Received-SPF: pass (google.com: domain of linux-crypto-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20221214194056.161492-1-michael.roth@amd.com> <20221214194056.161492-63-michael.roth@amd.com>
 <CAAH4kHZVaeL57bGAzeDjJDTumsnb96iAYBdhm7cs_8TjBg+v3w@mail.gmail.com> <d09e13c2-3a3d-924b-05b3-560fe1121516@amd.com>
In-Reply-To: <d09e13c2-3a3d-924b-05b3-560fe1121516@amd.com>
From:   Dionna Amalie Glaze <dionnaglaze@google.com>
Date:   Thu, 19 Jan 2023 17:40:10 -0800
Message-ID: <CAAH4kHYOtzgqSTZQFcRiZwPLCkLAThjsCMdjUCdsBTiP=W0Vxw@mail.gmail.com>
Subject: Re: [PATCH RFC v7 62/64] x86/sev: Add KVM commands for instance certs
To:     "Kalra, Ashish" <ashish.kalra@amd.com>
Cc:     Michael Roth <michael.roth@amd.com>, kvm@vger.kernel.org,
        linux-coco@lists.linux.dev, linux-mm@kvack.org,
        linux-crypto@vger.kernel.org, x86@kernel.org,
        linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com,
        jroedel@suse.de, thomas.lendacky@amd.com, hpa@zytor.com,
        ardb@kernel.org, pbonzini@redhat.com, seanjc@google.com,
        vkuznets@redhat.com, wanpengli@tencent.com, jmattson@google.com,
        luto@kernel.org, dave.hansen@linux.intel.com, slp@redhat.com,
        pgonda@google.com, peterz@infradead.org,
        srinivas.pandruvada@linux.intel.com, rientjes@google.com,
        dovmurik@linux.ibm.com, tobin@ibm.com, bp@alien8.de,
        vbabka@suse.cz, kirill@shutemov.name, ak@linux.intel.com,
        tony.luck@intel.com, marcorr@google.com,
        sathyanarayanan.kuppuswamy@linux.intel.com, alpergun@google.com,
        dgilbert@redhat.com, jarkko@kernel.org, harald@profian.com
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Thu, Jan 19, 2023 at 2:18 PM Kalra, Ashish <ashish.kalra@amd.com> wrote:
>
> Hello Dionna,
>
> Do you also have other updates to this patch with regard to review
> comments from Dov ?
>

Apart from the PAGE_ALIGN change, the result of the whole discussion
appears to only need the following immediately before the
copy_from_user of certs_uaddr in the snp_set_instance_certs function:

/* The size could shrink and leave garbage at the end. */
memset(sev->snp_certs_data, 0, SEV_FW_BLOB_MAX_SIZE);

I don't believe there is an off-by-one with the page shifting for the
number of pages because snp_certs_len is already rounded up to the
nearest page size. Any other change wrt the way the blob size is
decided between the guest and host should come later.

-- 
-Dionna Glaze, PhD (she/her)