On 07/06/16 10:26, Laszlo Ersek wrote:
> On 06/22/16 08:56, Haozhong Zhang wrote:
> > 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(-)
> >
>
> How can I test this series?
>
> I'm trying to satisfy the conditions in pc_build_feature_control_file(), so that "etc/msr_feature_control" is created. However, I cannot even trigger
>
> if (ecx & CPUID_EXT_VMX) {
> feature_control_bits |= FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX;
> }
>
> I tried various -cpu switches (with and without -enable-kvm); nothing seems to work. When I add "+vmx", QEMU always complains that vmx is not available. Any hints?
>
> (My laptop does support VMX, and it has FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX set in the corresponding host MSR.)
>
You may check if kvm-intel module is loaded with nested support by
'cat /sys/module/kvm_intel/parameters/nested'. If it's 0, you need to
reload kvm-intel with nested parameter: modprobe kvm-intel
nested=1. Moreover, you may also try qemu -cpu host to get the most
your host hardware supports.
Thanks,
Haozhong
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