linux-kernel - Re: [PATCH v3 04/16] x86/virt/tdx: Allocate page bitmap for Dynamic PAMT

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Message-ID: <ba3de7ec-56bd-4e24-a9d3-5d272afe4b0f@intel.com>
Date: Fri, 26 Sep 2025 16:41:23 +0800
From: Xiaoyao Li <xiaoyao.li@...el.com>
To: Rick Edgecombe <rick.p.edgecombe@...el.com>, kas@...nel.org,
 bp@...en8.de, chao.gao@...el.com, dave.hansen@...ux.intel.com,
 isaku.yamahata@...el.com, kai.huang@...el.com, 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, x86@...nel.org,
 yan.y.zhao@...el.com, vannapurve@...gle.com,
 Dan Williams <dan.j.williams@...el.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: Re: [PATCH v3 04/16] x86/virt/tdx: Allocate page bitmap for Dynamic
 PAMT

+ Dan,

On 9/19/2025 7:22 AM, Rick Edgecombe wrote:
> diff --git a/arch/x86/virt/vmx/tdx/tdx_global_metadata.c b/arch/x86/virt/vmx/tdx/tdx_global_metadata.c
> index 13ad2663488b..683925bcc9eb 100644
> --- a/arch/x86/virt/vmx/tdx/tdx_global_metadata.c
> +++ b/arch/x86/virt/vmx/tdx/tdx_global_metadata.c
> @@ -33,6 +33,9 @@ static int get_tdx_sys_info_tdmr(struct tdx_sys_info_tdmr *sysinfo_tdmr)
>   		sysinfo_tdmr->pamt_2m_entry_size = val;
>   	if (!ret && !(ret = read_sys_metadata_field(0x9100000100000012, &val)))
>   		sysinfo_tdmr->pamt_1g_entry_size = val;
> +	if (!ret && tdx_supports_dynamic_pamt(&tdx_sysinfo) &&
> +	    !(ret = read_sys_metadata_field(0x9100000100000013, &val)))
> +		sysinfo_tdmr->pamt_page_bitmap_entry_bits = val;
>   
>   	return ret;
>   }

It looks like the update is not produced by the script[1], but manually, 
right?

Looking at the history

   git log arch/x86/virt/vmx/tdx/tdx_global_metadata.c

It looks the expectation is always adding new fields by updating the 
script[1] and running it with the latest 'tdx_global_metadata.c'.

Dan Williams also expressed internally that we should have checked the 
script[1] into the kernel. I agree with him and it's never too late to 
do it.

[1]https://lore.kernel.org/kvm/0853b155ec9aac09c594caa60914ed6ea4dc0a71.camel@intel.com/