linux-kernel - Re: [PATCH Part2 v6 06/49] x86/sev: Add helper functions for RMPUPDATE and PSMASH instruction

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Message-ID: <YuraC/P4k0FgHM17@zn.tnic>
Date:   Wed, 3 Aug 2022 22:26:51 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     "Kalra, Ashish" <Ashish.Kalra@....com>
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Subject: Re: [PATCH Part2 v6 06/49] x86/sev: Add helper functions for
 RMPUPDATE and PSMASH instruction

On Mon, Aug 01, 2022 at 10:31:26PM +0000, Kalra, Ashish wrote:
> The struct rmpentry is the raw layout of the RMP table entry
> while struct rmpupdate is the structure expected by the rmpupdate
> instruction for programming the RMP table entries.
>
> Arguably, we can program a struct rmpupdate internally from a struct
> rmpentry.
>
> But we will still need struct rmpupdate for issuing the rmpupdate
> instruction, so it is probably cleaner to keep it this way, as it only
> has two main callers - rmp_make_private() and rmp_make_shared().

Ok, but then call it struct rmp_state. The APM says in the RMPUPDATE
blurb:

"The RCX register provides the effective address of a 16-byte data
structure which contains the new RMP state."

so the function signature should be:

static int rmpupdate(u64 pfn, struct rmp_state *new)

and this is basically the description of that. It can't get any more
user-friendly than this.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette