linux-kernel - Re: [PATCH] x86/sev: Fix kernel crash due to late update to read-only ghcb

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Date:   Thu, 30 Nov 2023 10:07:24 -0600
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Ingo Molnar <mingo@...nel.org>,
        Ashwin Dayanand Kamat <kashwindayan@...are.com>
Cc:     linux-kernel@...r.kernel.org, bp@...en8.de, brijesh.singh@....com,
        tglx@...utronix.de, mingo@...hat.com, dave.hansen@...ux.intel.com,
        x86@...nel.org, hpa@...or.com, jroedel@...e.de,
        stable@...r.kernel.org, ganb@...are.com, tkundu@...are.com,
        vsirnapalli@...are.com, akaher@...are.com, amakhalov@...are.com,
        namit@...are.com
Subject: Re: [PATCH] x86/sev: Fix kernel crash due to late update to read-only
 ghcb_version

On 11/30/23 03:30, Ingo Molnar wrote:
> 
> * Ashwin Dayanand Kamat <kashwindayan@...are.com> wrote:
> 
>> From: Ashwin Dayanand Kamat <ashwin.kamat@...adcom.com>
>>
>> kernel crash was observed because of page fault, while running
>> cpuhotplug ltp testcases on SEV-ES enabled systems. The crash was
>> observed during hotplug after the CPU was offlined and the process
>> was migrated to different cpu. setup_ghcb() is called again which
>> tries to update ghcb_version in sev_es_negotiate_protocol(). Ideally this
>> is a read_only variable which is initialised during booting.
>> This results in pagefault.
> 
> Applied to tip:x86/urgent, thanks.
> 
> Tom: I've added your Suggested-by and Acked-by, which appeared to be the
> case given the v1 discussion, let me know if that's not accurate.

All good.

Thanks,
Tom

> 
> I've also tidied up the changelog - final version attached below.
> 
> Thanks,
> 
> 	Ingo
>