Re: [Qemu-devel] [PATCH v3 0/2] Add QEMU support for Intel local MCE

[Haozhong Zhang]

On 06/03/16 14:09, Haozhong Zhang wrote:
> This is v3 of LMCE patch series. Previous ones can be found at
>  v2: https://lists.nongnu.org/archive/html/qemu-devel/2015-12/msg01731.html
>  v1: https://lists.nongnu.org/archive/html/qemu-devel/2015-12/msg01651.html
>  v0: https://lists.nongnu.org/archive/html/qemu-devel/2015-12/msg01498.html
> 
> Changes in v3:
>  * LMCE can be enabled only for non-intel guests.
>  * LMCE is disabled by default and a cpu option 'lmce=on/off' is added
>    to explicitly enable/disable LMCE.
>  * LMCE is disabled if KVM does not support (even though 'lmce=on').
>  * VM on LMCE-enabled QEMU can be only migrated to LMCE-enabled QEMU.
>  * MCG_LMCE_P is not included in MCE_CAP_DEF and instead added to
>    env->mcg_cap if LMCE is enabled.
>  * Code style fix.
> 
> This QEMU patch series along with the corresponding KVM patch (sent
> via another email with title "[PATCH v1] Add KVM support for Intel
> local MCE") enables Intel local MCE feature for guest.
> 
> Intel Local MCE (LMCE) is a feature on Intel Skylake Server CPU that
> can deliver MCE to a single processor thread instead of broadcasting
> to all threads, which can reduce software's load when processing MCE
> on machines with a large number of processor threads.
> 
> The technical details of LMCE can be found in Intel SDM Vol 3, Chapter
> "Machine-Check Architecture" (search for 'LMCE'). Basically,
>  * The capability of LMCE is indicated by bit 27 (MCG_LMCE_P) of
>    MSR_IA32_MCG_CAP.
>  * LMCE is enabled by setting bit 20 (MSR_IA32_FEATURE_CONTROL_LMCE)
>    of MSR_IA32_FEATURE_CONTROL and bit 0 (MCG_EXT_CTL_LMCE_EN) of
>    MSR_IA32_MCG_EXT_CTL.
>  * Software can determine if a MCE is local to the current processor
>    thread by checking bit 2 (MCG_STATUS_LMCE) of MSR_IA32_MCG_STATUS.
> 
> Haozhong Zhang (2):
>   target-i386: KVM: add basic Intel LMCE support
>   target-i386: add migration support for Intel LMCE

Forgot to note: Igor's patch "pc: add 2.7 machine" should be applied
before patch 2 "target-i386: add migration support for Intel LMCE".

Haozhong