Not all Xen environments support the xengnttab_grant_copy() operation.
E.g. where the OS is FreeBSD or Xen is older than 4.8.0.
This patch introduces an emulation of that operation using
xengnttab_map_domain_grant_refs() and memcpy() for those environments.
Signed-off-by: Paul Durrant <paul.durr...@citrix.com>
---
Cc: Stefano Stabellini <sstabell...@kernel.org>
Cc: Anthony Perard <anthony.per...@citrix.com>
v2:
- New in v2
---
hw/xen/xen_backend.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 53 insertions(+)
diff --git a/hw/xen/xen_backend.c b/hw/xen/xen_backend.c
index 50412d6..3c3fc2c 100644
--- a/hw/xen/xen_backend.c
+++ b/hw/xen/xen_backend.c
@@ -146,6 +146,55 @@ void xen_be_unmap_grant_refs(struct XenDevice *xendev,
void *ptr,
}
}
+static int compat_copy_grant_refs(struct XenDevice *xendev,
+ bool to_domain,
+ XenGrantCopySegment segs[],
+ unsigned int nr_segs)
+{
+ uint32_t *refs = g_new(uint32_t, nr_segs);
+ int prot = to_domain ? PROT_WRITE : PROT_READ;
+ void *pages;
+ unsigned int i;
+
+ for (i = 0; i < nr_segs; i++) {
+ XenGrantCopySegment *seg = &segs[i];
+
+ refs[i] = to_domain ?
+ seg->dest.foreign.ref : seg->source.foreign.ref;
+ }
+
+ pages = xengnttab_map_domain_grant_refs(xendev->gnttabdev, nr_segs,
+ xen_domid, refs, prot);
+ if (!pages) {
+ xen_pv_printf(xendev, 0,
+ "xengnttab_map_domain_grant_refs failed: %s\n",
+ strerror(errno));
+ g_free(refs);
+ return -1;
+ }
+
+ for (i = 0; i < nr_segs; i++) {
+ XenGrantCopySegment *seg = &segs[i];
+ void *page = pages + (i * XC_PAGE_SIZE);
+
+ if (to_domain) {
+ memcpy(page + seg->dest.foreign.offset, seg->source.virt,
+ seg->len);
+ } else {
+ memcpy(seg->dest.virt, page + seg->source.foreign.offset,
+ seg->len);
+ }
+ }
+
+ if (xengnttab_unmap(xendev->gnttabdev, pages, nr_segs)) {
+ xen_pv_printf(xendev, 0, "xengnttab_unmap failed: %s\n",
+ strerror(errno));
+ }
+
+ g_free(refs);
+ return 0;
+}
+
int xen_be_copy_grant_refs(struct XenDevice *xendev,
bool to_domain,
XenGrantCopySegment segs[],
@@ -157,6 +206,10 @@ int xen_be_copy_grant_refs(struct XenDevice *xendev,
assert(xendev->ops->flags & DEVOPS_FLAG_NEED_GNTDEV);
+ if (!xen_feature_grant_copy) {
+ return compat_copy_grant_refs(xendev, to_domain, segs, nr_segs);
+ }
+
xengnttab_segs = g_new0(xengnttab_grant_copy_segment_t, nr_segs);
for (i = 0; i < nr_segs; i++) {
--
2.1.4
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