KVM: s390: vsie: correctly set and handle guest TOD

Guest 2 sets up the epoch of guest 3 from his point of view. Therefore,
we have to add the guest 2 epoch to the guest 3 epoch. We also have to take
care of guest 2 epoch changes on STP syncs. This will work just fine by
also updating the guest 3 epoch when a vsie_block has been set for a VCPU.

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>

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 8ba7a98..6fdf1f7 100644 (file)
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -176,6 +176,8 @@ static int kvm_clock_sync(struct notifier_block *notifier, unsigned long val,
                        vcpu->arch.sie_block->epoch -= *delta;
                        if (vcpu->arch.cputm_enabled)
                                vcpu->arch.cputm_start += *delta;
+                       if (vcpu->arch.vsie_block)
+                               vcpu->arch.vsie_block->epoch -= *delta;
                }
        }
        return NOTIFY_OK;

diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index 90781ba..6895e7b 100644 (file)
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -843,12 +843,21 @@ static int acquire_gmap_shadow(struct kvm_vcpu *vcpu,
 static void register_shadow_scb(struct kvm_vcpu *vcpu,
                                struct vsie_page *vsie_page)
 {
+       struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
+
        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);
+       /*
+        * We have to adjust the g3 epoch by the g2 epoch. The epoch will
+        * automatically be adjusted on tod clock changes via kvm_sync_clock.
+        */
+       preempt_disable();
+       scb_s->epoch += vcpu->kvm->arch.epoch;
+       preempt_enable();
 }
 
 /*