From: Borislav Petkov <bp@alien8.de>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Ashok Raj <ashok.raj@intel.com>,
Thomas Gleixner <tglx@linutronix.de>, X86-kernel <x86@kernel.org>,
LKML Mailing List <linux-kernel@vger.kernel.org>,
Tony Luck <tony.luck@intel.com>, Ingo Molnar <mingo@kernel.org>,
alison.schofield@intel.com, reinette.chatre@intel.com,
Tom Lendacky <thomas.lendacky@amd.com>
Subject: Re: [PATCH v4 6/6] x86/microcode/intel: Print when early microcode loading fails
Date: Tue, 17 Jan 2023 19:40:31 +0100 [thread overview]
Message-ID: <Y8brnyIltcgtUvPn@zn.tnic> (raw)
In-Reply-To: <832b5c6c-cafa-e9e6-6e52-b741315d0865@intel.com>
On Tue, Jan 17, 2023 at 10:32:50AM -0800, Dave Hansen wrote:
> Well, we have an awful lot of pr_warn()'s in the kernel that talk about
> something that was tried and failed.
Well, is microcode loading failure worth to warn about?
What if there's no microcode for that CPU?
Now imagine in that case you issue a warning and then you get all those
bugzillas opened:
"Heeey, is my CPU broken, it says it cannot load microcode"
I sure don't want to be on the receiving end of this.
I don't think you wanna be there either.
> I actually kinda like the inverse.
>
> The common (boring) case where an update was needed and was successful.
> It's the one we don't need to tell users about at all. It barely
> deserves a message. Users expect that if there's an early update
> available, it'll get attempted, it will be successful and the kernel
> won't say much.
No argument there.
> The time we need to spam dmesg is when something upends user
> expectations and they might need to go do something. An early loading
> failure is exactly the place where they want to know. They want to know
> if they're running with known CPU bugs that would have been fixed by the
> early update
No, we already warn about that in the CPU mitigations code.
> or if they somehow have a botched early loading image.
If you can pick apart from this here:
/* write microcode via MSR 0x79 */
native_wrmsrl(MSR_IA32_UCODE_WRITE, (unsigned long)mc->bits);
what type of failure it is, then sure, let's warn.
But we should not warn just for every revision mismatch in there...
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2023-01-17 19:40 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-09 15:35 [PATCH v4 0/6] Some fixes and cleanups for microcode Ashok Raj
2023-01-09 15:35 ` [PATCH v4 1/6] x86/microcode: Add a parameter to microcode_check() to store CPU capabilities Ashok Raj
2023-01-21 14:54 ` [tip: x86/microcode] " tip-bot2 for Ashok Raj
2023-01-09 15:35 ` [PATCH v4 2/6] x86/microcode/core: Take a snapshot before and after applying microcode Ashok Raj
2023-01-21 14:54 ` [tip: x86/microcode] x86/microcode: Check CPU capabilities after late microcode update correctly tip-bot2 for Ashok Raj
2023-01-09 15:35 ` [PATCH v4 3/6] x86/microcode: Display revisions only when update is successful Ashok Raj
2023-01-09 15:35 ` [PATCH v4 4/6] x86/microcode/intel: Use a plain revision argument for print_ucode_rev() Ashok Raj
2023-01-15 19:25 ` Borislav Petkov
2023-01-15 19:39 ` Borislav Petkov
2023-01-17 16:05 ` Ashok Raj
2023-01-17 18:16 ` Borislav Petkov
2023-01-09 15:35 ` [PATCH v4 5/6] x86/microcode/intel: Print old and new rev during early boot Ashok Raj
2023-01-09 15:35 ` [PATCH v4 6/6] x86/microcode/intel: Print when early microcode loading fails Ashok Raj
2023-01-15 19:05 ` Borislav Petkov
2023-01-17 16:12 ` Ashok Raj
2023-01-17 16:29 ` Dave Hansen
2023-01-17 18:21 ` Borislav Petkov
2023-01-17 18:32 ` Dave Hansen
2023-01-17 18:40 ` Borislav Petkov [this message]
2023-01-17 20:40 ` Ashok Raj
2023-01-17 20:58 ` Luck, Tony
2023-01-19 17:59 ` Ashok Raj
2023-01-20 12:03 ` Borislav Petkov
2023-01-20 16:52 ` Ashok Raj
2023-01-17 21:00 ` Dave Hansen
2023-01-17 21:06 ` Borislav Petkov
2023-01-17 21:34 ` Ashok Raj
2023-01-17 19:10 ` Ashok Raj
2023-01-17 16:35 ` Dave Hansen
2023-01-17 17:59 ` Ashok Raj
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