Commit 2955c83f authored Mar 06, 2014 by Christian Borntraeger

KVM: s390: Optimize ucontrol path



Since commit 7c470539
(s390/kvm: avoid automatic sie reentry) we will run through the C code
of KVM on host interrupts instead of just reentering the guest. This
will result in additional ucontrol exits (at least HZ per second). Let
handle a 0 intercept in the kernel and dont return to userspace,
even if in ucontrol mode.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
CC: stable@vger.kernel.org

parent fed495d2

arch/s390/kvm/kvm-s390.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -896,7 +896,8 @@ static int vcpu_post_run(struct kvm_vcpu *vcpu, int exit_reason)

		if (rc == 0) {
		if (kvm_is_ucontrol(vcpu->kvm))
		rc = -EOPNOTSUPP;
		/* Don't exit for host interrupts. */
		rc = vcpu->arch.sie_block->icptcode ? -EOPNOTSUPP : 0;
		else
		rc = kvm_handle_sie_intercept(vcpu);
		}