Re: [PATCH] When switching to a vm8086 task, load segments as 16-bit (v2)

[Avi Kivity <avi@redhat.com>]

On 08/12/2009 03:11 PM, Avi Kivity wrote:
> On 08/11/2009 11:57 PM, Anthony Liguori wrote:
>> According to 16.2.5 in the SDM, eflags.vm in the tss is consulted 
>> before loading
>> and new segments.  If eflags.vm == 1, then the segments are treated 
>> as 16-bit
>> segments.  The LDTR and TR are not normally available in vm86 mode so 
>> if they
>> happen to somehow get loaded, they need to be treated as 32-bit 
>> segments.
>>
>> This fixes an invalid vmentry failure in a custom OS that was 
>> happening after
>> a task switch into vm8086 mode.  Since the segments were being 
>> mistakenly
>> treated as 32-bit, we loaded garbage state.
>
> I'm getting a Vista x64 installer failure on reboot with this.  One 
> possibility is that ->get_rflags() is returning the mangled flags 
> state (we add vm86 for real mode), which confuses the new code.
>

That's indeed the case, I'm testing a patch now.

-- 
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