linux-kernel - Re: [RFC PATCH v2 05/23] x86/tdx: Enhance tdh_phymem_page

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Message-ID: <b4cc4097-67fd-4d31-bf91-ef80e4fc7f61@linux.intel.com>
Date: Mon, 17 Nov 2025 10:09:42 +0800
From: Binbin Wu <binbin.wu@...ux.intel.com>
To: Yan Zhao <yan.y.zhao@...el.com>
Cc: seanjc@...gle.com, pbonzini@...hat.com, linux-kernel@...r.kernel.org,
 kvm@...r.kernel.org, x86@...nel.org, rick.p.edgecombe@...el.com,
 dave.hansen@...el.com, kas@...nel.org, tabba@...gle.com,
 ackerleytng@...gle.com, quic_eberman@...cinc.com, michael.roth@....com,
 david@...hat.com, vannapurve@...gle.com, vbabka@...e.cz,
 thomas.lendacky@....com, pgonda@...gle.com, zhiquan1.li@...el.com,
 fan.du@...el.com, jun.miao@...el.com, ira.weiny@...el.com,
 isaku.yamahata@...el.com, xiaoyao.li@...el.com, chao.p.peng@...el.com
Subject: Re: [RFC PATCH v2 05/23] x86/tdx: Enhance tdh_phymem_page_reclaim()
 to support huge pages



On 8/7/2025 5:42 PM, Yan Zhao wrote:
[...]
> diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
> index 64219c659844..9ed585bde062 100644
> --- a/arch/x86/virt/vmx/tdx/tdx.c
> +++ b/arch/x86/virt/vmx/tdx/tdx.c
> @@ -1966,19 +1966,27 @@ EXPORT_SYMBOL_GPL(tdh_vp_init);
>    * So despite the names, they must be interpted specially as described by the spec. Return
>    * them only for error reporting purposes.
>    */
> -u64 tdh_phymem_page_reclaim(struct page *page, u64 *tdx_pt, u64 *tdx_owner, u64 *tdx_size)
> +u64 tdh_phymem_page_reclaim(struct folio *folio, unsigned long start_idx, unsigned long npages,
> +			    u64 *tdx_pt, u64 *tdx_owner, u64 *tdx_size)
>   {
> +	struct page *start = folio_page(folio, start_idx);
>   	struct tdx_module_args args = {
> -		.rcx = page_to_phys(page),
> +		.rcx = page_to_phys(start),
>   	};
>   	u64 ret;
>   
> +	if (start_idx + npages > folio_nr_pages(folio))
> +		return TDX_OPERAND_INVALID;
> +
>   	ret = seamcall_ret(TDH_PHYMEM_PAGE_RECLAIM, &args);
>   
>   	*tdx_pt = args.rcx;
>   	*tdx_owner = args.rdx;
>   	*tdx_size = args.r8;
>   
> +	if (npages != (1 << (*tdx_size) * PTE_SHIFT))
> +		return TDX_SW_ERROR;

Nit:

The size check here is to  make sure the reclamation on the correct level,
however, tdx_size may not be updated if some other error occurs first.
Do you think it's better to check 'ret' first before returning TDX_SW_ERROR?
Otherwise, the error code provided by the TDX module, which may be helpful for
debugging,  will be buried under TDX_SW_ERROR.


> +
>   	return ret;
>   }
>   EXPORT_SYMBOL_GPL(tdh_phymem_page_reclaim);