linux-kernel - Re: [Part2 PATCH v5.1 12.4/31] crypto: ccp: Implement SEV_PLATFORM

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Message-ID: <20171011205407.qky5tr2jmjttse7g@pd.tnic>
Date:   Wed, 11 Oct 2017 22:54:07 +0200
From:   Borislav Petkov <bp@...e.de>
To:     Brijesh Singh <brijesh.singh@....com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Gary Hook <gary.hook@....com>,
        Tom Lendacky <thomas.lendacky@....com>,
        linux-crypto@...r.kernel.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [Part2 PATCH v5.1 12.4/31] crypto: ccp: Implement
 SEV_PLATFORM_STATUS ioctl command

On Wed, Oct 11, 2017 at 03:45:00PM -0500, Brijesh Singh wrote:
> OK, if userspace is going to pick bits apart then how about this:
> 
>  struct sev_data_status {
>          u8 api_major;                           /* Out */
>          u8 api_minor;                           /* Out */
>          u8 state;                               /* Out */
>          u32 flags;                              /* Out */
>          u8 build;                               /* Out */

I guess. Except the spec marks those as 31:24 and belonging to the dword
starting at offset 4 and you've made "build" a separate u8 and the dword
starts at offset 3. I mean, not a big deal, I think you can change the
spec for a change :-)

Because it looks like the 4 bytes starting at offset 3 really are meant
for miscellaneous bits. And then CONFIG.ES could've been bit 1 of the
byte at offset 3. Oh well...

> Please let me know if you are okay with my above structure.

But yeah, in the end of the day it probably doesn't matter a whole lot.
The spec just counts those in 32-bit quantities.

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--