KVM: PPC: Book3S: Add API for in-kernel XICS emulation

This adds the API for userspace to instantiate an XICS device in a VM
and connect VCPUs to it.  The API consists of a new device type for
the KVM_CREATE_DEVICE ioctl, a new capability KVM_CAP_IRQ_XICS, which
functions similarly to KVM_CAP_IRQ_MPIC, and the KVM_IRQ_LINE ioctl,
which is used to assert and deassert interrupt inputs of the XICS.

The XICS device has one attribute group, KVM_DEV_XICS_GRP_SOURCES.
Each attribute within this group corresponds to the state of one
interrupt source.  The attribute number is the same as the interrupt
source number.

This does not support irq routing or irqfd yet.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alexander Graf <agraf@suse.de>

4 files changed, 191 insertions, 25 deletions

diff --git a/arch/powerpc/kvm/book3s_xics.c b/arch/powerpc/kvm/book3s_xics.c
index ee841ed8a690..f7a103756618 100644
--- a/arch/powerpc/kvm/book3s_xics.c
+++ b/arch/powerpc/kvm/book3s_xics.c
@@ -11,6 +11,7 @@
 #include <linux/kvm_host.h>
 #include <linux/err.h>
 #include <linux/gfp.h>
+#include <linux/anon_inodes.h>
 
 #include <asm/uaccess.h>
 #include <asm/kvm_book3s.h>
@@ -55,8 +56,6 @@
  *
  * - Make ICS lockless as well, or at least a per-interrupt lock or hashed
  *   locks array to improve scalability
- *
- * - ioctl's to save/restore the entire state for snapshot & migration
  */
 
 /* -- ICS routines -- */
@@ -64,7 +63,8 @@
 static void icp_deliver_irq(struct kvmppc_xics *xics, struct kvmppc_icp *icp,
 			    u32 new_irq);
 
-static int ics_deliver_irq(struct kvmppc_xics *xics, u32 irq, u32 level)
+static int ics_deliver_irq(struct kvmppc_xics *xics, u32 irq, u32 level,
+			   bool report_status)
 {
 	struct ics_irq_state *state;
 	struct kvmppc_ics *ics;
@@ -81,6 +81,9 @@ static int ics_deliver_irq(struct kvmppc_xics *xics, u32 irq, u32 level)
 	if (!state->exists)
 		return -EINVAL;
 
+	if (report_status)
+		return state->asserted;
+
 	/*
 	 * We set state->asserted locklessly. This should be fine as
 	 * we are the only setter, thus concurrent access is undefined
@@ -96,7 +99,7 @@ static int ics_deliver_irq(struct kvmppc_xics *xics, u32 irq, u32 level)
 	/* Attempt delivery */
 	icp_deliver_irq(xics, NULL, irq);
 
-	return 0;
+	return state->asserted;
 }
 
 static void ics_check_resend(struct kvmppc_xics *xics, struct kvmppc_ics *ics,
@@ -891,8 +894,8 @@ static void xics_debugfs_init(struct kvmppc_xics *xics)
 	kfree(name);
 }
 
-struct kvmppc_ics *kvmppc_xics_create_ics(struct kvm *kvm,
-					  struct kvmppc_xics *xics, int irq)
+static struct kvmppc_ics *kvmppc_xics_create_ics(struct kvm *kvm,
+					struct kvmppc_xics *xics, int irq)
 {
 	struct kvmppc_ics *ics;
 	int i, icsid;
@@ -1044,34 +1047,138 @@ int kvmppc_xics_set_icp(struct kvm_vcpu *vcpu, u64 icpval)
 	return 0;
 }
 
-/* -- ioctls -- */
+static int xics_get_source(struct kvmppc_xics *xics, long irq, u64 addr)
+{
+	int ret;
+	struct kvmppc_ics *ics;
+	struct ics_irq_state *irqp;
+	u64 __user *ubufp = (u64 __user *) addr;
+	u16 idx;
+	u64 val, prio;
+
+	ics = kvmppc_xics_find_ics(xics, irq, &idx);
+	if (!ics)
+		return -ENOENT;
 
-int kvm_vm_ioctl_xics_irq(struct kvm *kvm, struct kvm_irq_level *args)
+	irqp = &ics->irq_state[idx];
+	mutex_lock(&ics->lock);
+	ret = -ENOENT;
+	if (irqp->exists) {
+		val = irqp->server;
+		prio = irqp->priority;
+		if (prio == MASKED) {
+			val |= KVM_XICS_MASKED;
+			prio = irqp->saved_priority;
+		}
+		val |= prio << KVM_XICS_PRIORITY_SHIFT;
+		if (irqp->asserted)
+			val |= KVM_XICS_LEVEL_SENSITIVE | KVM_XICS_PENDING;
+		else if (irqp->masked_pending || irqp->resend)
+			val |= KVM_XICS_PENDING;
+		ret = 0;
+	}
+	mutex_unlock(&ics->lock);
+
+	if (!ret && put_user(val, ubufp))
+		ret = -EFAULT;
+
+	return ret;
+}
+
+static int xics_set_source(struct kvmppc_xics *xics, long irq, u64 addr)
 {
-	struct kvmppc_xics *xics;
-	int r;
+	struct kvmppc_ics *ics;
+	struct ics_irq_state *irqp;
+	u64 __user *ubufp = (u64 __user *) addr;
+	u16 idx;
+	u64 val;
+	u8 prio;
+	u32 server;
+
+	if (irq < KVMPPC_XICS_FIRST_IRQ || irq >= KVMPPC_XICS_NR_IRQS)
+		return -ENOENT;
+
+	ics = kvmppc_xics_find_ics(xics, irq, &idx);
+	if (!ics) {
+		ics = kvmppc_xics_create_ics(xics->kvm, xics, irq);
+		if (!ics)
+			return -ENOMEM;
+	}
+	irqp = &ics->irq_state[idx];
+	if (get_user(val, ubufp))
+		return -EFAULT;
+
+	server = val & KVM_XICS_DESTINATION_MASK;
+	prio = val >> KVM_XICS_PRIORITY_SHIFT;
+	if (prio != MASKED &&
+	    kvmppc_xics_find_server(xics->kvm, server) == NULL)
+		return -EINVAL;
 
-	/* locking against multiple callers? */
+	mutex_lock(&ics->lock);
+	irqp->server = server;
+	irqp->saved_priority = prio;
+	if (val & KVM_XICS_MASKED)
+		prio = MASKED;
+	irqp->priority = prio;
+	irqp->resend = 0;
+	irqp->masked_pending = 0;
+	irqp->asserted = 0;
+	if ((val & KVM_XICS_PENDING) && (val & KVM_XICS_LEVEL_SENSITIVE))
+		irqp->asserted = 1;
+	irqp->exists = 1;
+	mutex_unlock(&ics->lock);
 
-	xics = kvm->arch.xics;
-	if (!xics)
-		return -ENODEV;
+	if (val & KVM_XICS_PENDING)
+		icp_deliver_irq(xics, NULL, irqp->number);
 
-	switch (args->level) {
-	case KVM_INTERRUPT_SET:
-	case KVM_INTERRUPT_SET_LEVEL:
-	case KVM_INTERRUPT_UNSET:
-		r = ics_deliver_irq(xics, args->irq, args->level);
-		break;
-	default:
-		r = -EINVAL;
+	return 0;
+}
+
+int kvm_set_irq(struct kvm *kvm, int irq_source_id, u32 irq, int level,
+		bool line_status)
+{
+	struct kvmppc_xics *xics = kvm->arch.xics;
+
+	return ics_deliver_irq(xics, irq, level, line_status);
+}
+
+static int xics_set_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
+{
+	struct kvmppc_xics *xics = dev->private;
+
+	switch (attr->group) {
+	case KVM_DEV_XICS_GRP_SOURCES:
+		return xics_set_source(xics, attr->attr, attr->addr);
 	}
+	return -ENXIO;
+}
 
-	return r;
+static int xics_get_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
+{
+	struct kvmppc_xics *xics = dev->private;
+
+	switch (attr->group) {
+	case KVM_DEV_XICS_GRP_SOURCES:
+		return xics_get_source(xics, attr->attr, attr->addr);
+	}
+	return -ENXIO;
 }
 
-void kvmppc_xics_free(struct kvmppc_xics *xics)
+static int xics_has_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
 {
+	switch (attr->group) {
+	case KVM_DEV_XICS_GRP_SOURCES:
+		if (attr->attr >= KVMPPC_XICS_FIRST_IRQ &&
+		    attr->attr < KVMPPC_XICS_NR_IRQS)
+			return 0;
+		break;
+	}
+	return -ENXIO;
+}
+
+static void kvmppc_xics_free(struct kvm_device *dev)
+{
+	struct kvmppc_xics *xics = dev->private;
 	int i;
 	struct kvm *kvm = xics->kvm;
 
@@ -1083,17 +1190,21 @@ void kvmppc_xics_free(struct kvmppc_xics *xics)
 	for (i = 0; i <= xics->max_icsid; i++)
 		kfree(xics->ics[i]);
 	kfree(xics);
+	kfree(dev);
 }
 
-int kvm_xics_create(struct kvm *kvm, u32 type)
+static int kvmppc_xics_create(struct kvm_device *dev, u32 type)
 {
 	struct kvmppc_xics *xics;
+	struct kvm *kvm = dev->kvm;
 	int ret = 0;
 
 	xics = kzalloc(sizeof(*xics), GFP_KERNEL);
 	if (!xics)
 		return -ENOMEM;
 
+	dev->private = xics;
+	xics->dev = dev;
 	xics->kvm = kvm;
 
 	/* Already there ? */
@@ -1120,6 +1231,35 @@ int kvm_xics_create(struct kvm *kvm, u32 type)
 	return 0;
 }
 
+struct kvm_device_ops kvm_xics_ops = {
+	.name = "kvm-xics",
+	.create = kvmppc_xics_create,
+	.destroy = kvmppc_xics_free,
+	.set_attr = xics_set_attr,
+	.get_attr = xics_get_attr,
+	.has_attr = xics_has_attr,
+};
+
+int kvmppc_xics_connect_vcpu(struct kvm_device *dev, struct kvm_vcpu *vcpu,
+			     u32 xcpu)
+{
+	struct kvmppc_xics *xics = dev->private;
+	int r = -EBUSY;
+
+	if (dev->ops != &kvm_xics_ops)
+		return -EPERM;
+	if (xics->kvm != vcpu->kvm)
+		return -EPERM;
+	if (vcpu->arch.irq_type)
+		return -EBUSY;
+
+	r = kvmppc_xics_create_icp(vcpu, xcpu);
+	if (!r)
+		vcpu->arch.irq_type = KVMPPC_IRQ_XICS;
+
+	return r;
+}
+
 void kvmppc_xics_free_icp(struct kvm_vcpu *vcpu)
 {
 	if (!vcpu->arch.icp)
diff --git a/arch/powerpc/kvm/book3s_xics.h b/arch/powerpc/kvm/book3s_xics.h
index e4fdec3dde77..dd9326c5c19b 100644
--- a/arch/powerpc/kvm/book3s_xics.h
+++ b/arch/powerpc/kvm/book3s_xics.h
@@ -88,6 +88,7 @@ struct kvmppc_ics {
 
 struct kvmppc_xics {
 	struct kvm *kvm;
+	struct kvm_device *dev;
 	struct dentry *dentry;
 	u32 max_icsid;
 	bool real_mode;
diff --git a/arch/powerpc/kvm/irq.h b/arch/powerpc/kvm/irq.h
index f1e27fdc8c2e..5a9a10b90762 100644
--- a/arch/powerpc/kvm/irq.h
+++ b/arch/powerpc/kvm/irq.h
@@ -10,6 +10,9 @@ static inline int irqchip_in_kernel(struct kvm *kvm)
 #ifdef CONFIG_KVM_MPIC
 	ret = ret || (kvm->arch.mpic != NULL);
 #endif
+#ifdef CONFIG_KVM_XICS
+	ret = ret || (kvm->arch.xics != NULL);
+#endif
 	smp_rmb();
 	return ret;
 }
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 270773f0d955..6316ee336e88 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -342,6 +342,9 @@ int kvm_dev_ioctl_check_extension(long ext)
 	case KVM_CAP_SPAPR_TCE:
 	case KVM_CAP_PPC_ALLOC_HTAB:
 	case KVM_CAP_PPC_RTAS:
+#ifdef CONFIG_KVM_XICS
+	case KVM_CAP_IRQ_XICS:
+#endif
 		r = 1;
 		break;
 #endif /* CONFIG_PPC_BOOK3S_64 */
@@ -837,6 +840,25 @@ static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu *vcpu,
 		break;
 	}
 #endif
+#ifdef CONFIG_KVM_XICS
+	case KVM_CAP_IRQ_XICS: {
+		struct file *filp;
+		struct kvm_device *dev;
+
+		r = -EBADF;
+		filp = fget(cap->args[0]);
+		if (!filp)
+			break;
+
+		r = -EPERM;
+		dev = kvm_device_from_filp(filp);
+		if (dev)
+			r = kvmppc_xics_connect_vcpu(dev, vcpu, cap->args[1]);
+
+		fput(filp);
+		break;
+	}
+#endif /* CONFIG_KVM_XICS */
 	default:
 		r = -EINVAL;
 		break;