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From: "Min Xu" <min.m.xu@intel.com>
To: "devel@edk2.groups.io" <devel@edk2.groups.io>,
	"kraxel@redhat.com" <kraxel@redhat.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>,
	"Justen, Jordan L" <jordan.l.justen@intel.com>,
	Brijesh Singh <brijesh.singh@amd.com>,
	"Erdem Aktas" <erdemaktas@google.com>,
	James Bottomley <jejb@linux.ibm.com>,
	"Yao, Jiewen" <jiewen.yao@intel.com>,
	Tom Lendacky <thomas.lendacky@amd.com>
Subject: Re: [edk2-devel] [PATCH V5 2/2] OvmfPkg/ResetVector: Enable Intel TDX in ResetVector of Ovmf
Date: Tue, 31 Aug 2021 03:09:08 +0000	[thread overview]
Message-ID: <PH0PR11MB5064CE64BDCBBFA2654308C7C5CC9@PH0PR11MB5064.namprd11.prod.outlook.com> (raw)
In-Reply-To: <20210830074058.22gfqmzrha4su6fh@sirius.home.kraxel.org>

On Monday, August 30, 2021 3:41 PM, Gerd Hoffmann wrote:
>   Hi,
> 
> >  _TdxPageTable:
> >     If 5-level page table is supported (GPAW is 52), a top level page
> >     directory pointers (1 * 256TB entry) is generated in this page.
> >  _OvmfPageTable:
> >     Initial page table for standard Ovmf.
> 
> Hmm, isn't 5-level paging independent from TDX?  Why mix the two?
> 
> I think a top level page directory should be added to the standard ovmf initial
> page tables instead, and setting up 5-level paging should not happen in tdx-
> specific code.
In current Ovmf implementation (OvmfPkg/ResetVector/Ia32/PageTables64.asm)
there are 6 pages reserved for initial page tables. It doesn't support 5-level paging.

TDX support GPAW 48 and 52. If GPAW is 52 we need an extra page to hold the top
level page directory pointers (1 * 256TB entry).

This TDX extra page reuses the memory region defined by PcdOvmfSecGhcbPageTableBase
In MEMFD. Because this memory region (PcdOvmfSecGhcbPageTableBase) will not
be consumed by SEV code in Tdx guest.
> 
Thanks!
Min

  reply	other threads:[~2021-08-31  3:09 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-30  2:35 [PATCH V5 0/2] Add Intel TDX support in OvmfPkg/ResetVector Min Xu
2021-08-30  2:35 ` [PATCH V5 1/2] OvmfPkg: Introduce Tdx BFV/CFV PCDs and PcdOvmfImageSizeInKb Min Xu
2021-08-30  7:03   ` Gerd Hoffmann
2021-08-31  3:29     ` [edk2-devel] " Min Xu
2021-08-31  5:13       ` Gerd Hoffmann
2021-08-31  6:17         ` Min Xu
2021-08-31 10:21           ` Gerd Hoffmann
2021-09-01  5:18             ` Min Xu
2021-09-01  6:10               ` Gerd Hoffmann
2021-09-01  6:57                 ` Ard Biesheuvel
2021-09-01  7:19                   ` Min Xu
2021-09-01  7:44                     ` Gerd Hoffmann
2021-09-01  8:59                     ` Yao, Jiewen
2021-09-01 16:53                       ` James Bottomley
2021-09-01 19:19                         ` Andrew Fish
2021-09-10 17:03                           ` Erdem Aktas
2021-08-30  2:35 ` [PATCH V5 2/2] OvmfPkg/ResetVector: Enable Intel TDX in ResetVector of Ovmf Min Xu
2021-08-30  7:40   ` Gerd Hoffmann
2021-08-31  3:09     ` Min Xu [this message]
2021-08-31  5:35       ` [edk2-devel] " Gerd Hoffmann
2021-09-02  0:05         ` Min Xu
2021-09-02  7:18           ` Gerd Hoffmann
2021-09-02  7:49             ` Min Xu
2021-09-03  3:03               ` Yao, Jiewen
2021-09-03  5:39                 ` Gerd Hoffmann
2021-09-09 13:54                   ` Min Xu
2021-09-10  8:19                     ` Gerd Hoffmann
2021-09-14  3:54                       ` Yao, Jiewen
2021-09-11  1:17   ` Erdem Aktas

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