Mailing List Archive

These allow a domain A which has been granted access on a page of domain B's
memory to issue domain C with a copy-grant on the same page. This is useful
e.g. for forwarding packets between domains.

Signed-off-by: Annie Li <annie.li@oracle.com>
---
drivers/xen/grant-table.c | 73 +++++++++++++++++++++++++++++++++++++++++++++
include/xen/grant_table.h | 12 +++++++
2 files changed, 85 insertions(+), 0 deletions(-)

diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index 4a10e3f..db3e7c0 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -130,6 +130,18 @@ struct gnttab_ops {
*/
void (*update_subpage_entry)(grant_ref_t, domid_t, unsigned long, int,
unsigned, unsigned);
+ /*
+ * Redirect an available grant entry on domain A to another grant
+ * reference of domain B, then allow domain C to use grant reference
+ * of domain B transitively. First parameter is an available grant entry
+ * reference on domain A, second one is id of domain C which accesses
+ * grant entry transitively, third one is grant type and flag
+ * information, forth one is id of domain B whose grant entry is finally
+ * accessed transitively, last one is grant entry transitive reference
+ * of domain B.
+ */
+ void (*update_trans_entry)(grant_ref_t, domid_t, int, domid_t,
+ grant_ref_t);
};

static struct gnttab_ops *gnttab_interface;
@@ -334,6 +346,66 @@ bool gnttab_subpage_grants_available(void)
}
EXPORT_SYMBOL_GPL(gnttab_subpage_grants_available);

+void gnttab_update_trans_entry_v2(grant_ref_t ref, domid_t domid,
+ int flags, domid_t trans_domid,
+ grant_ref_t trans_gref)
+{
+ gnttab_shared.v2[ref].transitive.trans_domid = trans_domid;
+ gnttab_shared.v2[ref].transitive.gref = trans_gref;
+ gnttab_shared.v2[ref].hdr.domid = domid;
+ wmb();
+ gnttab_shared.v2[ref].hdr.flags =
+ GTF_permit_access | GTF_transitive | flags;
+}
+
+int gnttab_grant_foreign_access_trans_ref(grant_ref_t ref, domid_t domid,
+ int flags, domid_t trans_domid,
+ grant_ref_t trans_gref)
+{
+ if (flags & (GTF_accept_transfer | GTF_reading |
+ GTF_writing | GTF_sub_page))
+ return -EPERM;
+
+ if (gnttab_interface->update_trans_entry == NULL)
+ return -ENOSYS;
+
+ gnttab_interface->update_trans_entry(ref, domid, flags, trans_domid,
+ trans_gref);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_trans_ref);
+
+int gnttab_grant_foreign_access_trans(domid_t domid, int flags,
+ domid_t trans_domid,
+ grant_ref_t trans_gref)
+{
+ int ref;
+
+ if (flags & (GTF_accept_transfer | GTF_reading |
+ GTF_writing | GTF_sub_page))
+ return -EPERM;
+
+ if (gnttab_interface->update_trans_entry == NULL)
+ return -ENOSYS;
+
+ ref = get_free_entries(1);
+ if (unlikely(ref < 0))
+ return -ENOSPC;
+
+ gnttab_interface->update_trans_entry(ref, domid, flags, trans_domid,
+ trans_gref);
+
+ return ref;
+}
+EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_trans);
+
+bool gnttab_trans_grants_available(void)
+{
+ return gnttab_interface->update_trans_entry != NULL;
+}
+EXPORT_SYMBOL_GPL(gnttab_trans_grants_available);
+
static int gnttab_query_foreign_access_v1(grant_ref_t ref)
{
return gnttab_shared.v1[ref].flags & (GTF_reading|GTF_writing);
@@ -887,6 +959,7 @@ static struct gnttab_ops gnttab_v2_ops = {
.end_foreign_transfer_ref = gnttab_end_foreign_transfer_ref_v2,
.query_foreign_access = gnttab_query_foreign_access_v2,
.update_subpage_entry = gnttab_update_subpage_entry_v2,
+ .update_trans_entry = gnttab_update_trans_entry_v2,
};

static void gnttab_request_version(void)
diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h
index 2b492b9..f1e17b7 100644
--- a/include/xen/grant_table.h
+++ b/include/xen/grant_table.h
@@ -65,6 +65,9 @@ int gnttab_grant_foreign_access(domid_t domid, unsigned long frame,
int gnttab_grant_foreign_access_subpage(domid_t domid, unsigned long frame,
int flags, unsigned page_off,
unsigned length);
+int gnttab_grant_foreign_access_trans(domid_t domid, int flags,
+ domid_t trans_domid,
+ grant_ref_t trans_gref);

/*
* Are sub-page grants available on this version of Xen? Returns true if they
@@ -73,6 +76,12 @@ int gnttab_grant_foreign_access_subpage(domid_t domid, unsigned long frame,
bool gnttab_subpage_grants_available(void);

/*
+ * Are transitive grants available on this version of Xen? Returns true if they
+ * are, and false if they're not.
+ */
+bool gnttab_trans_grants_available(void);
+
+/*
* End access through the given grant reference, iff the grant entry is no
* longer in use. Return 1 if the grant entry was freed, 0 if it is still in
* use.
@@ -121,6 +130,9 @@ int gnttab_grant_foreign_access_subpage_ref(grant_ref_t ref, domid_t domid,
unsigned long frame, int flags,
unsigned page_off,
unsigned length);
+int gnttab_grant_foreign_access_trans_ref(grant_ref_t ref, domid_t domid,
+ int flags, domid_t trans_domid,
+ grant_ref_t trans_gref);

void gnttab_grant_foreign_transfer_ref(grant_ref_t, domid_t domid,
unsigned long pfn);
--
1.7.6.4


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