From: Thomas Gleixner <tglx@linutronix.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
x86@kernel.org, Borislav Petkov <bp@alien8.de>,
Ashok Raj <ashok.raj@intel.com>,
Arjan van de Ven <arjan@linux.intel.com>
Subject: Re: [patch 29/30] x86/microcode: Prepare for minimal revision check
Date: Fri, 11 Aug 2023 11:38:51 +0200 [thread overview]
Message-ID: <871qg9j4us.ffs@tglx> (raw)
In-Reply-To: <20230810205427.GG212435@hirez.programming.kicks-ass.net>
On Thu, Aug 10 2023 at 22:54, Peter Zijlstra wrote:
> On Thu, Aug 10, 2023 at 08:38:09PM +0200, Thomas Gleixner wrote:
>> From: Thomas Gleixner <tglx@linutronix.de>
>>
>> Applying microcode late can be fatal for the running kernel when the update
>> changes functionality which is in use already in a non-compatible way,
>> e.g. by removing a CPUID bit.
>
> This includes all compatibility constraints? Because IIRC we've also had
> trouble because a CPUID bit got set. Kernel didn't know about, didn't
> manage it, but userspace saw the bit and happily tried to use it.
We don't know. If the microcoders screw that minrev constraint up, then
we are up the creek w/o a paddle as before.
> Ofc I can't remember the exact case :/ but anything that changes the
> xsave size/state would obviously cause trouble.
Details. :)
next prev parent reply other threads:[~2023-08-11 9:39 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-10 18:37 [patch 00/30] x86/microcode: Cleanup and late loading enhancements Thomas Gleixner
2023-08-10 18:37 ` [patch 01/30] x86/mm: Remove unused microcode.h include Thomas Gleixner
2023-08-10 18:37 ` [patch 02/30] x86/microcode: Hide the config knob Thomas Gleixner
2023-08-10 20:41 ` Ashok Raj
2023-08-11 11:22 ` Borislav Petkov
2023-08-10 18:37 ` [patch 03/30] x86/microcode/intel: Move microcode functions out of cpu/intel.c Thomas Gleixner
2023-08-10 18:37 ` [patch 04/30] x86/microcode: Include vendor headers into microcode.h Thomas Gleixner
2023-08-10 18:37 ` [patch 05/30] x86/microcode: Make reload_early_microcode() static Thomas Gleixner
2023-08-10 18:37 ` [patch 06/30] x86/microcode/intel: Rename get_datasize() since its used externally Thomas Gleixner
2023-08-10 18:37 ` [patch 07/30] x86/microcode: Move core specific defines to local header Thomas Gleixner
2023-08-10 18:37 ` [patch 08/30] x86/microcode/intel: Rip out mixed stepping support for Intel CPUs Thomas Gleixner
2023-08-11 22:25 ` Borislav Petkov
2023-08-12 7:16 ` Thomas Gleixner
2023-08-10 18:37 ` [patch 09/30] x86/microcode/intel: Remove debug code Thomas Gleixner
2023-08-11 10:45 ` Nikolay Borisov
2023-08-10 18:37 ` [patch 10/30] x86/microcode: Remove pointless mutex Thomas Gleixner
2023-08-10 18:37 ` [patch 11/30] x86/microcode/intel: Simplify scan_microcode() Thomas Gleixner
2023-08-10 18:37 ` [patch 12/30] x86/microcode/intel: Simplify and rename generic_load_microcode() Thomas Gleixner
2023-08-10 18:37 ` [patch 13/30] x86/microcode/intel: Cleanup code further Thomas Gleixner
2023-08-11 11:01 ` Nikolay Borisov
2023-08-10 18:37 ` [patch 14/30] x86/microcode/intel: Simplify early loading Thomas Gleixner
2023-08-10 18:37 ` [patch 15/30] x86/microcode/intel: Save the microcode only after a successful late-load Thomas Gleixner
2023-08-10 18:37 ` [patch 16/30] x86/microcode/intel: Switch to kvmalloc() Thomas Gleixner
2023-08-10 18:37 ` [patch 17/30] x86/microcode/intel: Unify microcode apply() functions Thomas Gleixner
2023-08-10 18:37 ` [patch 18/30] x86/microcode: Handle "nosmt" correctly Thomas Gleixner
2023-08-10 18:37 ` [patch 19/30] x86/microcode: Clarify the late load logic Thomas Gleixner
2023-08-10 18:37 ` [patch 20/30] x86/microcode: Sanitize __wait_for_cpus() Thomas Gleixner
2023-08-10 18:37 ` [patch 21/30] x86/microcode: Add per CPU result state Thomas Gleixner
2023-08-10 18:37 ` [patch 22/30] x86/microcode: Add per CPU control field Thomas Gleixner
2023-08-10 18:38 ` [patch 23/30] x86/microcode: Provide new control functions Thomas Gleixner
2023-08-10 20:25 ` Peter Zijlstra
2023-08-10 18:38 ` [patch 24/30] x86/microcode: Replace the all in one rendevouz handler Thomas Gleixner
2023-08-10 18:38 ` [patch 25/30] x86/microcode: Rendezvous and load in NMI Thomas Gleixner
2023-08-10 18:38 ` [patch 26/30] x86/microcode: Protect against instrumentation Thomas Gleixner
2023-08-10 20:36 ` Peter Zijlstra
2023-08-11 9:19 ` Thomas Gleixner
2023-08-10 18:38 ` [patch 27/30] x86/apic: Provide apic_force_nmi_on_cpu() Thomas Gleixner
2023-08-10 18:38 ` [patch 28/30] x86/microcode: Handle "offline" CPUs correctly Thomas Gleixner
2023-08-10 20:46 ` Peter Zijlstra
2023-08-10 20:50 ` Ashok Raj
2023-08-10 21:05 ` Peter Zijlstra
2023-08-10 21:49 ` Ashok Raj
2023-08-10 22:29 ` Peter Zijlstra
2023-08-10 23:02 ` Ashok Raj
2023-08-11 1:19 ` Thomas Gleixner
2023-08-11 1:31 ` Thomas Gleixner
2023-08-11 9:36 ` Thomas Gleixner
2023-08-12 16:47 ` Thomas Gleixner
2023-08-10 18:38 ` [patch 29/30] x86/microcode: Prepare for minimal revision check Thomas Gleixner
2023-08-10 20:54 ` Peter Zijlstra
2023-08-11 9:38 ` Thomas Gleixner [this message]
2023-08-11 14:20 ` Arjan van de Ven
2023-08-10 18:38 ` [patch 30/30] x86/microcode/intel: Add a minimum required revision for late-loads Thomas Gleixner
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