This is a note to let you know that I've just added the patch titled

KVM: s390: take care of clock-comparator sign control

to the 4.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: kvm-s390-take-care-of-clock-comparator-sign-control.patch and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From 5fe01793dd953ab947fababe8abaf5ed5258c8df Mon Sep 17 00:00:00 2001

From: David Hildenbrand david@redhat.com Date: Wed, 7 Feb 2018 12:46:42 +0100 Subject: KVM: s390: take care of clock-comparator sign control

From: David Hildenbrand david@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 david@redhat.com Message-Id: 20180207114647.6220-2-david@redhat.com Fixes: 8fa1696ea781 ("KVM: s390: Multiple Epoch Facility support") Cc: stable@vger.kernel.org Reviewed-by: Christian Borntraeger borntraeger@de.ibm.com Signed-off-by: Christian Borntraeger borntraeger@de.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@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 @@ -170,8 +170,15 @@ 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); }

@@ -1011,13 +1018,19 @@ 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);

Patches currently in stable-queue which might be from david@redhat.com are

queue-4.15/kvm-s390-take-care-of-clock-comparator-sign-control.patch queue-4.15/kvm-s390-provide-only-a-single-function-for-setting-the-tod-fix-sck.patch queue-4.15/kvm-s390-consider-epoch-index-on-tod-clock-syncs.patch queue-4.15/kvm-s390-consider-epoch-index-on-hotplugged-cpus.patch