KVM: s390: Multiple Epoch Facility support

Allow for the enablement of MEF and the support for the extended
epoch in SIE and VSIE for the extended guest TOD-Clock.

A new interface is used for getting/setting a guest's extended TOD-Clock
that uses a single ioctl invocation, KVM_S390_VM_TOD_EXT.  Since the
host time is a moving target that might see an epoch switch or STP sync
checks we need an atomic ioctl and cannot use the exisiting two
interfaces. The old method of getting and setting the guest TOD-Clock is
still retained and is used when the old ioctls are called.

Signed-off-by: Collin L. Walling <walling@linux.vnet.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.vnet.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com>
Reviewed-by: Jason J. Herne <jjherne@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

1 files changed, 101 insertions, 0 deletions

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index af09d3437631..e65b7637cc45 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -130,6 +130,12 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
 	{ NULL }
 };
 
+struct kvm_s390_tod_clock_ext {
+	__u8 epoch_idx;
+	__u64 tod;
+	__u8 reserved[7];
+} __packed;
+
 /* allow nested virtualization in KVM (if enabled by user space) */
 static int nested;
 module_param(nested, int, S_IRUGO);
@@ -874,6 +880,26 @@ static int kvm_s390_vm_get_migration(struct kvm *kvm,
 	return 0;
 }
 
+static int kvm_s390_set_tod_ext(struct kvm *kvm, struct kvm_device_attr *attr)
+{
+	struct kvm_s390_vm_tod_clock gtod;
+
+	if (copy_from_user(&gtod, (void __user *)attr->addr, sizeof(gtod)))
+		return -EFAULT;
+
+	if (test_kvm_facility(kvm, 139))
+		kvm_s390_set_tod_clock_ext(kvm, &gtod);
+	else if (gtod.epoch_idx == 0)
+		kvm_s390_set_tod_clock(kvm, gtod.tod);
+	else
+		return -EINVAL;
+
+	VM_EVENT(kvm, 3, "SET: TOD extension: 0x%x, TOD base: 0x%llx",
+		gtod.epoch_idx, gtod.tod);
+
+	return 0;
+}
+
 static int kvm_s390_set_tod_high(struct kvm *kvm, struct kvm_device_attr *attr)
 {
 	u8 gtod_high;
@@ -909,6 +935,9 @@ static int kvm_s390_set_tod(struct kvm *kvm, struct kvm_device_attr *attr)
 		return -EINVAL;
 
 	switch (attr->attr) {
+	case KVM_S390_VM_TOD_EXT:
+		ret = kvm_s390_set_tod_ext(kvm, attr);
+		break;
 	case KVM_S390_VM_TOD_HIGH:
 		ret = kvm_s390_set_tod_high(kvm, attr);
 		break;
@@ -922,6 +951,43 @@ static int kvm_s390_set_tod(struct kvm *kvm, struct kvm_device_attr *attr)
 	return ret;
 }
 
+static void kvm_s390_get_tod_clock_ext(struct kvm *kvm,
+					struct kvm_s390_vm_tod_clock *gtod)
+{
+	struct kvm_s390_tod_clock_ext htod;
+
+	preempt_disable();
+
+	get_tod_clock_ext((char *)&htod);
+
+	gtod->tod = htod.tod + kvm->arch.epoch;
+	gtod->epoch_idx = htod.epoch_idx + kvm->arch.epdx;
+
+	if (gtod->tod < htod.tod)
+		gtod->epoch_idx += 1;
+
+	preempt_enable();
+}
+
+static int kvm_s390_get_tod_ext(struct kvm *kvm, struct kvm_device_attr *attr)
+{
+	struct kvm_s390_vm_tod_clock gtod;
+
+	memset(&gtod, 0, sizeof(gtod));
+
+	if (test_kvm_facility(kvm, 139))
+		kvm_s390_get_tod_clock_ext(kvm, &gtod);
+	else
+		gtod.tod = kvm_s390_get_tod_clock_fast(kvm);
+
+	if (copy_to_user((void __user *)attr->addr, &gtod, sizeof(gtod)))
+		return -EFAULT;
+
+	VM_EVENT(kvm, 3, "QUERY: TOD extension: 0x%x, TOD base: 0x%llx",
+		gtod.epoch_idx, gtod.tod);
+	return 0;
+}
+
 static int kvm_s390_get_tod_high(struct kvm *kvm, struct kvm_device_attr *attr)
 {
 	u8 gtod_high = 0;
@@ -954,6 +1020,9 @@ static int kvm_s390_get_tod(struct kvm *kvm, struct kvm_device_attr *attr)
 		return -EINVAL;
 
 	switch (attr->attr) {
+	case KVM_S390_VM_TOD_EXT:
+		ret = kvm_s390_get_tod_ext(kvm, attr);
+		break;
 	case KVM_S390_VM_TOD_HIGH:
 		ret = kvm_s390_get_tod_high(kvm, attr);
 		break;
@@ -2369,6 +2438,9 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
 		vcpu->arch.sie_block->eca |= ECA_VX;
 		vcpu->arch.sie_block->ecd |= ECD_HOSTREGMGMT;
 	}
+	if (test_kvm_facility(vcpu->kvm, 139))
+		vcpu->arch.sie_block->ecd |= ECD_MEF;
+
 	vcpu->arch.sie_block->sdnxo = ((unsigned long) &vcpu->run->s.regs.sdnx)
 					| SDNXC;
 	vcpu->arch.sie_block->riccbd = (unsigned long) &vcpu->run->s.regs.riccb;
@@ -2855,6 +2927,35 @@ retry:
 	return 0;
 }
 
+void kvm_s390_set_tod_clock_ext(struct kvm *kvm,
+				 const struct kvm_s390_vm_tod_clock *gtod)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_s390_tod_clock_ext htod;
+	int i;
+
+	mutex_lock(&kvm->lock);
+	preempt_disable();
+
+	get_tod_clock_ext((char *)&htod);
+
+	kvm->arch.epoch = gtod->tod - htod.tod;
+	kvm->arch.epdx = gtod->epoch_idx - htod.epoch_idx;
+
+	if (kvm->arch.epoch > gtod->tod)
+		kvm->arch.epdx -= 1;
+
+	kvm_s390_vcpu_block_all(kvm);
+	kvm_for_each_vcpu(i, vcpu, kvm) {
+		vcpu->arch.sie_block->epoch = kvm->arch.epoch;
+		vcpu->arch.sie_block->epdx  = kvm->arch.epdx;
+	}
+
+	kvm_s390_vcpu_unblock_all(kvm);
+	preempt_enable();
+	mutex_unlock(&kvm->lock);
+}
+
 void kvm_s390_set_tod_clock(struct kvm *kvm, u64 tod)
 {
 	struct kvm_vcpu *vcpu;