RE: [Xen-devel] Re: [PATCH 1/6] MCE: Handle the vMCA bank correctly

["Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx>]

>-----Original Message-----
>From: Christoph Egger [mailto:Christoph.Egger@xxxxxxx]
>Sent: Friday, January 29, 2010 12:29 AM
>To: Jiang, Yunhong
>Cc: Frank.Vanderlinden@xxxxxxx; xen-devel@xxxxxxxxxxxxxxxxxxx; Keir Fraser; Jan
>Beulich
>Subject: Re: [Xen-devel] Re: [PATCH 1/6] MCE: Handle the vMCA bank correctly
>
>On Thursday 28 January 2010 14:50:50 Jiang, Yunhong wrote:
>> I checked Intel SDM manual, and it defined 0x400H to 0x457H for MCE MSR
>> (that is in fact for bank 0~21). MSR 0x480 is for IA32_VMX_MSR. The range
>> between 0x457 to 0x480 is undefined. And I didn't find any statement that
>> all MSRs till for MAX_NR_BANKS are defined as MCE MSRs.
>>
>> Is the MAX_NR_BANKS defined clearly in AMD platform?
>
>I don't know why we need/have MAX_NR_BANKS at all.
>On AMD, the number of banks is reported by MSR_IA32_MCG_CAP bit
>MCG_CAP_COUNT.
>Each bank has four MCE MSRs: CTRL, STATUS, ADDR and MISC.
>
>We have struct mcinfo_bank for them.
>MCE MSRs outside of them are covered by struct mcinfo_extended.
>
>Christoph

I remember after we change it from 128 to 30, it is originally it is for guest 
vMCE injection.
So I will not push this specific patch. Instead, I will try to clean-up the 
MAX_NR_BANKS for 4.1 development cycle. After all, 4.0 release is in RC2. But I 
think other patches are needed still.

--jyh

>
>>
>> In fact, I'm abit curious how should the MAX_NR_BANKS defined. I checked
>> the patch and seems it is originally 128, and later changed to 30.
>>
>> --jyh
>>
>> >-----Original Message-----
>> >From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
>> >[mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Christoph
>> > Egger Sent: Thursday, January 28, 2010 4:08 PM
>> >To: Jiang, Yunhong
>> >Cc: Frank.Vanderlinden@xxxxxxx; xen-devel@xxxxxxxxxxxxxxxxxxx; Keir
>> > Fraser; Jan Beulich
>> >Subject: [Xen-devel] Re: [PATCH 1/6] MCE: Handle the vMCA bank correctly
>> >
>> >On Thursday 28 January 2010 06:55:50 Jiang, Yunhong wrote:
>> >> Handle the vMCA bank correctly
>> >>
>> >> Currently the virtual MCE MSR assume all MSRs range from 0 to
>> >> MAX_NR_BANKS are always MCE MSR, this is not always correct.
>> >
>> >Please explain, why is this not ? Which MSR is reported that is not an MCE
>> >MSR ?
>> >
>> >Christoph
>> >
>> >> With this patch, the
>> >> mce_rdmsr/mce_wrmsr will only handle vMCE MSR range from 0 to the MCA
>> >
>> >banks
>> >
>> >> in the host platform. Please notice that some MSR beyond current MCA
>> >> banks in the host platform are really MCA MSRs, that should be handled
>> >> by general MSR handler.
>> >>
>> >> Signed-off-by: Jiang, Yunhong <yunhong.jiang@xxxxxxxxx>
>> >>
>> >> diff -r 221c9b796e32 xen/arch/x86/cpu/mcheck/mce.c
>> >> --- a/xen/arch/x86/cpu/mcheck/mce.c       Tue Jan 26 00:33:03 2010 +0800
>> >> +++ b/xen/arch/x86/cpu/mcheck/mce.c       Tue Jan 26 00:52:04 2010 +0800
>> >> @@ -716,8 +716,8 @@ int mce_rdmsr(uint32_t msr, uint64_t *va
>> >>          bank = (msr - MSR_IA32_MC0_CTL) / 4;
>> >>          if ( bank >= (d->arch.vmca_msrs.mcg_cap & MCG_CAP_COUNT) )
>> >>          {
>> >> -            mce_printk(MCE_QUIET, "MCE: bank %u does not exist\n",
>> >> bank); -            ret = -1;
>> >> +            mce_printk(MCE_QUIET, "MCE: MSR %x is not MCA MSR\n",
>msr);
>> >> +            ret = 0;
>> >>              break;
>> >>          }
>> >>          switch (msr & (MSR_IA32_MC0_CTL | 3))
>> >> @@ -848,8 +848,8 @@ int mce_wrmsr(u32 msr, u64 val)
>> >>          bank = (msr - MSR_IA32_MC0_CTL) / 4;
>> >>          if ( bank >= (d->arch.vmca_msrs.mcg_cap & MCG_CAP_COUNT) )
>> >>          {
>> >> -            mce_printk(MCE_QUIET, "MCE: bank %u does not exist\n",
>> >> bank); -            ret = -1;
>> >> +            mce_printk(MCE_QUIET, "MCE: MSR %x is not MCA MSR\n",
>msr);
>> >> +            ret = 0;
>> >>              break;
>> >>          }
>> >>          switch ( msr & (MSR_IA32_MC0_CTL | 3) )
>> >
>> >
>> >
>> >_______________________________________________
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>> >Xen-devel@xxxxxxxxxxxxxxxxxxx
>> >http://lists.xensource.com/xen-devel
>
>
>
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