Re: [RFC PATCH v2 03/23] x86/tdx: Enhance tdh_phymem_page_wbinvd_hkid() to invalidate huge pages

[Yan Zhao <yan.y.zhao@intel.com>]

On Tue, Dec 09, 2025 at 05:14:22PM -0800, Vishal Annapurve wrote:
> On Thu, Aug 7, 2025 at 2:42 AM Yan Zhao <yan.y.zhao@intel.com> wrote:
> >
> > index 0a2b183899d8..8eaf8431c5f1 100644
> > --- a/arch/x86/kvm/vmx/tdx.c
> > +++ b/arch/x86/kvm/vmx/tdx.c
> > @@ -1694,6 +1694,7 @@ static int tdx_sept_drop_private_spte(struct kvm *kvm, gfn_t gfn,
> >  {
> >         int tdx_level = pg_level_to_tdx_sept_level(level);
> >         struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm);
> > +       struct folio *folio = page_folio(page);
> >         gpa_t gpa = gfn_to_gpa(gfn);
> >         u64 err, entry, level_state;
> >
> > @@ -1728,8 +1729,9 @@ static int tdx_sept_drop_private_spte(struct kvm *kvm, gfn_t gfn,
> >                 return -EIO;
> >         }
> >
> > -       err = tdh_phymem_page_wbinvd_hkid((u16)kvm_tdx->hkid, page);
> > -
> > +       err = tdh_phymem_page_wbinvd_hkid((u16)kvm_tdx->hkid, folio,
> > +                                         folio_page_idx(folio, page),
> > +                                         KVM_PAGES_PER_HPAGE(level));
> 
> This code seems to assume that folio_order() always matches the level
> at which it is mapped in the EPT entries.
I don't think so.
Please check the implemenation of tdh_phymem_page_wbinvd_hkid() [1].
Only npages=KVM_PAGES_PER_HPAGE(level) will be invalidated, while npages
<= folio_nr_pages(folio).

[1] https://lore.kernel.org/all/20250807094202.4481-1-yan.y.zhao@intel.com/

> IIUC guest_memfd can decide
> to split folios to 4K for the complete huge folio before zapping the
> hugepage EPT mappings. I think it's better to just round the pfn to
> the hugepage address based on the level they were mapped at instead of
> relying on the folio order.