lkml.org 
[lkml]   [2015]   [May]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [Patch V1 2/3] x86, mce: Add infrastructure required to support LMCE
    On Fri, May 29, 2015 at 09:28:01AM -0700, Ashok Raj wrote:
    > Initialization and handling for LMCE
    > - boot time option to disable LMCE for that boot instance
    > - Check for capability via IA32_MCG_CAP
    > - provide ability to enable/disable LMCE on demand.
    >
    > See http://www.intel.com/sdm Volume 3 System Programming Guide, Chapter 15
    > for more information on MSR's and documentation on Local MCE.
    >
    > Signed-off-by: Ashok Raj <ashok.raj@intel.com>
    > ---
    > Documentation/x86/x86_64/boot-options.txt | 3 ++
    > arch/x86/include/asm/mce.h | 5 +++
    > arch/x86/kernel/cpu/mcheck/mce.c | 3 ++
    > arch/x86/kernel/cpu/mcheck/mce_intel.c | 75 +++++++++++++++++++++++++++++++
    > 4 files changed, 86 insertions(+)

    ...

    > +static bool lmce_supported(void)
    > +{
    > + u64 cap, feature_ctl;
    > + bool lmce_bios_support, retval;
    > +
    > + if (mca_cfg.lmce_disabled)
    > + return false;
    > +
    > + rdmsrl(MSR_IA32_MCG_CAP, cap);
    > + rdmsrl(MSR_IA32_FEATURE_CONTROL, feature_ctl);

    One more thing: You should check MCG_LMCE_P *first* and only read
    MSR_IA32_FEATURE_CONTROL if MCG_LMCE_P is set - otherwise this'll start
    blowing up on older machines which don't sport that new MSR and on kvm.

    > + /*
    > + * BIOS should indicate support for LMCE by setting
    > + * bit20 in IA32_FEATURE_CONTROL. without which touching
    > + * MCG_EXT_CTL will generate #GP fault.
    > + */
    > + lmce_bios_support = ((feature_ctl & (FEATURE_CONTROL_LMCE_BITS)) ==
    > + (FEATURE_CONTROL_LMCE_BITS));
    > +
    > + /*
    > + * MCG_CAP should indicate both MCG_SER_P and MCG_LMCE_P
    > + */

    Also, why do we need to look at MCG_SER_P for LMCE?

    Btw, we do that already in __mcheck_cpu_cap_init() so you could check
    mca_cfg.ser here instead.

    > + cap = ((cap & MCG_CAP_LMCE_BITS) == (MCG_CAP_LMCE_BITS));
    > + retval = (cap && lmce_bios_support);

    --
    Regards/Gruss,
    Boris.

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


    \
     
     \ /
      Last update: 2015-05-29 20:01    [W:2.972 / U:0.244 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site