Re: [RFC Part1 PATCH v3 02/17] x86/CPU/AMD: Add the Secure Encrypted Virtualization CPU feature

Tom Lendacky
2017-07-25T14:58:54Z

On 7/25/2017 9:36 AM, Borislav Petkov wrote:
> On Tue, Jul 25, 2017 at 09:29:40AM -0500, Tom Lendacky wrote:
>> Yup, we can do something like that. I believe the only change that
>> would be needed to your patch would be to move the IS_ENABLED() check
>> to after the physical address space reduction check.
>
> Yeah, I wasn't sure about that. The logic is that if BIOS has enabled
> SME and thus reduction is in place, we need to update x86_phys_bits on
> 32-bit regardless, right?
>
> But, come to think of it, that reduction won't have any effect since we
> have 32-bit addresses and the reduction is above 32-bits, right? And
> thus it is moot.

True, but it is more about being accurate and making sure the value is
correct where ever it may be used.

Thanks,
Tom

>
> Or?
>