diff options
| author | Liran Alon | 2019-04-15 17:45:26 +0200 |
|---|---|---|
| committer | Paolo Bonzini | 2019-04-30 21:32:14 +0200 |
| commit | 6c6a2ab962af8f197984c45d585814f9839e86d5 (patch) | |
| tree | 7ba181b88e0f162c325694b6086154603d5bc3ab /arch/x86/kvm/x86.c | |
| parent | KVM: x86: Add support of clear Trace_ToPA_PMI status (diff) | |
| download | kernel-qcow2-linux-6c6a2ab962af8f197984c45d585814f9839e86d5.tar.gz kernel-qcow2-linux-6c6a2ab962af8f197984c45d585814f9839e86d5.tar.xz kernel-qcow2-linux-6c6a2ab962af8f197984c45d585814f9839e86d5.zip | |
KVM: VMX: Nop emulation of MSR_IA32_POWER_CTL
Since commits 668fffa3f838 ("kvm: better MWAIT emulation for guestsâ€)
and 4d5422cea3b6 ("KVM: X86: Provide a capability to disable MWAIT interceptsâ€),
KVM was modified to allow an admin to configure certain guests to execute
MONITOR/MWAIT inside guest without being intercepted by host.
This is useful in case admin wishes to allocate a dedicated logical
processor for each vCPU thread. Thus, making it safe for guest to
completely control the power-state of the logical processor.
The ability to use this new KVM capability was introduced to QEMU by
commits 6f131f13e68d ("kvm: support -overcommit cpu-pm=on|offâ€) and
2266d4431132 ("i386/cpu: make -cpu host support monitor/mwaitâ€).
However, exposing MONITOR/MWAIT to a Linux guest may cause it's intel_idle
kernel module to execute c1e_promotion_disable() which will attempt to
RDMSR/WRMSR from/to MSR_IA32_POWER_CTL to manipulate the "C1E Enable"
bit. This behaviour was introduced by commit
32e9518005c8 ("intel_idle: export both C1 and C1Eâ€).
Becuase KVM doesn't emulate this MSR, running KVM with ignore_msrs=0
will cause the above guest behaviour to raise a #GP which will cause
guest to kernel panic.
Therefore, add support for nop emulation of MSR_IA32_POWER_CTL to
avoid #GP in guest in this scenario.
Future commits can optimise emulation further by reflecting guest
MSR changes to host MSR to provide guest with the ability to
fine-tune the dedicated logical processor power-state.
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Liran Alon <liran.alon@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/x86.c')
| -rw-r--r-- | arch/x86/kvm/x86.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index cedd396e3003..c09507057743 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1170,6 +1170,7 @@ static u32 emulated_msrs[] = { MSR_PLATFORM_INFO, MSR_MISC_FEATURES_ENABLES, MSR_AMD64_VIRT_SPEC_CTRL, + MSR_IA32_POWER_CTL, }; static unsigned num_emulated_msrs; |