Date:   Mon, 6 Feb 2023 21:11:11 +0100
From:   Borislav Petkov <bp@alien8.de>
To:     Tianyu Lan <ltykernel@gmail.com>
Cc:     Tom Lendacky <thomas.lendacky@amd.com>, luto@kernel.org,
        tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com,
        x86@kernel.org, hpa@zytor.com, seanjc@google.com,
        pbonzini@redhat.com, jgross@suse.com, tiala@microsoft.com,
        kirill@shutemov.name, jiangshan.ljs@antgroup.com,
        peterz@infradead.org, ashish.kalra@amd.com, srutherford@google.com,
        akpm@linux-foundation.org, anshuman.khandual@arm.com,
        pawan.kumar.gupta@linux.intel.com, adrian.hunter@intel.com,
        daniel.sneddon@linux.intel.com, alexander.shishkin@linux.intel.com,
        sandipan.das@amd.com, ray.huang@amd.com, brijesh.singh@amd.com,
        michael.roth@amd.com, venu.busireddy@oracle.com,
        sterritt@google.com, tony.luck@intel.com, samitolvanen@google.com,
        fenghua.yu@intel.com, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org, linux-hyperv@vger.kernel.org,
        linux-arch@vger.kernel.org
Subject: Re: [RFC PATCH V3 10/16] x86/hyperv: Add smp support for sev-snp
 guest
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On Fri, Feb 03, 2023 at 03:00:44PM +0800, Tianyu Lan wrote:
> > For the bits definition, use:
> > 
> >              u64 sev_feature_snp            : 1,
> >                  sev_feature_vtom            : 1,
> >                  sev_feature_reflectvc        : 1,
> >                  ...
> > 
> 
> Good suggestion. Thanks.

Actually, I'd prefer if you used a named union and drop all this
"sev_feature_" prefixes everywhere:

        union {
                struct {
                        u64 snp                     : 1;
                        u64 vtom                    : 1;
                        u64 reflectvc               : 1;
                        u64 restrict_injection      : 1;
                        u64 alternate_injection     : 1;
                        u64 full_debug              : 1;
                        u64 reserved1               : 1;
                        u64 snpbtb_isolation        : 1;
                        u64 resrved2                : 56;
                };
                u64 val;
        } sev_features;


so that you can do in code:

	struct sev_es_save_area *sev;

	...

	sev->sev_features.snp = ...

and so on.

Thx.

-- 
Regards/Gruss,
    Boris.

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