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, 114 insertions, 0 deletions

diff --git a/lib/crypto/arm/chacha.h b/lib/crypto/arm/chacha.h
new file mode 100644
index 000000000..836e49088
--- /dev/null
+++ b/lib/crypto/arm/chacha.h
@@ -0,0 +1,114 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * ChaCha and HChaCha functions (ARM optimized)
+ *
+ * Copyright (C) 2016-2019 Linaro, Ltd. <ard.biesheuvel@linaro.org>
+ * Copyright (C) 2015 Martin Willi
+ */
+
+#include <crypto/internal/simd.h>
+#include <linux/jump_label.h>
+#include <linux/kernel.h>
+
+#include <asm/cputype.h>
+#include <asm/hwcap.h>
+#include <asm/simd.h>
+
+asmlinkage void chacha_block_xor_neon(const struct chacha_state *state,
+				      u8 *dst, const u8 *src, int nrounds);
+asmlinkage void chacha_4block_xor_neon(const struct chacha_state *state,
+				       u8 *dst, const u8 *src,
+				       int nrounds, unsigned int nbytes);
+asmlinkage void hchacha_block_arm(const struct chacha_state *state,
+				  u32 out[HCHACHA_OUT_WORDS], int nrounds);
+asmlinkage void hchacha_block_neon(const struct chacha_state *state,
+				   u32 out[HCHACHA_OUT_WORDS], int nrounds);
+
+asmlinkage void chacha_doarm(u8 *dst, const u8 *src, unsigned int bytes,
+			     const struct chacha_state *state, int nrounds);
+
+static __ro_after_init DEFINE_STATIC_KEY_FALSE(use_neon);
+
+static inline bool neon_usable(void)
+{
+	return static_branch_likely(&use_neon) && crypto_simd_usable();
+}
+
+static void chacha_doneon(struct chacha_state *state, u8 *dst, const u8 *src,
+			  unsigned int bytes, int nrounds)
+{
+	u8 buf[CHACHA_BLOCK_SIZE];
+
+	while (bytes > CHACHA_BLOCK_SIZE) {
+		unsigned int l = min(bytes, CHACHA_BLOCK_SIZE * 4U);
+
+		chacha_4block_xor_neon(state, dst, src, nrounds, l);
+		bytes -= l;
+		src += l;
+		dst += l;
+		state->x[12] += DIV_ROUND_UP(l, CHACHA_BLOCK_SIZE);
+	}
+	if (bytes) {
+		const u8 *s = src;
+		u8 *d = dst;
+
+		if (bytes != CHACHA_BLOCK_SIZE)
+			s = d = memcpy(buf, src, bytes);
+		chacha_block_xor_neon(state, d, s, nrounds);
+		if (d != dst)
+			memcpy(dst, buf, bytes);
+		state->x[12]++;
+	}
+}
+
+static void hchacha_block_arch(const struct chacha_state *state,
+			       u32 out[HCHACHA_OUT_WORDS], int nrounds)
+{
+	if (!IS_ENABLED(CONFIG_KERNEL_MODE_NEON) || !neon_usable()) {
+		hchacha_block_arm(state, out, nrounds);
+	} else {
+		scoped_ksimd()
+			hchacha_block_neon(state, out, nrounds);
+	}
+}
+
+static void chacha_crypt_arch(struct chacha_state *state, u8 *dst,
+			      const u8 *src, unsigned int bytes, int nrounds)
+{
+	if (!IS_ENABLED(CONFIG_KERNEL_MODE_NEON) || !neon_usable() ||
+	    bytes <= CHACHA_BLOCK_SIZE) {
+		chacha_doarm(dst, src, bytes, state, nrounds);
+		state->x[12] += DIV_ROUND_UP(bytes, CHACHA_BLOCK_SIZE);
+		return;
+	}
+
+	do {
+		unsigned int todo = min_t(unsigned int, bytes, SZ_4K);
+
+		scoped_ksimd()
+			chacha_doneon(state, dst, src, todo, nrounds);
+
+		bytes -= todo;
+		src += todo;
+		dst += todo;
+	} while (bytes);
+}
+
+#define chacha_mod_init_arch chacha_mod_init_arch
+static void chacha_mod_init_arch(void)
+{
+	if (IS_ENABLED(CONFIG_KERNEL_MODE_NEON) && (elf_hwcap & HWCAP_NEON)) {
+		switch (read_cpuid_part()) {
+		case ARM_CPU_PART_CORTEX_A7:
+		case ARM_CPU_PART_CORTEX_A5:
+			/*
+			 * The Cortex-A7 and Cortex-A5 do not perform well with
+			 * the NEON implementation but do incredibly with the
+			 * scalar one and use less power.
+			 */
+			break;
+		default:
+			static_branch_enable(&use_neon);
+		}
+	}
+}