Re: [PATCH] KVM: x86: disable PEBS before a guest entry

2016-03-04 Thread Radim Krčmář
2016-03-03 13:32-0800, David Matlack: > On Thu, Mar 3, 2016 at 10:53 AM, Radim Krčmář wrote: >> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c >> @@ -1767,6 +1767,13 @@ static void clear_atomic_switch_msr(struct vcpu_vmx >> *vmx, unsigned msr) >> return; >>

Re: [PATCH] KVM: x86: disable PEBS before a guest entry

2016-03-03 Thread David Matlack
On Thu, Mar 3, 2016 at 10:53 AM, Radim Krčmář wrote: > Linux guests on Haswell (and also SandyBridge and Broadwell, at least) > would crash if you decided to run a host command that uses PEBS, like > perf record -e 'cpu/mem-stores/pp' -a > > This happens because KVM is using VMX MSR switching to

[PATCH] KVM: x86: disable PEBS before a guest entry

2016-03-03 Thread Radim Krčmář
Linux guests on Haswell (and also SandyBridge and Broadwell, at least) would crash if you decided to run a host command that uses PEBS, like perf record -e 'cpu/mem-stores/pp' -a This happens because KVM is using VMX MSR switching to disable PEBS, but SDM [2015-12] 18.4.4.4 Re-configuring PEBS F