linux-kernel - Re: [PATCH v3 00/16] TDX: Enable Dynamic PAMT

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Message-ID: <0fc9a9ed-b0ba-45fc-8bd2-1bf24c14ab7f@intel.com>
Date: Mon, 29 Sep 2025 09:22:48 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: Kiryl Shutsemau <kas@...nel.org>, Yan Zhao <yan.y.zhao@...el.com>
Cc: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>,
 "Gao, Chao" <chao.gao@...el.com>, "seanjc@...gle.com" <seanjc@...gle.com>,
 "bp@...en8.de" <bp@...en8.de>, "Annapurve, Vishal" <vannapurve@...gle.com>,
 "Huang, Kai" <kai.huang@...el.com>, "mingo@...hat.com" <mingo@...hat.com>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
 "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
 "linux-coco@...ts.linux.dev" <linux-coco@...ts.linux.dev>,
 "Yamahata, Isaku" <isaku.yamahata@...el.com>,
 "pbonzini@...hat.com" <pbonzini@...hat.com>,
 "tglx@...utronix.de" <tglx@...utronix.de>, "x86@...nel.org" <x86@...nel.org>
Subject: Re: [PATCH v3 00/16] TDX: Enable Dynamic PAMT

On 9/29/25 04:17, Kiryl Shutsemau wrote:
>> Do you have any suggestions for a better approach?
>>
>> e.g., could the PAMT pages be allocated from a dedicated pool that ensures they
>> reside in different 2MB ranges from guest private pages and TD control pages?
> It can work: allocate 2M a time for PAMT and piecemeal it to TDX module
> as needed. But it means if 2M allocation is failed, TDX is not functional.
> 
> Maybe just use a dedicated kmem_cache for PAMT allocations. Although, I
> am not sure if there's a way to specify to kmem_cache what pages to ask
> from page allocator.

That seems a bit obtuse rather than just respecting normal lock ordering
rules. No?