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KVM: s390: vsie: speed up VCPU external calls

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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>
This commit is contained in:
David Hildenbrand 2015-07-07 20:39:35 +02:00 committed by Christian Borntraeger
parent 94a15de8fb
commit b917ae573f
1 changed files with 6 additions and 0 deletions
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6
arch/s390/kvm/vsie.c
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@ -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);
}