[PATCH v2 5/5] vduse: Support registering userspace memory for IOTLB

Xie Yongji
2022-07-06T05:06:24Z

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 <xieyongji@bytedance.com>
---
drivers/vdpa/vdpa_user/vduse_dev.c | 139 +++++++++++++++++++++++++++++
include/uapi/linux/vduse.h | 28 ++++++
2 files changed, 167 insertions(+)

diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
index c47a5d9765cf..4467ae2381bb 100644
--- a/drivers/vdpa/vdpa_user/vduse_dev.c
+++ b/drivers/vdpa/vdpa_user/vduse_dev.c
@@ -21,6 +21,7 @@
#include <linux/uio.h>
#include <linux/vdpa.h>
#include <linux/nospec.h>
+#include <linux/sched/mm.h>
#include <uapi/linux/vduse.h>
#include <uapi/linux/vdpa.h>
#include <uapi/linux/virtio_config.h>
@@ -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 +927,101 @@ 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_dirty_lock(dev->iotlb_mem->pages,
+ dev->iotlb_mem->npages, true);
+ 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 *)),
+ GFP_KERNEL_ACCOUNT);
+ 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(&current->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;
+ }
+
+ ret = vduse_domain_add_user_bounce_pages(dev->domain,
+ page_list, pinned);
+ if (ret)
+ goto out;
+
+ atomic64_add(npages, &current->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 +1048,16 @@ 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 +1217,28 @@ 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 +1251,7 @@ 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 +1314,7 @@ 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
+ *
+ * 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