linux-kernel - Re: [PATCH v4 09/16] KVM: TDX: Allocate PAMT memory for TD control structures

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Message-ID: <516a8e3d-cae6-440c-94f2-a648cd6c1749@linux.intel.com>
Date: Tue, 25 Nov 2025 17:11:19 +0800
From: Binbin Wu <binbin.wu@...ux.intel.com>
To: Rick Edgecombe <rick.p.edgecombe@...el.com>
Cc: bp@...en8.de, chao.gao@...el.com, dave.hansen@...el.com,
 isaku.yamahata@...el.com, kai.huang@...el.com, kas@...nel.org,
 kvm@...r.kernel.org, linux-coco@...ts.linux.dev,
 linux-kernel@...r.kernel.org, mingo@...hat.com, pbonzini@...hat.com,
 seanjc@...gle.com, tglx@...utronix.de, vannapurve@...gle.com,
 x86@...nel.org, yan.y.zhao@...el.com, xiaoyao.li@...el.com,
 binbin.wu@...el.com
Subject: Re: [PATCH v4 09/16] KVM: TDX: Allocate PAMT memory for TD control
 structures



On 11/21/2025 8:51 AM, Rick Edgecombe wrote:
> From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
>
> TDX TD control structures are provided to the TDX module at 4KB page size
> and require PAMT backing. This means for Dynamic PAMT they need to also
> have 4KB backings installed.
>
> Previous changes introduced tdx_alloc_page()/tdx_free_page() that can
> allocate a page and automatically handle the DPAMT maintenance. Use them
> for vCPU control structures instead of alloc_page()/__free_page().

vCPU -> TD

>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> [update log]
> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@...el.com>
One typo above.

Reviewed-by: Binbin Wu <binbin.wu@...ux.intel.com>

> ---
> v3:
>   - Write log. Rename from “KVM: TDX: Allocate PAMT memory in __tdx_td_init()”
> ---
>   arch/x86/kvm/vmx/tdx.c | 16 ++++++----------
>   1 file changed, 6 insertions(+), 10 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> index 0eed334176b3..8c4c1221e311 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -2398,7 +2398,7 @@ static int __tdx_td_init(struct kvm *kvm, struct td_params *td_params,
>   
>   	atomic_inc(&nr_configured_hkid);
>   
> -	tdr_page = alloc_page(GFP_KERNEL);
> +	tdr_page = tdx_alloc_page();
>   	if (!tdr_page)
>   		goto free_hkid;
>   
> @@ -2411,7 +2411,7 @@ static int __tdx_td_init(struct kvm *kvm, struct td_params *td_params,
>   		goto free_tdr;
>   
>   	for (i = 0; i < kvm_tdx->td.tdcs_nr_pages; i++) {
> -		tdcs_pages[i] = alloc_page(GFP_KERNEL);
> +		tdcs_pages[i] = tdx_alloc_page();
>   		if (!tdcs_pages[i])
>   			goto free_tdcs;
>   	}
> @@ -2529,10 +2529,8 @@ static int __tdx_td_init(struct kvm *kvm, struct td_params *td_params,
>   teardown:
>   	/* Only free pages not yet added, so start at 'i' */
>   	for (; i < kvm_tdx->td.tdcs_nr_pages; i++) {
> -		if (tdcs_pages[i]) {
> -			__free_page(tdcs_pages[i]);
> -			tdcs_pages[i] = NULL;
> -		}
> +		tdx_free_page(tdcs_pages[i]);
> +		tdcs_pages[i] = NULL;
>   	}
>   	if (!kvm_tdx->td.tdcs_pages)
>   		kfree(tdcs_pages);
> @@ -2548,15 +2546,13 @@ static int __tdx_td_init(struct kvm *kvm, struct td_params *td_params,
>   
>   free_tdcs:
>   	for (i = 0; i < kvm_tdx->td.tdcs_nr_pages; i++) {
> -		if (tdcs_pages[i])
> -			__free_page(tdcs_pages[i]);
> +		tdx_free_page(tdcs_pages[i]);
>   	}
>   	kfree(tdcs_pages);
>   	kvm_tdx->td.tdcs_pages = NULL;
>   
>   free_tdr:
> -	if (tdr_page)
> -		__free_page(tdr_page);
> +	tdx_free_page(tdr_page);
>   	kvm_tdx->td.tdr_page = NULL;
>   
>   free_hkid: