linux-kernel - [Patch v3 Part2 3/9] x86/microcode/intel: Fix collect_cpu

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Message-Id: <20230130213955.6046-4-ashok.raj@intel.com>
Date:   Mon, 30 Jan 2023 13:39:49 -0800
From:   Ashok Raj <ashok.raj@...el.com>
To:     Borislav Petkov <bp@...en8.de>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Ashok Raj <ashok.raj@...el.com>,
        LKML <linux-kernel@...r.kernel.org>, x86 <x86@...nel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Tony Luck <tony.luck@...el.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Alison Schofield <alison.schofield@...el.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Stefan Talpalaru <stefantalpalaru@...oo.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Jonathan Corbet <corbet@....net>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Peter Zilstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        Andrew Cooper <Andrew.Cooper3@...rix.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Martin Pohlack <mpohlack@...zon.de>
Subject: [Patch v3 Part2 3/9] x86/microcode/intel: Fix collect_cpu_info() to reflect current microcode

Currently collect_cpu_info() is only returning what was cached earlier
instead of reading the current revision from the proper MSR.

Collect the current revision and report that value instead of reflecting
what was cached in the past.

[TBD:
    Need to change microcode/amd.c. I didn't quite follow the logic since
    it reports the revision from the patch file, instead of reporting the
    real PATCH_LEVEL MSR.

    Untested on AMD.
]

Signed-off-by: Ashok Raj <ashok.raj@...el.com>
Cc: LKML <linux-kernel@...r.kernel.org>
Cc: x86 <x86@...nel.org>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Tony Luck <tony.luck@...el.com>
Cc: Dave Hansen <dave.hansen@...el.com>
Cc: Alison Schofield <alison.schofield@...el.com>
Cc: Reinette Chatre <reinette.chatre@...el.com>
Cc: Thomas Gleixner (Intel) <tglx@...utronix.de>
Cc: Tom Lendacky <thomas.lendacky@....com>
Cc: Stefan Talpalaru <stefantalpalaru@...oo.com>
Cc: David Woodhouse <dwmw2@...radead.org>
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: Jonathan Corbet <corbet@....net>
Cc: Rafael J. Wysocki <rafael@...nel.org>
Cc: Peter Zilstra (Intel) <peterz@...radead.org>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Andrew Cooper <Andrew.Cooper3@...rix.com>
Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc: Martin Pohlack <mpohlack@...zon.de>
---
 arch/x86/kernel/cpu/microcode/intel.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index 467cf37ea90a..de8e591c42cd 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -542,6 +542,13 @@ static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
 {
 	struct cpuinfo_x86 *c = &cpu_data(cpu_num);
 	unsigned int val[2];
+	int rev;
+
+	/*
+	 * intel_get_microcode_revision() reads a per-core MSR
+	 * to read the revision (MSR_IA32_UCODE_REV).
+	 */
+	WARN_ON_ONCE(cpu_num != smp_processor_id());
 
 	memset(csig, 0, sizeof(*csig));
 
@@ -553,7 +560,9 @@ static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
 		csig->pf = 1 << ((val[1] >> 18) & 7);
 	}
 
-	csig->rev = c->microcode;
+	rev = intel_get_microcode_revision();
+	c->microcode = rev;
+	csig->rev = rev;
 
 	return 0;
 }
-- 
2.37.2