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Subject: Re: [PATCH Part1 v5 38/38] virt: sevguest: Add support to get
 extended report
To:     Brijesh Singh <brijesh.singh@amd.com>, 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
Cc:     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>,
        Tobin Feldman-Fitzthum <tobin@ibm.com>,
        Borislav Petkov <bp@alien8.de>,
        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,
        Dov Murik <dovmurik@linux.ibm.com>
References: <20210820151933.22401-1-brijesh.singh@amd.com>
 <20210820151933.22401-39-brijesh.singh@amd.com>
From:   Dov Murik <dovmurik@linux.ibm.com>
Message-ID: <bd5b2d47-2f66-87d9-ce1e-dfe717741d22@linux.ibm.com>
Date:   Tue, 31 Aug 2021 23:22:04 +0300
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Hi Brijesh,

On 20/08/2021 18:19, Brijesh Singh wrote:
> Version 2 of GHCB specification defines NAE to get the extended guest
> request. It is similar to the SNP_GET_REPORT ioctl. The main difference
> is related to the additional data that be returned. The additional
> data returned is a certificate blob that can be used by the SNP guest
> user. 

It seems like the SNP_GET_EXT_REPORT ioctl does everything that the
SNP_GET_REPORT ioctl does, and more.  Why expose SNP_GET_REPORT to
userspace at all?


-Dov


> The certificate blob layout is defined in the GHCB specification.
> The driver simply treats the blob as a opaque data and copies it to
> userspace.
> 
> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
> ---
>  Documentation/virt/coco/sevguest.rst  |  22 +++++
>  drivers/virt/coco/sevguest/sevguest.c | 126 ++++++++++++++++++++++++++
>  include/uapi/linux/sev-guest.h        |  13 +++
>  3 files changed, 161 insertions(+)
> 

[...]