KVM: async_pf: Async page fault support on s390

This patch enables async page faults for s390 kvm guests.
It provides the userspace API to enable and disable_wait this feature.
The disable_wait will enforce that the feature is off by waiting on it.
Also it includes the diagnose code, called by the guest to enable async page faults.

The async page faults will use an already existing guest interface for this
purpose, as described in "CP Programming Services (SC24-6084)".

Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

1 files changed, 58 insertions, 7 deletions

diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 9c9192b..1848080 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -31,7 +31,7 @@ static int is_ioint(u64 type)
 	return ((type & 0xfffe0000u) != 0xfffe0000u);
 }
 
-static int psw_extint_disabled(struct kvm_vcpu *vcpu)
+int psw_extint_disabled(struct kvm_vcpu *vcpu)
 {
 	return !(vcpu->arch.sie_block->gpsw.mask & PSW_MASK_EXT);
 }
@@ -78,11 +78,8 @@ static int __interrupt_is_deliverable(struct kvm_vcpu *vcpu,
 			return 1;
 		return 0;
 	case KVM_S390_INT_SERVICE:
-		if (psw_extint_disabled(vcpu))
-			return 0;
-		if (vcpu->arch.sie_block->gcr[0] & 0x200ul)
-			return 1;
-		return 0;
+	case KVM_S390_INT_PFAULT_INIT:
+	case KVM_S390_INT_PFAULT_DONE:
 	case KVM_S390_INT_VIRTIO:
 		if (psw_extint_disabled(vcpu))
 			return 0;
@@ -150,6 +147,8 @@ static void __set_intercept_indicator(struct kvm_vcpu *vcpu,
 	case KVM_S390_INT_EXTERNAL_CALL:
 	case KVM_S390_INT_EMERGENCY:
 	case KVM_S390_INT_SERVICE:
+	case KVM_S390_INT_PFAULT_INIT:
+	case KVM_S390_INT_PFAULT_DONE:
 	case KVM_S390_INT_VIRTIO:
 		if (psw_extint_disabled(vcpu))
 			__set_cpuflag(vcpu, CPUSTAT_EXT_INT);
@@ -223,6 +222,30 @@ static void __do_deliver_interrupt(struct kvm_vcpu *vcpu,
 		rc |= put_guest(vcpu, inti->ext.ext_params,
 				(u32 __user *)__LC_EXT_PARAMS);
 		break;
+	case KVM_S390_INT_PFAULT_INIT:
+		trace_kvm_s390_deliver_interrupt(vcpu->vcpu_id, inti->type, 0,
+						 inti->ext.ext_params2);
+		rc  = put_guest(vcpu, 0x2603, (u16 __user *) __LC_EXT_INT_CODE);
+		rc |= put_guest(vcpu, 0x0600, (u16 __user *) __LC_EXT_CPU_ADDR);
+		rc |= copy_to_guest(vcpu, __LC_EXT_OLD_PSW,
+				    &vcpu->arch.sie_block->gpsw, sizeof(psw_t));
+		rc |= copy_from_guest(vcpu, &vcpu->arch.sie_block->gpsw,
+				      __LC_EXT_NEW_PSW, sizeof(psw_t));
+		rc |= put_guest(vcpu, inti->ext.ext_params2,
+				(u64 __user *) __LC_EXT_PARAMS2);
+		break;
+	case KVM_S390_INT_PFAULT_DONE:
+		trace_kvm_s390_deliver_interrupt(vcpu->vcpu_id, inti->type, 0,
+						 inti->ext.ext_params2);
+		rc  = put_guest(vcpu, 0x2603, (u16 __user *) __LC_EXT_INT_CODE);
+		rc |= put_guest(vcpu, 0x0680, (u16 __user *) __LC_EXT_CPU_ADDR);
+		rc |= copy_to_guest(vcpu, __LC_EXT_OLD_PSW,
+				    &vcpu->arch.sie_block->gpsw, sizeof(psw_t));
+		rc |= copy_from_guest(vcpu, &vcpu->arch.sie_block->gpsw,
+				      __LC_EXT_NEW_PSW, sizeof(psw_t));
+		rc |= put_guest(vcpu, inti->ext.ext_params2,
+				(u64 __user *) __LC_EXT_PARAMS2);
+		break;
 	case KVM_S390_INT_VIRTIO:
 		VCPU_EVENT(vcpu, 4, "interrupt: virtio parm:%x,parm64:%llx",
 			   inti->ext.ext_params, inti->ext.ext_params2);
@@ -357,7 +380,7 @@ static int __try_deliver_ckc_interrupt(struct kvm_vcpu *vcpu)
 	return 1;
 }
 
-static int kvm_cpu_has_interrupt(struct kvm_vcpu *vcpu)
+int kvm_cpu_has_interrupt(struct kvm_vcpu *vcpu)
 {
 	struct kvm_s390_local_interrupt *li = &vcpu->arch.local_int;
 	struct kvm_s390_float_interrupt *fi = vcpu->arch.local_int.float_int;
@@ -737,6 +760,10 @@ int kvm_s390_inject_vm(struct kvm *kvm,
 		VM_EVENT(kvm, 5, "inject: sclp parm:%x", s390int->parm);
 		inti->ext.ext_params = s390int->parm;
 		break;
+	case KVM_S390_INT_PFAULT_DONE:
+		inti->type = s390int->type;
+		inti->ext.ext_params2 = s390int->parm64;
+		break;
 	case KVM_S390_MCHK:
 		VM_EVENT(kvm, 5, "inject: machine check parm64:%llx",
 			 s390int->parm64);
@@ -823,6 +850,10 @@ int kvm_s390_inject_vcpu(struct kvm_vcpu *vcpu,
 		inti->type = s390int->type;
 		inti->mchk.mcic = s390int->parm64;
 		break;
+	case KVM_S390_INT_PFAULT_INIT:
+		inti->type = s390int->type;
+		inti->ext.ext_params2 = s390int->parm64;
+		break;
 	case KVM_S390_INT_VIRTIO:
 	case KVM_S390_INT_SERVICE:
 	case KVM_S390_INT_IO_MIN...KVM_S390_INT_IO_MAX:
@@ -877,6 +908,8 @@ static inline int copy_irq_to_user(struct kvm_s390_interrupt_info *inti,
 
 	irq.type = inti->type;
 	switch (inti->type) {
+	case KVM_S390_INT_PFAULT_INIT:
+	case KVM_S390_INT_PFAULT_DONE:
 	case KVM_S390_INT_VIRTIO:
 	case KVM_S390_INT_SERVICE:
 		irq.u.ext = inti->ext;
@@ -956,6 +989,8 @@ static inline int copy_irq_from_user(struct kvm_s390_interrupt_info *inti,
 		return -EFAULT;
 
 	switch (inti->type) {
+	case KVM_S390_INT_PFAULT_INIT:
+	case KVM_S390_INT_PFAULT_DONE:
 	case KVM_S390_INT_VIRTIO:
 	case KVM_S390_INT_SERVICE:
 		target = (void *) &inti->ext;
@@ -1019,6 +1054,8 @@ static int enqueue_floating_irq(struct kvm_device *dev,
 static int flic_set_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
 {
 	int r = 0;
+	unsigned int i;
+	struct kvm_vcpu *vcpu;
 
 	switch (attr->group) {
 	case KVM_DEV_FLIC_ENQUEUE:
@@ -1028,6 +1065,20 @@ static int flic_set_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
 		r = 0;
 		clear_floating_interrupts(dev->kvm);
 		break;
+	case KVM_DEV_FLIC_APF_ENABLE:
+		dev->kvm->arch.gmap->pfault_enabled = 1;
+		break;
+	case KVM_DEV_FLIC_APF_DISABLE_WAIT:
+		dev->kvm->arch.gmap->pfault_enabled = 0;
+		/*
+		 * Make sure no async faults are in transition when
+		 * clearing the queues. So we don't need to worry
+		 * about late coming workers.
+		 */
+		synchronize_srcu(&dev->kvm->srcu);
+		kvm_for_each_vcpu(i, vcpu, dev->kvm)
+			kvm_clear_async_pf_completion_queue(vcpu);
+		break;
 	default:
 		r = -EINVAL;
 	}