Re: [PATCH v15 00/46] SEV-ES guest support

["Liming Gao" <liming.gao@intel.com>]

Laszlo:

-----Original Message-----
From: Laszlo Ersek <lersek@redhat.com> 
Sent: 2020年8月14日 3:54
To: Tom Lendacky <thomas.lendacky@amd.com>; devel@edk2.groups.io
Cc: Brijesh Singh <brijesh.singh@amd.com>; Ard Biesheuvel <ard.biesheuvel@arm.com>; Dong, Eric <eric.dong@intel.com>; Justen, Jordan L <jordan.l.justen@intel.com>; Gao, Liming <liming.gao@intel.com>; Kinney, Michael D <michael.d.kinney@intel.com>; Ni, Ray <ray.ni@intel.com>; Andrew Fish <afish@apple.com>; Anthony Perard <anthony.perard@citrix.com>; You, Benjamin <benjamin.you@intel.com>; Bi, Dandan <dandan.bi@intel.com>; Dong, Guo <guo.dong@intel.com>; Wu, Hao A <hao.a.wu@intel.com>; Wang, Jian J <jian.j.wang@intel.com>; Julien Grall <julien@xen.org>; Leif Lindholm <leif@nuviainc.com>; Ma, Maurice <maurice.ma@intel.com>
Subject: Re: [PATCH v15 00/46] SEV-ES guest support

On 08/13/20 15:22, Tom Lendacky wrote:
> From: Tom Lendacky <thomas.lendacky@amd.com>
> 
> This patch series provides support for running EDK2/OVMF under SEV-ES.
> 
> Secure Encrypted Virtualization - Encrypted State (SEV-ES) expands on 
> the SEV support to protect the guest register state from the 
> hypervisor. See
> "AMD64 Architecture Programmer's Manual Volume 2: System Programming", 
> section "15.35 Encrypted State (SEV-ES)" [1].
> 
> In order to allow a hypervisor to perform functions on behalf of a 
> guest, there is architectural support for notifying a guest's 
> operating system when certain types of VMEXITs are about to occur. 
> This allows the guest to selectively share information with the 
> hypervisor to satisfy the requested function. The notification is 
> performed using a new exception, the VMM Communication exception 
> (#VC). The information is shared through the Guest-Hypervisor Communication Block (GHCB) using the VMGEXIT instruction.
> The GHCB format and the protocol for using it is documented in "SEV-ES 
> Guest-Hypervisor Communication Block Standardization" [2].
> 
> The main areas of the EDK2 code that are updated to support SEV-ES are 
> around the exception handling support and the AP boot support.
> 
> Exception support is required starting in Sec, continuing through Pei 
> and into Dxe in order to handle #VC exceptions that are generated.  
> Each AP requires it's own GHCB page as well as a page to hold values 
> specific to that AP.
> 
> AP booting poses some interesting challenges. The INIT-SIPI-SIPI 
> sequence is typically used to boot the APs. However, the hypervisor is 
> not allowed to update the guest registers. The GHCB document [2] talks 
> about how SMP booting under SEV-ES is performed.
> 
> Since the GHCB page must be a shared (unencrypted) page, the processor 
> must be running in long mode in order for the guest and hypervisor to 
> communicate with each other. As a result, SEV-ES is only supported 
> under the X64 architecture.
> 
> This series adds a new library requirement for the VmgExitLib library 
> against the UefiCpuPkg CpuExceptionHandlerLib library and the 
> UefiCpuPkg MpInitLib library. The edk2-platforms repo requires 
> updates/patches to add the new library requirement. To accomodate 
> that, this series could be split between:
> 
> patch number 10:
>   UefiPayloadPkg: Prepare UefiPayloadPkg to use the VmgExitLib library
> 
> and patch number 11:
>   UefiCpuPkg/CpuExceptionHandler: Add base support for the #VC 
> exception
> 
> The updates to edk2-platforms can be applied at the split.
> 
> [1] https://www.amd.com/system/files/TechDocs/24593.pdf
> [2] https://developer.amd.com/wp-content/resources/56421.pdf
> 
> ---
> 
> These patches are based on commit:
> 65904cdbb33c ("UefiCpuPkg/MtrrLibUnitTest: Change to use static array 
> for CI test")
> 
> A version of the tree can be found at:
> https://github.com/AMDESE/ovmf/tree/sev-es-v24
> 
> Cc: Andrew Fish <afish@apple.com>
> Cc: Anthony Perard <anthony.perard@citrix.com>
> Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
> Cc: Benjamin You <benjamin.you@intel.com>
> Cc: Dandan Bi <dandan.bi@intel.com>
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Guo Dong <guo.dong@intel.com>
> Cc: Hao A Wu <hao.a.wu@intel.com>
> Cc: Jian J Wang <jian.j.wang@intel.com>
> Cc: Jordan Justen <jordan.l.justen@intel.com>
> Cc: Julien Grall <julien@xen.org>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Cc: Leif Lindholm <leif@nuviainc.com>
> Cc: Liming Gao <liming.gao@intel.com>
> Cc: Maurice Ma <maurice.ma@intel.com>
> Cc: Michael D Kinney <michael.d.kinney@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> 
> Changes since v14:
> - Address ECC errors
>   - Fix non-boolean comparison to use a comparison operator
>   - Separate declaration and initialization of variables
>   - Add period to first line of block comments
>   - Split single-line multiple declaration into multiple lines

The changes look good to me, thanks!

In this particular case, the updates do not invalidate my "Regression-tested-by" given under v14:

https://edk2.groups.io/g/devel/message/63921

"""
For all patches except #10 ("UefiPayloadPkg: Prepare UefiPayloadPkg to use the VmgExitLib library") and #46 ("Maintainers.txt: Add reviewers for the OvmfPkg SEV-related files"):

Regression-tested-by: Laszlo Ersek <lersek@redhat.com> """

So whoever merges this series should please apply that to the respective patches.

[Liming] Got it. This patch set has passed all review. I will help merge it for this stable tag stable202008. 

Thanks!
Laszlo