From 0eaeafa10f3b2bd027e95859a6785d4c7fcc174c Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Wed, 7 May 2008 09:22:53 +0200 Subject: [S390] s390-kvm: leave sie context on work. Removes preemption requirement From: Martin Schwidefsky This patch fixes a bug with cpu bound guest on kvm-s390. Sometimes it was impossible to deliver a signal to a spinning guest. We used preemption as a circumvention. The preemption notifiers called vcpu_load, which checked for pending signals and triggered a host intercept. But even with preemption, a sigkill was not delivered immediately. This patch changes the low level host interrupt handler to check for the SIE instruction, if TIF_WORK is set. In that case we change the instruction pointer of the return PSW to rerun the vcpu_run loop. The kvm code sees an intercept reason 0 if that happens. This patch adds accounting for these types of intercept as well. The advantages: - works with and without preemption - signals are delivered immediately - much better host latencies without preemption Acked-by: Carsten Otte Signed-off-by: Christian Borntraeger Signed-off-by: Martin Schwidefsky --- include/asm-s390/kvm_host.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/asm-s390/kvm_host.h') diff --git a/include/asm-s390/kvm_host.h b/include/asm-s390/kvm_host.h index f8204a4f2e0..18cbd8a3979 100644 --- a/include/asm-s390/kvm_host.h +++ b/include/asm-s390/kvm_host.h @@ -104,6 +104,7 @@ struct sie_block { struct kvm_vcpu_stat { u32 exit_userspace; + u32 exit_null; u32 exit_external_request; u32 exit_external_interrupt; u32 exit_stop_request; -- cgit v1.2.3