Re: [PATCH v6 05/16] KVM: TDX: Pass size to reclaim_page()

Binbin Wu
2023-11-19T06:57:39Z

On 11/7/2023 11:00 PM, isaku.yamahata@intel.com wrote:
> From: Xiaoyao Li <xiaoyao.li@intel.com>
>
> A 2MB large page can be tdh_mem_page_aug()'ed to TD directly. In this case,
> it needs to reclaim and clear the page as 2MB size.
>
> Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
> ---
> arch/x86/kvm/vmx/tdx.c | 27 +++++++++++++++------------
> 1 file changed, 15 insertions(+), 12 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> index a728175c4a6d..0fca863faeee 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -200,12 +200,13 @@ static void tdx_disassociate_vp_on_cpu(struct kvm_vcpu *vcpu)
> smp_call_function_single(cpu, tdx_disassociate_vp_arg, vcpu, 1);
> }
>
> -static void tdx_clear_page(unsigned long page_pa)
> +static void tdx_clear_page(unsigned long page_pa, int size)
Should use "unsigned long" instead of "int" for size to avoid implicit
type conversion.

> {
> const void *zero_page = (const void *) __va(page_to_phys(ZERO_PAGE(0)));
> void *page = __va(page_pa);
> unsigned long i;
>
> + WARN_ON_ONCE(size % PAGE_SIZE);
> /*
> * When re-assign one page from old keyid to a new keyid, MOVDIR64B is
> * required to clear/write the page with new keyid to prevent integrity
> @@ -214,7 +215,7 @@ static void tdx_clear_page(unsigned long page_pa)
> * clflush doesn't flush cache with HKID set. The cache line could be
> * poisoned (even without MKTME-i), clear the poison bit.
> */
> - for (i = 0; i < PAGE_SIZE; i += 64)
> + for (i = 0; i < size; i += 64)
> movdir64b(page + i, zero_page);
> /*
> * MOVDIR64B store uses WC buffer. Prevent following memory reads
> @@ -223,7 +224,7 @@ static void tdx_clear_page(unsigned long page_pa)
> __mb();
> }
>
> -static int __tdx_reclaim_page(hpa_t pa)
> +static int __tdx_reclaim_page(hpa_t pa, enum pg_level level)
> {
> struct tdx_module_args out;
> u64 err;
> @@ -241,17 +242,19 @@ static int __tdx_reclaim_page(hpa_t pa)
> pr_tdx_error(TDH_PHYMEM_PAGE_RECLAIM, err, &out);
> return -EIO;
> }
> + /* out.r8 == tdx sept page level */
> + WARN_ON_ONCE(out.r8 != pg_level_to_tdx_sept_level(level));
>
> return 0;
> }
>
> -static int tdx_reclaim_page(hpa_t pa)
> +static int tdx_reclaim_page(hpa_t pa, enum pg_level level)
> {
> int r;
>
> - r = __tdx_reclaim_page(pa);
> + r = __tdx_reclaim_page(pa, level);
> if (!r)
> - tdx_clear_page(pa);
> + tdx_clear_page(pa, KVM_HPAGE_SIZE(level));
> return r;
> }
>
> @@ -265,7 +268,7 @@ static void tdx_reclaim_td_page(unsigned long td_page_pa)
> * was already flushed by TDH.PHYMEM.CACHE.WB before here, So
> * cache doesn't need to be flushed again.
> */
> - if (tdx_reclaim_page(td_page_pa))
> + if (tdx_reclaim_page(td_page_pa, PG_LEVEL_4K))
> /*
> * Leak the page on failure:
> * tdx_reclaim_page() returns an error if and only if there's an
> @@ -497,7 +500,7 @@ void tdx_vm_free(struct kvm *kvm)
>
> if (!kvm_tdx->tdr_pa)
> return;
> - if (__tdx_reclaim_page(kvm_tdx->tdr_pa))
> + if (__tdx_reclaim_page(kvm_tdx->tdr_pa, PG_LEVEL_4K))
> return;
> /*
> * TDX module maps TDR with TDX global HKID. TDX module may access TDR
> @@ -510,7 +513,7 @@ void tdx_vm_free(struct kvm *kvm)
> pr_tdx_error(TDH_PHYMEM_PAGE_WBINVD, err, NULL);
> return;
> }
> - tdx_clear_page(kvm_tdx->tdr_pa);
> + tdx_clear_page(kvm_tdx->tdr_pa, PAGE_SIZE);
>
> free_page((unsigned long)__va(kvm_tdx->tdr_pa));
> kvm_tdx->tdr_pa = 0;
> @@ -1597,7 +1600,7 @@ static int tdx_sept_drop_private_spte(struct kvm *kvm, gfn_t gfn,
> * The HKID assigned to this TD was already freed and cache
> * was already flushed. We don't have to flush again.
> */
> - err = tdx_reclaim_page(hpa);
> + err = tdx_reclaim_page(hpa, level);
> if (KVM_BUG_ON(err, kvm))
> return -EIO;
> tdx_unpin(kvm, pfn);
> @@ -1630,7 +1633,7 @@ static int tdx_sept_drop_private_spte(struct kvm *kvm, gfn_t gfn,
> pr_tdx_error(TDH_PHYMEM_PAGE_WBINVD, err, NULL);
> return -EIO;
> }
> - tdx_clear_page(hpa);
> + tdx_clear_page(hpa, PAGE_SIZE);
Should here be KVM_HPAGE_SIZE(level) instead of  PAGE_SIZE?

> tdx_unpin(kvm, pfn);
> return 0;
> }
> @@ -1742,7 +1745,7 @@ static int tdx_sept_free_private_spt(struct kvm *kvm, gfn_t gfn,
> * already flushed. We don't have to flush again.
> */
> if (!is_hkid_assigned(kvm_tdx))
> - return tdx_reclaim_page(__pa(private_spt));
> + return tdx_reclaim_page(__pa(private_spt), PG_LEVEL_4K);
>
> /*
> * free_private_spt() is (obviously) called when a shadow page is being