On 01/10/2018 20:40, Sean Christopherson wrote:
>>> Given the multiple erratas that exist on VMX preemption timer and because this
>>> test requires immediate exit, I think it's worth doing a checkout of commit
>>> b5861e5cf (KVM: nVMX: Fix loss of pending IRQ/NMI before entering L2) directly
>>> (before the preemption timer changes are present) and running the tests again.
>>> They still pass on my Skylake-SP (Xeon Platinum 8167M) and I wonder if the
>>> results on your CPU will be different.
>>
>> Yeah, they pass on Kaby Lake too (Core i7-7600U) so I think we should
>> re-enable smp_send_reschedule on pre-Skylake processor. Sean, what do
>> you think?
>
> That's not good. The errata I'm aware of relate to the timer counting
> at the wrong frequency.
Indeed so did I. Now, I'm not sure why the test would pass on Nikita's
Skylake-SP, but one difference between my Kaby Lake and Haswell is that
the former is a consumer part that does not have APICv...
... and if I disable APICv the test starts to pass on the Haswell---with
APICv the KVM_REQ_EVENT is never requested because KVM does not need the
interrupt window. I've just sent a fix ("kvm: nVMX: fix entry with
pending interrupt if APICv is enabled"), all CCed people are welcomed to
review it so that I can include it in the next pull request to Greg.
Paolo
