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From: "Jan Beulich" <JBeulich@suse.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Juergen Gross <jgross@suse.com>, Xen-devel <xen-devel@lists.xen.org>
Subject: Re: [PATCH for-4.11] x86: Use spec_ctrl_{enter, exit}_idle() in the S3/S5 path
Date: Wed, 18 Apr 2018 10:14:27 -0600	[thread overview]
Message-ID: <5AD76EE302000078001BC773@prv1-mh.provo.novell.com> (raw)
In-Reply-To: <428287ee-8448-b06a-00a6-e5f2a3d57b31@citrix.com>

>>> On 18.04.18 at 18:02, <andrew.cooper3@citrix.com> wrote:
> On 18/04/18 16:43, Jan Beulich wrote:
>>>>> On 18.04.18 at 12:43, <andrew.cooper3@citrix.com> wrote:
>>> This avoids opencoding the functionality (and missing one bit of it), and and
>>> some comments explaining what is going on.
>> Missing which bit of it? The MSR writes aren't strictly necessary afaict, and
>> functionally clearing bti_ist_info is all that's needed for the entry path of
>> interest, while clearing use_shadow_spec_ctrl is all that's needed for the
>> exit-to-Xen path. Hence I'm don't see (yet) what bug it is you think this
>> fixes.
> 
> It is expected that we don't hand off control to the firmware in cases
> like this with the mitigations in place.  Here, it doesn't actually
> matter too much, but there is no point having the mitigations in effect
> when we're the final CPU and trying to shut down.

With an improved description the patch can certainly have my R-b; the
code change itself is clearly fine with me.

Jan



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  reply	other threads:[~2018-04-18 16:14 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-18 10:43 [PATCH for-4.11] x86: Use spec_ctrl_{enter, exit}_idle() in the S3/S5 path Andrew Cooper
2018-04-18 15:43 ` Jan Beulich
2018-04-18 16:02   ` Andrew Cooper
2018-04-18 16:14     ` Jan Beulich [this message]
2018-04-18 16:27       ` Andrew Cooper
2018-04-19  7:34         ` Jan Beulich
2018-04-19  6:40 ` Juergen Gross

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