On Fri, Feb 12, 2021 at 05:20:57PM -0400, Jason Gunthorpe wrote:
> On Fri, Feb 12, 2021 at 12:27:39PM -0700, Alex Williamson wrote:
> > Create an interface through vfio-core where a vfio bus driver (ex.
> > vfio-pci) can register the vm_operations_struct it uses to map device
> > memory, along with a set of registration callbacks. This allows
> > vfio-core to expose interfaces for IOMMU backends to match a
> > vm_area_struct to a bus driver and register a notifier for relavant
> > changes to the device mapping. For now we define only a notifier
> > action for closing the device.
> >
> > Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
> > drivers/vfio/vfio.c | 120 ++++++++++++++++++++++++++++++++++++++++++++++++++
> > include/linux/vfio.h | 20 ++++++++
> > 2 files changed, 140 insertions(+)
> >
> > diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
> > index 38779e6fd80c..568f5e37a95f 100644
> > +++ b/drivers/vfio/vfio.c
> > @@ -47,6 +47,8 @@ static struct vfio {
> > struct cdev group_cdev;
> > dev_t group_devt;
> > wait_queue_head_t release_q;
> > + struct list_head vm_ops_list;
> > + struct mutex vm_ops_lock;
> > } vfio;
> >
> > struct vfio_iommu_driver {
> > @@ -2354,6 +2356,121 @@ struct iommu_domain *vfio_group_iommu_domain(struct vfio_group *group)
> > }
> > EXPORT_SYMBOL_GPL(vfio_group_iommu_domain);
> >
> > +struct vfio_vma_ops {
> > + const struct vm_operations_struct *vm_ops;
> > + vfio_register_vma_nb_t *reg_fn;
> > + vfio_unregister_vma_nb_t *unreg_fn;
> > + struct list_head next;
> > +};
> > +
> > +int vfio_register_vma_ops(const struct vm_operations_struct *vm_ops,
> > + vfio_register_vma_nb_t *reg_fn,
> > + vfio_unregister_vma_nb_t *unreg_fn)
>
> This just feels a little bit too complicated
>
> I've recently learned from Daniel that we can use the address_space
> machinery to drive the zap_vma_ptes() via unmap_mapping_range(). This
> technique replaces all the open, close and vma_list logic in vfio_pci
Here is my effort to make rdma use this, it removes a lot of ugly code:
https://github.com/jgunthorpe/linux/commits/rdma_addr_space
Still needs some more detailed testing.
This gives an option to detect vfio VMAs by checking
if (vma->vm_file &&
file_inode(vma->vm_file) &&
file_inode(vma->vm_file)->i_sb->s_type == vfio_fs_type)
And all vfio VMA's can have some consistent vm_private_data, or at
worst a consistent extended vm operations struct.
Jason
