EDAC on arm64

[arnd@arndb.de (Arnd Bergmann)]

On Monday 02 March 2015 14:58:41 Catalin Marinas wrote:
> On Mon, Mar 02, 2015 at 10:59:32AM +0000, Will Deacon wrote:
> > On Sat, Feb 28, 2015 at 12:52:03AM +0000, Jon Masters wrote:
> > > Have you considered reviving the patch you posted previously for EDAC
> > > support (the atomic_scrub read/write test piece dependency)?
> > > 
> > > http://lists.infradead.org/pipermail/linux-arm-kernel/2014-April/249039.html
> > 
> > Well, we'd need a way to handle the non-coherent DMA case and it's really
> > not clear how to fix that.
> 
> I agree, that's where the discussions stopped. Basically the EDAC memory
> writing is racy with any non-cacheable memory accesses (by CPU or
> device). The only way we could safely use this is only if all the
> devices are coherent *and* KVM is disabled. With KVM, guests may access
> the memory uncached, so we hit the same problem.

Is this a setting of the host, or does the guest always have this capability?

If a guest can influence the caching of a page it has access to, I can
imagine all sorts of security problems with malicious guests regardless
of EDAC.

	Arnd