2015-10-13 18:28+0200, Paolo Bonzini:
> On 13/10/2015 17:39, Radim Krčmář wrote:
>> 2015-10-12 14:09+0200, Paolo Bonzini:
>>> Otherwise, two copies (one of them never used and thus bogus) are
>>> allocated for the regular and SMM address spaces. This breaks
>>> SMM with EPT but without unrestricted guest support, because the
>>> SMM copy of the identity page map is all zeros.
>>
>> (Have you found out why EPT+unrestricted didn't use the alternative SMM
>> mapping as well?)
>
> Yes, that I already knew; EPT+unrestricted uses CR0.PG=0 directly so
> it doesn't use the identity page at all. (CR0.PG=0 w/o unrestricted
> instead runs with CR0.PG=1. CR3 load and store exits are enabled,
> and the guest CR3 always points to the identity page map while the
> guest runs).
Thank you.
>>> + } else {
>>> + if (!slot->npages)
>>> + return 0;
>>> +
>>> + hva = 0;
>>> + }
>>> +
>>> + old = *slot;
>>
>> (Assignment could be in the 'else' == !size branch, GCC would have fun.)
>
> It would have fun _and_ warn, which is why it's not in the else branch. :)
I wondered if its "used uninitialized" analyzer got any better :)
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html