Re: [RFC PATCH v2 04/20] x86: Secure Memory Encryption (SME) support

From: Andy Lutomirski
Date: Tue Aug 30 2016 - 10:57:56 EST

On Aug 30, 2016 6:34 AM, "Tom Lendacky" <thomas.lendacky@xxxxxxx> wrote:
> On 08/25/2016 08:04 AM, Thomas Gleixner wrote:
> > On Mon, 22 Aug 2016, Tom Lendacky wrote:
> >
> >> Provide support for Secure Memory Encryption (SME). This initial support
> >> defines the memory encryption mask as a variable for quick access and an
> >> accessor for retrieving the number of physical addressing bits lost if
> >> SME is enabled.
> >
> > What is the reason that this needs to live in assembly code?
> In later patches this code is expanded and deals with a lot of page
> table manipulation, cpuid/rdmsr instructions, etc. and so I thought it
> was best to do it this way.

None of that sounds like it needs to be in asm, though.

I, at least, have a strong preference for minimizing the amount of asm
in the low-level arch code.