linux-kernel - [PATCH] iommu/amd: Fix type of type parameter to amd_iommufd_hw

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Message-Id: <20260122-amd-iommufd-fix-wifpts-v1-1-8ee604527875@kernel.org>
Date: Thu, 22 Jan 2026 14:42:38 -0700
From: Nathan Chancellor <nathan@...nel.org>
To: Joerg Roedel <joro@...tes.org>, 
 Suravee Suthikulpanit <suravee.suthikulpanit@....com>
Cc: Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>, 
 Vasant Hegde <vasant.hegde@....com>, Jason Gunthorpe <jgg@...pe.ca>, 
 Nicolin Chen <nicolinc@...dia.com>, iommu@...ts.linux.dev, 
 linux-kernel@...r.kernel.org, Nathan Chancellor <nathan@...nel.org>
Subject: [PATCH] iommu/amd: Fix type of type parameter to
 amd_iommufd_hw_info()

When building with -Wincompatible-function-pointer-types-strict, a
warning designed to catch kernel control flow integrity (kCFI) issues at
build time, there is an instance around amd_iommufd_hw_info():

  drivers/iommu/amd/iommu.c:3141:13: error: incompatible function pointer types initializing 'void *(*)(struct device *, u32 *, enum iommu_hw_info_type *)' (aka 'void *(*)(struct device *, unsigned int *, enum iommu_hw_info_type *)') with an expression of type 'void *(struct device *, u32 *, u32 *)' (aka 'void *(struct device *, unsigned int *, unsigned int *)') [-Werror,-Wincompatible-function-pointer-types-strict]
   3141 |         .hw_info = amd_iommufd_hw_info,
        |                    ^~~~~~~~~~~~~~~~~~~

While 'u32 *' and 'enum iommu_hw_info_type *' are ABI compatible, hence
no regular warning from -Wincompatible-function-pointer-types, the
mismatch will trigger a kCFI violation when amd_iommufd_hw_info() is
called indirectly.

Update the type parameter of amd_iommufd_hw_info() to be
'enum iommu_hw_info_type *' to match the prototype in
'struct iommu_ops', clearing up the warning and kCFI violation.

Fixes: 7d8b06ecc45b ("iommu/amd: Add support for hw_info for iommu capability query")
Signed-off-by: Nathan Chancellor <nathan@...nel.org>
---
 drivers/iommu/amd/iommufd.c | 2 +-
 drivers/iommu/amd/iommufd.h | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/amd/iommufd.c b/drivers/iommu/amd/iommufd.c
index ad627fd5ccc7..96ec6a4a760d 100644
--- a/drivers/iommu/amd/iommufd.c
+++ b/drivers/iommu/amd/iommufd.c
@@ -11,7 +11,7 @@
 
 static const struct iommufd_viommu_ops amd_viommu_ops;
 
-void *amd_iommufd_hw_info(struct device *dev, u32 *length, u32 *type)
+void *amd_iommufd_hw_info(struct device *dev, u32 *length, enum iommu_hw_info_type *type)
 {
 	struct iommu_hw_info_amd *hwinfo;
 
diff --git a/drivers/iommu/amd/iommufd.h b/drivers/iommu/amd/iommufd.h
index f05aad495b5b..62e9e1bebfbe 100644
--- a/drivers/iommu/amd/iommufd.h
+++ b/drivers/iommu/amd/iommufd.h
@@ -7,7 +7,7 @@
 #define AMD_IOMMUFD_H
 
 #if IS_ENABLED(CONFIG_AMD_IOMMU_IOMMUFD)
-void *amd_iommufd_hw_info(struct device *dev, u32 *length, u32 *type);
+void *amd_iommufd_hw_info(struct device *dev, u32 *length, enum iommu_hw_info_type *type);
 size_t amd_iommufd_get_viommu_size(struct device *dev, enum iommu_viommu_type viommu_type);
 int amd_iommufd_viommu_init(struct iommufd_viommu *viommu, struct iommu_domain *parent,
 			    const struct iommu_user_data *user_data);

---
base-commit: c0a652a3d1970caa0023632ae3a4ea21991d2f1a
change-id: 20260122-amd-iommufd-fix-wifpts-dfd944cbc17e

Best regards,
--  
Nathan Chancellor <nathan@...nel.org>