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From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Wed, 11 Jul 2018 09:28:39 -0700
Message-ID: <CA+55aFzrG+GV5ySVUiiod8Va5P0_vmUuh25Pner1r7c_aQgH9g@mail.gmail.com>
Subject: Re: [PATCH 00/39 v7] PTI support for x86-32
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To: Joerg Roedel <joro@8bytes.org>
Cc: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@kernel.org>, Peter Anvin <hpa@zytor.com>, the arch/x86 maintainers <x86@kernel.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, linux-mm <linux-mm@kvack.org>, Andrew Lutomirski <luto@kernel.org>, Dave Hansen <dave.hansen@intel.com>, Josh Poimboeuf <jpoimboe@redhat.com>, =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= <jgross@suse.com>, Peter Zijlstra <peterz@infradead.org>, Borislav Petkov <bp@alien8.de>, Jiri Kosina <jkosina@suse.cz>, Boris Ostrovsky <boris.ostrovsky@oracle.com>, Brian Gerst <brgerst@gmail.com>, David Laight <David.Laight@aculab.com>, Denys Vlasenko <dvlasenk@redhat.com>, Eduardo Valentin <eduval@amazon.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Will Deacon <will.deacon@arm.com>, "Liguori, Anthony" <aliguori@amazon.com>, Daniel Gruss <daniel.gruss@iaik.tugraz.at>, Hugh Dickins <hughd@google.com>, Kees Cook <keescook@google.com>, Andrea Arcangeli <aarcange@redhat.com>, Waiman Long <llong@redhat.com>, Pavel Machek <pavel@ucw.cz>, "David H . Gutteridge" <dhgutteridge@sympatico.ca>, Joerg Roedel <jroedel@suse.de>

On Wed, Jul 11, 2018 at 4:30 AM Joerg Roedel <joro@8bytes.org> wrote:
>
> I did the load-testing again with 'perf top', the ldt_gdt
> self-test and a kernel-compile running in a loop again.

So none of the patches looked scary to me, but then, neither did
earlier versions.

It's the testing that worries me most. Pretty much no developers run
32-bit any more, and I'd be most worried about the odd interactions
that might be hw-specific. Some crazy EFI mapping setup or the similar
odd case that simply requires a particular configuration or setup.

But I guess those issues will never be found until we just spring this
all on the unsuspecting public.

                 Linus