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authorDavid Vrabel <david.vrabel@citrix.com>2014-12-02 16:13:26 +0000
committerDavid Vrabel <david.vrabel@citrix.com>2016-01-07 13:21:53 +0000
commita4cdb556cae05cd3e7b602b3a44c01420c4e2258 (patch)
treef21957dcd64da3d2be1a0891b523b8ff46e58d1d /drivers/xen
parent6a1f513776b78c994045287073e55bae44ed9f8c (diff)
downloadlinux-a4cdb556cae05cd3e7b602b3a44c01420c4e2258.tar.bz2
xen/gntdev: add ioctl for grant copy
Add IOCTL_GNTDEV_GRANT_COPY to allow applications to copy between user space buffers and grant references. This interface is similar to the GNTTABOP_copy hypercall ABI except the local buffers are provided using a virtual address (instead of a GFN and offset). To avoid userspace from having to page align its buffers the driver will use two or more ops if required. If the ioctl returns 0, the application must check the status of each segment with the segments status field. If the ioctl returns a -ve error code (EINVAL or EFAULT), the status of individual ops is undefined. Signed-off-by: David Vrabel <david.vrabel@citrix.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Diffstat (limited to 'drivers/xen')
-rw-r--r--drivers/xen/gntdev.c203
1 files changed, 203 insertions, 0 deletions
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index cbd3836ec8fa..dc495383ad73 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;