From: "H. Peter Anvin" <hpa@zytor.com>
To: Andy Lutomirski <luto@kernel.org>
Cc: Dan Rue <dan.rue@linaro.org>, Shuah Khan <shuah@kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Dmitry Safonov <dsafonov@virtuozzo.com>,
Borislav Petkov <bp@alien8.de>,
"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: Fri, 26 Jan 2018 14:51:19 -0800 [thread overview]
Message-ID: <9630de94-83ba-85ad-c5f3-a515f7aa7243@zytor.com> (raw)
In-Reply-To: <CALCETrWvkd68wPCxGwmzqgsLTr_59+=L9u8obwt+f+oUQwDY=w@mail.gmail.com>
On 01/26/18 11:46, Andy Lutomirski wrote:
>
> Under QEMU TCG, gs stays equal to 1. On native or KVM, on Skylake, it
> changes to 0.
>
> On KVM or native, I do not observe do_debug getting called with %gs ==
> 1. On TCG, I do. I don't think that's precisely the problem that's
> causing the test to fail, since the test doesn't use TF or ptrace, but
> I wouldn't be shocked if it's related.
>
> hpa, any insight?
>
> (NB: if you want to play with this as I've described it, you may need
> to make invalid_selector() in ptrace.c always return false. The
> current implementation is too strict and causes problems.)
>
Looking at it. I want to grok this in the general context of fsgsbase
as well, of course.
-hpa
prev parent reply other threads:[~2018-01-26 22:55 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
2018-01-26 22:56 ` Borislav Petkov
2018-01-28 19:21 ` Andy Lutomirski
2018-01-26 22:51 ` H. Peter Anvin [this message]
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