From: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
[ 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@xxxxxxxxxx>
Message-Id: <20220606180829.102503-7-mlevitsk@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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;
--
2.35.1
