Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
In-Reply-To: <20180323174447.55F35636@viggo.jf.intel.com>
References: <20180323174447.55F35636@viggo.jf.intel.com>
From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Fri, 23 Mar 2018 11:26:49 -0700
Message-ID: <CA+55aFwEC1O+6qRc35XwpcuLSgJ+0GP6ciqw_1Oc-msX=efLvQ@mail.gmail.com>
Subject: Re: [PATCH 00/11] Use global pages with PTI
To:     Dave Hansen <dave.hansen@linux.intel.com>
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-mm <linux-mm@kvack.org>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Andrew Lutomirski <luto@kernel.org>,
        Kees Cook <keescook@google.com>,
        Hugh Dickins <hughd@google.com>,
        =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= <jgross@suse.com>,
        "the arch/x86 maintainers" <x86@kernel.org>, namit@vmware.com
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Fri, Mar 23, 2018 at 10:44 AM, Dave Hansen
<dave.hansen@linux.intel.com> wrote:
>
> This adds one major change from the last version of the patch set
> (present in the last patch).  It makes all kernel text global for non-
> PCID systems.  This keeps kernel data protected always, but means that
> it will be easier to find kernel gadgets via meltdown on old systems
> without PCIDs.  This heuristic is, I think, a reasonable one and it
> keeps us from having to create any new pti=foo options

Sounds sane.

The patches look reasonable, but I hate seeing a patch series like
this where the only ostensible reason is performance, and there are no
performance numbers anywhere..

             Linus