linux-kernel - Re: [PATCH] x86/mce/AMD: Fix partial SMCA bank init when CPU 0 != thread 0

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Date:   Wed, 28 Jun 2017 11:22:19 +0200
From:   Borislav Petkov <bp@...e.de>
To:     Jack Miller <jack@...ezen.org>
Cc:     linux-kernel@...r.kernel.org, tglx@...utronix.de,
        Yazen.Ghannam@....com, x86@...nel.org
Subject: Re: [PATCH] x86/mce/AMD: Fix partial SMCA bank init when CPU 0 !=
 thread 0

On Tue, Jun 27, 2017 at 07:06:30PM -0500, Jack Miller wrote:
> After a call to firmware SwitchBSP(),

What is that and who does that?

> Linux can be booted with a thread
> that isn't the first in the system. That thread automatically becomes
> CPU 0.

Btw, you should be seeing other explosions too as a lot of code assumes
CPU 0 is the BSP.

...

> Signed-off-by: Jack Miller <jack@...ezen.org>
> ---
>  arch/x86/kernel/cpu/mcheck/mce_amd.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/mcheck/mce_amd.c b/arch/x86/kernel/cpu/mcheck/mce_amd.c
> index 6e4a047e4b68..9d74adcf34d2 100644
> --- a/arch/x86/kernel/cpu/mcheck/mce_amd.c
> +++ b/arch/x86/kernel/cpu/mcheck/mce_amd.c
> @@ -170,8 +170,8 @@ static void get_smca_bank_info(unsigned int bank)
>  	struct smca_hwid *s_hwid;
>  	u32 high, instance_id;
>  
> -	/* Collect bank_info using CPU 0 for now. */
> -	if (cpu)
> +	/* Collect bank_info using hardware thread 0 for now. */
> +	if (apic->get_apic_id(apic->read(APIC_ID)) != 0)

Does

	if (cpu != boot_cpu_data.cpu_index)
		return;

work?


-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
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