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, 40 insertions, 0 deletions

diff --git a/lib/crypto/arm/blake2b.h b/lib/crypto/arm/blake2b.h
new file mode 100644
index 000000000..5c7649852
--- /dev/null
+++ b/lib/crypto/arm/blake2b.h
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * BLAKE2b digest algorithm, NEON accelerated
+ *
+ * Copyright 2020 Google LLC
+ */
+
+#include <asm/neon.h>
+#include <asm/simd.h>
+
+static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_neon);
+
+asmlinkage void blake2b_compress_neon(struct blake2b_ctx *ctx,
+				      const u8 *data, size_t nblocks, u32 inc);
+
+static void blake2b_compress(struct blake2b_ctx *ctx,
+			     const u8 *data, size_t nblocks, u32 inc)
+{
+	if (!static_branch_likely(&have_neon) || !may_use_simd()) {
+		blake2b_compress_generic(ctx, data, nblocks, inc);
+		return;
+	}
+	do {
+		const size_t blocks = min_t(size_t, nblocks,
+					    SZ_4K / BLAKE2B_BLOCK_SIZE);
+
+		scoped_ksimd()
+			blake2b_compress_neon(ctx, data, blocks, inc);
+
+		data += blocks * BLAKE2B_BLOCK_SIZE;
+		nblocks -= blocks;
+	} while (nblocks);
+}
+
+#define blake2b_mod_init_arch blake2b_mod_init_arch
+static void blake2b_mod_init_arch(void)
+{
+	if (elf_hwcap & HWCAP_NEON)
+		static_branch_enable(&have_neon);
+}