From: Borislav Petkov <bp@alien8.de>
To: Juergen Gross <jgross@suse.com>
Cc: linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org,
x86@kernel.org, boris.ostrovsky@oracle.com, hpa@zytor.com,
tglx@linutronix.de, mingo@redhat.com
Subject: Re: [PATCH] x86/amd: don't set X86_BUG_SYSRET_SS_ATTRS if forced to zero
Date: Tue, 25 Apr 2017 21:18:09 +0200 [thread overview]
Message-ID: <20170425191809.uvdt4jimnbvqbyf2@pd.tnic> (raw)
In-Reply-To: <f3cf034d-1a26-cfce-cf67-ebaa3b377cfc@suse.com>
On Tue, Apr 25, 2017 at 08:34:34PM +0200, Juergen Gross wrote:
> And what happens when there is a scheduling event right here?
> __switch_to() will see X86_BUG_SYSRET_SS_ATTRS set and take a wrong
> path.
So the whole thing we're doing right now is wrong: set bit and then
clear bit.
We should not set the bit at all and there won't be any window to get it
wrong.
So can we do something like this instead:
if (!cpu_has(c, X86_FEATURE_XENPV))
set_cpu_bug(c, X86_BUG_SYSRET_SS_ATTRS);
or is XENPV the wrong thing to test?
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
next prev parent reply other threads:[~2017-04-25 19:18 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-25 18:00 [PATCH] x86/amd: don't set X86_BUG_SYSRET_SS_ATTRS if forced to zero Juergen Gross
2017-04-25 18:24 ` Borislav Petkov
2017-04-25 18:24 ` Borislav Petkov
2017-04-25 18:34 ` Juergen Gross
2017-04-25 19:18 ` Borislav Petkov [this message]
2017-04-25 20:17 ` [Xen-devel] " Andrew Cooper
2017-04-25 20:27 ` Borislav Petkov
2017-04-25 20:27 ` [Xen-devel] " Borislav Petkov
2017-04-25 20:17 ` Andrew Cooper
2017-04-26 4:45 ` Juergen Gross
2017-04-26 6:35 ` Borislav Petkov
2017-04-26 6:35 ` Borislav Petkov
2017-04-26 18:24 ` Juergen Gross
2017-04-26 18:24 ` Juergen Gross
2017-04-26 22:04 ` Borislav Petkov
2017-04-26 22:04 ` Borislav Petkov
2017-04-27 4:44 ` Juergen Gross
2017-04-27 4:44 ` Juergen Gross
2017-04-26 4:45 ` Juergen Gross
2017-04-25 19:18 ` Borislav Petkov
2017-04-25 18:34 ` Juergen Gross
2017-04-25 18:00 Juergen Gross
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