Re: [RESEND RFC PATCH] x86/bugs: Add "unknown" reporting for MMIO Stale Data

['Pawan Gupta']

On Fri, Jul 29, 2022 at 10:40:20AM +0000, David Laight wrote:
> From: Pawan Gupta
> > Sent: 29 July 2022 03:29
> > 
> > On Thu, Jul 28, 2022 at 02:00:13PM +0200, Borislav Petkov wrote:
> > > On Thu, Jul 14, 2022 at 06:30:18PM -0700, Pawan Gupta wrote:
> > > > Older CPUs beyond its Servicing period are not listed in the affected
> > > > processor list for MMIO Stale Data vulnerabilities. These CPUs currently
> > > > report "Not affected" in sysfs, which may not be correct.
> 
> I looked this up....
> 
> The mitigations seem to rely on unprivileged code not being able
> to do MMIO accesses.
> That isn't true, device drivers can mmap PCIe addresses directly
> into user program address space.
> While unlikely, there is no reason this can't be supported for
> non-root processes.

Agree. Would it be fair to assume that processes that get direct
hardware access are trusted?