2 files changed, 253 insertions, 0 deletions

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index cbd3836..dc49538 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -748,6 +748,206 @@ static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u)
 	return rc;
 }
 
+#define GNTDEV_COPY_BATCH 24
+
+struct gntdev_copy_batch {
+	struct gnttab_copy ops[GNTDEV_COPY_BATCH];
+	struct page *pages[GNTDEV_COPY_BATCH];
+	s16 __user *status[GNTDEV_COPY_BATCH];
+	unsigned int nr_ops;
+	unsigned int nr_pages;
+};
+
+static int gntdev_get_page(struct gntdev_copy_batch *batch, void __user *virt,
+			   bool writeable, unsigned long *gfn)
+{
+	unsigned long addr = (unsigned long)virt;
+	struct page *page;
+	unsigned long xen_pfn;
+	int ret;
+
+	ret = get_user_pages_fast(addr, 1, writeable, &page);
+	if (ret < 0)
+		return ret;
+
+	batch->pages[batch->nr_pages++] = page;
+
+	xen_pfn = page_to_xen_pfn(page) + XEN_PFN_DOWN(addr & ~PAGE_MASK);
+	*gfn = pfn_to_gfn(xen_pfn);
+
+	return 0;
+}
+
+static void gntdev_put_pages(struct gntdev_copy_batch *batch)
+{
+	unsigned int i;
+
+	for (i = 0; i < batch->nr_pages; i++)
+		put_page(batch->pages[i]);
+	batch->nr_pages = 0;
+}
+
+static int gntdev_copy(struct gntdev_copy_batch *batch)
+{
+	unsigned int i;
+
+	gnttab_batch_copy(batch->ops, batch->nr_ops);
+	gntdev_put_pages(batch);
+
+	/*
+	 * For each completed op, update the status if the op failed
+	 * and all previous ops for the segment were successful.
+	 */
+	for (i = 0; i < batch->nr_ops; i++) {
+		s16 status = batch->ops[i].status;
+		s16 old_status;
+
+		if (status == GNTST_okay)
+			continue;
+
+		if (__get_user(old_status, batch->status[i]))
+			return -EFAULT;
+
+		if (old_status != GNTST_okay)
+			continue;
+
+		if (__put_user(status, batch->status[i]))
+			return -EFAULT;
+	}
+
+	batch->nr_ops = 0;
+	return 0;
+}
+
+static int gntdev_grant_copy_seg(struct gntdev_copy_batch *batch,
+				 struct gntdev_grant_copy_segment *seg,
+				 s16 __user *status)
+{
+	uint16_t copied = 0;
+
+	/*
+	 * Disallow local -> local copies since there is only space in
+	 * batch->pages for one page per-op and this would be a very
+	 * expensive memcpy().
+	 */
+	if (!(seg->flags & (GNTCOPY_source_gref | GNTCOPY_dest_gref)))
+		return -EINVAL;
+
+	/* Can't cross page if source/dest is a grant ref. */
+	if (seg->flags & GNTCOPY_source_gref) {
+		if (seg->source.foreign.offset + seg->len > XEN_PAGE_SIZE)
+			return -EINVAL;
+	}
+	if (seg->flags & GNTCOPY_dest_gref) {
+		if (seg->dest.foreign.offset + seg->len > XEN_PAGE_SIZE)
+			return -EINVAL;
+	}
+
+	if (put_user(GNTST_okay, status))
+		return -EFAULT;
+
+	while (copied < seg->len) {
+		struct gnttab_copy *op;
+		void __user *virt;
+		size_t len, off;
+		unsigned long gfn;
+		int ret;
+
+		if (batch->nr_ops >= GNTDEV_COPY_BATCH) {
+			ret = gntdev_copy(batch);
+			if (ret < 0)
+				return ret;
+		}
+
+		len = seg->len - copied;
+
+		op = &batch->ops[batch->nr_ops];
+		op->flags = 0;
+
+		if (seg->flags & GNTCOPY_source_gref) {
+			op->source.u.ref = seg->source.foreign.ref;
+			op->source.domid = seg->source.foreign.domid;
+			op->source.offset = seg->source.foreign.offset + copied;
+			op->flags |= GNTCOPY_source_gref;
+		} else {
+			virt = seg->source.virt + copied;
+			off = (unsigned long)virt & ~XEN_PAGE_MASK;
+			len = min(len, (size_t)XEN_PAGE_SIZE - off);
+
+			ret = gntdev_get_page(batch, virt, false, &gfn);
+			if (ret < 0)
+				return ret;
+
+			op->source.u.gmfn = gfn;
+			op->source.domid = DOMID_SELF;
+			op->source.offset = off;
+		}
+
+		if (seg->flags & GNTCOPY_dest_gref) {
+			op->dest.u.ref = seg->dest.foreign.ref;
+			op->dest.domid = seg->dest.foreign.domid;
+			op->dest.offset = seg->dest.foreign.offset + copied;
+			op->flags |= GNTCOPY_dest_gref;
+		} else {
+			virt = seg->dest.virt + copied;
+			off = (unsigned long)virt & ~XEN_PAGE_MASK;
+			len = min(len, (size_t)XEN_PAGE_SIZE - off);
+
+			ret = gntdev_get_page(batch, virt, true, &gfn);
+			if (ret < 0)
+				return ret;
+
+			op->dest.u.gmfn = gfn;
+			op->dest.domid = DOMID_SELF;
+			op->dest.offset = off;
+		}
+
+		op->len = len;
+		copied += len;
+
+		batch->status[batch->nr_ops] = status;
+		batch->nr_ops++;
+	}
+
+	return 0;
+}
+
+static long gntdev_ioctl_grant_copy(struct gntdev_priv *priv, void __user *u)
+{
+	struct ioctl_gntdev_grant_copy copy;
+	struct gntdev_copy_batch batch;
+	unsigned int i;
+	int ret = 0;
+
+	if (copy_from_user(&copy, u, sizeof(copy)))
+		return -EFAULT;
+
+	batch.nr_ops = 0;
+	batch.nr_pages = 0;
+
+	for (i = 0; i < copy.count; i++) {
+		struct gntdev_grant_copy_segment seg;
+
+		if (copy_from_user(&seg, &copy.segments[i], sizeof(seg))) {
+			ret = -EFAULT;
+			goto out;
+		}
+
+		ret = gntdev_grant_copy_seg(&batch, &seg, &copy.segments[i].status);
+		if (ret < 0)
+			goto out;
+
+		cond_resched();
+	}
+	if (batch.nr_ops)
+		ret = gntdev_copy(&batch);
+	return ret;
+
+  out:
+	gntdev_put_pages(&batch);
+	return ret;
+}
+
 static long gntdev_ioctl(struct file *flip,
 			 unsigned int cmd, unsigned long arg)
 {
@@ -767,6 +967,9 @@ static long gntdev_ioctl(struct file *flip,
 	case IOCTL_GNTDEV_SET_UNMAP_NOTIFY:
 		return gntdev_ioctl_notify(priv, ptr);
 
+	case IOCTL_GNTDEV_GRANT_COPY:
+		return gntdev_ioctl_grant_copy(priv, ptr);
+
 	default:
 		pr_debug("priv %p, unknown cmd %x\n", priv, cmd);
 		return -ENOIOCTLCMD;
diff --git a/include/uapi/xen/gntdev.h b/include/uapi/xen/gntdev.h
index aa7610a..d066197 100644
--- a/include/uapi/xen/gntdev.h
+++ b/include/uapi/xen/gntdev.h
@@ -144,6 +144,56 @@ struct ioctl_gntdev_unmap_notify {
 	__u32 event_channel_port;
 };
 
+struct gntdev_grant_copy_segment {
+	union {
+		void __user *virt;
+		struct {
+			grant_ref_t ref;
+			__u16 offset;
+			domid_t domid;
+		} foreign;
+	} source, dest;
+	__u16 len;
+
+	__u16 flags;  /* GNTCOPY_* */
+	__s16 status; /* GNTST_* */
+};
+
+/*
+ * Copy between grant references and local buffers.
+ *
+ * The copy is split into @count @segments, each of which can copy
+ * to/from one grant reference.
+ *
+ * Each segment is similar to struct gnttab_copy in the hypervisor ABI
+ * except the local buffer is specified using a virtual address
+ * (instead of a GFN and offset).
+ *
+ * The local buffer may cross a Xen page boundary -- the driver will
+ * split segments into multiple ops if required.
+ *
+ * Returns 0 if all segments have been processed and @status in each
+ * segment is valid.  Note that one or more segments may have failed
+ * (status != GNTST_okay).
+ *
+ * If the driver had to split a segment into two or more ops, @status
+ * includes the status of the first failed op for that segment (or
+ * GNTST_okay if all ops were successful).
+ *
+ * If -1 is returned, the status of all segments is undefined.
+ *
+ * EINVAL: A segment has local buffers for both source and
+ *         destination.
+ * EINVAL: A segment crosses the boundary of a foreign page.
+ * EFAULT: A segment's local buffer is not accessible.
+ */
+#define IOCTL_GNTDEV_GRANT_COPY \
+	_IOC(_IOC_NONE, 'G', 8, sizeof(struct ioctl_gntdev_grant_copy))
+struct ioctl_gntdev_grant_copy {
+	unsigned int count;
+	struct gntdev_grant_copy_segment __user *segments;
+};
+
 /* Clear (set to zero) the byte specified by index */
 #define UNMAP_NOTIFY_CLEAR_BYTE 0x1
 /* Send an interrupt on the indicated event channel */