linux-kernel - Re: [PATCH 1/2] x86/microcode/intel: Refresh the revisions that determine old

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Message-ID: <20250819182840.ajjl5txvooe47un7@desk>
Date: Tue, 19 Aug 2025 11:28:40 -0700
From: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
To: Andrew Cooper <andrew.cooper3@...rix.com>
Cc: Sohil Mehta <sohil.mehta@...el.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
	Borislav Petkov <bp@...en8.de>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, "H . Peter Anvin" <hpa@...or.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Josh Poimboeuf <jpoimboe@...nel.org>,
	Dave Hansen <dave.hansen@...el.com>,
	Nikolay Borisov <nik.borisov@...e.com>,
	Alex Murray <alex.murray@...onical.com>,
	linux-kernel@...r.kernel.org, stable@...nel.org
Subject: Re: [PATCH 1/2] x86/microcode/intel: Refresh the revisions that
 determine old_microcode

On Tue, Aug 19, 2025 at 12:18:45PM +0100, Andrew Cooper wrote:
> On 19/08/2025 6:19 am, Pawan Gupta wrote:
> > On Mon, Aug 18, 2025 at 12:01:36PM -0700, Sohil Mehta wrote:
> >> Update the minimum expected revisions of Intel microcode based on the
> >> microcode-20250512 (May 2025) release.
> >>
> >> Cc: <stable@...nel.org> # v6.15+
> >> Signed-off-by: Sohil Mehta <sohil.mehta@...el.com>
> >> ---
> >>  .../kernel/cpu/microcode/intel-ucode-defs.h   | 86 +++++++++++--------
> >>  1 file changed, 48 insertions(+), 38 deletions(-)
> >>
> >> diff --git a/arch/x86/kernel/cpu/microcode/intel-ucode-defs.h b/arch/x86/kernel/cpu/microcode/intel-ucode-defs.h
> >> index cb6e601701ab..2d48e6593540 100644
> >> --- a/arch/x86/kernel/cpu/microcode/intel-ucode-defs.h
> >> +++ b/arch/x86/kernel/cpu/microcode/intel-ucode-defs.h
> >> @@ -67,9 +67,8 @@
> >>  { .flags = X86_CPU_ID_FLAG_ENTRY_VALID, .vendor = X86_VENDOR_INTEL, .family = 0x6,  .model = 0x55, .steppings = 0x0008, .driver_data = 0x1000191 },
> >>  { .flags = X86_CPU_ID_FLAG_ENTRY_VALID, .vendor = X86_VENDOR_INTEL, .family = 0x6,  .model = 0x55, .steppings = 0x0010, .driver_data = 0x2007006 },
> >>  { .flags = X86_CPU_ID_FLAG_ENTRY_VALID, .vendor = X86_VENDOR_INTEL, .family = 0x6,  .model = 0x55, .steppings = 0x0020, .driver_data = 0x3000010 },
> >> -{ .flags = X86_CPU_ID_FLAG_ENTRY_VALID, .vendor = X86_VENDOR_INTEL, .family = 0x6,  .model = 0x55, .steppings = 0x0040, .driver_data = 0x4003605 },
> > ".model = 0x55, .steppings = 0x0040" is being removed? Total number of
> > entries in the table are being reduced by ~10.
> 
> That's because early in a CPUs lifecycle, microcode for the late
> pre-production steppings are still included in the public repo, but
> eventually dropped.

Sometimes Linux care about the pre-production steppings, other times we
don't.

> Alas, these deletions are documented as well as everything else is in
> the changelog...

Should this file reflect those deletions as well? As an example, if an
ancient part gets removed from the microcode repo, it may still be worth
for Linux to keep the record of its last microcode version.