linux-kernel - Re: [PATCH 38/62] x86/sev-es: Handle instruction fetches from user-space

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20200313091221.GA16378@suse.de>
Date:   Fri, 13 Mar 2020 10:12:21 +0100
From:   Joerg Roedel <jroedel@...e.de>
To:     Andy Lutomirski <luto@...nel.org>
Cc:     Joerg Roedel <joro@...tes.org>, X86 ML <x86@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        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>,
        LKML <linux-kernel@...r.kernel.org>,
        kvm list <kvm@...r.kernel.org>,
        Linux Virtualization <virtualization@...ts.linux-foundation.org>
Subject: Re: [PATCH 38/62] x86/sev-es: Handle instruction fetches from
 user-space

On Wed, Feb 12, 2020 at 01:42:48PM -0800, Andy Lutomirski wrote:
> I realize that this is a somewhat arbitrary point in the series to
> complain about this, but: the kernel already has infrastructure to
> decode and fix up an instruction-based exception.  See
> fixup_umip_exception().  Please refactor code so that you can share
> the same infrastructure rather than creating an entirely new thing.

Okay, but 'infrastructure' is a bold word for the call path down
fixup_umip_exception(). It uses the in-kernel instruction decoder, which
I already use in my patch-set. But I agree that some code in this
patch-set is duplicated and already present in the instruction decoder,
and that fixup_umip_exception() has more robust instruction decoding.

I factor the instruction decoding part out and make is usable for the
#VC handler too and remove the code that is already present in the
instruction decoder.

Regards,

	Joerg