linux-kernel - [patch V5 09/39] x86/microcode/intel: Simplify scan

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Message-ID: <20231017211722.460700412@linutronix.de>
Date:   Tue, 17 Oct 2023 23:23:35 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, Borislav Petkov <bp@...en8.de>
Subject: [patch V5 09/39] x86/microcode/intel: Simplify scan_microcode()

From: Thomas Gleixner <tglx@...utronix.de>

Make it readable and comprehensible.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 arch/x86/kernel/cpu/microcode/intel.c | 28 +++++++---------------------
 1 file changed, 7 insertions(+), 21 deletions(-)
---
diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index 1f45f5c44246..24dd4835d544 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -268,22 +268,16 @@ static void save_microcode_patch(void *data, unsigned int size)
 	intel_ucode_patch = (struct microcode_intel *)p;
 }
 
-/*
- * Get microcode matching with BSP's model. Only CPUs with the same model as
- * BSP can stay in the platform.
- */
-static struct microcode_intel *
-scan_microcode(void *data, size_t size, struct ucode_cpu_info *uci, bool save)
+/* Scan CPIO for microcode matching the boot CPU's family, model, stepping */
+static struct microcode_intel *scan_microcode(void *data, size_t size,
+					      struct ucode_cpu_info *uci, bool save)
 {
 	struct microcode_header_intel *mc_header;
 	struct microcode_intel *patch = NULL;
 	u32 cur_rev = uci->cpu_sig.rev;
 	unsigned int mc_size;
 
-	while (size) {
-		if (size < sizeof(struct microcode_header_intel))
-			break;
-
+	for (; size >= sizeof(struct microcode_header_intel); size -= mc_size, data += mc_size) {
 		mc_header = (struct microcode_header_intel *)data;
 
 		mc_size = get_totalsize(mc_header);
@@ -291,27 +285,19 @@ scan_microcode(void *data, size_t size, struct ucode_cpu_info *uci, bool save)
 		    intel_microcode_sanity_check(data, false, MC_HEADER_TYPE_MICROCODE) < 0)
 			break;
 
-		size -= mc_size;
-
-		if (!intel_find_matching_signature(data, uci->cpu_sig.sig,
-						   uci->cpu_sig.pf)) {
-			data += mc_size;
+		if (!intel_find_matching_signature(data, uci->cpu_sig.sig, uci->cpu_sig.pf))
 			continue;
-		}
 
 		/* BSP scan: Check whether there is newer microcode */
 		if (!save && cur_rev >= mc_header->rev)
-			goto next;
+			continue;
 
 		/* Save scan: Check whether there is newer or matching microcode */
 		if (save && cur_rev != mc_header->rev)
-			goto next;
+			continue;
 
 		patch = data;
 		cur_rev = mc_header->rev;
-
-next:
-		data += mc_size;
 	}
 
 	if (size)