atomic64_add(npages, ¤t->mm->pinned_vm); > + > + mem->pages = page_list; > + mem->npages = pinned; > + mem->iova = iova; > + mem->mm = current->mm; > + mmgrab(current->mm); > + > + dev->iotlb_mem = mem; > +out: > + if (ret && pinned > 0) > + unpin_user_pages(page_list, pinned); > + > + mmap_read_unlock(current->mm); > +unlock: > + if (ret) { > + vfree(page_list); > + kfree(mem); > + } > + mutex_unlock(&dev->mem_lock); > + return ret; > +} > + > static long vduse_dev_ioctl(struct file *file, unsigned int cmd, > unsigned long arg) > { > @@ -943,6 +1047,16 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd, > if (entry.start > entry.last) > break; > > + if (domain->bounce_map && dev->iotlb_mem) { > + ret = -EEXIST; > + if (entry.start >= 0 && > + entry.last < domain->bounce_size) > + break; > + > + if (entry.start < domain->bounce_size) > + entry.start = domain->bounce_size; > + } > + > spin_lock(&domain->iotlb_lock); > map = vhost_iotlb_itree_first(domain->iotlb, > entry.start, entry.last); > @@ -1102,6 +1216,28 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd, > ret = 0; > break; > } > + case VDUSE_IOTLB_REG_UMEM: { > + struct vduse_iotlb_umem umem; > + > + ret = -EFAULT; > + if (copy_from_user(&umem, argp, sizeof(umem))) > + break; > + > + ret = vduse_dev_reg_iotlb_mem(dev, umem.iova, > + umem.uaddr, umem.size); > + break; > + } > + case VDUSE_IOTLB_DEREG_UMEM: { > + struct vduse_iotlb_umem umem; > + > + ret = -EFAULT; > + if (copy_from_user(&umem, argp, sizeof(umem))) > + break; > + > + ret = vduse_dev_dereg_iotlb_mem(dev, umem.iova, > + umem.size); > + break; > + } > default: > ret = -ENOIOCTLCMD; > break; > @@ -1114,6 +1250,7 @@ static int vduse_dev_release(struct inode *inode, struct file *file) > { > struct vduse_dev *dev = file->private_data; > > + vduse_dev_dereg_iotlb_mem(dev, 0, dev->domain->bounce_size); > spin_lock(&dev->msg_lock); > /* Make sure the inflight messages can processed after reconncection */ > list_splice_init(&dev->recv_list, &dev->send_list); > @@ -1176,6 +1313,7 @@ static struct vduse_dev *vduse_dev_create(void) > return NULL; > > mutex_init(&dev->lock); > + mutex_init(&dev->mem_lock); > spin_lock_init(&dev->msg_lock); > INIT_LIST_HEAD(&dev->send_list); > INIT_LIST_HEAD(&dev->recv_list); > diff --git a/include/uapi/linux/vduse.h b/include/uapi/linux/vduse.h > index c201b7a77c2c..1b17391e228f 100644 > --- a/include/uapi/linux/vduse.h > +++ b/include/uapi/linux/vduse.h > @@ -227,6 +227,34 @@ struct vduse_iotlb_info { > /* Get IOTLB information, e.g. bounce buffer size */ > #define VDUSE_IOTLB_GET_INFO _IOR(VDUSE_BASE, 0x18, struct vduse_iotlb_info) > > +/** > + * struct vduse_iotlb_umem - userspace memory configuration > + * @uaddr: start address of userspace memory, it must be aligned to page size > + * @iova: IOVA of userspace memory, it must be equal to bounce iova returned > + * by VDUSE_IOTLB_GET_INFO now > + * @size: size of userspace memory, it must be equal to bounce size returned > + * by VDUSE_IOTLB_GET_INFO now > + * @reserved: for future use, needs to be initialized to zero You should check that it's 0 in that case, otherwise userspace will conveniently forget. > + * > + * Structure used by VDUSE_IOTLB_REG_UMEM and VDUSE_IOTLB_DEREG_UMEM > + * ioctls to register/de-register userspace memory for IOTLB. > + */ > +struct vduse_iotlb_umem { > + __u64 uaddr; > + __u64 iova; > + __u64 size; > + __u64 reserved[3]; > +}; > + > +/* > + * Register userspace memory for IOTLB. Now we only support registering > + * userspace memory as bounce buffer. > + */ > +#define VDUSE_IOTLB_REG_UMEM _IOW(VDUSE_BASE, 0x19, struct vduse_iotlb_umem) > + > +/* De-register the userspace memory. Caller should set iova and size field. */ > +#define VDUSE_IOTLB_DEREG_UMEM _IOW(VDUSE_BASE, 0x1a, struct vduse_iotlb_umem) > + > /* The control messages definition for read(2)/write(2) on /dev/vduse/$NAME */ > > /** > -- > 2.20.1