[Qemu-devel] [PATCH v5 0/4] Add QEMU support for Intel local MCE

[Haozhong Zhang]

Changes in v5:
 * v4 Patch 1&2 are now merged into v5 Patch 1. (Paolo Bonzini)
 * Add a separate Patch 3 to automatically enable LMCE for "-cpu host"
   if host does support. (Eduardo Habkost)
 * Move the sanity check of misconfiguration of LMCE to a separate
   Patch 4. I'm fine to drop it if it's considered to be
   unnecessary. (Eduardo Habkost)
 * Move check of MCG_LMCE_P capability to the existing code in
   kvm_arch_init_vcpu(). The difference is that if LMCE is not
   supported by host but MCG_LMCE_P is included in env->mcg_cap,
   kvm_arch_init_vcpu() return with error instead of just reporting a
   warning. (Eduardo Habkost)
 * Fix setting has_msr_feature_control in kvm_arch_init_vcpu(). (Paolo
   Bonzini)
 * Fix the type error in fw_cfg file "etc/msr_feature_control".

Changes in v4:
 * Abort starting QEMU if lmce option is present but host does support
   LMCE. (Eduardo Habkost)
 * Remove setting MSR_IA32_FEATURE_CONTROL, which should be left to
   guest. (Radim Krčmá, Paolo Bonzini
 * Adjust error messages in mce_init(). (Boris Petkov)
 * Move adding option 'lmce' to patch 1. (Eduardo Habkost, Paolo Bonzini)
 * Adjust LMCE error message in cpu_post_load(). (Eduardo Habkost)
 * (Patch 3) Add a fw_cfg file 'etc/msr_feature_control' to advise
   bits should be set in MSR_IA32_FEATURE_CONTROL. (Paolo Bonzini)
 * Fix SOB chain in patch 1.

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 series
(sent via another email with title "[PATCH v3 0/3] 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.

Ashok Raj (1):
  target-i386: KVM: add basic Intel LMCE support

Haozhong Zhang (3):
  i386: publish advised value of MSR_IA32_FEATURE_CONTROL via fw_cfg
  target-i386: enable LMCE for '-cpu host' if supported by host
  target-i386: abort migration if LMCE config mismatch

 hw/i386/pc.c          | 29 +++++++++++++++++++++++++++++
 target-i386/cpu.c     | 19 ++++++++++++++++++-
 target-i386/cpu.h     | 16 ++++++++++++++++
 target-i386/kvm.c     | 36 +++++++++++++++++++++++++++++++++---
 target-i386/machine.c | 25 +++++++++++++++++++++++++
 5 files changed, 121 insertions(+), 4 deletions(-)

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2.9.0