linux-kernel - Re: [PATCH v3 54/75] x86/sev-es: Handle DR7 read/write events

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Message-ID: <20200611130633.GD11924@8bytes.org>
Date:   Thu, 11 Jun 2020 15:06:33 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Borislav Petkov <bp@...en8.de>
Cc:     x86@...nel.org, 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>,
        Tom Lendacky <thomas.lendacky@....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>,
        Joerg Roedel <jroedel@...e.de>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH v3 54/75] x86/sev-es: Handle DR7 read/write events

On Mon, May 25, 2020 at 12:59:35PM +0200, Borislav Petkov wrote:
> On Tue, Apr 28, 2020 at 05:17:04PM +0200, Joerg Roedel wrote:
> > +	if (data)
> > +		data->dr7 = val;
> 
> Are we still returning ES_OK if !data?

Yes, it just means we ignore DR7 writes when they happen early before
runtime_data is allocated. Since the DR7 value never makes it to the
hardware register anyway, it doesn't matter.


	Joerg