linux-kernel - Re: [PATCH Part1 RFC v3 11/22] x86/sev: Add helper for validating pages in early enc attribute changes

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Date:   Wed, 16 Jun 2021 12:07:28 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Brijesh Singh <brijesh.singh@....com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-efi@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        linux-coco@...ts.linux.dev, linux-mm@...ck.org,
        linux-crypto@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Joerg Roedel <jroedel@...e.de>,
        Tom Lendacky <thomas.lendacky@....com>,
        "H. Peter Anvin" <hpa@...or.com>, Ard Biesheuvel <ardb@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Sergio Lopez <slp@...hat.com>, Peter Gonda <pgonda@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        David Rientjes <rientjes@...gle.com>, tony.luck@...el.com,
        npmccallum@...hat.com
Subject: Re: [PATCH Part1 RFC v3 11/22] x86/sev: Add helper for validating
 pages in early enc attribute changes

On Mon, Jun 14, 2021 at 04:01:44PM -0500, Brijesh Singh wrote:
> Now that we have to defined a Linux specific reason set, we could
> potentially define a new error code "Invalid response code" and return

I don't understand - you have a WARN for the following check:

                if (WARN(GHCB_MSR_PSC_RESP_VAL(val),
                         "Failed to change page state to '%s' paddr 0x%lx error 0x%llx\n",

what's wrong with doing:

                if (WARN(GHCB_RESP_CODE(val) != GHCB_MSR_PSC_RESP,
                         "Wrong PSC response code: 0x%x\n",
                         (unsigned int)GHCB_RESP_CODE(val)))
                        goto e_term;


above it too?

-- 
Regards/Gruss,
    Boris.

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