Re: [PATCH 2/4] x86/mce/amd: Introduce deferred error interrupt handler

[Borislav Petkov]

On Thu, Apr 30, 2015 at 09:49:23AM -0500, Aravind Gopalakrishnan wrote:
> Changes introduced in the patch-
>   - Assign vector number 0xf4 for Deferred errors
>   - Declare deferred_interrupt, allocate gate and bind it
>     to DEFERRED_APIC_VECTOR.
>   - Declare smp_deferred_interrupt to be used as the
>     entry point for the interrupt in mce_amd.c
>   - Define trace_deferred_interrupt for tracing
>   - Enable deferred error interrupt selectively upon detection
>     of 'succor' bitfield
>   - Setup amd_deferred_error_interrupt() to handle the interrupt
>     and assign it to def_int_vector if feature is present in HW.
>     Else, let default handler deal with it.
>   - Provide Deferred error interrupt stats on
>     /proc/interrupts by incrementing irq_deferred_count

This commit message should explain the feature in more high-level way,
what is it good for and so on, not what you're adding.

That I can see. :-)

> Signed-off-by: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@xxxxxxx>
> ---
>  arch/x86/include/asm/entry_arch.h        |   3 +
>  arch/x86/include/asm/hardirq.h           |   3 +
>  arch/x86/include/asm/hw_irq.h            |   2 +
>  arch/x86/include/asm/irq_vectors.h       |   1 +
>  arch/x86/include/asm/mce.h               |   3 +
>  arch/x86/include/asm/trace/irq_vectors.h |   6 ++
>  arch/x86/include/asm/traps.h             |   3 +-
>  arch/x86/kernel/cpu/mcheck/mce_amd.c     | 101 +++++++++++++++++++++++++++++++
>  arch/x86/kernel/entry_64.S               |   5 ++
>  arch/x86/kernel/irq.c                    |   6 ++
>  arch/x86/kernel/irqinit.c                |   4 ++
>  arch/x86/kernel/traps.c                  |   4 ++
>  12 files changed, 140 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/include/asm/entry_arch.h b/arch/x86/include/asm/entry_arch.h
> index dc5fa66..f7b957b 100644
> --- a/arch/x86/include/asm/entry_arch.h
> +++ b/arch/x86/include/asm/entry_arch.h
> @@ -50,4 +50,7 @@ BUILD_INTERRUPT(thermal_interrupt,THERMAL_APIC_VECTOR)
>  BUILD_INTERRUPT(threshold_interrupt,THRESHOLD_APIC_VECTOR)
>  #endif
>  
> +#ifdef CONFIG_X86_MCE_AMD
> +BUILD_INTERRUPT(deferred_interrupt, DEFERRED_APIC_VECTOR)

All the other names are written out so you can simply do

BUILD_INTERRUPT(deferred_error_interrupt, DEFERRED_ERROR_VECTOR)

> +#endif
>  #endif
> diff --git a/arch/x86/include/asm/hardirq.h b/arch/x86/include/asm/hardirq.h
> index 0f5fb6b..448451c 100644
> --- a/arch/x86/include/asm/hardirq.h
> +++ b/arch/x86/include/asm/hardirq.h
> @@ -33,6 +33,9 @@ typedef struct {
>  #ifdef CONFIG_X86_MCE_THRESHOLD
>  	unsigned int irq_threshold_count;
>  #endif
> +#ifdef CONFIG_X86_MCE_AMD
> +	unsigned int irq_deferred_count;

Right
	unsigned int irq_deferred_error_count;

> +#endif
>  #if IS_ENABLED(CONFIG_HYPERV) || defined(CONFIG_XEN)
>  	unsigned int irq_hv_callback_count;
>  #endif
> diff --git a/arch/x86/include/asm/hw_irq.h b/arch/x86/include/asm/hw_irq.h
> index e9571dd..7cf2670 100644
> --- a/arch/x86/include/asm/hw_irq.h
> +++ b/arch/x86/include/asm/hw_irq.h

...

> +static void deferred_error_interrupt_enable(struct cpuinfo_x86 *c)
> +{
> +	u32 low = 0, high = 0;
> +	int def_offset = -1, def_new;
> +
> +	if (rdmsr_safe(MSR_CU_DEF_ERR, &low, &high))
> +		return;
> +
> +	def_new = (low & MASK_DEF_LVTOFF) >> 4;
> +	if (c->x86 == 0x15 && c->x86_model == 0x60 &&
> +	    !(low & MASK_DEF_LVTOFF)) {

What's the family check for? for BIOSes which don't set the LVT offset
to 2, as they should?

If so, we probably should say

	pr_err(FW_BUG "Your BIOS is not setting up LVT offset 0x2 for deferred error IRQs correctly.\n");

or similar...

> +		def_new = DEF_LVT_OFF;
> +		low = (low & ~MASK_DEF_LVTOFF) | (DEF_LVT_OFF << 4);
> +	}
> +
> +	def_offset = setup_APIC_deferred_error(def_offset, def_new);
> +
> +	if ((def_offset == def_new) &&
> +	    (def_int_vector != amd_deferred_error_interrupt))
> +		def_int_vector = amd_deferred_error_interrupt;
> +
> +	low = (low & ~MASK_DEF_INT_TYPE) | DEF_INT_TYPE_APIC;
> +	wrmsr(MSR_CU_DEF_ERR, low, high);
> +}

...

> +/* Apic interrupt handler for deferred errors */
> +static void amd_deferred_error_interrupt(void)
> +{
> +	u64 status;
> +	unsigned int bank;
> +	struct mce m;
> +
> +	for (bank = 0; bank < mca_cfg.banks; ++bank) {
> +		rdmsrl(MSR_IA32_MCx_STATUS(bank), status);
> +
> +		if (!(status & MCI_STATUS_VAL) ||
> +		    !(status & MCI_STATUS_DEFERRED))
> +			continue;
> +
> +		mce_setup(&m);
> +		m.bank = bank;
> +		m.status = status;
> +		mce_log(&m);
> +		wrmsrl(MSR_IA32_MCx_STATUS(bank), 0);
> +		break;
> +	}

That's very similar to what we do in the end of
amd_threshold_interrupt(). You could add a generic __log_error() static
helper in a pre-patch and then call it here.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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