linux-kernel - Re: [PATCH 2/2] x86/mce/amd: Ensure quirks are applied in resume path as well

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Date:   Wed, 9 Jan 2019 23:08:43 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     "S, Shirish" <Shirish.S@....com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>,
        "maintainer : X86 ARCHITECTURE" <x86@...nel.org>,
        Tony Luck <tony.luck@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        "open list : X86 ARCHITECTURE" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] x86/mce/amd: Ensure quirks are applied in resume
 path as well

On Mon, Jan 07, 2019 at 10:37:24AM +0000, S, Shirish wrote:
> This patch adds threshold quirk applicable for family 15

Same issue with "This patch" here.

> in resume path as well, since mce_amd_feature_init()
> does not have quirks applied when originating from mce_syscore_resume(),
> resulting in the below message at every successful resume:
> 
> "[Firmware Bug]: cpu 0, invalid threshold interrupt offset ..."
> 
> Signed-off-by: Shirish S <shirish.s@....com>
> ---
>  arch/x86/kernel/cpu/mce/amd.c | 34 ++++++++++++++++++++++++++++++++++
>  1 file changed, 34 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/mce/amd.c b/arch/x86/kernel/cpu/mce/amd.c
> index 89298c8..27cbf66 100644
> --- a/arch/x86/kernel/cpu/mce/amd.c
> +++ b/arch/x86/kernel/cpu/mce/amd.c
> @@ -545,6 +545,34 @@ prepare_threshold_block(unsigned int bank, unsigned int block, u32 addr,
>  	return offset;
>  }
>  
> +void disable_err_thresholding(struct cpuinfo_x86 *c)
> +{
> +	int i;
> +	u64 hwcr;
> +	bool need_toggle;
> +	u32 msrs[] = {
> +		0x00000413, /* MC4_MISC0 */
> +		0xc0000408, /* MC4_MISC1 */
> +	};
> +
> +	if (c->x86_model >= 0x10 && c->x86_model <= 0x7f) {

You can save yourself an indentation level by reversing the logic here:

	if (c->x86 != 0x15)
		return;

Also, I'm wondering if you simply can't do

	if (c->x86_model < 0x10)
		return;

The assumption being that all the models - even after 0x7f - are highly
unlikely to get MC4_MISC thresholding supported, all of a sudden. Might
wanna run it by HW guys first though.

> +		rdmsrl(MSR_K7_HWCR, hwcr);
> +
> +		/* McStatusWrEn has to be set */
> +		need_toggle = !(hwcr & BIT(18));
> +
> +		if (need_toggle)
> +			wrmsrl(MSR_K7_HWCR, hwcr | BIT(18));
> +
> +		/* Clear CntP bit safely */
> +		for (i = 0; i < ARRAY_SIZE(msrs); i++)
> +			msr_clear_bit(msrs[i], 62);
> +
> +		/* restore old settings */
> +		if (need_toggle)
> +			wrmsrl(MSR_K7_HWCR, hwcr);
> +	}

So you copied the same code from __mcheck_cpu_apply_quirks().

No.

In a first patch, you carve that CntP clearing code in a separate
function disable_err_thresholding() like you've done before.

Then, in a second patch, you call it from mce/amd.c and you move all the
family/model checks inside the function so that you have a sole

	disable_err_thresholding();

calls where you need them.

You don't have to pass in struct cpuinfo_x86 *c - you can use
boot_cpu_data in the function.

> +}
>  /* cpu init entry point, called from mce.c with preempt off */
>  void mce_amd_feature_init(struct cpuinfo_x86 *c)
>  {
> @@ -552,6 +580,12 @@ void mce_amd_feature_init(struct cpuinfo_x86 *c)
>  	unsigned int bank, block, cpu = smp_processor_id();
>  	int offset = -1;
>  
> +	/* Disable error thresholding bank in S3 resume path as well,

What S3 resume path? That's the CPU init path.

Also, kernel comments style is:

	/*
	 * A sentence ending with a full-stop.
	 * Another sentence. ...
	 * More sentences. ...
	 */


Good luck!

:-)

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.