Thanks Tom. Below is exactly what I am looking for: "the decision to use the SVSM API will be based on the VMPL level at which OVMF is running."
OVMF needs to detect SEV-SNP, then make next level decision on VMPL. Makes sense to me. Thank you Yao, Jiewen > -----Original Message----- > From: Tom Lendacky <thomas.lenda...@amd.com> > Sent: Sunday, January 28, 2024 1:49 AM > To: Yao, Jiewen <jiewen....@intel.com>; devel@edk2.groups.io > Cc: Ard Biesheuvel <ardb+tianoc...@kernel.org>; Aktas, Erdem > <erdemak...@google.com>; Gerd Hoffmann <kra...@redhat.com>; Laszlo Ersek > <ler...@redhat.com>; Liming Gao <gaolim...@byosoft.com.cn>; Kinney, Michael > D <michael.d.kin...@intel.com>; Xu, Min M <min.m...@intel.com>; Liu, > Zhiguang <zhiguang....@intel.com>; Kumar, Rahul R <rahul.r.ku...@intel.com>; > Ni, Ray <ray...@intel.com>; Michael Roth <michael.r...@amd.com> > Subject: Re: [PATCH 00/16] Provide SEV-SNP support for running under an SVSM > > On 1/26/24 22:04, Yao, Jiewen wrote: > > Thanks Tom. > > Please give me some time to digest this patch set before I can give some > feedback. > > > > One quick question to you: > > With this patch, we need to support multiple SEV modes: > > 1. SEV guest firmware > > 2. SEV-ES guest firmware > > 3. SEV-SNP guest firmware > > 4. SEV-SNP SVSM guest firmware > > This last mode is still an SNP guest, it just requires invoking an API to > perform operations that require VMPL0 permissions. I'm not sure what you > mean by having firmware at the end of each mode. The same firmware is used > for all SEV guest modes as well as non-SEV guests. > > > And all these mode requires runtime detection. Am I right? > > Yes > > > If so, where is the flag to set those mode? > > There are function calls available to detect the SEV mode. See the > implementation of MemEncryptSevIsEnabled(), MemEncryptSevEsIsEnabled() and > MemEncryptSevSnpIsEnabled(). > > OvmfPkg/Library/BaseMemEncryptSevLib/SecMemEncryptSevLibInternal.c > OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLibInternal.c > OvmfPkg/Library/BaseMemEncryptSevLib/DxeMemEncryptSevLibInternal.c > > (OvmfPkg/Sec/AmdSev.c also has some early detection support) > > Note: > - An SEV-SNP guest is also considered an SEV-ES and SEV guest. > - An SEV-ES guest is also considered an SEV guest. > > Within the CcExitLib library, the decision to use the SVSM API will be > based on the VMPL level at which OVMF is running. > > Thanks, > Tom > > > > > Please correct me if my understanding is wrong. > > > > Thank you > > Yao, Jiewen > > > >> -----Original Message----- > >> From: Tom Lendacky <thomas.lenda...@amd.com> > >> Sent: Saturday, January 27, 2024 6:13 AM > >> To: devel@edk2.groups.io > >> Cc: Ard Biesheuvel <ardb+tianoc...@kernel.org>; Aktas, Erdem > >> <erdemak...@google.com>; Gerd Hoffmann <kra...@redhat.com>; Yao, > Jiewen > >> <jiewen....@intel.com>; Laszlo Ersek <ler...@redhat.com>; Liming Gao > >> <gaolim...@byosoft.com.cn>; Kinney, Michael D > <michael.d.kin...@intel.com>; > >> Xu, Min M <min.m...@intel.com>; Liu, Zhiguang <zhiguang....@intel.com>; > >> Kumar, Rahul R <rahul.r.ku...@intel.com>; Ni, Ray <ray...@intel.com>; > Michael > >> Roth <michael.r...@amd.com> > >> Subject: [PATCH 00/16] Provide SEV-SNP support for running under an SVSM > >> > >> > >> BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=4654 > >> > >> This series adds SEV-SNP support for running OVMF under an Secure VM > >> Service Module (SVSM) at a less privileged VM Privilege Level (VMPL). > >> By running at a less priviledged VMPL, the SVSM can be used to provide > >> services, e.g. a virtual TPM, for the guest OS within the SEV-SNP > >> confidential VM (CVM) rather than trust such services from the hypervisor. > >> > >> Currently, OVMF expects to run at the highest VMPL, VMPL0, and there are > >> certain SNP related operations that require that VMPL level. Specifically, > >> the PVALIDATE instruction and the RMPADJUST instruction when setting the > >> the VMSA attribute of a page (used when starting APs). > >> > >> If OVMF is to run at a less privileged VMPL, e.g. VMPL2, then it must > >> use an SVSM (which is running at VMPL0) to perform the operations that > >> it is no longer able to perform. > >> > >> How OVMF interacts with and uses the SVSM is documented in the SVSM > >> specification [1] and the GHCB specification [2]. > >> > >> This series introduces support to run OVMF under an SVSM. It consists > >> of: > >> - Reorganize the page state change support to not directly use the > >> GHCB buffer since an SVSM will use the calling area buffer, instead > >> - Detecting the presence of an SVSM > >> - When not running at VMPL0, invoking the SVSM for page validation and > >> VMSA page creation/deletion > >> - Retrieving the list of vCPU APIC IDs and starting up all APs without > >> performing a broadcast SIPI > >> - Detecting and allowing OVMF to run in a VMPL other than 0 when an > >> SVSM is present > >> > >> The series is based off of commit: > >> > >> 7d7decfa3dc8 ("UefiPayloadPkg/Crypto: Support external Crypto drivers.") > >> > >> [1] https://www.amd.com/content/dam/amd/en/documents/epyc-technical- > >> docs/specifications/58019.pdf > >> [2] https://www.amd.com/content/dam/amd/en/documents/epyc-technical- > >> docs/specifications/56421.pdf > >> > >> --- > >> > >> Tom Lendacky (16): > >> OvmfPkg/BaseMemEncryptSevLib: Re-organize page state change support > >> MdePkg/Register/Amd: Define the SVSM related information > >> MdePkg/BaseLib: Add a new VMGEXIT instruction invocation for SVSM > >> UefiCpuPkg/CcExitLib: Extend the CcExitLib library to support an SVSM > >> Ovmfpkg/CcExitLib: Extend CcExitLib to handle SVSM related services > >> OvmfPkg: Create a calling area used to communicate with the SVSM > >> OvmfPkg/CcExitLib: Add support for the SVSM_CORE_PVALIDATE call > >> OvmfPkg/CcExitLib: Add support for the SVSM create/delete vCPU calls > >> UefiCpuPkg/MpInitLib: Use CcExitSnpVmsaRmpAdjust() to set/clear VMSA > >> MdePkg: GHCB APIC ID retrieval support definitions > >> UefiCpuPkg: Create APIC ID list PCD > >> OvmfPkg/PlatformPei: Retrieve APIC IDs from the hypervisor > >> UefiCpuPkg/MpInitLib: Always use AP Create if PcdSevSnpApicIds is set > >> UefiCpuPkg/MpInitLib: AP creation support under an SVSM > >> Ovmfpkg/CcExitLib: Provide SVSM discovery support > >> OvmfPkg/BaseMemEncryptLib: Check for presence of an SVSM when not at > >> VMPL0 > >> > >> OvmfPkg/OvmfPkg.dec | > >> 4 + > >> UefiCpuPkg/UefiCpuPkg.dec | > >> 7 +- > >> OvmfPkg/AmdSev/AmdSevX64.fdf | > >> 9 +- > >> OvmfPkg/OvmfPkgX64.fdf | > >> 3 + > >> MdePkg/Library/BaseLib/BaseLib.inf | > >> 2 + > >> OvmfPkg/Library/CcExitLib/CcExitLib.inf | > >> 5 +- > >> OvmfPkg/Library/CcExitLib/SecCcExitLib.inf | > >> 5 +- > >> OvmfPkg/PlatformPei/PlatformPei.inf | > >> 3 + > >> OvmfPkg/ResetVector/ResetVector.inf | > >> 2 + > >> UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf | > >> 1 + > >> UefiCpuPkg/Library/MpInitLib/PeiMpInitLib.inf | > >> 3 +- > >> MdePkg/Include/Library/BaseLib.h | > >> 39 ++ > >> MdePkg/Include/Register/Amd/Fam17Msr.h | > >> 19 +- > >> MdePkg/Include/Register/Amd/Ghcb.h | > >> 19 +- > >> MdePkg/Include/Register/Amd/Msr.h | > >> 3 +- > >> MdePkg/Include/Register/Amd/Svsm.h | > >> 101 ++++ > >> MdePkg/Include/Register/Amd/SvsmMsr.h | > >> 35 ++ > >> OvmfPkg/Include/WorkArea.h | > >> 7 + > >> OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChange.h | > 4 > >> +- > >> OvmfPkg/Library/CcExitLib/CcExitSvsm.h | > >> 29 ++ > >> UefiCpuPkg/Include/Library/CcExitLib.h | > >> 71 ++- > >> UefiCpuPkg/Library/MpInitLib/MpLib.h | > >> 27 +- > >> OvmfPkg/Library/BaseMemEncryptSevLib/X64/DxeSnpSystemRamValidate.c > | > >> 16 +- > >> OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiDxeVirtualMemory.c | > 25 > >> +- > >> OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiSnpSystemRamValidate.c > | > >> 20 +- > >> OvmfPkg/Library/BaseMemEncryptSevLib/X64/SecSnpSystemRamValidate.c > | > >> 25 +- > >> > OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChangeInternal.c | > >> 203 ++++---- > >> OvmfPkg/Library/CcExitLib/CcExitSvsm.c | > >> 532 > >> ++++++++++++++++++++ > >> OvmfPkg/Library/CcExitLib/CcExitVcHandler.c | > >> 29 +- > >> OvmfPkg/PlatformPei/AmdSev.c | > >> 100 +++- > >> UefiCpuPkg/Library/CcExitLibNull/CcExitLibNull.c | > >> 82 ++- > >> UefiCpuPkg/Library/MpInitLib/Ia32/AmdSev.c | > >> 19 +- > >> UefiCpuPkg/Library/MpInitLib/MpLib.c | > >> 7 +- > >> UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c | > >> 127 +++-- > >> MdePkg/Library/BaseLib/Ia32/VmgExitSvsm.nasm | > >> 39 ++ > >> MdePkg/Library/BaseLib/X64/VmgExitSvsm.nasm | > >> 94 ++++ > >> OvmfPkg/ResetVector/ResetVector.nasmb | > >> 6 +- > >> OvmfPkg/ResetVector/X64/OvmfSevMetadata.asm | > >> 9 + > >> UefiCpuPkg/UefiCpuPkg.uni | > >> 3 + > >> 39 files changed, 1524 insertions(+), 210 deletions(-) > >> create mode 100644 MdePkg/Include/Register/Amd/Svsm.h > >> create mode 100644 MdePkg/Include/Register/Amd/SvsmMsr.h > >> create mode 100644 OvmfPkg/Library/CcExitLib/CcExitSvsm.h > >> create mode 100644 OvmfPkg/Library/CcExitLib/CcExitSvsm.c > >> create mode 100644 MdePkg/Library/BaseLib/Ia32/VmgExitSvsm.nasm > >> create mode 100644 MdePkg/Library/BaseLib/X64/VmgExitSvsm.nasm > >> > >> -- > >> 2.42.0 > > -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. 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