KVM: s390: Make the simple ipte mutex specific to a VM instead of global

The ipte-locking should be done for each VM seperately, not globally.
This way we avoid possible congestions when the simple ipte-lock is used
and multiple VMs are running.

Suggested-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Thomas Huth <thuth@linux.vnet.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

arch/s390/include/asm/kvm_host.h

@@ -434,6 +434,8 @@ struct kvm_arch{
 	int user_cpu_state_ctrl;
 	struct s390_io_adapter *adapters[MAX_S390_IO_ADAPTERS];
 	wait_queue_head_t ipte_wq;
+	int ipte_lock_count;
+	struct mutex ipte_mutex;
 	spinlock_t start_stop_lock;
 	struct kvm_s390_crypto crypto;
 };

arch/s390/kvm/gaccess.c

@@ -207,25 +207,23 @@ union raddress {
 	unsigned long pfra : 52; /* Page-Frame Real Address */
 };
 
-static int ipte_lock_count;
-static DEFINE_MUTEX(ipte_mutex);
 
 int ipte_lock_held(struct kvm_vcpu *vcpu)
 {
 	union ipte_control *ic = &vcpu->kvm->arch.sca->ipte_control;
 
 	if (vcpu->arch.sie_block->eca & 1)
 		return ic->kh != 0;
-	return ipte_lock_count != 0;
+	return vcpu->kvm->arch.ipte_lock_count != 0;
 }
 
 static void ipte_lock_simple(struct kvm_vcpu *vcpu)
 {
 	union ipte_control old, new, *ic;
 
-	mutex_lock(&ipte_mutex);
-	ipte_lock_count++;
-	if (ipte_lock_count > 1)
+	mutex_lock(&vcpu->kvm->arch.ipte_mutex);
+	vcpu->kvm->arch.ipte_lock_count++;
+	if (vcpu->kvm->arch.ipte_lock_count > 1)
 		goto out;
 	ic = &vcpu->kvm->arch.sca->ipte_control;
 	do {
@@ -238,16 +236,16 @@ static void ipte_lock_simple(struct kvm_vcpu *vcpu)
 		new.k = 1;
 	} while (cmpxchg(&ic->val, old.val, new.val) != old.val);
 out:
-	mutex_unlock(&ipte_mutex);
+	mutex_unlock(&vcpu->kvm->arch.ipte_mutex);
 }
 
 static void ipte_unlock_simple(struct kvm_vcpu *vcpu)
 {
 	union ipte_control old, new, *ic;
 
-	mutex_lock(&ipte_mutex);
-	ipte_lock_count--;
-	if (ipte_lock_count)
+	mutex_lock(&vcpu->kvm->arch.ipte_mutex);
+	vcpu->kvm->arch.ipte_lock_count--;
+	if (vcpu->kvm->arch.ipte_lock_count)
 		goto out;
 	ic = &vcpu->kvm->arch.sca->ipte_control;
 	do {
@@ -256,7 +254,7 @@ static void ipte_unlock_simple(struct kvm_vcpu *vcpu)
 	} while (cmpxchg(&ic->val, old.val, new.val) != old.val);
 	wake_up(&vcpu->kvm->arch.ipte_wq);
 out:
-	mutex_unlock(&ipte_mutex);
+	mutex_unlock(&vcpu->kvm->arch.ipte_mutex);
 }
 
 static void ipte_lock_siif(struct kvm_vcpu *vcpu)

arch/s390/kvm/kvm-s390.c

@@ -453,6 +453,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 	spin_lock_init(&kvm->arch.float_int.lock);
 	INIT_LIST_HEAD(&kvm->arch.float_int.list);
 	init_waitqueue_head(&kvm->arch.ipte_wq);
+	mutex_init(&kvm->arch.ipte_mutex);
 
 	debug_register_view(kvm->arch.dbf, &debug_sprintf_view);
 	VM_EVENT(kvm, 3, "%s", "vm created");