From: Maxim Levitsky mlevitsk@redhat.com
[ Upstream commit 18869f26df1a11ed11031dfb7392bc7d774062e8 ]
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: Maxim Levitsky mlevitsk@redhat.com Message-Id: 20220606180829.102503-7-mlevitsk@redhat.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- virt/kvm/kvm_main.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 717ee1b2e058..8f88f168012e 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -3305,9 +3305,11 @@ 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);
@@ -3317,9 +3319,11 @@ 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;