[MODERATED] Re: [PATCH 1/6] Patch 1

[Linus Torvalds <torvalds@linux-foundation.org>]

On Wed, 25 Apr 2018, speck for Andi Kleen wrote:
> 
> This doesn't help unfortunately because it could also leak data inside
> the guest. If skipping EPT causes the PA to point to some other page
> inside the same guest you can leak that data. And that other page might
> be owned by the kernel or by some other process.

Do you even read what I write?

THAT'S EXACTLY WHAT I TALKED ABOUT IN THE REST OF THE EMAIL.

> There was also another case, brought up by Google ChromeOS, where they
> control/trust the guest kernel and want to rely on it from accessing
> data outside the current guest, so not needing flush mitigations in the VMM. 
> That one is a bit more dubious, but I guess it's also not completely broken.

And I mentioned this exact case too. But pointed out that there is NO WAY 
IN HELL that your patch will fix it either but that there are other 
possible alternatives to mitigate things if you trust the guest OS.

Of course, if you trust the guest, then why the hell are you even doing 
virtualization in the first place? 

                Linus