Re: [Xen-devel] Bisected Xen-unstable: "Segment register inaccessible for d1v0" when starting HVM guest on intel

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 01.07.14 at 11:39, <JBeulich@xxxxxxxx> wrote:
>>>> On 01.07.14 at 11:03, <feng.wu@xxxxxxxxx> wrote:
>> Also, for SMAP hardware behaves differently between CPL=3 and CPL<3,
>> 
>> " If CPL < 3, SMAP protections are disabled if EFLAGS.AC = 1. If CPL = 3, 
>> SMAP applies to all supervisor-mode data accesses (these are implicit
>> supervisor accesses) regardless of the value of EFLAGS.AC."
> 
> Ah, right, I mis-read the combination of conditions. Which implies
> that in the spirit of this we mustn't bypass the CPL check by way
> of the flag suggested by Andrew (or else the hypervisor copy/clear
> operations wouldn't be treated as supervisor mode accesses in the
> sense above anymore).

Which in the end raises the question why the VMCS loading gets
done in vmx_do_resume() instead of vmx_ctxt_switch_to().

Jan


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