linux-kernel - [patch V4 14/30] x86/microcode/amd: Read revision from hardware in collect_cpu_info

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Date:   Mon,  2 Oct 2023 13:59:51 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, Borislav Petkov <bp@...en8.de>,
        "Chang S. Bae" <chang.seok.bae@...el.com>,
        Arjan van de Ven <arjan@...ux.intel.com>,
        Nikolay Borisov <nik.borisov@...e.com>
Subject: [patch V4 14/30] x86/microcode/amd: Read revision from hardware in
 collect_cpu_info_amd()

Prepare to decrapify the core initialization logic which invokes
microcode_ops::apply_microcode() several times just to set
cpu_data::microcode.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
V2: New patch
---
 arch/x86/kernel/cpu/microcode/amd.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/x86/kernel/cpu/microcode/amd.c
+++ b/arch/x86/kernel/cpu/microcode/amd.c
@@ -634,12 +634,12 @@ void reload_ucode_amd(unsigned int cpu)
 
 static int collect_cpu_info_amd(int cpu, struct cpu_signature *csig)
 {
-	struct cpuinfo_x86 *c = &cpu_data(cpu);
 	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
+	u32 dummy __always_unused;
 	struct ucode_patch *p;
 
 	csig->sig = cpuid_eax(0x00000001);
-	csig->rev = c->microcode;
+	rdmsr(MSR_AMD64_PATCH_LEVEL, csig->rev, dummy);
 
 	/*
 	 * a patch could have been loaded early, set uci->mc so that