5 May
2025
5 May
'25
5:28 p.m.
On Mon, May 05, 2025 at 10:21:03AM -0700, Nicolin Chen wrote:
+void iommufd_ctx_free_mmap(struct iommufd_ctx *ictx, unsigned long immap_id) +{
- kfree(mtree_erase(&ictx->mt_mmap, immap_id >> PAGE_SHIFT));
MMIO lifecycle question: what happens if a region is removed from the maple tree (and is therefore no longer mappable), but is still mapped and in use by userspace?
I think we should probably zap it and make any existing VMAs SIGBUS... Otherwise it is hard to reason about from the kernel side
I added in v3 a pair of open/close op that would refcount the vIOMMU object (owner of the mmap region). This would EBUSY the vIOMMU destroy ioctl that would call this function.
That's no good, we can't have VMAs prevent cleaning up iommufd objects, the right thing is to zap it with invalidate_mapping_range()
Jason