RE: [Xen-devel] [PATCH][SVM][1/2] fix SVM 64bit hv cores>0 reboot/hang issue

["Woller, Thomas" <thomas.woller@xxxxxxx>]

> 
> Zeroing them out is probably the best thing to do. Xen 
> doesn't bother to change them while it executes because 
> ds/es/ss are effectively unused in 64-bit mode. The fact they 
> happen to contain __USER_DS is utterly unimportant.
Good to hear that...

> 
> You probably need to worry about fs and gs as well. They're 
> not causing you problems now because guests don't usually set 
> those registers to non-zero values, but if they ever do then 
> you'll presumably have problems?
Just to be clear here, the host registers are what is giving us 
problems. When the microcode loads the host selectors in the vmexit
microcode logic, then the consistency check fails on ds,es (0x2B)
due to GDT entries not in memory at that moment. 

I think that we'll go with not modifying gs,fs now - they are currently
NULL in the host context.

> I'll wait for further advice before applying this patch.
So, if you would, please apply the previous patch, exactly as is.

Also, if you could please apply to the 3.0-testing tree, that would
help also.  

Thanks,
Tom


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