Re: [PATCH 01/12] iommu/vt-d: Use iommu_get_domain_for_dev() in debugfs

From: Baolu Lu
Date: Wed Jun 01 2022 - 01:47:42 EST


On 2022/5/31 23:59, Jason Gunthorpe wrote:
On Tue, May 31, 2022 at 02:52:28PM +0100, Robin Murphy wrote:

+                break;
+            pgtable_walk_level(m, phys_to_virt(phys_addr),

Also, obligatory reminder that pfn_valid() only means that pfn_to_page()
gets you a valid struct page. Whether that page is direct-mapped kernel
memory or not is a different matter.

Even though this is debugfs, if the operation is sketchy like that and
can theortically crash the kernel the driver should test capabilities,
CAP_SYS_RAWIO or something may be appropriate. I don't think we have a
better cap for 'userspace may crash the kernel'

Yes. We should test both CAP_SYS_ADMIN and CAP_SYS_RAWIO.

Best regards,
baolu