linux-kernel - Re: [PATCH 1/2] x86/sev: Add KVM commands for instance certs

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Message-ID: <CAAH4kHacW+hd8vB8QgkTjdw6+z-0ngjCqgr=zuGTwqqRnqUPQw@mail.gmail.com>
Date:   Wed, 12 Oct 2022 18:02:01 -0700
From:   Dionna Amalie Glaze <dionnaglaze@...gle.com>
To:     "Kalra, Ashish" <ashish.kalra@....com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        "the arch/x86 maintainers" <x86@...nel.org>,
        Tom Lendacky <Thomas.Lendacky@....com>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: Re: [PATCH 1/2] x86/sev: Add KVM commands for instance certs

> >> +    /* Page-align the length */
> >> +    length = (params.certs_len + PAGE_SIZE - 1) & PAGE_MASK;
> >
> > Probably can use PAGE_ALIGN() here.
> >

Ah, thanks. Will add in v2.

>
> Though, one thing i don't understand is that why do we need to issue
> the SNP_GUEST_REQUEST to FW if we are going to return the VMM
> overriden certs back to the guest ?
>
> Thanks,
> Ashish

If I'm reading the spec right, certs are supposed to come along with
the guest request when the user issues an extended guest request. If
the length is correct, we issue the command to get the report and we
simply override what the psp returns for the certs.

Is that your understanding too? If so, are you saying there's a bug in
this implementation?

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