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From: "Gerd Hoffmann" <kraxel@redhat.com>
To: Brijesh Singh <brijesh.singh@amd.com>
Cc: devel@edk2.groups.io, James Bottomley <jejb@linux.ibm.com>,
	Min Xu <min.m.xu@intel.com>, Jiewen Yao <jiewen.yao@intel.com>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	Jordan Justen <jordan.l.justen@intel.com>,
	Ard Biesheuvel <ardb+tianocore@kernel.org>,
	Erdem Aktas <erdemaktas@google.com>,
	Michael Roth <Michael.Roth@amd.com>
Subject: Re: [PATCH v6 15/29] OvmfPkg/MemEncryptSevLib: add support to validate system RAM
Date: Fri, 3 Sep 2021 09:04:24 +0200	[thread overview]
Message-ID: <20210903070424.huj2hrkj3jejq3lx@sirius.home.kraxel.org> (raw)
In-Reply-To: <19ba1918-7c3b-04d7-f415-8c5b1a9e64c8@amd.com>

  Hi,

> IIRC, in the TDX proposal, I got the impression that TDX implementation
> will skip the PEI phase, and it jumps from SEC->DXE. The SEC phase
> somehow will know the guest memory range and validate it.

Well, their design review document lists two configurations, one (named
"config-a" in the slides) following the existing boot flow and another
("config-b") which skips PEI.

The motivation for config-b is not clear from the design review
document.  The slides describe what they are doing but there isn't much
information on _why_ things are done that way.  Asked a few days ago,
answer is still outstanding.

I'd prefer to not have two completely different initialization code
paths in ovmf.  Easier for TDX/SNP code sharing, also easier for
long-term maintenance.

> Approach #1
> 
> The main advantage is that EDK2 core and guest OS can accept the memory
> without any validation step. [ ... ]

> Approach #2
> 
> The main advantage of this approach is that it can support lazy
> validation, and it can undoubtedly help reduce boot time. [ ... ]

> This patch series implements #1. And we will be looking at approach #2
> after the base is enabled. Approach #2 builds upon #1. As you
> highlighted below that we have not seen the patches for the Lazy
> validation here so its hard to comment but I am hopeful that it will
> integrated just fine with the SNP.

Good, that plan makes sense to me.

take care,
  Gerd


  reply	other threads:[~2021-09-03  7:04 UTC|newest]

Thread overview: 59+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-01 16:16 [PATCH v6 00/29] Add AMD Secure Nested Paging (SEV-SNP) support Brijesh Singh
2021-09-01 16:16 ` [PATCH v6 01/29] OvmfPkg: reserve SNP secrets page Brijesh Singh
2021-09-01 16:16 ` [PATCH v6 02/29] OvmfPkg: reserve CPUID page for SEV-SNP Brijesh Singh
2021-09-02  8:04   ` Gerd Hoffmann
2021-09-02 12:28     ` Brijesh Singh
2021-09-02 21:17       ` Brijesh Singh
2021-09-03  6:28         ` Gerd Hoffmann
2021-09-03 11:56           ` [edk2-devel] " Brijesh Singh
2021-09-01 16:16 ` [PATCH v6 03/29] OvmfPkg/ResetVector: introduce SEV-SNP boot block GUID Brijesh Singh
2021-09-01 16:16 ` [PATCH v6 04/29] OvmfPkg/ResetVector: invalidate the GHCB page Brijesh Singh
2021-09-01 16:16 ` [PATCH v6 05/29] OvmfPkg/ResetVector: check the vmpl level Brijesh Singh
2021-09-01 16:16 ` [PATCH v6 06/29] OvmfPkg/ResetVector: pre-validate the data pages used in SEC phase Brijesh Singh
2021-09-02  8:20   ` Gerd Hoffmann
2021-09-06  1:10     ` [edk2-devel] " Min Xu
2021-09-06 12:16       ` Gerd Hoffmann
2021-09-06 13:19         ` Min Xu
2021-09-07  7:07           ` Gerd Hoffmann
2021-09-07 13:27             ` Brijesh Singh
2021-09-08  6:36               ` Min Xu
2021-09-14  3:49             ` Yao, Jiewen
2021-09-16  7:42               ` Gerd Hoffmann
2021-09-01 16:16 ` [PATCH v6 07/29] OvmfPkg/ResetVector: use SEV-SNP-validated CPUID values Brijesh Singh
2021-09-01 16:16 ` [PATCH v6 08/29] UefiCpuPkg: Define the SEV-SNP specific dynamic PCDs Brijesh Singh
2021-09-01 16:16 ` [PATCH v6 09/29] OvmfPkg/MemEncryptSevLib: add MemEncryptSevSnpEnabled() Brijesh Singh
2021-09-01 16:16 ` [PATCH v6 10/29] OvmfPkg/SecMain: move SEV specific routines in AmdSev.c Brijesh Singh
2021-09-01 16:16 ` [PATCH v6 11/29] OvmfPkg/SecMain: register GHCB gpa for the SEV-SNP guest Brijesh Singh
2021-09-01 16:16 ` [PATCH v6 12/29] OvmfPkg/VmgExitLib: use SEV-SNP-validated CPUID values Brijesh Singh
2021-09-01 16:16 ` [PATCH v6 13/29] OvmfPkg/PlatformPei: register GHCB gpa for the SEV-SNP guest Brijesh Singh
2021-09-01 16:16 ` [PATCH v6 14/29] OvmfPkg/AmdSevDxe: do not use extended PCI config space Brijesh Singh
2021-09-01 16:16 ` [PATCH v6 15/29] OvmfPkg/MemEncryptSevLib: add support to validate system RAM Brijesh Singh
2021-09-02  9:50   ` Gerd Hoffmann
2021-09-02 13:34     ` Brijesh Singh
2021-09-03  7:04       ` Gerd Hoffmann [this message]
2021-09-01 16:16 ` [PATCH v6 16/29] OvmfPkg/BaseMemEncryptSevLib: skip the pre-validated " Brijesh Singh
2021-09-01 16:16 ` [PATCH v6 17/29] OvmfPkg/MemEncryptSevLib: add support to validate > 4GB memory in PEI phase Brijesh Singh
2021-09-01 16:16 ` [PATCH v6 18/29] OvmfPkg/SecMain: pre-validate the memory used for decompressing Fv Brijesh Singh
2021-09-01 16:16 ` [PATCH v6 19/29] OvmfPkg/PlatformPei: validate the system RAM when SNP is active Brijesh Singh
2021-09-01 16:16 ` [PATCH v6 20/29] OvmfPkg/PlatformPei: set the SEV-SNP enabled PCD Brijesh Singh
2021-09-01 16:16 ` [PATCH v6 21/29] OvmfPkg/PlatformPei: set the Hypervisor Features PCD Brijesh Singh
2021-09-01 16:16 ` [PATCH v6 22/29] MdePkg/GHCB: increase the GHCB protocol max version Brijesh Singh
2021-09-01 16:16 ` [PATCH v6 23/29] UefiCpuPkg/MpLib: add support to register GHCB GPA when SEV-SNP is enabled Brijesh Singh
2021-09-01 16:16 ` [PATCH v6 24/29] UefiCpuPkg/MpInitLib: use BSP to do extended topology check Brijesh Singh
2021-09-01 16:16 ` [PATCH v6 25/29] OvmfPkg/MemEncryptSevLib: change the page state in the RMP table Brijesh Singh
2021-09-01 16:16 ` [PATCH v6 26/29] OvmfPkg/MemEncryptSevLib: skip page state change for Mmio address Brijesh Singh
2021-09-01 16:16 ` [PATCH v6 27/29] OvmfPkg/PlatformPei: mark cpuid and secrets memory reserved in EFI map Brijesh Singh
2021-09-01 16:16 ` [PATCH v6 28/29] OvmfPkg/AmdSev: expose the SNP reserved pages through configuration table Brijesh Singh
2021-09-01 16:16 ` [PATCH v6 29/29] UefiCpuPkg/MpInitLib: Use SEV-SNP AP Creation NAE event to launch APs Brijesh Singh
2021-09-07  2:36 ` [PATCH v6 00/29] Add AMD Secure Nested Paging (SEV-SNP) support Yao, Jiewen
2021-09-08  2:29   ` Min Xu
2021-09-08  6:03     ` Yao, Jiewen
2021-09-08 19:45   ` Brijesh Singh
2021-09-09  0:31     ` Min Xu
2021-09-09 10:51       ` Brijesh Singh
2021-09-09 11:22         ` Gerd Hoffmann
2021-09-09 11:40           ` Brijesh Singh
2021-09-09 11:45             ` [edk2-devel] " Min Xu
2021-09-09 11:55         ` Yao, Jiewen
2021-09-12 22:55   ` Brijesh Singh
2021-09-13  0:33     ` Yao, Jiewen

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