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: 7d8b06e ("iommu/amd: Add support for hw_info for iommu capability query")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

Author: nathanchance

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;
 

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);