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Date:   Mon, 23 Aug 2021 16:16:51 +0200
From:   Borislav Petkov <bp@alien8.de>
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,
        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>,
        Sean Christopherson <seanjc@google.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>,
        Michael Roth <michael.roth@amd.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        "Kirill A . Shutemov" <kirill@shutemov.name>,
        Andi Kleen <ak@linux.intel.com>, tony.luck@intel.com,
        marcorr@google.com, sathyanarayanan.kuppuswamy@linux.intel.com
Subject: Re: [PATCH Part1 v5 11/38] x86/compressed: Add helper for validating
 pages in the decompression stage
Message-ID: <YSOt01Qk9KOsTVj/@zn.tnic>
References: <20210820151933.22401-1-brijesh.singh@amd.com>
 <20210820151933.22401-12-brijesh.singh@amd.com>
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On Fri, Aug 20, 2021 at 10:19:06AM -0500, Brijesh Singh wrote:
> diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h
> index d426c30ae7b4..1cd8ce838af8 100644
> --- a/arch/x86/include/asm/sev-common.h
> +++ b/arch/x86/include/asm/sev-common.h
> @@ -57,6 +57,26 @@
>  #define GHCB_MSR_AP_RESET_HOLD_REQ	0x006
>  #define GHCB_MSR_AP_RESET_HOLD_RESP	0x007
>  
> +/* SNP Page State Change */

Let's make it very clear here that those cmd numbers below are actually
part of the protocol and not randomly chosen:

/*
 * ...
 *
 * 0x014 – SNP Page State Change Request
 *
 * GHCBData[55:52] – Page operation:
 *   0x0001 – Page assignment, Private
 *   0x0002 – Page assignment, Shared
 */

> +enum psc_op {
> +	SNP_PAGE_STATE_PRIVATE = 1,
> +	SNP_PAGE_STATE_SHARED,
> +};
> +

-- 
Regards/Gruss,
    Boris.

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