KVM: s390: Provide guest TOD Clock Get/Set Controls

Provide controls for setting/getting the guest TOD clock based on the VM
attribute interface.

Provide TOD and TOD_HIGH vm attributes on s390 for managing guest Time Of
Day clock value.

TOD_HIGH is presently always set to 0. In the future it will contain a high
order expansion of the tod clock value after it overflows the 64-bits of
the TOD.

Signed-off-by: Jason J. Herne <jjherne@linux.vnet.ibm.com>
Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

3 files changed, 134 insertions, 0 deletions

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index a2dcd0e099f7..8e22aa0f97fd 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -528,6 +528,7 @@ struct kvm_arch{
         struct mutex ipte_mutex;
         spinlock_t start_stop_lock;
         struct kvm_s390_crypto crypto;
+        u64 epoch;
 };
 
 #define KVM_HVA_ERR_BAD         (-1UL)
diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h
index 7e9165e1bec5..cb64319d3e51 100644
--- a/arch/s390/include/uapi/asm/kvm.h
+++ b/arch/s390/include/uapi/asm/kvm.h
@@ -57,12 +57,17 @@ struct kvm_s390_io_adapter_req {
 
 /* kvm attr_group  on vm fd */
 #define KVM_S390_VM_MEM_CTRL            0
+#define KVM_S390_VM_TOD                 1
 
 /* kvm attributes for mem_ctrl */
 #define KVM_S390_VM_MEM_ENABLE_CMMA     0
 #define KVM_S390_VM_MEM_CLR_CMMA        1
 #define KVM_S390_VM_MEM_LIMIT_SIZE      2
 
+/* kvm attributes for KVM_S390_VM_TOD */
+#define KVM_S390_VM_TOD_LOW             0
+#define KVM_S390_VM_TOD_HIGH            1
+
 /* for KVM_GET_REGS and KVM_SET_REGS */
 struct kvm_regs {
         /* general purpose regs for s390 */
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 3677b8ca647f..9cf899e9a5d4 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -342,6 +342,113 @@ static int kvm_s390_set_mem_control(struct kvm *kvm, struct kvm_device_attr *att
         return ret;
 }
 
+static int kvm_s390_set_tod_high(struct kvm *kvm, struct kvm_device_attr *attr)
+{
+        u8 gtod_high;
+
+        if (copy_from_user(&gtod_high, (void __user *)attr->addr,
+                                           sizeof(gtod_high)))
+                return -EFAULT;
+
+        if (gtod_high != 0)
+                return -EINVAL;
+
+        return 0;
+}
+
+static int kvm_s390_set_tod_low(struct kvm *kvm, struct kvm_device_attr *attr)
+{
+        struct kvm_vcpu *cur_vcpu;
+        unsigned int vcpu_idx;
+        u64 host_tod, gtod;
+        int r;
+
+        if (copy_from_user(&gtod, (void __user *)attr->addr, sizeof(gtod)))
+                return -EFAULT;
+
+        r = store_tod_clock(&host_tod);
+        if (r)
+                return r;
+
+        mutex_lock(&kvm->lock);
+        kvm->arch.epoch = gtod - host_tod;
+        kvm_for_each_vcpu(vcpu_idx, cur_vcpu, kvm) {
+                cur_vcpu->arch.sie_block->epoch = kvm->arch.epoch;
+                exit_sie(cur_vcpu);
+        }
+        mutex_unlock(&kvm->lock);
+        return 0;
+}
+
+static int kvm_s390_set_tod(struct kvm *kvm, struct kvm_device_attr *attr)
+{
+        int ret;
+
+        if (attr->flags)
+                return -EINVAL;
+
+        switch (attr->attr) {
+        case KVM_S390_VM_TOD_HIGH:
+                ret = kvm_s390_set_tod_high(kvm, attr);
+                break;
+        case KVM_S390_VM_TOD_LOW:
+                ret = kvm_s390_set_tod_low(kvm, attr);
+                break;
+        default:
+                ret = -ENXIO;
+                break;
+        }
+        return ret;
+}
+
+static int kvm_s390_get_tod_high(struct kvm *kvm, struct kvm_device_attr *attr)
+{
+        u8 gtod_high = 0;
+
+        if (copy_to_user((void __user *)attr->addr, &gtod_high,
+                                         sizeof(gtod_high)))
+                return -EFAULT;
+
+        return 0;
+}
+
+static int kvm_s390_get_tod_low(struct kvm *kvm, struct kvm_device_attr *attr)
+{
+        u64 host_tod, gtod;
+        int r;
+
+        r = store_tod_clock(&host_tod);
+        if (r)
+                return r;
+
+        gtod = host_tod + kvm->arch.epoch;
+        if (copy_to_user((void __user *)attr->addr, &gtod, sizeof(gtod)))
+                return -EFAULT;
+
+        return 0;
+}
+
+static int kvm_s390_get_tod(struct kvm *kvm, struct kvm_device_attr *attr)
+{
+        int ret;
+
+        if (attr->flags)
+                return -EINVAL;
+
+        switch (attr->attr) {
+        case KVM_S390_VM_TOD_HIGH:
+                ret = kvm_s390_get_tod_high(kvm, attr);
+                break;
+        case KVM_S390_VM_TOD_LOW:
+                ret = kvm_s390_get_tod_low(kvm, attr);
+                break;
+        default:
+                ret = -ENXIO;
+                break;
+        }
+        return ret;
+}
+
 static int kvm_s390_vm_set_attr(struct kvm *kvm, struct kvm_device_attr *attr)
 {
         int ret;
@@ -350,6 +457,9 @@ static int kvm_s390_vm_set_attr(struct kvm *kvm, struct kvm_device_attr *attr)
         case KVM_S390_VM_MEM_CTRL:
                 ret = kvm_s390_set_mem_control(kvm, attr);
                 break;
+        case KVM_S390_VM_TOD:
+                ret = kvm_s390_set_tod(kvm, attr);
+                break;
         default:
                 ret = -ENXIO;
                 break;
@@ -366,6 +476,9 @@ static int kvm_s390_vm_get_attr(struct kvm *kvm, struct kvm_device_attr *attr)
         case KVM_S390_VM_MEM_CTRL:
                 ret = kvm_s390_get_mem_control(kvm, attr);
                 break;
+        case KVM_S390_VM_TOD:
+                ret = kvm_s390_get_tod(kvm, attr);
+                break;
         default:
                 ret = -ENXIO;
                 break;
@@ -391,6 +504,17 @@ static int kvm_s390_vm_has_attr(struct kvm *kvm, struct kvm_device_attr *attr)
                         break;
                 }
                 break;
+        case KVM_S390_VM_TOD:
+                switch (attr->attr) {
+                case KVM_S390_VM_TOD_LOW:
+                case KVM_S390_VM_TOD_HIGH:
+                        ret = 0;
+                        break;
+                default:
+                        ret = -ENXIO;
+                        break;
+                }
+                break;
         default:
                 ret = -ENXIO;
                 break;
@@ -541,6 +665,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 
         kvm->arch.css_support = 0;
         kvm->arch.use_irqchip = 0;
+        kvm->arch.epoch = 0;
 
         spin_lock_init(&kvm->arch.start_stop_lock);
 
@@ -686,6 +811,9 @@ static void kvm_s390_vcpu_initial_reset(struct kvm_vcpu *vcpu)
 
 void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
 {
+        mutex_lock(&vcpu->kvm->lock);
+        vcpu->arch.sie_block->epoch = vcpu->kvm->arch.epoch;
+        mutex_unlock(&vcpu->kvm->lock);
         if (!kvm_is_ucontrol(vcpu->kvm))
                 vcpu->arch.gmap = vcpu->kvm->arch.gmap;
 }