linux-kernel - Re: [RFC PATCH 09/21] KVM: TDX: Enable 2MB mapping size after TD is RUNNABLE

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Message-ID: <kqzzfujanfc22spwuuqkwvrbtnx3xz5mua6vgkrc7oaztxzcla@z3am7lzyjxmz>
Date: Fri, 20 Jun 2025 22:26:46 +0300
From: Kirill Shutemov <kirill.shutemov@...el.com>
To: Sean Christopherson <seanjc@...gle.com>
Cc: Rick P Edgecombe <rick.p.edgecombe@...el.com>, 
	Yan Y Zhao <yan.y.zhao@...el.com>, Fan Du <fan.du@...el.com>, Xiaoyao Li <xiaoyao.li@...el.com>, 
	Kai Huang <kai.huang@...el.com>, "quic_eberman@...cinc.com" <quic_eberman@...cinc.com>, 
	Dave Hansen <dave.hansen@...el.com>, "david@...hat.com" <david@...hat.com>, 
	"thomas.lendacky@....com" <thomas.lendacky@....com>, "vbabka@...e.cz" <vbabka@...e.cz>, 
	Zhiquan1 Li <zhiquan1.li@...el.com>, "kvm@...r.kernel.org" <kvm@...r.kernel.org>, 
	"michael.roth@....com" <michael.roth@....com>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, 
	Chao P Peng <chao.p.peng@...el.com>, "pbonzini@...hat.com" <pbonzini@...hat.com>, 
	Ira Weiny <ira.weiny@...el.com>, Isaku Yamahata <isaku.yamahata@...el.com>, 
	"binbin.wu@...ux.intel.com" <binbin.wu@...ux.intel.com>, "ackerleytng@...gle.com" <ackerleytng@...gle.com>, 
	Vishal Annapurve <vannapurve@...gle.com>, "tabba@...gle.com" <tabba@...gle.com>, 
	"jroedel@...e.de" <jroedel@...e.de>, Jun Miao <jun.miao@...el.com>, 
	"pgonda@...gle.com" <pgonda@...gle.com>, "x86@...nel.org" <x86@...nel.org>
Subject: Re: [RFC PATCH 09/21] KVM: TDX: Enable 2MB mapping size after TD is
 RUNNABLE

On Fri, Jun 20, 2025 at 11:40:31AM -0700, Sean Christopherson wrote:
> On Fri, Jun 20, 2025, Kirill Shutemov wrote:
> > On Fri, Jun 20, 2025 at 09:32:45AM -0700, Sean Christopherson wrote:
> > > On Wed, Jun 18, 2025, Kirill Shutemov wrote:
> > > > On Wed, Jun 18, 2025 at 04:22:59AM +0300, Edgecombe, Rick P wrote:
> > > > > On Tue, 2025-06-17 at 08:52 +0800, Yan Zhao wrote:
> > > > > > > hopefully is just handling accepting a whole range that is not 2MB aligned.
> > > > > > > But
> > > > > > > I think we need to verify this more.
> > > > > > Ok.
> > > > > 
> > > > > In Linux guest if a memory region is not 2MB aligned the guest will accept the
> > > 
> > > What is a "memory region" in this context?  An e820 region?  Something else?
> > 
> > EFI memory map entry.
> 
> I forget, for TDX, is the EFI map built by guest firmware or by the VMM?

Guest BIOS.

The BIOS would accept some memory on its own (typically the first 4G) and
leave the rest to be accepted by OS. EFI boot services can also accept
memory on OS request (e.g. on memory allocation), updating the map.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov