From: Ashok Raj <ashok.raj@intel.com>
To: Borislav Petkov <bp@alien8.de>, Thomas Gleixner <tglx@linutronix.de>
Cc: X86-kernel <x86@kernel.org>,
LKML Mailing List <linux-kernel@vger.kernel.org>,
Dave Hansen <dave.hansen@intel.com>,
"Tony Luck" <tony.luck@intel.com>,
Alison Schofield <alison.schofield@intel.com>,
Reinette Chatre <reinette.chatre@intel.com>,
Tom Lendacky <thomas.lendacky@amd.com>,
Ashok Raj <ashok.raj@intel.com>
Subject: Re: [PATCH v3 2/2] x86/microcode/core: Take a snapshot before and after applying microcode
Date: Wed, 28 Dec 2022 10:36:22 -0800 [thread overview]
Message-ID: <Y6yMpt+RMUL3Cqu1@a4bf019067fa.jf.intel.com> (raw)
In-Reply-To: <20221227210144.5112-2-ashok.raj@intel.com>
On Tue, Dec 27, 2022 at 01:01:44PM -0800, Ashok Raj wrote:
> The kernel caches features about each CPU's features at boot in an
> x86_capability[] structure. The microcode update takes one snapshot and
> compares it with the saved copy at boot.
>
> However, the capabilities in the boot copy can be turned off as a result of
> certain command line parameters or configuration restrictions. This can
> cause a mismatch when comparing the values before and after the microcode
> update.
>
> microcode_check() is called after an update to report any previously
> cached CPUID bits might have changed due to the update.
>
I'll send you a clean version. Somehow this picked up an interim change and
the change to microcode_check() is not there. I remember testing but it
happened to be a different system I updated.
I'll send something after the new years.. working during holidays isn't
efficient :-(.
Cheers,
Ashok
next prev parent reply other threads:[~2022-12-28 18:36 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-27 19:23 [PATCH v2 0/6] Some fixes and cleanups for microcode Ashok Raj
2022-12-27 19:23 ` [PATCH v2 1/6] x86/microcode/core: Move microcode_check() to cpu/microcode/core.c Ashok Raj
2022-12-27 19:50 ` Borislav Petkov
2022-12-27 19:59 ` Ashok Raj
2022-12-27 21:01 ` [PATCH v3 1/2] x86/microcode: Add a parameter to microcode_check() to store CPU capabilities Ashok Raj
2022-12-27 21:01 ` [PATCH v3 2/2] x86/microcode/core: Take a snapshot before and after applying microcode Ashok Raj
2022-12-28 18:36 ` Ashok Raj [this message]
2022-12-27 19:23 ` [PATCH v2 2/6] " Ashok Raj
2022-12-27 19:23 ` [PATCH v2 3/6] x86/microcode: Display revisions only when update is successful Ashok Raj
2022-12-27 19:23 ` [PATCH v2 4/6] x86/microcode/intel: Use a plain revision argument for print_ucode_rev() Ashok Raj
2022-12-27 19:23 ` [PATCH v2 5/6] x86/microcode/intel: Print old and new rev during early boot Ashok Raj
2022-12-27 19:23 ` [PATCH v2 6/6] x86/microcode/intel: Print when early microcode loading fails Ashok Raj
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