linux-kernel - Re: [PATCH RFC v7 62/64] x86/sev: Add KVM commands for instance certs

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Message-ID: <CAAH4kHYOtzgqSTZQFcRiZwPLCkLAThjsCMdjUCdsBTiP=W0Vxw@mail.gmail.com>
Date:   Thu, 19 Jan 2023 17:40:10 -0800
From:   Dionna Amalie Glaze <dionnaglaze@...gle.com>
To:     "Kalra, Ashish" <ashish.kalra@....com>
Cc:     Michael Roth <michael.roth@....com>, kvm@...r.kernel.org,
        linux-coco@...ts.linux.dev, linux-mm@...ck.org,
        linux-crypto@...r.kernel.org, x86@...nel.org,
        linux-kernel@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
        jroedel@...e.de, thomas.lendacky@....com, hpa@...or.com,
        ardb@...nel.org, pbonzini@...hat.com, seanjc@...gle.com,
        vkuznets@...hat.com, wanpengli@...cent.com, jmattson@...gle.com,
        luto@...nel.org, dave.hansen@...ux.intel.com, slp@...hat.com,
        pgonda@...gle.com, peterz@...radead.org,
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        dgilbert@...hat.com, jarkko@...nel.org, harald@...fian.com
Subject: Re: [PATCH RFC v7 62/64] x86/sev: Add KVM commands for instance certs

On Thu, Jan 19, 2023 at 2:18 PM Kalra, Ashish <ashish.kalra@....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)