On Mon, Aug 02, 2010 at 10:24:43AM -0400, Avi Kivity wrote:
> On 08/02/2010 05:11 PM, Roedel, Joerg wrote:
> > This is testing the failure case without the nested-svm efer patch I
> > submitted last week. The sequence above (which switches from long mode
> > to real mode and back to long mode) fails without this patch.
>
> A direct test would be to
>
> mov $MSR_EFER, %ecx
> rdmsr
> xor $EFER_NX, %eax
> wrmsr
>
> and see that L1 EFER was updated.
>
> I don't object to the more complicated test, but in general prefer
> simpler, direct tests so that when they fail we know exactly why.
True, smaller tests are generally better. But I think its good to also
test that the whole sequence works. I can add a seperate test for the
efer bug if you want.
It gets more tricky to test cr0 or cr4 writes because this will require
to put the nested guest into real-mode or protected-mode directly.
Joerg
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