linux-kernel - [PATCH] iommu/vt-d: fix constant-out-of-range warning

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Date: Tue, 13 Feb 2024 10:58:20 +0100
From: Arnd Bergmann <arnd@...nel.org>
To: David Woodhouse <dwmw2@...radead.org>,
	Lu Baolu <baolu.lu@...ux.intel.com>
Cc: Arnd Bergmann <arnd@...db.de>,
	Joerg Roedel <joro@...tes.org>,
	Will Deacon <will@...nel.org>,
	Robin Murphy <robin.murphy@....com>,
	Nathan Chancellor <nathan@...nel.org>,
	Nick Desaulniers <ndesaulniers@...gle.com>,
	Bill Wendling <morbo@...gle.com>,
	Justin Stitt <justinstitt@...gle.com>,
	Kevin Tian <kevin.tian@...el.com>,
	Yi Liu <yi.l.liu@...el.com>,
	Jason Gunthorpe <jgg@...pe.ca>,
	Jacob Pan <jacob.jun.pan@...ux.intel.com>,
	iommu@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	llvm@...ts.linux.dev
Subject: [PATCH] iommu/vt-d: fix constant-out-of-range warning

From: Arnd Bergmann <arnd@...db.de>

On 32-bit builds, the vt-d driver causes a warning with clang:

drivers/iommu/intel/nested.c:112:13: error: result of comparison of constant 18446744073709551615 with expression of type 'unsigned long' is always false [-Werror,-Wtautological-constant-out-of-range-compare]
  112 |         if (npages == U64_MAX)
      |             ~~~~~~ ^  ~~~~~~~

This can be easily avoided by making the variable a 64-bit type, which matches
both the caller and the use anyway.

Fixes: f6f3721244a8 ("iommu/vt-d: Add iotlb flush for nested domain")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/iommu/intel/nested.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/intel/nested.c b/drivers/iommu/intel/nested.c
index f26c7f1c46cc..77a09c982979 100644
--- a/drivers/iommu/intel/nested.c
+++ b/drivers/iommu/intel/nested.c
@@ -95,7 +95,7 @@ static void nested_flush_dev_iotlb(struct dmar_domain *domain, u64 addr,
 }
 
 static void intel_nested_flush_cache(struct dmar_domain *domain, u64 addr,
-				     unsigned long npages, bool ih)
+				     u64 npages, bool ih)
 {
 	struct iommu_domain_info *info;
 	unsigned int mask;
-- 
2.39.2