linux-kernel - Re: [PATCH v6 02/76] KVM: SVM: Add GHCB definitions

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Message-ID: <20200825110446.GC12107@zn.tnic>
Date:   Tue, 25 Aug 2020 13:04:46 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Joerg Roedel <joro@...tes.org>
Cc:     x86@...nel.org, Joerg Roedel <jroedel@...e.de>,
        Tom Lendacky <thomas.lendacky@....com>, hpa@...or.com,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Jiri Slaby <jslaby@...e.cz>,
        Dan Williams <dan.j.williams@...el.com>,
        Juergen Gross <jgross@...e.com>,
        Kees Cook <keescook@...omium.org>,
        David Rientjes <rientjes@...gle.com>,
        Cfir Cohen <cfir@...gle.com>,
        Erdem Aktas <erdemaktas@...gle.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Mike Stunes <mstunes@...are.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Martin Radev <martin.b.radev@...il.com>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH v6 02/76] KVM: SVM: Add GHCB definitions

On Tue, Aug 25, 2020 at 11:22:24AM +0200, Joerg Roedel wrote:
> I don't think so, if I look at the history of these checks their whole
> purpose seems to be to alert the developer/maintainer when their size
> changes and that they might not fit on the stack anymore. But that is
> taken care of in patch 1.

Why? What's wrong with:

	BUILD_BUG_ON(sizeof(struct vmcb_save_area) != VMCB_SAVE_AREA_SIZE);
	BUILD_BUG_ON(sizeof(struct vmcb_control_area) != VMCB_CONTROL_AREA_SIZE);
	BUILD_BUG_ON(sizeof(struct ghcb) != PAGE_SIZE);

?

-- 
Regards/Gruss,
    Boris.

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