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.
> +
> 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.
>
> __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;
> }
