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Date:   Fri, 16 Jul 2021 19:33:31 +0000
From:   Sean Christopherson <seanjc@google.com>
To:     Brijesh Singh <brijesh.singh@amd.com>
Cc:     x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
        linux-efi@vger.kernel.org, platform-driver-x86@vger.kernel.org,
        linux-coco@lists.linux.dev, linux-mm@kvack.org,
        linux-crypto@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Joerg Roedel <jroedel@suse.de>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Ard Biesheuvel <ardb@kernel.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Andy Lutomirski <luto@kernel.org>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Sergio Lopez <slp@redhat.com>, Peter Gonda <pgonda@google.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
        David Rientjes <rientjes@google.com>,
        Dov Murik <dovmurik@linux.ibm.com>,
        Tobin Feldman-Fitzthum <tobin@ibm.com>,
        Borislav Petkov <bp@alien8.de>,
        Michael Roth <michael.roth@amd.com>,
        Vlastimil Babka <vbabka@suse.cz>, tony.luck@intel.com,
        npmccallum@redhat.com, brijesh.ksingh@gmail.com
Subject: Re: [PATCH Part2 RFC v4 22/40] KVM: SVM: Add KVM_SNP_INIT command
Message-ID: <YPHfC1mI8dQkkzyV@google.com>
References: <20210707183616.5620-1-brijesh.singh@amd.com>
 <20210707183616.5620-23-brijesh.singh@amd.com>
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In-Reply-To: <20210707183616.5620-23-brijesh.singh@amd.com>
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On Wed, Jul 07, 2021, Brijesh Singh wrote:
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 3fd9a7e9d90c..989a64aa1ae5 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1678,6 +1678,9 @@ enum sev_cmd_id {
>  	/* Guest Migration Extension */
>  	KVM_SEV_SEND_CANCEL,
>  
> +	/* SNP specific commands */
> +	KVM_SEV_SNP_INIT = 256,

Is there any meaning behind '256'?  If not, why skip a big chunk?  I wouldn't be
concerned if it weren't for KVM_SEV_NR_MAX, whose existence arguably implies that
0-KVM_SEV_NR_MAX-1 are all valid SEV commands.

> +
>  	KVM_SEV_NR_MAX,
>  };