Re: [RFC PATCH 12/12] KVM: TDX: Rename nr_premapped to nr_pending_tdh_mem_page_adds

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

On Tue, Aug 26, 2025 at 05:05:22PM -0700, Sean Christopherson wrote:
> Rename "nr_premapped" to an asurdly verbose "nr_pending_tdh_mem_page_adds"
> to make it explicitly clear what the counter tracks.  "pre-map" is far
> too similar to "pre-fault", especially since tdx_sept_set_private_spte()
> deals with both "pre_fault_allowed" and the counter.
> 
> No functional change intended.
> 
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
>  arch/x86/kvm/vmx/tdx.c | 8 ++++----
>  arch/x86/kvm/vmx/tdx.h | 9 +++++++--
>  2 files changed, 11 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> index 5d2bb27f22da..f9ac590e8ff0 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -1639,7 +1639,7 @@ static int tdx_sept_set_private_spte(struct kvm *kvm, gfn_t gfn,
>  		if (KVM_BUG_ON(kvm->arch.pre_fault_allowed, kvm))
>  			return -EIO;
>  
> -		kvm_tdx->nr_premapped++;
> +		kvm_tdx->nr_pending_tdh_mem_page_adds++;
>  		return 0;
>  	}
>  
> @@ -1771,7 +1771,7 @@ static int tdx_sept_zap_private_spte(struct kvm *kvm, gfn_t gfn,
>  	if (tdx_is_sept_zap_err_due_to_premap(kvm_tdx, err, entry, level)) {
>  		lockdep_assert_held(&kvm->slots_lock);
>  
> -		if (KVM_BUG_ON(--kvm_tdx->nr_premapped < 0, kvm))
> +		if (KVM_BUG_ON(--kvm_tdx->nr_pending_tdh_mem_page_adds < 0, kvm))
>  			return -EIO;
>  
>  		return 0;
> @@ -2846,7 +2846,7 @@ static int tdx_td_finalize(struct kvm *kvm, struct kvm_tdx_cmd *cmd)
>  	 * Pages are pending for KVM_TDX_INIT_MEM_REGION to issue
>  	 * TDH.MEM.PAGE.ADD().
>  	 */
> -	if (kvm_tdx->nr_premapped)
> +	if (kvm_tdx->nr_pending_tdh_mem_page_adds)
>  		return -EINVAL;
>  
>  	cmd->hw_error = tdh_mr_finalize(&kvm_tdx->td);
> @@ -3160,7 +3160,7 @@ static int tdx_gmem_post_populate(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn,
>  		goto out;
>  	}
>  
> -	KVM_BUG_ON(--kvm_tdx->nr_premapped < 0, kvm);
> +	KVM_BUG_ON(--kvm_tdx->nr_pending_tdh_mem_page_adds < 0, kvm);
>  
>  	if (arg->flags & KVM_TDX_MEASURE_MEMORY_REGION) {
>  		for (i = 0; i < PAGE_SIZE; i += TDX_EXTENDMR_CHUNKSIZE) {
> diff --git a/arch/x86/kvm/vmx/tdx.h b/arch/x86/kvm/vmx/tdx.h
> index 04ba9ea3e0ba..45d86f9fa41c 100644
> --- a/arch/x86/kvm/vmx/tdx.h
> +++ b/arch/x86/kvm/vmx/tdx.h
> @@ -36,8 +36,13 @@ struct kvm_tdx {
>  
>  	struct tdx_td td;
>  
> -	/* For KVM_TDX_INIT_MEM_REGION. */
> -	unsigned long nr_premapped;
> +	/*
> +	 * The number of pages that KVM_TDX_INIT_MEM_REGION has mapped into the
> +	 * S-EPT, but not yet initialized via TDH.MEM.PAGE_ADD.  Used to sanity
> +	 * check adding pages to the image, and to ensure that all pages have
> +	 * been initialized before finalizing the TD.
> +	 */
To ensure the consistency between mirror EPT and S-EPT? (as in
https://lore.kernel.org/all/aK7Ji3kAoDaEYn3h@yzhao56-desk.sh.intel.com).

tdx_td_finalize() holds slots_lock, so it can't run in-between a
KVM_TDX_INIT_MEM_REGION.

> +	unsigned long nr_pending_tdh_mem_page_adds;
>  
>  	/*
>  	 * Prevent vCPUs from TD entry to ensure SEPT zap related SEAMCALLs do
> -- 
> 2.51.0.268.g9569e192d0-goog
>