Christian Borntraeger 7a72f7a140 KVM: track pid for VCPU only on KVM_RUN ioctl ... We currently track the pid of the task that runs the VCPU in vcpu_load. If a yield to that VCPU is triggered while the PID of the wrong thread is active, the wrong thread might receive a yield, but this will most likely not help the executing thread at all. Instead, if we only track the pid on the KVM_RUN ioctl, there are two possibilities: 1) the thread that did a non-KVM_RUN ioctl is holding a mutex that the VCPU thread is waiting for. In this case, the VCPU thread is not runnable, but we also do not do a wrong yield. 2) the thread that did a non-KVM_RUN ioctl is sleeping, or doing something that does not block the VCPU thread. In this case, the VCPU thread can receive the directed yield correctly. Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> CC: Rik van Riel <riel@redhat.com> CC: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com> CC: Michael Mueller <mimu@linux.vnet.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>		2014-12-04 15:29:13 +01:00
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kvm	KVM: track pid for VCPU only on KVM_RUN ioctl	2014-12-04 15:29:13 +01:00