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[GIT,PULL,48/51] KVM: s390: vsie: speed up VCPU external calls

Message ID 1466514809-146638-49-git-send-email-borntraeger@de.ibm.com (mailing list archive)
State New, archived
Headers show

Commit Message

Christian Borntraeger June 21, 2016, 1:13 p.m. UTC 
From: David Hildenbrand <dahi@linux.vnet.ibm.com>

Whenever a SIGP external call is injected via the SIGP external call
interpretation facility, the VCPU is not kicked. When a VCPU is currently
in the VSIE, the external call might not be processed immediately.

Therefore we have to provoke partial execution exceptions, which leads to a
kick of the VCPU and therefore also kick out of VSIE. This is done by
simulating the WAIT state. This bit has no other side effects.

Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
 arch/s390/kvm/vsie.c | 6 ++++++
 1 file changed, 6 insertions(+)
diff mbox

Patch

diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index c8c8763..90781ba 100644
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -844,6 +844,11 @@  static void register_shadow_scb(struct kvm_vcpu *vcpu,
 				struct vsie_page *vsie_page)
 {
 	WRITE_ONCE(vcpu->arch.vsie_block, &vsie_page->scb_s);
+	/*
+	 * External calls have to lead to a kick of the vcpu and
+	 * therefore the vsie -> Simulate Wait state.
+	 */
+	atomic_or(CPUSTAT_WAIT, &vcpu->arch.sie_block->cpuflags);
 }
 
 /*
@@ -851,6 +856,7 @@  static void register_shadow_scb(struct kvm_vcpu *vcpu,
  */
 static void unregister_shadow_scb(struct kvm_vcpu *vcpu)
 {
+	atomic_andnot(CPUSTAT_WAIT, &vcpu->arch.sie_block->cpuflags);
 	WRITE_ONCE(vcpu->arch.vsie_block, NULL);
 }