linux-kernel - [tip: x86/microcode] x86/microcode/intel: Do not print microcode revision and processor flags

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Message-ID: <167007547263.4906.10472927215347122978.tip-bot2@tip-bot2>
Date:   Sat, 03 Dec 2022 13:51:12 -0000
From:   "tip-bot2 for Ashok Raj" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Tony Luck <tony.luck@...el.com>, Ashok Raj <ashok.raj@...el.com>,
        "Borislav Petkov (AMD)" <bp@...en8.de>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/microcode] x86/microcode/intel: Do not print microcode
 revision and processor flags

The following commit has been merged into the x86/microcode branch of tip:

Commit-ID:     5b1586ab064ca24c6a7a6be7a9d0cb9e237ef39a
Gitweb:        https://git.kernel.org/tip/5b1586ab064ca24c6a7a6be7a9d0cb9e237ef39a
Author:        Ashok Raj <ashok.raj@...el.com>
AuthorDate:    Tue, 29 Nov 2022 13:08:26 -08:00
Committer:     Borislav Petkov (AMD) <bp@...en8.de>
CommitterDate: Sat, 03 Dec 2022 14:41:06 +01:00

x86/microcode/intel: Do not print microcode revision and processor flags

collect_cpu_info() is used to collect the current microcode revision and
processor flags on every CPU.

It had a weird mechanism to try to mimick a "once" functionality in the
sense that, that information should be issued only when it is differing
from the previous CPU.

However (1):

the new calling sequence started doing that in parallel:

  microcode_init()
  |-> schedule_on_each_cpu(setup_online_cpu)
      |-> collect_cpu_info()

resulting in multiple redundant prints:

  microcode: sig=0x50654, pf=0x80, revision=0x2006e05
  microcode: sig=0x50654, pf=0x80, revision=0x2006e05
  microcode: sig=0x50654, pf=0x80, revision=0x2006e05

However (2):

dumping this here is not that important because the kernel does not
support mixed silicon steppings microcode. Finally!

Besides, there is already a pr_info() in microcode_reload_late() that
shows both the old and new revisions.

What is more, the CPU signature (sig=0x50654) and Processor Flags
(pf=0x80) above aren't that useful to the end user, they are available
via /proc/cpuinfo and they don't change anyway.

Remove the redundant pr_info().

  [ bp: Heavily massage. ]

Fixes: b6f86689d5b7 ("x86/microcode: Rip out the subsys interface gunk")
Reported-by: Tony Luck <tony.luck@...el.com>
Signed-off-by: Ashok Raj <ashok.raj@...el.com>
Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
Link: https://lore.kernel.org/r/20221103175901.164783-2-ashok.raj@intel.com
---
 arch/x86/kernel/cpu/microcode/intel.c | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index c4a00fb..4f93875 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -554,7 +554,6 @@ void reload_ucode_intel(void)
 
 static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
 {
-	static struct cpu_signature prev;
 	struct cpuinfo_x86 *c = &cpu_data(cpu_num);
 	unsigned int val[2];
 
@@ -570,13 +569,6 @@ static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
 
 	csig->rev = c->microcode;
 
-	/* No extra locking on prev, races are harmless. */
-	if (csig->sig != prev.sig || csig->pf != prev.pf || csig->rev != prev.rev) {
-		pr_info("sig=0x%x, pf=0x%x, revision=0x%x\n",
-			csig->sig, csig->pf, csig->rev);
-		prev = *csig;
-	}
-
 	return 0;
 }