From mboxrd@z Thu Jan  1 00:00:00 1970
From: George Dunlap <george.dunlap@eu.citrix.com>
Subject: Re: XSA-60 - how to get back to a sane state
Date: Mon, 2 Dec 2013 19:43:17 +0000
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To: Jan Beulich <JBeulich@suse.com>, xen-devel <xen-devel@lists.xenproject.org>
Cc: Jinsong Liu <jinsong.liu@intel.com>, Keir Fraser <keir@xen.org>, Andrew Cooper <andrew.cooper3@citrix.com>, Zhenzhong Duan <zhenzhong.duan@oracle.com>, Donald D Dugger <donald.d.dugger@intel.com>, Jun Nakajima <jun.nakajima@intel.com>
List-Id: xen-devel@lists.xenproject.org

On 12/02/2013 02:28 PM, Jan Beulich wrote:
> All,
>
> Jinsong's patches having been in for nearly a month now, but not
> being in a shape that would make releasing in 4.4 or backporting to
> the older trees desirable, we need to come to a conclusion on
> which way to go. Currently it looks like we have three options, but
> of course I'll be happy to see other (better!) ones proposed.
>
> 1) Stay with what we have.
>
> 2) Revert 86d60e85 ("VMX: flush cache when vmentry back to UC
> guest") in its entirety plus, perhaps, the change 62652c00 ("VMX:
> fix cr0.cd handling") did to vmx_ctxt_switch_to().
>
> 3) Apply the attached patch that Andrew and I have been putting
> together, with the caveat that it's still incomplete (see below).
>
> The latter two are based on the observation that the amount of
> cache flushing we do with what is in the master tree right now is
> more than what we did prior to that patch series but still
> insufficient. Hence the revert would get us back to the earlier
> state (and obviously eliminate the performance problems that
> were observed when doing too eager flushing), whereas
> applying the extra 5th patch would get us closer to a proper
> solution.

What's missing is a description of the pros and cons of 1 and 2.  Do you 
have any links to threads describing the problem?

  -George