Merge tag 'for-linus-4.1b-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

Pull xen bug fixes from David Vrabel:

 - fix blkback regression if using persistent grants

 - fix various event channel related suspend/resume bugs

 - fix AMD x86 regression with X86_BUG_SYSRET_SS_ATTRS

 - SWIOTLB on ARM now uses frames <4 GiB (if available) so device only
   capable of 32-bit DMA work.

* tag 'for-linus-4.1b-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen: Add __GFP_DMA flag when xen_swiotlb_init gets free pages on ARM
  hypervisor/x86/xen: Unset X86_BUG_SYSRET_SS_ATTRS on Xen PV guests
  xen/events: Set irq_info->evtchn before binding the channel to CPU in __startup_pirq()
  xen/console: Update console event channel on resume
  xen/xenbus: Update xenbus event channel on resume
  xen/events: Clear cpu_evtchn_mask before resuming
  xen-pciback: Add name prefix to global 'permissive' variable
  xen: Suspend ticks on all CPUs during suspend
  xen/grant: introduce func gnttab_unmap_refs_sync()
  xen/blkback: safely unmap purge persistent grants

1 files changed, 28 insertions, 0 deletions

diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index 17972fbacddc..b1c7170e5c9e 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -123,6 +123,11 @@ struct gnttab_ops {
 	int (*query_foreign_access)(grant_ref_t ref);
 };
 
+struct unmap_refs_callback_data {
+	struct completion completion;
+	int result;
+};
+
 static struct gnttab_ops *gnttab_interface;
 
 static int grant_table_version;
@@ -863,6 +868,29 @@ void gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item)
 }
 EXPORT_SYMBOL_GPL(gnttab_unmap_refs_async);
 
+static void unmap_refs_callback(int result,
+		struct gntab_unmap_queue_data *data)
+{
+	struct unmap_refs_callback_data *d = data->data;
+
+	d->result = result;
+	complete(&d->completion);
+}
+
+int gnttab_unmap_refs_sync(struct gntab_unmap_queue_data *item)
+{
+	struct unmap_refs_callback_data data;
+
+	init_completion(&data.completion);
+	item->data = &data;
+	item->done = &unmap_refs_callback;
+	gnttab_unmap_refs_async(item);
+	wait_for_completion(&data.completion);
+
+	return data.result;
+}
+EXPORT_SYMBOL_GPL(gnttab_unmap_refs_sync);
+
 static int gnttab_map_frames_v1(xen_pfn_t *frames, unsigned int nr_gframes)
 {
 	int rc;