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authorChristian Borntraeger <borntraeger@de.ibm.com>2008-05-07 09:22:53 +0200
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2008-05-07 09:23:01 +0200
commit0eaeafa10f3b2bd027e95859a6785d4c7fcc174c (patch)
tree97676107c28393326944bd3d922e7eeaa5caf942 /arch/s390/kvm/intercept.c
parent2688905e6a9b3647bf7b452cb0ff2bdb166bd8fe (diff)
[S390] s390-kvm: leave sie context on work. Removes preemption requirement
From: Martin Schwidefsky <schwidefsky@de.ibm.com> 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 <cotte@de.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/kvm/intercept.c')
-rw-r--r--arch/s390/kvm/intercept.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
index 349581a26103..47a0b642174c 100644
--- a/arch/s390/kvm/intercept.c
+++ b/arch/s390/kvm/intercept.c
@@ -105,6 +105,9 @@ static intercept_handler_t instruction_handlers[256] = {
static int handle_noop(struct kvm_vcpu *vcpu)
{
switch (vcpu->arch.sie_block->icptcode) {
+ case 0x0:
+ vcpu->stat.exit_null++;
+ break;
case 0x10:
vcpu->stat.exit_external_request++;
break;