x86/amd_node: Fix PCI device reference counting in amd_smn_init()grafted

The local "root" pointer is a temporary variable used during the device
search. Therefore, refcount related to the search iterators should be cleaned
up after the search is complete.

Use the __free() cleanup macro to ensure the refcount is decremented when the
temporary pointer goes out of scope.

Additionally, increment the refcount when caching a root pointer. This ensures
the in-use refcount is separate from the temporary search refcounting.

Finally, drop the redundant "root = NULL" before the second search loop. The
pci_get_class() iterator always decrements the refcount of its "from"
argument, so the first loop can only fall through with "root" already NULL.

Fixes: 0a4b61d9c2e4 ("x86/amd_node: Fix AMD root device caching")
Closes: https://sashiko.dev/#/patchset/20260806160159.230453-1-jason.andryuk%40amd.com
Reported-by: Sashiko <sashiko-bot@kernel.org>
Assisted-by: LLM
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Cc: <stable@kernel.org>
Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com

1 files changed, 131 insertions, 0 deletions

diff --git a/include/asm-generic/hugetlb.h b/include/asm-generic/hugetlb.h
new file mode 100644
index 000000000..635c41cc3
--- /dev/null
+++ b/include/asm-generic/hugetlb.h
@@ -0,0 +1,131 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_GENERIC_HUGETLB_H
+#define _ASM_GENERIC_HUGETLB_H
+
+#include <linux/swap.h>
+#include <linux/swapops.h>
+
+static inline unsigned long huge_pte_write(pte_t pte)
+{
+	return pte_write(pte);
+}
+
+static inline unsigned long huge_pte_dirty(pte_t pte)
+{
+	return pte_dirty(pte);
+}
+
+static inline pte_t huge_pte_mkwrite(pte_t pte)
+{
+	return pte_mkwrite_novma(pte);
+}
+
+#ifndef __HAVE_ARCH_HUGE_PTE_WRPROTECT
+static inline pte_t huge_pte_wrprotect(pte_t pte)
+{
+	return pte_wrprotect(pte);
+}
+#endif
+
+static inline pte_t huge_pte_mkdirty(pte_t pte)
+{
+	return pte_mkdirty(pte);
+}
+
+static inline pte_t huge_pte_modify(pte_t pte, pgprot_t newprot)
+{
+	return pte_modify(pte, newprot);
+}
+
+#ifndef __HAVE_ARCH_HUGE_PTE_MKUFFD
+static inline pte_t huge_pte_mkuffd(pte_t pte)
+{
+	return huge_pte_wrprotect(pte_mkuffd(pte));
+}
+#endif
+
+#ifndef __HAVE_ARCH_HUGE_PTE_CLEAR_UFFD
+static inline pte_t huge_pte_clear_uffd(pte_t pte)
+{
+	return pte_clear_uffd(pte);
+}
+#endif
+
+#ifndef __HAVE_ARCH_HUGE_PTE_UFFD
+static inline int huge_pte_uffd(pte_t pte)
+{
+	return pte_uffd(pte);
+}
+#endif
+
+#ifndef __HAVE_ARCH_HUGE_PTE_CLEAR
+static inline void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
+		    pte_t *ptep, unsigned long sz)
+{
+	pte_clear(mm, addr, ptep);
+}
+#endif
+
+#ifndef __HAVE_ARCH_HUGE_SET_HUGE_PTE_AT
+static inline void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
+		pte_t *ptep, pte_t pte, unsigned long sz)
+{
+	set_pte_at(mm, addr, ptep, pte);
+}
+#endif
+
+#ifndef __HAVE_ARCH_HUGE_PTEP_GET_AND_CLEAR
+static inline pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
+		unsigned long addr, pte_t *ptep, unsigned long sz)
+{
+	return ptep_get_and_clear(mm, addr, ptep);
+}
+#endif
+
+#ifndef __HAVE_ARCH_HUGE_PTEP_CLEAR_FLUSH
+static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
+		unsigned long addr, pte_t *ptep)
+{
+	return ptep_clear_flush(vma, addr, ptep);
+}
+#endif
+
+#ifndef __HAVE_ARCH_HUGE_PTE_NONE
+static inline int huge_pte_none(pte_t pte)
+{
+	return pte_none(pte);
+}
+#endif
+
+#ifndef __HAVE_ARCH_HUGE_PTEP_SET_WRPROTECT
+static inline void huge_ptep_set_wrprotect(struct mm_struct *mm,
+		unsigned long addr, pte_t *ptep)
+{
+	ptep_set_wrprotect(mm, addr, ptep);
+}
+#endif
+
+#ifndef __HAVE_ARCH_HUGE_PTEP_SET_ACCESS_FLAGS
+static inline int huge_ptep_set_access_flags(struct vm_area_struct *vma,
+		unsigned long addr, pte_t *ptep,
+		pte_t pte, int dirty)
+{
+	return ptep_set_access_flags(vma, addr, ptep, pte, dirty);
+}
+#endif
+
+#ifndef __HAVE_ARCH_HUGE_PTEP_GET
+static inline pte_t huge_ptep_get(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
+{
+	return ptep_get(ptep);
+}
+#endif
+
+#ifndef __HAVE_ARCH_GIGANTIC_PAGE_RUNTIME_SUPPORTED
+static inline bool gigantic_page_runtime_supported(void)
+{
+	return IS_ENABLED(CONFIG_ARCH_HAS_GIGANTIC_PAGE);
+}
+#endif /* __HAVE_ARCH_GIGANTIC_PAGE_RUNTIME_SUPPORTED */
+
+#endif /* _ASM_GENERIC_HUGETLB_H */