From 2955c83f72801245afd0fe5c560cc75b82bea9aa Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Thu, 6 Mar 2014 16:01:38 +0100 Subject: [PATCH] KVM: s390: Optimize ucontrol path Since commit 7c470539c95630c1f2a10f109e96f249730b75eb (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 Reviewed-by: Cornelia Huck CC: stable@vger.kernel.org --- arch/s390/kvm/kvm-s390.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 6268357..7337c57 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -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); } -- 2.7.4