Am Montag 18 Mai 2009 16:26:15 schrieb Avi Kivity: > Christian Borntraeger wrote: > > Sorry for the late question, but I missed your first version. Is there a > > way to change that code to use virtio instead of PCI? That would allow us > > to use this driver on s390 and maybe other virtio transports. > > Opinion differs. See the discussion in > http://article.gmane.org/gmane.comp.emulators.kvm.devel/30119. > > To summarize, Anthony thinks it should use virtio, while I believe > virtio is useful for exporting guest memory, not for importing host memory. I think the current virtio interface is not ideal for importing host memory, but we can change that. If you look at the dcssblk driver for s390, it allows a guest to map shared memory segments via a diagnose (hypercall). This driver uses PCI regions to map memory. My point is, that the method to map memory is completely irrelevant, we just need something like mmap/shmget between the guest and the host. We could define an interface in virtio, that can be used by any transport. In case of pci this could be a simple pci map operation. What do you think about something like: (CCed Rusty) --- include/linux/virtio.h | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) Index: linux-2.6/include/linux/virtio.h =================================================================== --- linux-2.6.orig/include/linux/virtio.h +++ linux-2.6/include/linux/virtio.h @@ -71,6 +71,31 @@ struct virtqueue_ops { }; /** + * virtio_device_ops - operations for virtio devices + * @map_region: map host buffer at a given address + * vdev: the struct virtio_device we're talking about. + * addr: The address where the buffer should be mapped (hint only) + * length: THe length of the mapping + * identifier: the token that identifies the host buffer + * Returns the mapping address or an error pointer. + * @unmap_region: unmap host buffer from the address + * vdev: the struct virtio_device we're talking about. + * addr: The address where the buffer is mapped + * Returns 0 on success or an error + * + * TBD, we might need query etc. + */ +struct virtio_device_ops { + void * (*map_region)(struct virtio_device *vdev, + void *addr, + size_t length, + int identifier); + int (*unmap_region)(struct virtio_device *vdev, void *addr); +/* we might need query region and other stuff */ +}; + + +/** * virtio_device - representation of a device using virtio * @index: unique position on the virtio bus * @dev: underlying device. @@ -85,6 +110,7 @@ struct virtio_device struct device dev; struct virtio_device_id id; struct virtio_config_ops *config; + struct virtio_device_ops *ops; /* Note that this is a Linux set_bit-style bitmap. */ unsigned long features[1]; void *priv; -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
