[PATCH 03/20] iommu/vt-d: Fix CACHE_TAG_NESTING_DEVTLB polluting shared variables in flush loop

[Lu Baolu <baolu.lu@linux.intel.com>]

From: Guanghui Feng <guanghuifeng@linux.alibaba.com>

In cache_tag_flush_range(), the CACHE_TAG_NESTING_DEVTLB case modifies the
shared local variables 'addr' and 'mask' before falling through to
CACHE_TAG_DEVTLB. This causes all subsequent CACHE_TAG_DEVTLB entries in
the same loop iteration to incorrectly use the full-range flush parameters
(addr=0, mask=MAX_AGAW_PFN_WIDTH) instead of the precisely calculated PSI
range. This is not the intended behavior, as regular DEVTLB entries should
always perform targeted range-based invalidation.

Fix this by having CACHE_TAG_NESTING_DEVTLB directly call
cache_tag_flush_devtlb_psi() with the full-range constants and break,
instead of modifying shared variables and falling through. This ensures
CACHE_TAG_DEVTLB always uses the original calculated addr and mask for
precise range flush.

Signed-off-by: Guanghui Feng <guanghuifeng@linux.alibaba.com>
Signed-off-by: Guixin Liu <kanie@linux.alibaba.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/iommu/intel/cache.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/intel/cache.c b/drivers/iommu/intel/cache.c
index fdc88817709f..26a758b0f501 100644
--- a/drivers/iommu/intel/cache.c
+++ b/drivers/iommu/intel/cache.c
@@ -454,9 +454,8 @@ void cache_tag_flush_range(struct dmar_domain *domain, unsigned long start,
 			 * affected by a change in S2. So just flush the entire
 			 * device cache.
 			 */
-			addr = 0;
-			mask = MAX_AGAW_PFN_WIDTH;
-			fallthrough;
+			cache_tag_flush_devtlb_psi(domain, tag, 0, MAX_AGAW_PFN_WIDTH);
+			break;
 		case CACHE_TAG_DEVTLB:
 			cache_tag_flush_devtlb_psi(domain, tag, addr, mask);
 			break;
-- 
2.43.0