Commit 18869f26 authored by Maxim Levitsky's avatar Maxim Levitsky Committed by Paolo Bonzini
Browse files

KVM: x86: disable preemption around the call to kvm_arch_vcpu_{un|}blocking 



On SVM, if preemption happens right after the call to finish_rcuwait
but before call to kvm_arch_vcpu_unblocking on SVM/AVIC, it itself
will re-enable AVIC, and then we will try to re-enable it again
in kvm_arch_vcpu_unblocking which will lead to a warning
in __avic_vcpu_load.

The same problem can happen if the vCPU is preempted right after the call
to kvm_arch_vcpu_blocking but before the call to prepare_to_rcuwait
and in this case, we will end up with AVIC enabled during sleep -
Ooops.

Signed-off-by: default avatarMaxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220606180829.102503-7-mlevitsk@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 66c768d3

virt/kvm/kvm_main.c

+6 −2
Original line number Diff line number Diff line
@@ -3328,9 +3328,11 @@ bool kvm_vcpu_block(struct kvm_vcpu *vcpu) 


	vcpu->stat.generic.blocking = 1;



	preempt_disable();

	kvm_arch_vcpu_blocking(vcpu);



	prepare_to_rcuwait(wait);

	preempt_enable();



	for (;;) {

		set_current_state(TASK_INTERRUPTIBLE);
@@ -3340,9 +3342,11 @@ bool kvm_vcpu_block(struct kvm_vcpu *vcpu) 
		waited = true;

		schedule();

	}

	finish_rcuwait(wait);



	preempt_disable();

	finish_rcuwait(wait);

	kvm_arch_vcpu_unblocking(vcpu);

	preempt_enable();



	vcpu->stat.generic.blocking = 0;