Re: [RFC PATCH v4 03/28] x86: Add the Secure Memory Encryption CPU feature

Borislav Petkov
2017-02-16T20:06:30Z

On Thu, Feb 16, 2017 at 01:42:13PM -0600, Tom Lendacky wrote:
> I realize it's a bit more code and expands the changes but I thought it
> would be a bit clearer as to what was going on this way. And then the
> follow on patch for the physical address reduction goes in nicely, too.

Well, the code from the next patch should go to AMD-specific place like
arch/x86/kernel/cpu/amd.c anyway, where you don't have to do vendor
checks.

> If you prefer I stay with the scattered feature approach and then clear
> the bit based on the MSR at the end of init_amd() I can do that. I'm
> not attached to either method.

Yes please. We should keep the shole X86_FEATURE machinery from
exploding in size. Especially if CPUID_0x8000001f is not a leaf we're
going to be adding the majority of its bits, to warrant a separate
->x86_capability array element.

[If it does later, we can always move it to a separate element. ]

Thanks.

--
Regards/Gruss,
Boris.

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