[PATCH 29/60] kvm: Implement KVM_CREATE_PLANE ioctl

[Jörg Rödel]

From: Paolo Bonzini <pbonzini@xxxxxxxxxx>

Add a new VM ioctl to create a new plane. It returns a new file
descriptor which supports per-plane ioctls.

Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Co-developed-by: Joerg Roedel <joerg.roedel@xxxxxxx>
Signed-off-by: Joerg Roedel <joerg.roedel@xxxxxxx>
---
 include/uapi/linux/kvm.h |  2 ++
 virt/kvm/kvm_main.c      | 75 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 77 insertions(+)

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 813f964a6dc1..24e34b8e4819 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1355,6 +1355,8 @@ struct kvm_s390_keyop {
 #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_CREATE_PLANE	  _IO(KVMIO, 0xe4)
+
 /*
  * ioctls for vcpu fds
  */
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 5a0277e2ac7c..03a44ff62f0f 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -4843,6 +4843,34 @@ static long kvm_vcpu_compat_ioctl(struct file *filp,
 }
 #endif
 
+static long kvm_plane_ioctl(struct file *filp, unsigned int ioctl,
+			    unsigned long arg)
+{
+	struct kvm_plane *plane = filp->private_data;
+
+	if (plane->kvm->mm != current->mm || plane->kvm->vm_dead)
+		return -EIO;
+
+	switch (ioctl) {
+	default:
+		return -ENOTTY;
+	}
+}
+
+static int kvm_plane_release(struct inode *inode, struct file *filp)
+{
+	struct kvm_plane *plane = filp->private_data;
+
+	kvm_put_kvm(plane->kvm);
+	return 0;
+}
+
+static struct file_operations kvm_plane_fops = {
+	.unlocked_ioctl = kvm_plane_ioctl,
+	.release = kvm_plane_release,
+	KVM_COMPAT(kvm_plane_ioctl),
+};
+
 static int kvm_device_mmap(struct file *filp, struct vm_area_struct *vma)
 {
 	struct kvm_device *dev = filp->private_data;
@@ -5288,6 +5316,49 @@ static int kvm_vm_ioctl_get_stats_fd(struct kvm *kvm)
 	return fd;
 }
 
+static int kvm_vm_ioctl_create_plane(struct kvm *kvm, unsigned id)
+{
+	struct kvm_plane *plane;
+	struct file *file;
+	int r, fd;
+
+	if (id >= kvm_arch_max_planes(kvm) ||
+	    WARN_ON_ONCE(id >= KVM_MAX_PLANES))
+		return -EINVAL;
+
+	guard(mutex)(&kvm->lock);
+	if (kvm->planes[id])
+		return -EEXIST;
+
+	fd = get_unused_fd_flags(O_CLOEXEC);
+	if (fd < 0)
+		return fd;
+
+	plane = kvm_create_plane(kvm, id);
+	if (!plane) {
+		r = -ENOMEM;
+		goto put_fd;
+	}
+
+	kvm_get_kvm(kvm);
+	file = anon_inode_getfile("kvm-plane", &kvm_plane_fops, plane, O_RDWR);
+	if (IS_ERR(file)) {
+		r = PTR_ERR(file);
+		goto put_kvm;
+	}
+
+	fd_install(fd, file);
+	return fd;
+
+put_kvm:
+	kvm_put_kvm(kvm);
+	kvm_destroy_one_plane(plane);
+put_fd:
+	put_unused_fd(fd);
+	return r;
+}
+
+
 #define SANITY_CHECK_MEM_REGION_FIELD(field)					\
 do {										\
 	BUILD_BUG_ON(offsetof(struct kvm_userspace_memory_region, field) !=		\
@@ -5306,6 +5377,9 @@ static long kvm_vm_ioctl(struct file *filp,
 	if (kvm->mm != current->mm || kvm->vm_dead)
 		return -EIO;
 	switch (ioctl) {
+	case KVM_CREATE_PLANE:
+		r = kvm_vm_ioctl_create_plane(kvm, arg);
+		break;
 	case KVM_CREATE_VCPU:
 		r = kvm_vm_ioctl_create_vcpu(kvm, arg);
 		break;
@@ -6676,6 +6750,7 @@ int kvm_init(unsigned vcpu_size, unsigned vcpu_align, struct module *module)
 	kvm_chardev_ops.owner = module;
 	kvm_vm_fops.owner = module;
 	kvm_vcpu_fops.owner = module;
+	kvm_plane_fops.owner = module;
 	kvm_device_fops.owner = module;
 
 	kvm_preempt_ops.sched_in = kvm_sched_in;
-- 
2.53.0