From: Andy Lutomirski <luto@amacapital.net>
Date: Mon, 10 Nov 2014 19:19:15 +0000 (-0800)
Subject: x86, kvm, vmx: Don't set LOAD_IA32_EFER when host and guest match
X-Git-Tag: omap-for-v3.19/fixes-rc1~43^2~65
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=54b98bff8ef4ccfc6f638c5ed868d2d51cdde585;p=pandora-kernel.git

x86, kvm, vmx: Don't set LOAD_IA32_EFER when host and guest match

There's nothing to switch if the host and guest values are the same.
I am unable to find evidence that this makes any difference
whatsoever.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
[I could see a difference on Nehalem.  From 5 runs:

 userspace exit, guest!=host   12200 11772 12130 12164 12327
 userspace exit, guest=host    11983 11780 11920 11919 12040
 lightweight exit, guest!=host  3214  3220  3238  3218  3337
 lightweight exit, guest=host   3178  3193  3193  3187  3220

 This passes the t-test with 99% confidence for userspace exit,
 98.5% confidence for lightweight exit. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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