linux-kernel - Re: [PATCH v3 25/75] x86/sev-es: Add support for handling IOIO exceptions

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Date:   Thu, 4 Jun 2020 07:59:33 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Joerg Roedel <joro@...tes.org>
Cc:     x86@...nel.org, hpa@...or.com, Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Hellstrom <thellstrom@...are.com>,
        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 25/75] x86/sev-es: Add support for handling IOIO
 exceptions

On Thu, Jun 04, 2020 at 12:15:02PM +0200, Joerg Roedel wrote:
> On Wed, Jun 03, 2020 at 04:07:16PM -0700, Sean Christopherson wrote:
> > On Wed, Jun 03, 2020 at 04:23:25PM +0200, Joerg Roedel wrote:
> > > User-space can also cause IOIO #VC exceptions, and user-space can be
> > > 32-bit legacy code with segments, so es_base has to be taken into
> > > account.
> > 
> > Is there actually a use case for this?  Exposing port IO to userspace
> > doesn't exactly improve security.
> 
> Might be true, but Linux supports it and this patch-set is not the place
> to challenge this feature.

But SEV already broke it, no?