From: Andrew Cooper <andrew.cooper3@citrix.com>
To: David Laight <david.laight.linux@gmail.com>,
"Chang S. Bae" <chang.seok.bae@intel.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
linux-kernel@vger.kernel.org, x86@kernel.org, tglx@kernel.org,
mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
hpa@zytor.com, arjan.van.de.ven@intel.com, sohil.mehta@intel.com,
stable@vger.kernel.org
Subject: Re: [PATCH v3] x86/microcode/intel: Reject problematic loading on Granite Rapids systems
Date: Thu, 17 Sep 2026 12:50:26 +0200 [thread overview]
Message-ID: <68e7850e-44a8-450d-96ad-2cd4948ac5af@citrix.com> (raw)
In-Reply-To: <20260917101455.3e1ac9a5@pumpkin>
On 17/09/2026 11:14 am, David Laight wrote:
> On Wed, 16 Sep 2026 22:59:39 +0000
> "Chang S. Bae" <chang.seok.bae@intel.com> wrote:
>
>> Microcode updates can usually jump revisions. However, there is an
>> erratum on Granite Rapids systems. If they "jump over" revision
>> 0x1000405, they result in #MC. Avoid it.
> A probably silly question.
> Is it valid to downgrade microcode?
Yes, and it does happen in practice.
Intel microcode contains a field called the Security Version Number.
The SVN bumps as infrequently as possible, but does bump when necessary.
There is a hard block on the SVN going backwards, but as long as you're
not violating this constraint, you can upgrade or downgrade microcode as
desired.
~Andrew
next prev parent reply other threads:[~2026-09-17 10:50 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-01 23:16 [PATCH 0/8] x86/microcode: Address GNR errata and follow-up Chang S. Bae
2026-09-01 23:16 ` [PATCH 1/8] x86/microcode/intel: Reject problematic loading on GNR systems Chang S. Bae
2026-09-02 13:11 ` Sohil Mehta
2026-09-02 13:21 ` Van De Ven, Arjan
2026-09-08 23:03 ` Chang S. Bae
2026-09-02 14:23 ` Dave Hansen
2026-09-03 1:51 ` Borislav Petkov
2026-09-03 21:04 ` Chang S. Bae
2026-09-08 22:32 ` [PATCH v2] x86/microcode/intel: Reject problematic loading on Granite Rapids systems Chang S. Bae
2026-09-08 23:16 ` Dave Hansen
2026-09-09 0:13 ` Borislav Petkov
2026-09-09 0:39 ` Chang S. Bae
2026-09-09 0:14 ` Andrew Cooper
2026-09-16 22:59 ` [PATCH v3] " Chang S. Bae
2026-09-17 9:14 ` David Laight
2026-09-17 10:50 ` Andrew Cooper [this message]
2026-09-17 13:35 ` Van De Ven, Arjan
2026-09-17 17:52 ` Sohil Mehta
2026-09-17 18:11 ` Chang S. Bae
2026-09-17 18:43 ` Van De Ven, Arjan
2026-09-17 18:25 ` Chang S. Bae
2026-09-01 23:16 ` [PATCH 2/8] x86/microcode: Solidify base_rev= option parsing Chang S. Bae
2026-09-01 23:16 ` [PATCH 3/8] x86/microcode: Accept a boolean for force_minrev parameter Chang S. Bae
2026-09-01 23:16 ` [PATCH 4/8] x86/microcode: Mark early_data __initdata Chang S. Bae
2026-09-01 23:16 ` [PATCH RFC 5/8] x86/microcode: Decouple minimum revision check from late loading Chang S. Bae
2026-09-01 23:16 ` [PATCH RFC 6/8] x86/microcode/intel: Apply minimum revision check to early loading Chang S. Bae
2026-09-01 23:16 ` [PATCH RFC 7/8] x86/microcode: Introduce iterative late loading Chang S. Bae
2026-09-01 23:16 ` [PATCH RFC 8/8] x86/microcode/intel: Select the lowest loadable revision for iterative loading Chang S. Bae
2026-09-08 23:07 ` [PATCH 0/8] x86/microcode: Address GNR errata and follow-up Chang S. Bae
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