linux-kernel - Re: [PATCH v2 06/16] x86/mce/amd: Prep DFR handler before enabling banks

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Date: Wed, 24 Apr 2024 20:34:29 +0200
From: Borislav Petkov <bp@...en8.de>
To: Yazen Ghannam <yazen.ghannam@....com>
Cc: linux-edac@...r.kernel.org, linux-kernel@...r.kernel.org,
	tony.luck@...el.com, x86@...nel.org, Avadhut.Naik@....com,
	John.Allen@....com
Subject: Re: [PATCH v2 06/16] x86/mce/amd: Prep DFR handler before enabling
 banks

On Thu, Apr 04, 2024 at 10:13:49AM -0500, Yazen Ghannam wrote:
> Scalable MCA systems use the per-bank MCA_CONFIG register to enable
> deferred error interrupts. This is done as part of SMCA configuration.
> 
> Currently, the deferred error interrupt handler is set up after SMCA
> configuration.
> 
> Move the deferred error interrupt handler set up before SMCA
> configuration. This ensures the kernel is ready to receive the
> interrupts before the hardware is configured to send them.
> 
> Signed-off-by: Yazen Ghannam <yazen.ghannam@....com>
> ---
> 
> Notes:
>     Link:
>     https://lkml.kernel.org/r/20231118193248.1296798-11-yazen.ghannam@amd.com
>     
>     v1->v2:
>     * No change.
> 
>  arch/x86/kernel/cpu/mce/amd.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/mce/amd.c b/arch/x86/kernel/cpu/mce/amd.c
> index 3093fed06194..e8e78d91082b 100644
> --- a/arch/x86/kernel/cpu/mce/amd.c
> +++ b/arch/x86/kernel/cpu/mce/amd.c
> @@ -589,6 +589,9 @@ static void deferred_error_interrupt_enable(struct cpuinfo_x86 *c)
>  	u32 low = 0, high = 0;
>  	int def_offset = -1, def_new;
>  
> +	if (!mce_flags.succor)

Does succor imply smca?

Because you have now this order:

	deferred_error_interrupt_enable(c);

	...

	configure_smca(bank);

and that one tests mce_flags.smca

Now, if succor didn't imply smca, we'll enable the DF irq handler for
no good reason on (succor=true && smca=false) systems.

If the implication is given:

Reviewed-by: Borislav Petkov (AMD) <bp@...en8.de>

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette