linux-kernel - [RFC][PATCH 1/4] x86/cpu: Introduce new microcode matching helper

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Message-Id: <20241120202410.8D208F0C@davehans-spike.ostc.intel.com>
Date: Wed, 20 Nov 2024 12:24:10 -0800
From: Dave Hansen <dave.hansen@...ux.intel.com>
To: linux-kernel@...r.kernel.org
Cc: x86@...nel.org,tglx@...utronix.de,bp@...en8.de,kan.liang@...ux.intel.com,Dave Hansen <dave.hansen@...ux.intel.com>
Subject: [RFC][PATCH 1/4] x86/cpu: Introduce new microcode matching helper


From: Dave Hansen <dave.hansen@...ux.intel.com>

The 'x86_cpu_id' and 'x86_cpu_desc' structures are very similar and
need to be consolidated.  There is a microcode version matching
function for 'x86_cpu_desc' but not 'x86_cpu_id'.

Create one for 'x86_cpu_id'.

This essentially just leverages the x86_cpu_id->driver_data field
to replace the less generic x86_cpu_desc->x86_microcode_rev field.

Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
---

 b/arch/x86/include/asm/cpu_device_id.h |    1 +
 b/arch/x86/kernel/cpu/match.c          |   11 +++++++++++
 2 files changed, 12 insertions(+)

diff -puN arch/x86/include/asm/cpu_device_id.h~min-ucode-rev arch/x86/include/asm/cpu_device_id.h
--- a/arch/x86/include/asm/cpu_device_id.h~min-ucode-rev	2024-11-20 12:22:04.944380677 -0800
+++ b/arch/x86/include/asm/cpu_device_id.h	2024-11-20 12:22:04.948380830 -0800
@@ -278,5 +278,6 @@ struct x86_cpu_desc {
 
 extern const struct x86_cpu_id *x86_match_cpu(const struct x86_cpu_id *match);
 extern bool x86_cpu_has_min_microcode_rev(const struct x86_cpu_desc *table);
+extern bool x86_match_min_microcode_rev(const struct x86_cpu_id *table);
 
 #endif /* _ASM_X86_CPU_DEVICE_ID */
diff -puN arch/x86/kernel/cpu/match.c~min-ucode-rev arch/x86/kernel/cpu/match.c
--- a/arch/x86/kernel/cpu/match.c~min-ucode-rev	2024-11-20 12:22:04.944380677 -0800
+++ b/arch/x86/kernel/cpu/match.c	2024-11-20 12:22:04.948380830 -0800
@@ -86,3 +86,14 @@ bool x86_cpu_has_min_microcode_rev(const
 	return true;
 }
 EXPORT_SYMBOL_GPL(x86_cpu_has_min_microcode_rev);
+
+bool x86_match_min_microcode_rev(const struct x86_cpu_id *table)
+{
+	const struct x86_cpu_id *res = x86_match_cpu(table);
+
+	if (!res || res->driver_data > boot_cpu_data.microcode)
+		return false;
+
+	return true;
+}
+EXPORT_SYMBOL_GPL(x86_match_min_microcode_rev);
_