Re: [RFC/PATCH 1/1] s390/kvm: Fix BUG in include/linux/kvm_host.h:745
On Tue, Jan 08, 2013 at 04:23:10PM +0100, Christian Borntraeger wrote: 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. CC: Frederic Weisbecker fweis...@gmail.com CC: Gleb Natapov g...@redhat.com Signed-off-by: Christian Borntraeger borntrae...@de.ibm.com Applied, thanks. -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
[RFC/PATCH 1/1] 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. CC: Frederic Weisbecker fweis...@gmail.com CC: Gleb Natapov g...@redhat.com Signed-off-by: Christian Borntraeger borntrae...@de.ibm.com --- arch/s390/kvm/kvm-s390.c | 2 ++ 1 file changed, 2 insertions(+) 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 @@ static int __vcpu_run(struct kvm_vcpu *vcpu) 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, -- 1.7.11.4 -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFC/PATCH 1/1] s390/kvm: Fix BUG in include/linux/kvm_host.h:745
2013/1/8 Christian Borntraeger borntrae...@de.ibm.com: 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. CC: Frederic Weisbecker fweis...@gmail.com CC: Gleb Natapov g...@redhat.com Signed-off-by: Christian Borntraeger borntrae...@de.ibm.com --- arch/s390/kvm/kvm-s390.c | 2 ++ 1 file changed, 2 insertions(+) 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 @@ static int __vcpu_run(struct kvm_vcpu *vcpu) kvm_s390_deliver_pending_interrupts(vcpu); vcpu-arch.sie_block-icptcode = 0; + preempt_disable(); kvm_guest_enter(); + preempt_enable(); Sorry for the issue. The fix looks good to me, thanks! Acked-by: Frederic Weisbecker fweis...@gmail.com -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
