Re: [PATCH] vfio/type1: Cleanup remaining vaddr removal/update fragments

Alex Williamson
2022-12-12T21:28:04Z

On Mon, 12 Dec 2022 15:59:11 -0500
Steven Sistare <steven.sistare@oracle.com> wrote:

> On 12/12/2022 10:58 AM, Alex Williamson wrote:
> > On Mon, 12 Dec 2022 09:17:54 -0400
> > Jason Gunthorpe <jgg@ziepe.ca> wrote:
> >
> >> On Sat, Dec 10, 2022 at 09:14:06AM -0500, Steven Sistare wrote:
> >>
> >>> Thank you for your thoughtful response. Rather than debate the degree of
> >>> of vulnerability, I propose an alternate solution. The technical crux of
> >>> the matter is support for mediated devices.
> >>
> >> I'm not sure I'm convinced about that. It is easy to make problematic
> >> situations with mdevs, but that doesn't mean other cases don't exist
> >> too eg what happens if userspace suspends and then immediately does
> >> something to trigger a domain attachment? Doesn't it still deadlock
> >> the kernel?
> >
> > The opportunity for that to deadlock isn't obvious to me, a replay
> > would be stalled waiting for invalid vaddrs, but this is essentially
> > the user deadlocking themselves. There's also code there to handle the
> > process getting killed while waiting, making it interruptible. Thanks,
>
> I will submit new patches tomorrow to exclude mdevs. Almost done.

I've dropped the removal commits from my next branch in the interim.
Thanks,

Alex