Re: [Xen-devel] [PATCH] [SVM]: Make 32bit legacy guests boot again

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

I'm flying blind since I don't have an AMD box to hand to test on, but I
think changeset 19869 will probably fix this.

 -- Keir

On 29/06/2009 12:36, "Christoph Egger" <Christoph.Egger@xxxxxxx> wrote:

> 
> Your changes broke the boot of 64bit guests. I see a triple fault now.
> 
> Christoph
> 
> 
> On Monday 29 June 2009 11:17:39 Keir Fraser wrote:
>> I forgot to push. Should be there now.
>> 
>>   -- Keir
>> 
>> On 29/06/2009 09:39, "Christoph Egger" <Christoph.Egger@xxxxxxx> wrote:
>>> Tnx. I will check as soon as it appears in the public staging tree.
>>> 
>>> Christoph
>>> 
>>> On Saturday 27 June 2009 11:35:20 Keir Fraser wrote:
>>>> Changeset 19856 is a cleaned up and streamlined version of this patch.
>>>> Please take a look. It also fixes a couple of largely theoretical
>>>> issues: * Should depend on EFER.LMA not EFER.LME
>>>>  * Should handle the LMA 1->0 transition (i.e., return to legacy mode).
>>>> 
>>>>  -- Keir
>>>> 
>>>> On 26/06/2009 16:19, "Christoph Egger" <Christoph.Egger@xxxxxxx> wrote:
>>>>> Hi!
>>>>> 
>>>>> Attached patch fixes a bug introduced in c/s 19648.
>>>>> 
>>>>> 32bit legacy guests have the sysenter/sysexit instructions available.
>>>>> Therefore, we have to disable intercepts for the sysenter MSRs or the
>>>>> guest stucks in an infinite loop of #GPs, otherwise.
>>>>> 
>>>>> For guests in 64bit mode and 32bit compat mode, sysenter/sysexit
>>>>> instructions aren't available. The sysenter MSRs have to be intercepted
>>>>> to make the instruction emulation working.
>>>>> 
>>>>> Attach patch first assumes the guest is in 32bit legacy mode and
>>>>> therefore disables the sysenter MSRs in construct_vmcb().
>>>>> Access to the MSR_EFER is intercepted. When the guest enables longmode,
>>>>> then enable interception of the sysenter MSRs.
>>>>> 
>>>>> Signed-off-by: Christoph Egger <Christoph.Egger@xxxxxxx>
> 
> 



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