diff mbox series

[v2,4/6] VT-d: restrict iommu_flush_all() to cache writeback

Message ID bf99949c-0e09-13a5-3ad9-a6c26377bdbf@suse.com (mailing list archive)
State New, archived
Headers show
Series x86: reduce cache flushing overhead | expand

Commit Message

Jan Beulich May 3, 2023, 9:46 a.m. UTC 
We don't need to invalidate caches here; all we're after is that earlier
writes have made it to main memory (and aiui even that just in case).

Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
This, aiui, being an analogue to uses of iommu_sync_cache() (just not
range restricted), I wonder whether it shouldn't be conditional upon
iommu_non_coherent. Then again I'm vaguely under the impression that
we had been here before, possibly even as far as questioning the need
for this call altogether.
---
v2: FLUSH_WRITEBACK -> FLUSH_CACHE_WRITEBACK.
diff mbox series

Patch

--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -693,7 +693,7 @@  static int __must_check iommu_flush_all(
     bool_t flush_dev_iotlb;
     int rc = 0;
 
-    flush_local(FLUSH_CACHE);
+    flush_local(FLUSH_CACHE_WRITEBACK);
 
     for_each_drhd_unit ( drhd )
     {