Hi,
On 2/19/16 00:18, Paolo Bonzini wrote:
On 18/02/2016 17:27, Radim Krčmář wrote:
2016-02-18 16:53+0100, Paolo Bonzini:
Patch 9 is okay, but it is also necessary to clear IsRunning in
kvm_arch_vcpu_blocking and set it in kvm_arch_vcpu_unblocking. In
addition, vcpu_put/vcpu_load should not modify IsRunning between
kvm_arch_vcpu_blocking and kvm_arch_vcpu_unblocking. Do you agree?
Yes.
I think we don't need to clear IsRunning on preemption, which would
simplify the protection. (I haven't thought much about userspace exit,
so maybe we could skip that one as well, but we don't need to now.)
The reason for that is that KVM knows that the VCPU was scheduled out,
so it couldn't do much in the AVIC VMEXIT.
(KVM could force scheduler to pritioritize the VCPU, but our kick
doesn't do that now and it seems like a bad idea.)
Does it seem reasonable?
Yes, and in fact it wouldn't need to clear and set IsRunning on
vcpu_put/vcpu_load; only on vcpu_blocking/vcpu_unblocking.
The IsRunning flag is more of a IsNotHalted flag, in the end.
Paolo
Good point. I have made the change by introducing new function pointer,
kvm_x86_ops.vcpu_blocking() and kvm_x86_ops.vcpu_unblocking(). Then
provides the hook to set/unset the IsRunningBit here. Also, I no longer
set the bit in the vcpu_load/vcpu_put.
If this is okay. I'll send out V2 soon.
Thanks,
Suravee
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