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authorAlexey Kardashevskiy <aik@ozlabs.ru>2013-08-05 20:52:36 +0400
committerAlex Williamson <alex.williamson@redhat.com>2013-08-05 20:52:36 +0400
commit6cdd97821322352b94bb92f271b4466ad38a2468 (patch)
treea79a322ca2ae87302f7ba85c0a286e7ec6b76bb6 /include/linux
parentc095ba7224d8edc71dcef0d655911399a8bd4a3f (diff)
downloadlinux-6cdd97821322352b94bb92f271b4466ad38a2468.tar.xz
vfio: add external user support
VFIO is designed to be used via ioctls on file descriptors returned by VFIO. However in some situations support for an external user is required. The first user is KVM on PPC64 (SPAPR TCE protocol) which is going to use the existing VFIO groups for exclusive access in real/virtual mode on a host to avoid passing map/unmap requests to the user space which would made things pretty slow. The protocol includes: 1. do normal VFIO init operation: - opening a new container; - attaching group(s) to it; - setting an IOMMU driver for a container. When IOMMU is set for a container, all groups in it are considered ready to use by an external user. 2. User space passes a group fd to an external user. The external user calls vfio_group_get_external_user() to verify that: - the group is initialized; - IOMMU is set for it. If both checks passed, vfio_group_get_external_user() increments the container user counter to prevent the VFIO group from disposal before KVM exits. 3. The external user calls vfio_external_user_iommu_id() to know an IOMMU ID. PPC64 KVM uses it to link logical bus number (LIOBN) with IOMMU ID. 4. When the external KVM finishes, it calls vfio_group_put_external_user() to release the VFIO group. This call decrements the container user counter. Everything gets released. The "vfio: Limit group opens" patch is also required for the consistency. Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/vfio.h7
1 files changed, 7 insertions, 0 deletions
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index ac8d488e4372..24579a0312a0 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -90,4 +90,11 @@ extern void vfio_unregister_iommu_driver(
TYPE tmp; \
offsetof(TYPE, MEMBER) + sizeof(tmp.MEMBER); }) \
+/*
+ * External user API
+ */
+extern struct vfio_group *vfio_group_get_external_user(struct file *filep);
+extern void vfio_group_put_external_user(struct vfio_group *group);
+extern int vfio_external_user_iommu_id(struct vfio_group *group);
+
#endif /* VFIO_H */