Re: [PATCH] KVM: is_long_mode should check for EFER_LMA

[Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>]

Amit Shah wrote:
> >From bfed574c93b36a19e2976ddcaae7939dd6c6fc41 Mon Sep 17 00:00:00 2001
> From: Amit Shah <amit.shah-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
> Date: Sat, 3 Nov 2007 02:38:00 +0530
> Subject: [PATCH] KVM: is_long_mode should check for EFER_LMA
>
> is_long_mode currently checks the LongModeEnable bit in
> EFER instead of the LongModeActive bit. This should work
> for most cases, but for some broken implementations that
> set the LME bit before enabling PAE in CR4 to enter long
> mode.
>
> This is noticed on a solaris guest on an AMD host (but might
> not be specific to AMD).
>
>   

Patch looks good and obviously correct to me.  But:

- why do you say 'broken implementations'?  do you mean 'broken 
guests'?  I think that behavior is as specified.
- what guest action triggered the failure? (e.g. mov cr4, or what?)
- please supply a patch to the testsuite that adds a regression test for 
this issue.


-- 
Any sufficiently difficult bug is indistinguishable from a feature.


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