From: Dan Rue <dan.rue@linaro.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andy Lutomirski <luto@amacapital.net>,
Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@alien8.de>,
Shuah Khan <shuah@kernel.org>, Ingo Molnar <mingo@kernel.org>,
Dmitry Safonov <dsafonov@virtuozzo.com>,
"open list:KERNEL SELFTEST FRAMEWORK"
<linux-kselftest@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: selftests/x86/fsgsbase_64 test problem
Date: Tue, 27 Feb 2018 16:59:55 -0600 [thread overview]
Message-ID: <20180227225955.s2vs4g7oc7tdi72i@xps> (raw)
In-Reply-To: <0b0a3cea-d951-d3be-16de-a0e9d50cb2ba@zytor.com>
On Mon, Jan 29, 2018 at 10:30:05AM -0800, H. Peter Anvin wrote:
> On 01/29/18 10:26, Andy Lutomirski wrote:
> >>>
> >>> That will utterly suck on non-UMIP machines that have
> >>> hypervisor-provided UMIP emulation.
> >>
> >> Is that a valid thing to optimize for, especially given that paranoid
> >> entries aren't the most common anyway?
> >
> > A bunch of people seem to care about NMI performance for perf.
> >
>
> That wasn't really the question...
>
> > And the current patch set works without this trick.
>
> But I believe the tricks it uses are fragile.
>
> > FWIW, if we switch all entries to the entry text trampoline, we get direct percpu access for free.
>
> That might be a better option.
Has there been any conclusion to this thread? I can still reproduce the
issue on mainline and next.
Thanks,
Dan
next prev parent reply other threads:[~2018-02-27 23:00 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-26 15:36 Dan Rue
2018-01-26 16:22 ` Andy Lutomirski
2018-01-26 18:59 ` Andy Lutomirski
2018-01-26 19:46 ` Andy Lutomirski
2018-01-26 22:38 ` Andy Lutomirski
2018-01-26 22:42 ` Andy Lutomirski
2018-01-28 19:21 ` Andy Lutomirski
2018-01-29 9:13 ` H. Peter Anvin
2018-01-29 16:37 ` Andy Lutomirski
2018-01-29 18:12 ` H. Peter Anvin
2018-01-29 18:26 ` Andy Lutomirski
2018-01-29 18:30 ` H. Peter Anvin
2018-02-27 22:59 ` Dan Rue [this message]
2018-01-26 22:56 ` Borislav Petkov
2018-01-28 19:21 ` Andy Lutomirski
2018-01-26 22:51 ` H. Peter Anvin
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