Re: [PATCH v2] Linux VM workaround for Knights Landing A/D leak

[H. Peter Anvin]

On 06/14/16 13:47, Borislav Petkov wrote:
> On Tue, Jun 14, 2016 at 01:20:06PM -0700, H. Peter Anvin wrote:
>> static_cpu_has_bug() should turn into 5-byte NOP in the common (bugless)
>> case.
> 
> Yeah, it does. I looked at the asm.
> 
> I wasn't 100% sure because I vaguely remember gcc reordering things in
> some pathological case but I'm most likely remembering wrong because if
> it were doing that, then the whole nopping out won't work. F'get about
> it. :)
> 

There was that.  It is still possible that we end up with NOP a JMP
right before another JMP; we could perhaps make the patching code
smarter and see if we have a JMP immediately after.

	-hpa