Commit b917ae57 authored Jul 07, 2015 by David Hildenbrand Committed by Christian Borntraeger Jun 21, 2016

KVM: s390: vsie: speed up VCPU external calls

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>

parent 94a15de8

arch/s390/kvm/vsie.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -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);
		}

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