[PATCH 19/19] KVM: introduce a KVM_DELETE_DEVICE ioctl

["Cédric Le Goater" <clg@kaod.org>]

This will be used to destroy the KVM XICS or XIVE device when the
sPAPR machine is reseted. When the VM boots, the CAS negotiation
process will determine which interrupt mode to use and the appropriate
KVM device will then be created.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
---
 include/linux/kvm_host.h              |  2 ++
 include/uapi/linux/kvm.h              |  2 ++
 arch/powerpc/kvm/book3s_xive.c        | 38 +++++++++++++++++++++++++-
 arch/powerpc/kvm/book3s_xive_native.c | 24 +++++++++++++++++
 virt/kvm/kvm_main.c                   | 39 +++++++++++++++++++++++++++
 5 files changed, 104 insertions(+), 1 deletion(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index c38cc5eb7e73..259b6885dc74 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1218,6 +1218,8 @@ struct kvm_device_ops {
 	 */
 	void (*destroy)(struct kvm_device *dev);
 
+	int (*delete)(struct kvm_device *dev);
+
 	int (*set_attr)(struct kvm_device *dev, struct kvm_device_attr *attr);
 	int (*get_attr)(struct kvm_device *dev, struct kvm_device_attr *attr);
 	int (*has_attr)(struct kvm_device *dev, struct kvm_device_attr *attr);
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 52bf74a1616e..b00cb4d986cf 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1331,6 +1331,8 @@ struct kvm_s390_ucas_mapping {
 #define KVM_GET_DEVICE_ATTR	  _IOW(KVMIO,  0xe2, struct kvm_device_attr)
 #define KVM_HAS_DEVICE_ATTR	  _IOW(KVMIO,  0xe3, struct kvm_device_attr)
 
+#define KVM_DELETE_DEVICE	  _IOWR(KVMIO,  0xf0, struct kvm_create_device)
+
 /*
  * ioctls for vcpu fds
  */
diff --git a/arch/powerpc/kvm/book3s_xive.c b/arch/powerpc/kvm/book3s_xive.c
index 9b4751713554..5449fb4c87f9 100644
--- a/arch/powerpc/kvm/book3s_xive.c
+++ b/arch/powerpc/kvm/book3s_xive.c
@@ -1109,11 +1109,19 @@ void kvmppc_xive_disable_vcpu_interrupts(struct kvm_vcpu *vcpu)
 void kvmppc_xive_cleanup_vcpu(struct kvm_vcpu *vcpu)
 {
 	struct kvmppc_xive_vcpu *xc = vcpu->arch.xive_vcpu;
-	struct kvmppc_xive *xive = xc->xive;
+	struct kvmppc_xive *xive;
 	int i;
 
+	if (!kvmppc_xics_enabled(vcpu))
+		return;
+
+	if (!xc)
+		return;
+
 	pr_devel("cleanup_vcpu(cpu=%d)\n", xc->server_num);
 
+	xive = xc->xive;
+
 	/* Ensure no interrupt is still routed to that VP */
 	xc->valid = false;
 	kvmppc_xive_disable_vcpu_interrupts(vcpu);
@@ -1150,6 +1158,10 @@ void kvmppc_xive_cleanup_vcpu(struct kvm_vcpu *vcpu)
 	}
 	/* Free the VP */
 	kfree(xc);
+
+	/* Cleanup the vcpu */
+	vcpu->arch.irq_type = KVMPPC_IRQ_DEFAULT;
+	vcpu->arch.xive_vcpu = NULL;
 }
 
 int kvmppc_xive_connect_vcpu(struct kvm_device *dev,
@@ -1861,6 +1873,29 @@ static void kvmppc_xive_free(struct kvm_device *dev)
 	kfree(dev);
 }
 
+static int kvmppc_xive_delete(struct kvm_device *dev)
+{
+	struct kvm *kvm = dev->kvm;
+	unsigned int i;
+	struct kvm_vcpu *vcpu;
+
+	if (!kvm->arch.xive)
+		return -EPERM;
+
+	/*
+	 * call kick_all_cpus_sync() to ensure that all CPUs have
+	 * executed any pending interrupts
+	 */
+	if (is_kvmppc_hv_enabled(kvm))
+		kick_all_cpus_sync();
+
+	kvm_for_each_vcpu(i, vcpu, kvm)
+		kvmppc_xive_cleanup_vcpu(vcpu);
+
+	kvmppc_xive_free(dev);
+	return 0;
+}
+
 static int kvmppc_xive_create(struct kvm_device *dev, u32 type)
 {
 	struct kvmppc_xive *xive;
@@ -2035,6 +2070,7 @@ struct kvm_device_ops kvm_xive_ops = {
 	.create = kvmppc_xive_create,
 	.init = kvmppc_xive_init,
 	.destroy = kvmppc_xive_free,
+	.delete = kvmppc_xive_delete,
 	.set_attr = xive_set_attr,
 	.get_attr = xive_get_attr,
 	.has_attr = xive_has_attr,
diff --git a/arch/powerpc/kvm/book3s_xive_native.c b/arch/powerpc/kvm/book3s_xive_native.c
index 12edac29995e..7367962e670a 100644
--- a/arch/powerpc/kvm/book3s_xive_native.c
+++ b/arch/powerpc/kvm/book3s_xive_native.c
@@ -979,6 +979,29 @@ static void kvmppc_xive_native_free(struct kvm_device *dev)
 	kfree(dev);
 }
 
+static int kvmppc_xive_native_delete(struct kvm_device *dev)
+{
+	struct kvm *kvm = dev->kvm;
+	unsigned int i;
+	struct kvm_vcpu *vcpu;
+
+	if (!kvm->arch.xive)
+		return -EPERM;
+
+	/*
+	 * call kick_all_cpus_sync() to ensure that all CPUs have
+	 * executed any pending interrupts
+	 */
+	if (is_kvmppc_hv_enabled(kvm))
+		kick_all_cpus_sync();
+
+	kvm_for_each_vcpu(i, vcpu, kvm)
+		kvmppc_xive_native_cleanup_vcpu(vcpu);
+
+	kvmppc_xive_native_free(dev);
+	return 0;
+}
+
 /*
  * ESB MMIO address of chip 0
  */
@@ -1350,6 +1373,7 @@ struct kvm_device_ops kvm_xive_native_ops = {
 	.create = kvmppc_xive_native_create,
 	.init = kvmppc_xive_native_init,
 	.destroy = kvmppc_xive_native_free,
+	.delete = kvmppc_xive_native_delete,
 	.set_attr = kvmppc_xive_native_set_attr,
 	.get_attr = kvmppc_xive_native_get_attr,
 	.has_attr = kvmppc_xive_native_has_attr,
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 1f888a103f78..c93c35c43675 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3009,6 +3009,31 @@ static int kvm_ioctl_create_device(struct kvm *kvm,
 	return 0;
 }
 
+static int kvm_ioctl_delete_device(struct kvm *kvm,
+				   struct kvm_create_device *cd)
+{
+	struct fd f;
+	struct kvm_device *dev;
+	int ret;
+
+	f = fdget(cd->fd);
+	if (!f.file)
+		return -EBADF;
+
+	dev = kvm_device_from_filp(f.file);
+	fdput(f);
+
+	if (!dev)
+		return -EPERM;
+
+	mutex_lock(&kvm->lock);
+	list_del(&dev->vm_node);
+	mutex_unlock(&kvm->lock);
+	ret = dev->ops->delete(dev);
+
+	return ret;
+}
+
 static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg)
 {
 	switch (arg) {
@@ -3253,6 +3278,20 @@ static long kvm_vm_ioctl(struct file *filp,
 		r = 0;
 		break;
 	}
+	case KVM_DELETE_DEVICE: {
+		struct kvm_create_device cd;
+
+		r = -EFAULT;
+		if (copy_from_user(&cd, argp, sizeof(cd)))
+			goto out;
+
+		r = kvm_ioctl_delete_device(kvm, &cd);
+		if (r)
+			goto out;
+
+		r = 0;
+		break;
+	}
 	case KVM_CHECK_EXTENSION:
 		r = kvm_vm_ioctl_check_extension_generic(kvm, arg);
 		break;
-- 
2.20.1