KVM: Introduce a 'release' method for KVM devices (2bde9b3e) · Commits · 戴 / test

When a P9 sPAPR VM boots, the CAS negotiation process determines which interrupt mode to use (XICS legacy or XIVE native) and invokes a machine reset to activate the chosen mode. To be able to switch from one interrupt mode to another, we introduce the capability to release a KVM device without destroying the VM. The KVM device interface is extended with a new 'release' method which is called when the file descriptor of the device is closed. Once 'release' is called, the 'destroy' method will not be called anymore as the device is removed from the device list of the VM. Cc: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by:

Cédric Le Goater <clg@kaod.org> Reviewed-by:

David Gibson <david@gibson.dropbear.id.au> Signed-off-by:

Paul Mackerras <paulus@ozlabs.org>

include/linux/kvm_host.h

+9 −0

Original line number	Diff line number	Diff line
		@@ -1240,6 +1240,15 @@ struct kvm_device_ops {
		*/
		void (destroy)(struct kvm_device dev);

		/*
		* Release is an alternative method to free the device. It is
		* called when the device file descriptor is closed. Once
		* release is called, the destroy method will not be called
		* anymore as the device is removed from the device list of
		* the VM. kvm->lock is held.
		*/
		void (release)(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);

virt/kvm/kvm_main.c

+13 −0

Original line number	Diff line number	Diff line
		@@ -2938,6 +2938,19 @@ static int kvm_device_release(struct inode inode, struct file filp)
		struct kvm_device *dev = filp->private_data;
		struct kvm *kvm = dev->kvm;

		if (!dev)
		return -ENODEV;

		if (dev->kvm != kvm)
		return -EPERM;

		if (dev->ops->release) {
		mutex_lock(&kvm->lock);
		list_del(&dev->vm_node);
		dev->ops->release(dev);
		mutex_unlock(&kvm->lock);
		}

		kvm_put_kvm(kvm);
		return 0;
		}

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