Re: [PATCH 04/10] swiotlb: Use free_decrypted_pages()

[Edgecombe, Rick P]

On Wed, 2023-10-18 at 06:43 +0200, Christoph Hellwig wrote:
> On Tue, Oct 17, 2023 at 01:24:59PM -0700, Rick Edgecombe wrote:
> > On TDX it is possible for the untrusted host to cause
> > set_memory_encrypted() or set_memory_decrypted() to fail such that
> > an
> > error is returned and the resulting memory is shared. Callers need
> > to take
> > care to handle these errors to avoid returning decrypted (shared)
> > memory to
> > the page allocator, which could lead to functional or security
> > issues.
> > 
> > Swiotlb could free decrypted/shared pages if set_memory_decrypted()
> > fails.
> > Use the recently added free_decrypted_pages() to avoid this.
> > 
> > In swiotlb_exit(), check for set_memory_encrypted() errors
> > manually,
> > because the pages are not nessarily going to the page allocator.
> 
> Whatever recently introduced it didn't make it to my mailbox.  Please
> always CC everyone on every patch in a series, everything else is
> impossible to review.

Ok. The series touches a bunch of set_memory() callers all over, so I
was trying to manage the CC list to something reasonable. I tried to
give a summary in each commit, but I guess it wasn't in depth enough.
Here is the lore link, if you haven't already found it:
https://lore.kernel.org/lkml/20231017202505.340906-1-rick.p.edgecombe@xxxxxxxxx/