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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v2] introduce grant copy for user land
This patch introduces the interface to allow user-space applications
execute grant-copy operations. This is done by sending an ioctl to the
grant device.
Signed-off-by: Thanos Makatos <thanos.makatos@xxxxxxxxxx>
---
drivers/xen/gntdev.c | 171 +++++++++++++++++++++++++++++++++++++++++++++
include/uapi/xen/gntdev.h | 69 ++++++++++++++++++
2 files changed, 240 insertions(+)
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 51f4c95..7b4a8e0 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -705,6 +705,174 @@ static long gntdev_ioctl_notify(struct gntdev_priv *priv,
void __user *u)
return rc;
}
+static int gntdev_gcopy_batch(int nr_segments, unsigned long gcopy_cb,
+ struct gntdev_grant_copy_segment __user *__segments, int dir,
+ int src, int dst) {
+
+ static const int batch_size = PAGE_SIZE / (sizeof(struct page*) +
+ sizeof(struct gnttab_copy) + sizeof(struct
gntdev_grant_copy_segment));
+ struct page **pages = (struct page **)gcopy_cb;
+ struct gnttab_copy *batch = (struct gnttab_copy *)((unsigned long)pages
+
+ sizeof(struct page*) * batch_size);
+ struct gntdev_grant_copy_segment *segments =
+ (struct gntdev_grant_copy_segment *)((unsigned long)batch +
+ sizeof(struct gnttab_copy) * batch_size);
+ unsigned int nr_pinned = 0, nr_segs2cp = 0;
+ int err = 0, i;
+ const int write = dir == GNTCOPY_IOCTL_g2s;
+
+ nr_segments = min(nr_segments, batch_size);
+
+ if (unlikely(copy_from_user(segments, __segments,
+ sizeof(struct gntdev_grant_copy_segment) *
nr_segments))) {
+ pr_debug("failed to copy %d segments from user", nr_segments);
+ err = -EFAULT;
+ goto out;
+ }
+
+ for (i = 0; i < nr_segments; i++) {
+
+ xen_pfn_t pgaddr;
+ unsigned long start, offset;
+ struct gntdev_grant_copy_segment *seg = &segments[i];
+
+ if (dir == GNTCOPY_IOCTL_s2g || dir == GNTCOPY_IOCTL_g2s) {
+
+ start = (unsigned long)seg->self.iov.iov_base &
PAGE_MASK;
+ offset = (unsigned long)seg->self.iov.iov_base &
~PAGE_MASK;
+ if (unlikely(offset + seg->self.iov.iov_len >
PAGE_SIZE)) {
+ pr_warn("segments crossing page boundaries not
yet "
+ "implemented\n");
+ err = -ENOSYS;
+ goto out;
+ }
+
+ err = get_user_pages_fast(start, 1, write, &pages[i]);
+ if (unlikely(err != 1)) {
+ pr_debug("failed to get user page %lu", start);
+ err = -EFAULT;
+ goto out;
+ }
+
+ nr_pinned++;
+
+ pgaddr = pfn_to_mfn(page_to_pfn(pages[i]));
+ }
+
+ nr_segs2cp++;
+
+ switch (dir) {
+ case GNTCOPY_IOCTL_g2s: /* copy from guest */
+ batch[i].len = seg->self.iov.iov_len;
+ batch[i].source.u.ref = seg->self.ref;
+ batch[i].source.domid = src;
+ batch[i].source.offset = seg->self.offset;
+ batch[i].dest.u.gmfn = pgaddr;
+ batch[i].dest.domid = DOMID_SELF;
+ batch[i].dest.offset = offset;
+ batch[i].flags = GNTCOPY_source_gref;
+ break;
+ case GNTCOPY_IOCTL_s2g: /* copy to guest */
+ batch[i].len = seg->self.iov.iov_len;
+ batch[i].source.u.gmfn = pgaddr;
+ batch[i].source.domid = DOMID_SELF;
+ batch[i].source.offset = offset;
+ batch[i].dest.u.ref = seg->self.ref;
+ batch[i].dest.domid = dst;
+ batch[i].dest.offset = seg->self.offset;
+ batch[i].flags = GNTCOPY_dest_gref;
+ break;
+ case GNTCOPY_IOCTL_g2g: /* copy guest to guest */
+ batch[i].len = seg->g2g.len;
+ batch[i].source.u.ref = seg->g2g.src.ref;
+ batch[i].source.domid = src;
+ batch[i].source.offset = seg->g2g.src.offset;
+ batch[i].dest.u.ref = seg->g2g.dst.ref;
+ batch[i].dest.domid = dst;
+ batch[i].dest.offset = seg->g2g.dst.offset;
+ batch[i].flags = GNTCOPY_source_gref |
GNTCOPY_dest_gref;
+ break;
+ default:
+ pr_debug("invalid grant-copy direction %d\n", dir);
+ err = -EINVAL;
+ goto out;
+ }
+ }
+
+ gnttab_batch_copy(batch, nr_segs2cp);
+ for (i = 0; i < nr_segs2cp; i++) {
+ err = put_user(batch[i].status, &__segments[i].status);
+ if (unlikely(err)) {
+ pr_debug("failed to copy error code %d to user: %d\n",
+ batch[i].status, err);
+ goto out;
+ }
+ }
+
+out:
+ for (i = 0; i < nr_pinned; i++)
+ put_page(pages[i]);
+
+ if (unlikely(err))
+ return err;
+
+ return nr_segs2cp;
+}
+
+static long gntdev_ioctl_grant_copy(struct gntdev_priv *priv, void __user *u)
+{
+ struct ioctl_gntdev_grant_copy op;
+ unsigned int remaining;
+ int err = 0;
+ unsigned long gcopy_cb = 0;
+
+ if (unlikely(copy_from_user(&op, u, sizeof(op)))) {
+ pr_debug("failed to copy grant-copy parameters from user");
+ err = -EFAULT;
+ goto out;
+ }
+
+ if (unlikely(op.dir != GNTCOPY_IOCTL_s2g && op.dir != GNTCOPY_IOCTL_g2s
&&
+ op.dir != GNTCOPY_IOCTL_g2g)) {
+ pr_debug("invalid copy direction %d\n", op.dir);
+ err = -EINVAL;
+ goto out;
+ }
+
+ if (!op.count) {
+ pr_debug("no segments to transfer");
+ err = 0;
+ goto out;
+ }
+
+ gcopy_cb = get_zeroed_page(GFP_KERNEL);
+ if (unlikely(!gcopy_cb)) {
+ pr_debug("failed to allocate page");
+ err = -ENOMEM;
+ goto out;
+ }
+
+ remaining = op.count;
+
+ while (remaining > 0) {
+ err = gntdev_gcopy_batch(remaining, gcopy_cb,
+ op.segments + (op.count - remaining), op.dir,
op.src, op.dst);
+ if (unlikely(err < 0)) {
+ pr_debug("failed to grant-copy %d segments: %d",
+ op.count - remaining, err);
+ goto out;
+ }
+ remaining -= err;
+ }
+
+ err = 0;
+
+out:
+ if (likely(gcopy_cb))
+ free_page(gcopy_cb);
+ return err;
+}
+
static long gntdev_ioctl(struct file *flip,
unsigned int cmd, unsigned long arg)
{
@@ -724,6 +892,9 @@ 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 5304bd3..17da5e9 100644
--- a/include/uapi/xen/gntdev.h
+++ b/include/uapi/xen/gntdev.h
@@ -33,6 +33,12 @@
#ifndef __LINUX_PUBLIC_GNTDEV_H__
#define __LINUX_PUBLIC_GNTDEV_H__
+#ifdef __KERNEL__
+#include <linux/uio.h>
+#else
+#include <sys/uio.h>
+#endif
+
struct ioctl_gntdev_grant_ref {
/* The domain ID of the grant to be mapped. */
uint32_t domid;
@@ -142,6 +148,69 @@ struct ioctl_gntdev_unmap_notify {
uint32_t event_channel_port;
};
+struct gntdev_grant_copy_segment {
+
+ union {
+ /* copy from (to) self to (from) guest */
+ struct {
+ /*
+ * source address and length
+ */
+ struct iovec iov;
+
+ /* the granted page */
+ uint32_t ref;
+
+ /* offset in the granted page */
+ uint16_t offset;
+ } self;
+
+ /* copy from guest to guest */
+ struct {
+ uint16_t len;
+
+ struct {
+ /* the granted page */
+ uint32_t ref;
+
+ /* offset in the granted page */
+ uint16_t offset;
+ } src, dst;
+ } g2g;
+ };
+
+ /* grant copy result (GNTST_XXX) */
+ int16_t status;
+};
+
+/* grant-copy from self to guest */
+#define GNTCOPY_IOCTL_s2g 0
+/* grant-copy from guest to self */
+#define GNTCOPY_IOCTL_g2s 1
+/* grant-copy from guest to guest */
+#define GNTCOPY_IOCTL_g2g 2
+
+#define IOCTL_GNTDEV_GRANT_COPY \
+_IOC(_IOC_NONE, 'G', 8, sizeof(struct ioctl_gntdev_grant_copy))
+struct ioctl_gntdev_grant_copy {
+ /*
+ * copy direction, see GNTCOPY_IOCTL_XXX
+ */
+ int dir;
+
+ /*
+ * domain IDs:
+ * When the source (destination) domain is the one executing the
+ * grant-copy operation, the @src (@dst) parameter is ignored.
+ */
+ uint32_t src;
+ uint32_t dst;
+
+ 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 */
--
1.7.9.5
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