linux-kernel - [PATCH v2] iommu/vt-d: Fix to flush cache of PASID directory table

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Message-Id: <20230616081045.721873-1-yanfei.xu@intel.com>
Date:   Fri, 16 Jun 2023 16:10:45 +0800
From:   Yanfei Xu <yanfei.xu@...el.com>
To:     dwmw2@...radead.org, baolu.lu@...ux.intel.com, joro@...tes.org,
        will@...nel.org, robin.murphy@....com, tina.zhang@...el.com
Cc:     iommu@...ts.linux.dev, linux-kernel@...r.kernel.org,
        yanfei.xu@...el.com
Subject: [PATCH v2] iommu/vt-d: Fix to flush cache of PASID directory table

Even the PCI devices don't support pasid capability, PASID
table is mandatory for a PCI device in scalable mode. However
flushing cache of pasid directory table for these devices are
not taken after pasid table is allocated as the "size" of
table is zero. Fix it by calculating the size by page order.

Found this when reading the code, no actual problem encountered
for now

Fixes: 194b3348bdbb ("iommu/vt-d: Fix PASID directory pointer coherency")
Suggested-by: Lu Baolu <baolu.lu@...ux.intel.com>
Signed-off-by: Yanfei Xu <yanfei.xu@...el.com>
---
v1->v2:
  use variable "order" to calculate the table size (Suggested by baolu)

 drivers/iommu/intel/pasid.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c
index c5d479770e12..49fc5a038a14 100644
--- a/drivers/iommu/intel/pasid.c
+++ b/drivers/iommu/intel/pasid.c
@@ -129,7 +129,7 @@ int intel_pasid_alloc_table(struct device *dev)
 	info->pasid_table = pasid_table;
 
 	if (!ecap_coherent(info->iommu->ecap))
-		clflush_cache_range(pasid_table->table, size);
+		clflush_cache_range(pasid_table->table, (1 << order) * PAGE_SIZE);
 
 	return 0;
 }
-- 
2.34.1