On Tue, May 23, 2023 at 01:39:11PM -0700, Dave Hansen wrote: > On 5/4/23 15:53, Dexuan Cui wrote: > > When a TDX guest runs on Hyper-V, the hv_netvsc driver's netvsc_init_buf() > > allocates buffers using vzalloc(), and needs to share the buffers with the > > host OS by calling set_memory_decrypted(), which is not working for > > vmalloc() yet. Add the support by handling the pages one by one. > > I think this sets a bad precedent. > > There are consequences for converting pages between shared and private. > Doing it on a vmalloc() mapping is guaranteed to fracture the underlying > EPT/SEPT mappings. > > How does this work with load_unaligned_zeropad()? Couldn't it be > running around poking at one of these vmalloc()'d pages via the direct > map during a shared->private conversion before the page has been accepted? Alias processing in __change_page_attr_set_clr() will change direct mapping if you call it on vmalloc()ed memory. I think we are safe wrt load_unaligned_zeropad() here. -- Kiryl Shutsemau / Kirill A. Shutemov
