Messages in this thread | | | From | David Matlack <> | Date | Thu, 4 Aug 2022 16:43:48 -0700 | Subject | Re: [RFC PATCH v6 037/104] KVM: x86/mmu: Allow non-zero value for non-present SPTE |
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On Thu, Aug 4, 2022 at 4:23 PM Sean Christopherson <seanjc@google.com> wrote: > On Thu, Aug 04, 2022, David Matlack wrote: > > On Thu, May 05, 2022 at 11:14:31AM -0700, isaku.yamahata@intel.com wrote: > > > +#ifdef CONFIG_X86_64 > > > +#define SHADOW_NONPRESENT_VALUE BIT_ULL(63) > > > +static_assert(!(SHADOW_NONPRESENT_VALUE & SPTE_MMU_PRESENT_MASK)); > > > +#else > > > +#define SHADOW_NONPRESENT_VALUE 0ULL > > > +#endif > > > > The terminology "shadow_nonpresent" implies it would be the opposite of > > e.g. is_shadow_present_pte(), when in fact they are completely > > different concepts. > > You can fight Paolo over that one :-) I agree it looks a bit odd when juxtaposed > with is_shadow_present_pte(), but at the same time I agree with Paolo that > SHADOW_INIT_VALUE is also funky. > > https://lore.kernel.org/all/9dfc44d6-6b20-e864-8d4f-09ab7d489b97@redhat.com
Ah ok, thanks for the context.
> > > Also, this is a good opportunity to follow the same naming terminology > > as REMOVED_SPTE in the TDP MMU. > > > > How about EMPTY_SPTE? > > No, because "empty" implies there's nothing there, and it very much matters that > the SUPPRESS_VE bit is set for TDX.
Fair point. My other idea was INITIAL_SPTE but that's already covered by Paolo's objection above :)
I'll change my vote to NONPRESENT_SPTE.
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