On Wed, May 29, 2024 at 10:52:31PM -0600, Alex Williamson wrote:
> With the vfio device fd tied to the address space of the pseudo fs
> inode, we can use the mm to track all vmas that might be mmap'ing
> device BARs, which removes our vma_list and all the complicated lock
> ordering necessary to manually zap each related vma.
>
> Note that we can no longer store the pfn in vm_pgoff if we want to use
> unmap_mapping_range() to zap a selective portion of the device fd
> corresponding to BAR mappings.
>
> This also converts our mmap fault handler to use vmf_insert_pfn()
> because we no longer have a vma_list to avoid the concurrency problem
> with io_remap_pfn_range(). The goal is to eventually use the vm_ops
> huge_fault handler to avoid the additional faulting overhead, but
> vmf_insert_pfn_{pmd,pud}() need to learn about pfnmaps first.
>
Do we also consider looped vmf_insert_pfn() in mmap fault handler? e.g.
for (i = vma->vm_start; i < vma->vm_end; i += PAGE_SIZE) {
offset = (i - vma->vm_start) >> PAGE_SHIFT;
ret = vmf_insert_pfn(vma, i, base_pfn + offset);
if (ret != VM_FAULT_NOPAGE) {
zap_vma_ptes(vma, vma->vm_start, vma->vm_end - vma->vm_start);
goto up_out;
}
}
Thanks
Yan
