From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: "Xen-Devel (E-mail)" <xen-devel@lists.xensource.com>
Subject: Re: write_tsc in a PV domain?
Date: Tue, 25 Aug 2009 15:28:01 -0700 [thread overview]
Message-ID: <4A946571.30904@goop.org> (raw)
In-Reply-To: <2812f1b0-adb1-48bc-925e-5fc1e6b22f0c@default>
On 08/25/09 14:54, Dan Magenheimer wrote:
> Is it "legal" to write to the TSC, e.g. via wrmsr(0x10,x,y),
> in a PV kernel? Assuming this were executed and would cause
> a GPF, I can't find the code in Xen that would handle it, or
> even ignore it.
>
arch/x86/traps.c:emulate_privileged_op(), case 0x30. It looks like
writing to 0x10 would be silently ignored. Allowing it would require
careful handling to avoid screwing up timekeeping (you'd need to update
the timekeeping parameters), but also fairly pointless because it would
only affect the pcpu that the vcpu happens to be running on at that moment.
J
next prev parent reply other threads:[~2009-08-25 22:28 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-08-25 21:54 write_tsc in a PV domain? Dan Magenheimer
2009-08-25 22:28 ` Jeremy Fitzhardinge [this message]
2009-08-25 23:09 ` Dan Magenheimer
2009-08-26 6:23 ` Keir Fraser
2009-08-26 15:42 ` Dan Magenheimer
2009-08-26 15:58 ` Keir Fraser
2009-08-26 19:45 ` Jeremy Fitzhardinge
2009-08-26 20:23 ` Dan Magenheimer
2009-08-26 22:30 ` Jeremy Fitzhardinge
2009-08-26 23:10 ` Dan Magenheimer
2009-08-27 8:39 ` Chris Lalancette
2009-08-27 13:00 ` Dan Magenheimer
2009-08-27 13:17 ` Chris Lalancette
2009-08-27 8:48 ` Alan Cox
2009-08-27 19:10 ` Jeremy Fitzhardinge
2009-08-28 3:29 ` Dan Magenheimer
2009-08-28 9:49 ` Alan Cox
2009-08-28 15:16 ` Dan Magenheimer
2009-08-28 15:30 ` Alan Cox
2009-08-28 17:49 ` rdtsc: correctness vs performance on Xen (and KVM?) Dan Magenheimer
2009-08-31 23:52 ` Dan Magenheimer
2009-09-01 0:22 ` Jeremy Fitzhardinge
2009-09-01 13:54 ` Dan Magenheimer
2009-09-01 14:34 ` Keir Fraser
2009-09-01 14:53 ` Dan Magenheimer
2009-09-01 15:08 ` Keir Fraser
2009-09-01 15:26 ` Dan Magenheimer
2009-09-01 15:32 ` Jan Beulich
2009-09-01 15:56 ` Dan Magenheimer
2009-09-01 16:04 ` Jan Beulich
2009-09-01 16:41 ` Dan Magenheimer
2009-09-02 7:05 ` Jan Beulich
2009-09-01 21:25 ` Keir Fraser
2009-09-01 22:08 ` Dan Magenheimer
2009-09-01 22:21 ` Jeremy Fitzhardinge
2009-09-01 22:41 ` Dan Magenheimer
2009-09-01 23:26 ` Jeremy Fitzhardinge
2009-09-02 7:20 ` Keir Fraser
2009-09-02 21:44 ` Jeremy Fitzhardinge
2009-09-02 21:50 ` Keir Fraser
2009-09-02 22:05 ` Jeremy Fitzhardinge
2009-09-03 8:23 ` Jan Beulich
2009-09-03 17:29 ` Jeremy Fitzhardinge
2009-09-04 7:19 ` Jan Beulich
2009-09-04 15:44 ` Jeremy Fitzhardinge
2009-09-03 14:22 ` Dan Magenheimer
2009-09-02 7:16 ` Jan Beulich
2009-09-02 7:01 ` Jan Beulich
2009-09-01 16:06 ` Keir Fraser
2009-09-01 16:55 ` Dan Magenheimer
2009-09-01 15:43 ` Keir Fraser
2009-08-28 17:49 ` write_tsc in a PV domain? Dan Magenheimer
2009-08-28 17:02 ` Jeremy Fitzhardinge
2009-08-28 17:49 ` Dan Magenheimer
2009-08-28 23:01 ` Jeremy Fitzhardinge
2009-08-29 17:51 ` Dan Magenheimer
2009-08-31 18:11 ` Dan Magenheimer
2009-08-31 19:06 ` Keir Fraser
2009-08-31 21:06 ` Dan Magenheimer
2009-09-01 7:16 ` Keir Fraser
2009-08-31 19:18 ` Jeremy Fitzhardinge
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