Re: [PATCH] X86/KVM: Do not allow DISABLE_EXITS_MWAIT when LAPIC ARAT is not available

2018-04-11 Thread Sean Christopherson
On Wed, 2018-04-11 at 11:16 +0200, KarimAllah Ahmed wrote: > If the processor does not have an "Always Running APIC Timer" (aka ARAT), > we should not give guests direct access to MWAIT. The LAPIC timer would > stop ticking in deep C-states, so any host deadlines would not wakeup the > host

Re: [PATCH] X86/KVM: Do not allow DISABLE_EXITS_MWAIT when LAPIC ARAT is not available

2018-04-11 Thread Sean Christopherson
On Wed, 2018-04-11 at 11:16 +0200, KarimAllah Ahmed wrote: > If the processor does not have an "Always Running APIC Timer" (aka ARAT), > we should not give guests direct access to MWAIT. The LAPIC timer would > stop ticking in deep C-states, so any host deadlines would not wakeup the > host

Re: [PATCH] X86/KVM: Do not allow DISABLE_EXITS_MWAIT when LAPIC ARAT is not available

2018-04-11 Thread Paolo Bonzini
On 11/04/2018 11:16, KarimAllah Ahmed wrote: > If the processor does not have an "Always Running APIC Timer" (aka ARAT), > we should not give guests direct access to MWAIT. The LAPIC timer would > stop ticking in deep C-states, so any host deadlines would not wakeup the > host kernel. > > The

Re: [PATCH] X86/KVM: Do not allow DISABLE_EXITS_MWAIT when LAPIC ARAT is not available

2018-04-11 Thread Paolo Bonzini
On 11/04/2018 11:16, KarimAllah Ahmed wrote: > If the processor does not have an "Always Running APIC Timer" (aka ARAT), > we should not give guests direct access to MWAIT. The LAPIC timer would > stop ticking in deep C-states, so any host deadlines would not wakeup the > host kernel. > > The

[PATCH] X86/KVM: Do not allow DISABLE_EXITS_MWAIT when LAPIC ARAT is not available

2018-04-11 Thread KarimAllah Ahmed
If the processor does not have an "Always Running APIC Timer" (aka ARAT), we should not give guests direct access to MWAIT. The LAPIC timer would stop ticking in deep C-states, so any host deadlines would not wakeup the host kernel. The host kernel intel_idle driver handles this by switching to

[PATCH] X86/KVM: Do not allow DISABLE_EXITS_MWAIT when LAPIC ARAT is not available

2018-04-11 Thread KarimAllah Ahmed
If the processor does not have an "Always Running APIC Timer" (aka ARAT), we should not give guests direct access to MWAIT. The LAPIC timer would stop ticking in deep C-states, so any host deadlines would not wakeup the host kernel. The host kernel intel_idle driver handles this by switching to