linux-kernel - Re: [PATCH v7] x86/mce: retrieve poison range from hardware

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Message-ID: <d6c8eee3-53fb-d234-faa3-40dd055441a6@oracle.com>
Date:   Tue, 23 Aug 2022 16:38:33 +0000
From:   Jane Chu <jane.chu@...cle.com>
To:     Dan Williams <dan.j.williams@...el.com>,
        Ingo Molnar <mingo@...nel.org>,
        "ying.huang@...el.com" <ying.huang@...el.com>,
        "Luck, Tony" <tony.luck@...el.com>
CC:     "bp@...en8.de" <bp@...en8.de>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "hch@....de" <hch@....de>,
        "nvdimm@...ts.linux.dev" <nvdimm@...ts.linux.dev>
Subject: Re: [PATCH v7] x86/mce: retrieve poison range from hardware

 >>> I suppose this wants to go upstream via the tree the bug came from 
(NVDIMM
 >>> tree? ACPI tree?), or should we pick it up into the x86 tree?
 >>
 >> No idea.  Maintainers?
 >
 > There's no real NVDIMM dependency here, just a general cleanup of how
 > APEI error granularities are managed. So I think it is appropriate for
 > this to go through the x86 tree via the typical path for mce related
 > topics.

+ Huang, Ying.

x86 maintainers,

Please let me know if you need another revision.

thanks,
-jane


On 8/8/2022 4:30 PM, Dan Williams wrote:
> Jane Chu wrote:
>> On 8/3/2022 1:53 AM, Ingo Molnar wrote:
>>>
>>> * Jane Chu <jane.chu@...cle.com> wrote:
>>>
>>>> With Commit 7917f9cdb503 ("acpi/nfit: rely on mce->misc to determine
>>>
>>> s/Commit/commit
>>
>> Maintainers,
>> Would you prefer a v8, or take care the comment upon accepting the patch?
>>
>>>
>>>> poison granularity") that changed nfit_handle_mce() callback to report
>>>> badrange according to 1ULL << MCI_MISC_ADDR_LSB(mce->misc), it's been
>>>> discovered that the mce->misc LSB field is 0x1000 bytes, hence injecting
>>>> 2 back-to-back poisons and the driver ends up logging 8 badblocks,
>>>> because 0x1000 bytes is 8 512-byte.
>>>>
>>>> Dan Williams noticed that apei_mce_report_mem_error() hardcode
>>>> the LSB field to PAGE_SHIFT instead of consulting the input
>>>> struct cper_sec_mem_err record.  So change to rely on hardware whenever
>>>> support is available.
>>>>
>>>> Link: https://lore.kernel.org/r/7ed50fd8-521e-cade-77b1-738b8bfb8502@oracle.com
>>>>
>>>> Reviewed-by: Dan Williams <dan.j.williams@...el.com>
>>>> Reviewed-by: Ingo Molnar <mingo@...nel.org>
>>>> Signed-off-by: Jane Chu <jane.chu@...cle.com>
>>>> ---
>>>>    arch/x86/kernel/cpu/mce/apei.c | 13 ++++++++++++-
>>>>    1 file changed, 12 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/arch/x86/kernel/cpu/mce/apei.c b/arch/x86/kernel/cpu/mce/apei.c
>>>> index 717192915f28..8ed341714686 100644
>>>> --- a/arch/x86/kernel/cpu/mce/apei.c
>>>> +++ b/arch/x86/kernel/cpu/mce/apei.c
>>>> @@ -29,15 +29,26 @@
>>>>    void apei_mce_report_mem_error(int severity, struct cper_sec_mem_err *mem_err)
>>>>    {
>>>>    	struct mce m;
>>>> +	int lsb;
>>>>    
>>>>    	if (!(mem_err->validation_bits & CPER_MEM_VALID_PA))
>>>>    		return;
>>>>    
>>>> +	/*
>>>> +	 * Even if the ->validation_bits are set for address mask,
>>>> +	 * to be extra safe, check and reject an error radius '0',
>>>> +	 * and fall back to the default page size.
>>>> +	 */
>>>> +	if (mem_err->validation_bits & CPER_MEM_VALID_PA_MASK)
>>>> +		lsb = find_first_bit((void *)&mem_err->physical_addr_mask, PAGE_SHIFT);
>>>> +	else
>>>> +		lsb = PAGE_SHIFT;
>>>> +
>>>>    	mce_setup(&m);
>>>>    	m.bank = -1;
>>>>    	/* Fake a memory read error with unknown channel */
>>>>    	m.status = MCI_STATUS_VAL | MCI_STATUS_EN | MCI_STATUS_ADDRV | MCI_STATUS_MISCV | 0x9f;
>>>> -	m.misc = (MCI_MISC_ADDR_PHYS << 6) | PAGE_SHIFT;
>>>> +	m.misc = (MCI_MISC_ADDR_PHYS << 6) | lsb;
>>>
>>> LGTM.
>>>
>>> I suppose this wants to go upstream via the tree the bug came from (NVDIMM
>>> tree? ACPI tree?), or should we pick it up into the x86 tree?
>>
>> No idea.  Maintainers?
> 
> There's no real NVDIMM dependency here, just a general cleanup of how
> APEI error granularities are managed. So I think it is appropriate for
> this to go through the x86 tree via the typical path for mce related
> topics.