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From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	gang.wei@intel.com, JBeulich@suse.com,
	xen-devel@lists.xenproject.org, ian.campbell@citrix.com,
	keir@xen.org, tim@xen.org
Subject: Re: [PATCH RFC] x86: Limit MSR_IA32_THERM_CONTROL and MSR_IA32_ENERGY_PERF_BIAS
Date: Fri, 18 Dec 2015 21:31:38 +0000	[thread overview]
Message-ID: <56747B3A.1050707@citrix.com> (raw)
In-Reply-To: <1450471606-19129-2-git-send-email-konrad.wilk@oracle.com>

On 18/12/2015 20:46, Konrad Rzeszutek Wilk wrote:
> Those two allow the OS pinned dom0 to change the T-state
> (throttling) behind the Xen cpufreq code.
>
> The patch that introduced this: f78e2193b6409577314167ed9e077de7ac3e652f
>
>     x86: Enable THERM_CONTROL_MSR write for dom0 even when cpufreq=xen
>
>     Signed-off-by: Wei Gang <gang.wei@intel.com>
>     Signed-off-by: Keir Fraser <keir.fraser@citrix.com>
>
> is very lacking on details.
>
> Anyhow this patch in effect reverts the above commit. It is also
> lacking in details :-)
>
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

We absolutely shouldn't let dom0 play with controls behind the back of a
driver in Xen.

It would be nice if we can find out some of the reasoning behind this
change, but I am in principle for it.

~Andrew

  reply	other threads:[~2015-12-18 21:31 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-12-18 20:46 [RFC PATCH] THERM_CONTROL_MSR mucks with Xen cpufreq code Konrad Rzeszutek Wilk
2015-12-18 20:46 ` [PATCH RFC] x86: Limit MSR_IA32_THERM_CONTROL and MSR_IA32_ENERGY_PERF_BIAS Konrad Rzeszutek Wilk
2015-12-18 21:31   ` Andrew Cooper [this message]
2015-12-21 11:39     ` Jan Beulich
2015-12-21 11:42   ` Jan Beulich

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