Re: [PATCH v6 14/16] KVM: x86/tdp_mmu: TDX: Implement merge pages into a large page

Binbin Wu
2023-11-22T07:50:56Z

On 11/7/2023 11:00 PM, isaku.yamahata@intel.com wrote:
> From: Isaku Yamahata <isaku.yamahata@intel.com>
>
> Implement merge_private_stp callback.

Not just merge_private_stp, but also unzap_private_spte.

Also, for the shortlog, should it be "KVM: VMX" instead of "KVM:
x86/tdp_mmu"?

>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
> ---
> arch/x86/kvm/vmx/tdx.c | 72 ++++++++++++++++++++++++++++++++++++
> arch/x86/kvm/vmx/tdx_arch.h | 1 +
> arch/x86/kvm/vmx/tdx_errno.h | 2 +
> arch/x86/kvm/vmx/tdx_ops.h | 6 +++
> 4 files changed, 81 insertions(+)
>
> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> index 91eca578a7da..df53a971ff21 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -1684,6 +1684,49 @@ static int tdx_sept_split_private_spt(struct kvm *kvm, gfn_t gfn,
> return 0;
> }
>
> +static int tdx_sept_merge_private_spt(struct kvm *kvm, gfn_t gfn,
> + enum pg_level level, void *private_spt)
> +{
> + int tdx_level = pg_level_to_tdx_sept_level(level);
> + struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm);
> + struct tdx_module_args out;
> + gpa_t gpa = gfn_to_gpa(gfn) & KVM_HPAGE_MASK(level);
> + u64 err;
> +
> + /* See comment in tdx_sept_set_private_spte() */
> + err = tdh_mem_page_promote(kvm_tdx->tdr_pa, gpa, tdx_level, &out);
> + if (unlikely(err == TDX_ERROR_SEPT_BUSY))
> + return -EAGAIN;
> + if (unlikely(err == (TDX_EPT_INVALID_PROMOTE_CONDITIONS |
> + TDX_OPERAND_ID_RCX)))
> + /*
> + * Some pages are accepted, some pending. Need to wait for TD
> + * to accept all pages. Tell it the caller.
> + */
> + return -EAGAIN;
> + if (KVM_BUG_ON(err, kvm)) {
> + pr_tdx_error(TDH_MEM_PAGE_PROMOTE, err, &out);
> + return -EIO;
> + }
> + WARN_ON_ONCE(out.rcx != __pa(private_spt));
> +
> + /*
> + * TDH.MEM.PAGE.PROMOTE frees the Secure-EPT page for the lower level.
Is it better to use "unlink" instead of "free" to avoid confusion?

> + * Flush cache for reuse.
> + */
> + do {
> + err = tdh_phymem_page_wbinvd(set_hkid_to_hpa(__pa(private_spt),
> + to_kvm_tdx(kvm)->hkid));
> + } while (unlikely(err == (TDX_OPERAND_BUSY | TDX_OPERAND_ID_RCX)));
> + if (WARN_ON_ONCE(err)) {
> + pr_tdx_error(TDH_PHYMEM_PAGE_WBINVD, err, NULL);
> + return -EIO;
> + }
> +
> + tdx_clear_page(__pa(private_spt), PAGE_SIZE);
> + return 0;
> +}
> +
> static int tdx_sept_zap_private_spte(struct kvm *kvm, gfn_t gfn,
> enum pg_level level)
> {
> @@ -1758,6 +1801,33 @@ static void tdx_track(struct kvm *kvm)
>
> }
>
> +static int tdx_sept_unzap_private_spte(struct kvm *kvm, gfn_t gfn,
> + enum pg_level level)
> +{
> + int tdx_level = pg_level_to_tdx_sept_level(level);
> + struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm);
> + gpa_t gpa = gfn_to_gpa(gfn) & KVM_HPAGE_MASK(level);
> + struct tdx_module_args out;
> + u64 err;
> +
> + do {
> + err = tdh_mem_range_unblock(kvm_tdx->tdr_pa, gpa, tdx_level, &out);
> +
> + /*
> + * tdh_mem_range_block() is accompanied with tdx_track() via kvm
> + * remote tlb flush. Wait for the caller of
> + * tdh_mem_range_block() to complete TDX track.
> + */
> + } while (err == (TDX_TLB_TRACKING_NOT_DONE | TDX_OPERAND_ID_SEPT));
> + if (unlikely(err == TDX_ERROR_SEPT_BUSY))
> + return -EAGAIN;
> + if (KVM_BUG_ON(err, kvm)) {
> + pr_tdx_error(TDH_MEM_RANGE_UNBLOCK, err, &out);
> + return -EIO;
> + }
> + return 0;
> +}
> +
> static int tdx_sept_free_private_spt(struct kvm *kvm, gfn_t gfn,
> enum pg_level level, void *private_spt)
> {
> @@ -3204,9 +3274,11 @@ int __init tdx_hardware_setup(struct kvm_x86_ops *x86_ops)
> x86_ops->link_private_spt = tdx_sept_link_private_spt;
> x86_ops->free_private_spt = tdx_sept_free_private_spt;
> x86_ops->split_private_spt = tdx_sept_split_private_spt;
> + x86_ops->merge_private_spt = tdx_sept_merge_private_spt;
> x86_ops->set_private_spte = tdx_sept_set_private_spte;
> x86_ops->remove_private_spte = tdx_sept_remove_private_spte;
> x86_ops->zap_private_spte = tdx_sept_zap_private_spte;
> + x86_ops->unzap_private_spte = tdx_sept_unzap_private_spte;
>
> return 0;
>
> diff --git a/arch/x86/kvm/vmx/tdx_arch.h b/arch/x86/kvm/vmx/tdx_arch.h
> index cab6a74446a0..fb7e54953a85 100644
> --- a/arch/x86/kvm/vmx/tdx_arch.h
> +++ b/arch/x86/kvm/vmx/tdx_arch.h
> @@ -29,6 +29,7 @@
> #define TDH_MNG_KEY_FREEID 20
> #define TDH_MNG_INIT 21
> #define TDH_VP_INIT 22
> +#define TDH_MEM_PAGE_PROMOTE 23
> #define TDH_MEM_SEPT_RD 25
> #define TDH_VP_RD 26
> #define TDH_MNG_KEY_RECLAIMID 27
> diff --git a/arch/x86/kvm/vmx/tdx_errno.h b/arch/x86/kvm/vmx/tdx_errno.h
> index bb093e292fef..940d6de332eb 100644
> --- a/arch/x86/kvm/vmx/tdx_errno.h
> +++ b/arch/x86/kvm/vmx/tdx_errno.h
> @@ -23,6 +23,8 @@
> #define TDX_FLUSHVP_NOT_DONE 0x8000082400000000ULL
> #define TDX_EPT_WALK_FAILED 0xC0000B0000000000ULL
> #define TDX_EPT_ENTRY_NOT_FREE 0xC0000B0200000000ULL
> +#define TDX_TLB_TRACKING_NOT_DONE 0xC0000B0800000000ULL
> +#define TDX_EPT_INVALID_PROMOTE_CONDITIONS 0xC0000B0900000000ULL
> #define TDX_EPT_ENTRY_STATE_INCORRECT 0xC0000B0D00000000ULL
>
> /*
> diff --git a/arch/x86/kvm/vmx/tdx_ops.h b/arch/x86/kvm/vmx/tdx_ops.h
> index 38ab0ab1509c..774fee3b2d46 100644
> --- a/arch/x86/kvm/vmx/tdx_ops.h
> +++ b/arch/x86/kvm/vmx/tdx_ops.h
> @@ -190,6 +190,12 @@ static inline u64 tdh_mem_page_demote(hpa_t tdr, gpa_t gpa, int level, hpa_t pag
> return tdx_seamcall_sept(TDH_MEM_PAGE_DEMOTE, gpa | level, tdr, page, 0, out);
> }
>
> +static inline u64 tdh_mem_page_promote(hpa_t tdr, gpa_t gpa, int level,
> + struct tdx_module_args *out)
> +{
> + return tdx_seamcall_sept(TDH_MEM_PAGE_PROMOTE, gpa | level, tdr, 0, 0, out);
> +}
> +
> static inline u64 tdh_mr_extend(hpa_t tdr, gpa_t gpa,
> struct tdx_module_args *out)
> {