linux-kernel - Re: [PATCH] x86/microcode: Update microcode for all cores in parallel

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Date:   Sat, 24 Aug 2019 10:51:56 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Mihai Carabas <mihai.carabas@...cle.com>
Cc:     linux-kernel@...r.kernel.org, ashok.raj@...el.com,
        boris.ostrovsky@...cle.com, konrad.wilk@...cle.com,
        patrick.colp@...cle.com, kanth.ghatraju@...cle.com,
        Jon.Grimm@....com, Thomas.Lendacky@....com
Subject: Re: [PATCH] x86/microcode: Update microcode for all cores in parallel

On Thu, Aug 22, 2019 at 11:43:47PM +0300, Mihai Carabas wrote:
> From: Ashok Raj <ashok.raj@...el.com>
> 
> Microcode update was changed to be serialized due to restrictions after
> Spectre days. Updating serially on a large multi-socket system can be
> painful since we do this one CPU at a time. Cloud customers have expressed
> discontent as services disappear for a prolonged time. The restriction is
> that only one core goes through the update while other cores are quiesced.
> The update is now done only on the first thread of each core while other
> siblings simply wait for this to complete.
> 
> Signed-off-by: Ashok Raj <ashok.raj@...el.com>
> Signed-off-by: Mihai Carabas <mihai.carabas@...cle.com>
> ---
>  arch/x86/kernel/cpu/microcode/core.c  | 44 ++++++++++++++++++++++++-----------
>  arch/x86/kernel/cpu/microcode/intel.c | 14 ++++-------
>  2 files changed, 36 insertions(+), 22 deletions(-)

Thanks, I did some cleaning up and smoke testing. It looks ok so far.
The versions I'm going to hammer on more - and I'd appreciate it if you
did so too, when possible - as a reply to this message.

-- 
Regards/Gruss,
    Boris.

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