linux-kernel - Re: [RFC PATCH 02/21] x86/virt/tdx: Enhance tdh_mem_page

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Message-ID: <f6b76fc5131b2c53d9e37487ded0507820ef56bf.camel@intel.com>
Date: Wed, 9 Jul 2025 14:08:59 +0000
From: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
To: "Zhao, Yan Y" <yan.y.zhao@...el.com>
CC: "kvm@...r.kernel.org" <kvm@...r.kernel.org>, "Li, Xiaoyao"
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Subject: Re: [RFC PATCH 02/21] x86/virt/tdx: Enhance tdh_mem_page_aug() to
 support huge pages

On Wed, 2025-07-09 at 10:23 +0800, Yan Zhao wrote:

> 2. using struct folio, I need to introduce "start_idx" as well (as below),
>    because it's likely that guest_memfd provides a huge folio while KVM wants to
>    map it at 4KB.

Seems ok to me.

> 
> u64 tdh_mem_page_aug(struct tdx_td *td, u64 gpa, int level, struct folio *folio, 
>                      unsigned long start_idx, u64 *ext_err1, u64 *ext_err2)      
> {                                                                                
>         struct page *start = folio_page(folio, start_idx);                       
>         unsigned long npages = 1 << (level * PTE_SHIFT);                         
>         struct tdx_module_args args = {                                          
>                 .rcx = gpa | level,                                              
>                 .rdx = tdx_tdr_pa(td),                                           
>                 .r8 = page_to_phys(start),                                       
>         };                                                                       
>         u64 ret;                                                                 
>                                                                                  
>         if (start_idx + npages > folio_nr_pages(folio))                          
>                 return TDX_SW_ERROR;                                             
>                                                                                  
>         for (int i = 0; i < npages; i++)                                         
>                 tdx_clflush_page(nth_page(start, i));                            
>                                                                                  
>         ret = seamcall_ret(TDH_MEM_PAGE_AUG, &args);                             
>                                                                                  
>         *ext_err1 = args.rcx;                                                    
>         *ext_err2 = args.rdx;                                                    
>                                                                                  
>         return ret;                                                              
> }