KVM: s390: lazy enable RI
Only enable runtime instrumentation if the guest issues an RI related
instruction or if userspace changes the riccb to a valid state.
This makes entry/exit a tiny bit faster.
Initial patch by Christian Borntraeger
Signed-off-by: Fan Zhang <zhangfan@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index dead20a..892abf4 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -1938,8 +1938,6 @@
vcpu->arch.sie_block->eca |= 1;
if (sclp.has_sigpif)
vcpu->arch.sie_block->eca |= 0x10000000U;
- if (test_kvm_facility(vcpu->kvm, 64))
- vcpu->arch.sie_block->ecb3 |= 0x01;
if (test_kvm_facility(vcpu->kvm, 129)) {
vcpu->arch.sie_block->eca |= 0x00020000;
vcpu->arch.sie_block->ecd |= 0x20000000;
@@ -2694,6 +2692,19 @@
if (vcpu->arch.pfault_token == KVM_S390_PFAULT_TOKEN_INVALID)
kvm_clear_async_pf_completion_queue(vcpu);
}
+ /*
+ * If userspace sets the riccb (e.g. after migration) to a valid state,
+ * we should enable RI here instead of doing the lazy enablement.
+ */
+ if ((kvm_run->kvm_dirty_regs & KVM_SYNC_RICCB) &&
+ test_kvm_facility(vcpu->kvm, 64)) {
+ struct runtime_instr_cb *riccb =
+ (struct runtime_instr_cb *) &kvm_run->s.regs.riccb;
+
+ if (riccb->valid)
+ vcpu->arch.sie_block->ecb3 |= 0x01;
+ }
+
kvm_run->kvm_dirty_regs = 0;
}