s390/kvm: Fix BUG in include/linux/kvm_host.h:745
commit b080935c8638e08134629d0a9ebdf35669bec14d
kvm: Directly account vtime to system on guest switch
also removed the irq_disable/enable around kvm guest switch, which
is correct in itself. Unfortunately, there is a BUG ON that (correctly)
checks for preemptible to cover the call to rcu later on.
(Introduced with commit 8fa2206821953a50a3a02ea33fcfb3ced2fd9997
KVM: make guest mode entry to be rcu quiescent state)
This check might trigger depending on the kernel config.
Lets make sure that no preemption happens during kvm_guest_enter.
We can enable preemption again after the call to
rcu_virt_note_context_switch returns.
Please note that we continue to run s390 guests with interrupts
enabled.
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
CC: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index c9011bf..f090e81 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -613,7 +613,9 @@
kvm_s390_deliver_pending_interrupts(vcpu);
vcpu->arch.sie_block->icptcode = 0;
+ preempt_disable();
kvm_guest_enter();
+ preempt_enable();
VCPU_EVENT(vcpu, 6, "entering sie flags %x",
atomic_read(&vcpu->arch.sie_block->cpuflags));
trace_kvm_s390_sie_enter(vcpu,