Xen devel - Jul 2005 - Re: [Xen-changelog] Fix NX/XD enable on secondary CPUs.

Xen patchbot -unstable <patchbot-unstable@lists.xensource.com> writes:
> Fix NX/XD enable on secondary CPUs.
> Signed-off-by: Keir Fraser <keir@xensource.com>
I think I have this problem with PAE as well.  Machine is SMP
(hyperthreaded).  PAE dom0 boots fine on CPU #0.  PAE domU is bound to
CPU #1 by default and boots to the login prompt as well, but only with
NX disabled (and network disabled, but that''s another story ...).

With NX-enabled domU boot I get this ...

  (XEN) (file=traps.c, line=872) Non-priv domain attempted
RDMSR(c0000080,00000000,20100000).
  (XEN) (file=traps.c, line=864) Non-priv domain attempted
WRMSR(c0000080,00000800,00000000).

... and the kernel crashes shortly later, I guess due to NX pte entry
without NX being enabled on CPU #1.  It crashes right after the first
set_fixmap call which creates a pte entry with NX set.

  Gerd

-- 
panic("it works"); /* avoid being flooded with debug messages */

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Does EFER_NX need setting for 32-bit PAE?

We don''t set it for *any* cpus in x86_32 builds, even cpu0...

  -- Keir

On 13 Jul 2005, at 11:17, Gerd Knorr wrote:
> I think I have this problem with PAE as well.  Machine is SMP
> (hyperthreaded).  PAE dom0 boots fine on CPU #0.  PAE domU is bound to
> CPU #1 by default and boots to the login prompt as well, but only with
> NX disabled (and network disabled, but that''s another story ...).
>
> With NX-enabled domU boot I get this ...
>
>   (XEN) (file=traps.c, line=872) Non-priv domain attempted 
> RDMSR(c0000080,00000000,20100000).
>   (XEN) (file=traps.c, line=864) Non-priv domain attempted 
> WRMSR(c0000080,00000800,00000000).
>
> ... and the kernel crashes shortly later, I guess due to NX pte entry
> without NX being enabled on CPU #1.  It crashes right after the first
> set_fixmap call which creates a pte entry with NX set.

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On Wed, Jul 13, 2005 at 11:52:27AM +0100, Keir Fraser
wrote:
> 
> Does EFER_NX need setting for 32-bit PAE?
> 
> We don''t set it for *any* cpus in x86_32 builds, even cpu0...
The Dom0 linux kernel probably does for CPU #0 ...
> >  (XEN) (file=traps.c, line=872) Non-priv domain attempted 
> >RDMSR(c0000080,00000000,20100000).
> >  (XEN) (file=traps.c, line=864) Non-priv domain attempted 
> >WRMSR(c0000080,00000800,00000000).
... what the DomU kernel isn''t allowed to do on CPU #1.

  Gerd

-- 
panic("it works"); /* avoid being flooded with debug messages */

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