4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Hildenbrand <da...@redhat.com>

commit 5fe01793dd953ab947fababe8abaf5ed5258c8df upstream.

Missed when enabling the Multiple-epoch facility. If the facility is
installed and the control is set, a sign based comaprison has to be
performed.

Right now we would inject wrong interrupts and ignore interrupt
conditions. Also the sleep time is calculated in a wrong way.

Signed-off-by: David Hildenbrand <da...@redhat.com>
Message-Id: <20180207114647.6220-2-da...@redhat.com>
Fixes: 8fa1696ea781 ("KVM: s390: Multiple Epoch Facility support")
Cc: sta...@vger.kernel.org
Reviewed-by: Christian Borntraeger <borntrae...@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntrae...@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 arch/s390/kvm/interrupt.c |   25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -173,8 +173,15 @@ static int ckc_interrupts_enabled(struct
 
 static int ckc_irq_pending(struct kvm_vcpu *vcpu)
 {
-       if (vcpu->arch.sie_block->ckc >= kvm_s390_get_tod_clock_fast(vcpu->kvm))
+       const u64 now = kvm_s390_get_tod_clock_fast(vcpu->kvm);
+       const u64 ckc = vcpu->arch.sie_block->ckc;
+
+       if (vcpu->arch.sie_block->gcr[0] & 0x0020000000000000ul) {
+               if ((s64)ckc >= (s64)now)
+                       return 0;
+       } else if (ckc >= now) {
                return 0;
+       }
        return ckc_interrupts_enabled(vcpu);
 }
 
@@ -1004,13 +1011,19 @@ int kvm_cpu_has_pending_timer(struct kvm
 
 static u64 __calculate_sltime(struct kvm_vcpu *vcpu)
 {
-       u64 now, cputm, sltime = 0;
+       const u64 now = kvm_s390_get_tod_clock_fast(vcpu->kvm);
+       const u64 ckc = vcpu->arch.sie_block->ckc;
+       u64 cputm, sltime = 0;
 
        if (ckc_interrupts_enabled(vcpu)) {
-               now = kvm_s390_get_tod_clock_fast(vcpu->kvm);
-               sltime = tod_to_ns(vcpu->arch.sie_block->ckc - now);
-               /* already expired or overflow? */
-               if (!sltime || vcpu->arch.sie_block->ckc <= now)
+               if (vcpu->arch.sie_block->gcr[0] & 0x0020000000000000ul) {
+                       if ((s64)now < (s64)ckc)
+                               sltime = tod_to_ns((s64)ckc - (s64)now);
+               } else if (now < ckc) {
+                       sltime = tod_to_ns(ckc - now);
+               }
+               /* already expired */
+               if (!sltime)
                        return 0;
                if (cpu_timer_interrupts_enabled(vcpu)) {
                        cputm = kvm_s390_get_cpu_timer(vcpu);


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