On Wed, May 14, 2025 at 03:17:40AM +0800, Edgecombe, Rick P wrote:
> On Thu, 2025-04-24 at 11:05 +0800, Yan Zhao wrote:
> > From: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
> >
> > KVM invokes tdx_clear_page() to zero pages using movdir64b().
> > Include level information to enable tdx_clear_page() to zero a huge page.
> >
> > [Yan: split out, let tdx_clear_page() accept level]
> >
> > Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
> > Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
> > Signed-off-by: Yan Zhao <yan.y.zhao@xxxxxxxxx>
> > ---
> > arch/x86/kvm/vmx/tdx.c | 19 ++++++++++++++-----
> > 1 file changed, 14 insertions(+), 5 deletions(-)
> >
> > diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> > index 03885cb2869b..1186085795ac 100644
> > --- a/arch/x86/kvm/vmx/tdx.c
> > +++ b/arch/x86/kvm/vmx/tdx.c
> > @@ -276,7 +276,7 @@ static inline void tdx_disassociate_vp(struct kvm_vcpu *vcpu)
> > vcpu->cpu = -1;
> > }
> >
> > -static void tdx_clear_page(struct page *page)
> > +static void __tdx_clear_page(struct page *page)
> > {
> > const void *zero_page = (const void *) page_to_virt(ZERO_PAGE(0));
> > void *dest = page_to_virt(page);
> > @@ -295,6 +295,15 @@ static void tdx_clear_page(struct page *page)
> > __mb();
> > }
> >
> > +static void tdx_clear_page(struct page *page, int level)
> > +{
> > + unsigned long nr = KVM_PAGES_PER_HPAGE(level);
> > + unsigned long idx = 0;
> > +
> > + while (nr--)
> > + __tdx_clear_page(nth_page(page, idx++));
>
> You shouldn't need both idx and nr.
>
> > +}
>
> Since tdx_clear_page() has a __mb(), it is probably worth checking that this
> generates efficient code, considering the loops within loops pattern.
The concern makes sense!
Will convert level to size and use "for (i = 0; i < size; i += 64)" for
movdir64b().
> > +
> > static void tdx_no_vcpus_enter_start(struct kvm *kvm)
> > {
> > struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm);
> > @@ -340,11 +349,10 @@ static int tdx_reclaim_page(struct page *page)
> >
> > r = __tdx_reclaim_page(page);
> > if (!r)
> > - tdx_clear_page(page);
> > + tdx_clear_page(page, PG_LEVEL_4K);
> > return r;
> > }
> >
> > -
> > /*
> > * Reclaim the TD control page(s) which are crypto-protected by TDX guest's
> > * private KeyID. Assume the cache associated with the TDX private KeyID has
> > @@ -588,7 +596,7 @@ static void tdx_reclaim_td_control_pages(struct kvm *kvm)
> > pr_tdx_error(TDH_PHYMEM_PAGE_WBINVD, err);
> > return;
> > }
> > - tdx_clear_page(kvm_tdx->td.tdr_page);
> > + tdx_clear_page(kvm_tdx->td.tdr_page, PG_LEVEL_4K);
>
> Why not the __tdx_clear_page() variant? The patch adds it, but doesn't really
> use it. Just implement it all in tdx_clear_page() then.
Ok.
> >
> > __free_page(kvm_tdx->td.tdr_page);
> > kvm_tdx->td.tdr_page = NULL;
> > @@ -1621,7 +1629,8 @@ static int tdx_sept_drop_private_spte(struct kvm *kvm, gfn_t gfn,
> > pr_tdx_error(TDH_PHYMEM_PAGE_WBINVD, err);
> > return -EIO;
> > }
> > - tdx_clear_page(page);
> > +
> > + tdx_clear_page(page, level);
> > tdx_unpin(kvm, page);
> > return 0;
> > }
>
