Paolo Bonzini <pbonzini@xxxxxxxxxx> writes: > On 14/07/2016 19:38, Bandan Das wrote: >> Paolo Bonzini <pbonzini@xxxxxxxxxx> writes: >> >>> On 13/07/2016 17:47, Bandan Das wrote: >>>>>> I wanted to keep it the former way because "PT_PRESENT_MASK is equal to VMX_EPT_READABLE_MASK" >>>>>> is an assumption all throughout. I wanted to use this section to catch mismatches. >>>>> >>>>> I think there's no such assumption anymore, actually. Can you double >>>>> check? If there are any, that's where the BUILD_BUG_ON should be. >>>> >>>> What I meant is how they are the same bit. is_shadow_present_pte() is probably one >>>> and another one is link_shadow_page() which already has a BUILD_BUG_ON(). >>> >>> You're right about link_shadow_page()! We probably should change the >>> PT_PRESENT_MASK to shadow_present_mask there (and then readability in >>> the EPT execonly case is still provided by shadow_user_mask). >> >> Makes sense. Would you like a new version with that added or can that be a >> separate patch ? > > I've already done it and pushed it to kvm/next. :) Ah, thank you! >>> For is_shadow_present_pte() you have removed it in patch 1 though. >> >> Right. But the assumption is still that is_shadow_present_pte() works because >> EPT_READABLE and PT_PRESENT are the same. > > is_shadow_present_pte() tests 0xFFFFFFFF, so it does not depend on bit 0 > alone, for neither EPT nor "normal" page tables. Yeah... Let me rephrase, is_shadow_present_pte works because the assumption is that both of the bits are in the first 32 bits :) You proved me wrong though, this assumption does not mean a BUILD_BUG for the equal condition is required here. Bandan > Paolo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
