答复: [PATCH v2 4/4] x86/mce: Add Zhaoxin LMCE support

[Tony W Wang-oc <TonyWWang-oc@zhaoxin.com>]

On Tue, Sep 10, 2019, Borislav Petkov wrote:
>On Tue, Sep 10, 2019 at 08:20:07AM +0000, Tony W Wang-oc wrote:
>> Zhaoxin newer CPUs support LMCE that compatible with Intel's
>> "Machine-Check Architecture", so add support for Zhaoxin LMCE
>> in mce/core.c.
>>
>> Signed-off-by: Tony W Wang-oc <TonyWWang-oc@zhaoxin.com>
>> ---
>> v1->v2:
>>  - Fix redefinition of "mce_zhaoxin_feature_clear"
>>
>>  arch/x86/include/asm/mce.h     |  2 ++
>>  arch/x86/kernel/cpu/mce/core.c | 25 +++++++++++++++++++++++--
>>  2 files changed, 25 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/mce.h b/arch/x86/include/asm/mce.h
>> index 0986a11..01840ec 100644
>> --- a/arch/x86/include/asm/mce.h
>> +++ b/arch/x86/include/asm/mce.h
>> @@ -352,8 +352,10 @@ static inline void mce_hygon_feature_init(struct
>cpuinfo_x86 *c)	{ return mce_am
>>
>>  #ifdef CONFIG_CPU_SUP_ZHAOXIN
>>  void mce_zhaoxin_feature_init(struct cpuinfo_x86 *c);
>> +void mce_zhaoxin_feature_clear(struct cpuinfo_x86 *c);
>>  #else
>>  static inline void mce_zhaoxin_feature_init(struct cpuinfo_x86 *c) { }
>> +static inline void mce_zhaoxin_feature_clear(struct cpuinfo_x86 *c) { }
>>  #endif
>>
>>  #endif /* _ASM_X86_MCE_H */
>> diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
>> index 8a36833..595d3af7ac 100644
>> --- a/arch/x86/kernel/cpu/mce/core.c
>> +++ b/arch/x86/kernel/cpu/mce/core.c
>> @@ -1129,6 +1129,17 @@ static bool __mc_check_crashing_cpu(int cpu)
>>  		u64 mcgstatus;
>>
>>  		mcgstatus = mce_rdmsrl(MSR_IA32_MCG_STATUS);
>> +
>> +		if (boot_cpu_data.x86_vendor == X86_VENDOR_ZHAOXIN) {
>> +			if (mcgstatus & MCG_STATUS_LMCES) {
>> +				return false;
>> +			} else {
>> +				if (mcgstatus & MCG_STATUS_RIPV)
>> +					mce_wrmsrl(MSR_IA32_MCG_STATUS, 0);
>> +				return true;
>> +			}
>> +		}
>
>Simplify:
>
>                if (boot_cpu_data.x86_vendor == X86_VENDOR_ZHAOXIN) {
>                        if (mcgstatus & MCG_STATUS_LMCES)
>                                return false;
>		}
>
>		<--- Now here, on your CPUs which don't set MCG_STATUS_LMCES,
>it will fallback to clearing the status register. I.e., what you do in the else
>clause.
>

On Zhaoxin CPUs don't set MCG_STATUS_LMCES, to avoid rendezvous timeout if 
this CPU is offline or crashing_cpu was set, we want return true regardless of
MCG_STATUS_RIPV's setting. 

Without my else clause, original codes return true only when MCG_STATUS_RIPV
be setted.

For better readability, will add comment and change coding style in v3.

Sincerely
TonyWWang-oc