Re: [PATCH v1 1/2] x86/mm, kexec: Fix memory corruption with SME on successive kexecs

[Tom Lendacky]

On 7/27/2017 12:34 PM, Linus Torvalds wrote:
> On Thu, Jul 27, 2017 at 7:15 AM, Tom Lendacky <thomas.lendacky@xxxxxxx> wrote:
> > I can #ifdef the wbinvd based on whether AMD_MEM_ENCRYPT is configured
> > or not so that the wbinvd is avoided if not configured.
>
> I suspect an ifdef will be useless, since things like distro kernels
> tend to enable everything.
>
> So it should probably be disabled dynamically, and only done if the
> AMD memory encryption thing has actually been active.
>
> [ There have also been various actual errata with wbinvd, so there
> tends to be a non-performance reason to try to avoid it unless
> strictly required ]

Ok, I'll make the wbinvd a run time decision based on whether SME is
active at the time.

Thanks,
Tom

>                 Linus