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

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Date:   Wed, 11 Oct 2017 15:53:39 -0500
From:   Brijesh Singh <brijesh.singh@....com>
To:     Borislav Petkov <bp@...e.de>
Cc:     brijesh.singh@....com, 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 10/11/2017 03:45 PM, Brijesh Singh wrote:
> 
> 
> On 10/11/2017 03:28 PM, Borislav Petkov wrote:
>> On Wed, Oct 11, 2017 at 03:10:49PM -0500, Brijesh Singh wrote:
>>> The current 'struct sev_data_status' matches with the firmware names 
>>> and the
>>> bit fields. Only thing I did was the fields with no name is called as
>>> "reservedX"
>>
>> Ok, I see it. So what you actually wanna do is:
>>
>> struct sev_data_status {
>>          u8 api_major;                           /* Out */
>>          u8 api_minor;                           /* Out */
>>          u8 state;                               /* Out */
>>          u8 flags;                               /* Out */
>>          u32 config;                             /* Out */
>>          u32 guest_count;                        /* Out */
>> } __packed;
>>
> 
> 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 */
>           u32 guest_count;                        /* Out */
>   } __packed;
> 


BTW, I kept the build name because KVM driver prints some debug 
information like this:

pr_info_once("SEV: api_major %d api_minor %d build %d\n",
               status->api_major, status->api_minor, status->build);

Of course, I can modify it to access bit field if we decide to go with 
your recommended structure - thanks