[RESEND PATCH RFC v3 00/22] Add AMD Secure Nested Paging (SEV-SNP) support
(I missed adding email@example.com, resending the series)
SEV-SNP builds upon existing SEV and SEV-ES functionality while adding
new hardware-based memory protections. SEV-SNP adds strong memory integrity
protection to help prevent malicious hypervisor-based attacks like data
replay, memory re-mapping and more in order to create an isolated memory
This series provides the basic building blocks to support booting the SEV-SNP
VMs, it does not cover all the security enhancement introduced by the SEV-SNP
such as interrupt protection.
Many of the integrity guarantees of SEV-SNP are enforced through a new
structure called the Reverse Map Table (RMP). Adding a new page to SEV-SNP
VM requires a 2-step process. First, the hypervisor assigns a page to the
guest using the new RMPUPDATE instruction. This transitions the page to
guest-invalid. Second, the guest validates the page using the new PVALIDATE
instruction. The SEV-SNP VMs can use the new "Page State Change Request NAE"
defined in the GHCB specification to ask hypervisor to add or remove page
from the RMP table.
Each page assigned to the SEV-SNP VM can either be validated or unvalidated,
as indicated by the Validated flag in the page's RMP entry. There are two
approaches that can be taken for the page validation: Pre-validation and
Under pre-validation, the pages are validated prior to first use. And under
lazy validation, pages are validated when first accessed. An access to a
unvalidated page results in a #VC exception, at which time the exception
handler may validate the page. Lazy validation requires careful tracking of
the validated pages to avoid validating the same GPA more than once. The
recently introduced "Unaccepted" memory type can be used to communicate the
unvalidated memory ranges to the Guest OS.
At this time we only support the pre-validation. OVMF detects all the available
system RAM in the PEI phase. When SEV-SNP is enabled, the memory is validated
before it is made available to the EDK2 core.
This series does not implements the following SEV-SNP features yet:
* CPUID filtering
* Lazy validation
* Interrupt security
The series builds on SNP pre-patch posted here: https://tinyurl.com/pu6admks
APM 2: https://www.amd.com/system/files/TechDocs/24593.pdf (section 15.36)
The complete source is available at
SEV-SNP firmware specification:
Cc: James Bottomley <jejb@...>
Cc: Min Xu <min.m.xu@...>
Cc: Jiewen Yao <jiewen.yao@...>
Cc: Tom Lendacky <thomas.lendacky@...>
Cc: Jordan Justen <jordan.l.justen@...>
Cc: Ard Biesheuvel <ardb+tianocore@...>
Cc: Laszlo Ersek <lersek@...>
Cc: Erdem Aktas <erdemaktas@...>
Changes since v2:
* Add support for the AP creation.
* Use the module-scoping override to make AmdSevDxe use the IO port for PCI reads.
* Use the reserved memory type for CPUID and Secrets page.
Changes since v1:
* Drop the interval tree support to detect the pre-validated overlap region.
* Use an array to keep track of pre-validated regions.
* Add support to query the Hypervisor feature and verify that SNP feature is supported.
* Introduce MemEncryptSevClearMmioPageEncMask() to clear the C-bit from MMIO ranges.
* Pull the SevSecretDxe and SevSecretPei into OVMF package build.
* Extend the SevSecretDxe to expose confidential computing blob location through
EFI configuration table.
Brijesh Singh (21):
UefiCpuPkg: Define the SEV-SNP specific dynamic PCDs
OvmfPkg/MemEncryptSevLib: add MemEncryptSevSnpEnabled()
OvmfPkg/MemEncryptSevLib: extend the workarea to include SNP enabled
OvmfPkg/MemEncryptSevLib: extend Es Workarea to include hv features
OvmfPkg: reserve Secrets page in MEMFD
OvmfPkg: reserve CPUID page for the SEV-SNP guest
OvmfPkg/ResetVector: validate the data pages used in SEC phase
OvmfPkg/ResetVector: invalidate the GHCB page
OvmfPkg: add library to support registering GHCB GPA
OvmfPkg/PlatformPei: register GHCB gpa for the SEV-SNP guest
UefiCpuPkg/MpLib: add support to register GHCB GPA when SEV-SNP is
OvmfPkg/AmdSevDxe: do not use extended PCI config space
OvmfPkg/MemEncryptSevLib: add support to validate system RAM
OvmfPkg/BaseMemEncryptSevLib: skip the pre-validated system RAM
OvmfPkg/MemEncryptSevLib: add support to validate > 4GB memory in PEI
OvmfPkg/SecMain: pre-validate the memory used for decompressing Fv
OvmfPkg/PlatformPei: validate the system RAM when SNP is active
OvmfPkg/MemEncryptSevLib: Change the page state in the RMP table
OvmfPkg/MemEncryptSevLib: skip page state change for Mmio address
OvmfPkg/AmdSev: expose the SNP reserved pages through configuration
MdePkg/GHCB: increase the GHCB protocol max version
Tom Lendacky (1):
UefiCpuPkg/MpInitLib: Use SEV-SNP AP Creation NAE event to launch APs
OvmfPkg/OvmfPkg.dec | 21 ++
UefiCpuPkg/UefiCpuPkg.dec | 11 +
OvmfPkg/AmdSev/AmdSevX64.dsc | 5 +-
OvmfPkg/Bhyve/BhyveX64.dsc | 5 +-
OvmfPkg/OvmfPkgIa32.dsc | 2 +
OvmfPkg/OvmfPkgIa32X64.dsc | 7 +-
OvmfPkg/OvmfPkgX64.dsc | 8 +-
OvmfPkg/OvmfXen.dsc | 5 +-
OvmfPkg/OvmfPkgX64.fdf | 17 +-
OvmfPkg/AmdSev/SecretDxe/SecretDxe.inf | 4 +
OvmfPkg/AmdSev/SecretPei/SecretPei.inf | 1 +
.../DxeMemEncryptSevLib.inf | 3 +
.../PeiMemEncryptSevLib.inf | 7 +
.../SecMemEncryptSevLib.inf | 3 +
.../GhcbRegisterLib/GhcbRegisterLib.inf | 33 +++
OvmfPkg/PlatformPei/PlatformPei.inf | 5 +
OvmfPkg/ResetVector/ResetVector.inf | 4 +
OvmfPkg/Sec/SecMain.inf | 3 +
UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf | 4 +
UefiCpuPkg/Library/MpInitLib/PeiMpInitLib.inf | 4 +
MdePkg/Include/Register/Amd/Ghcb.h | 2 +-
.../Guid/ConfidentialComputingSecret.h | 18 ++
OvmfPkg/Include/Library/GhcbRegisterLib.h | 27 ++
OvmfPkg/Include/Library/MemEncryptSevLib.h | 31 +-
.../X64/SnpPageStateChange.h | 31 ++
.../BaseMemEncryptSevLib/X64/VirtualMemory.h | 19 ++
UefiCpuPkg/Library/MpInitLib/MpLib.h | 19 ++
OvmfPkg/AmdSev/SecretDxe/SecretDxe.c | 22 ++
OvmfPkg/AmdSev/SecretPei/SecretPei.c | 15 +-
.../DxeMemEncryptSevLibInternal.c | 27 ++
.../Ia32/MemEncryptSevLib.c | 17 ++
.../PeiMemEncryptSevLibInternal.c | 27 ++
.../SecMemEncryptSevLibInternal.c | 19 ++
.../X64/DxeSnpSystemRamValidate.c | 40 +++
.../X64/PeiDxeVirtualMemory.c | 167 ++++++++++-
.../X64/PeiSnpSystemRamValidate.c | 126 ++++++++
.../X64/SecSnpSystemRamValidate.c | 36 +++
.../X64/SnpPageStateChangeInternal.c | 230 +++++++++++++++
.../Library/GhcbRegisterLib/GhcbRegisterLib.c | 97 +++++++
OvmfPkg/PlatformPei/AmdSev.c | 81 ++++++
OvmfPkg/PlatformPei/MemDetect.c | 12 +
OvmfPkg/Sec/SecMain.c | 106 +++++++
UefiCpuPkg/Library/MpInitLib/DxeMpLib.c | 11 +-
.../MpInitLib/Ia32/SevSnpRmpAdjustInternal.c | 31 ++
UefiCpuPkg/Library/MpInitLib/MpLib.c | 274 ++++++++++++++++--
.../MpInitLib/X64/SevSnpRmpAdjustInternal.c | 44 +++
OvmfPkg/FvmainCompactScratchEnd.fdf.inc | 5 +
OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm | 23 ++
OvmfPkg/ResetVector/Ia32/PageTables64.asm | 227 +++++++++++++++
OvmfPkg/ResetVector/ResetVector.nasmb | 6 +
UefiCpuPkg/Library/MpInitLib/MpEqu.inc | 1 +
UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm | 51 ++++
52 files changed, 1956 insertions(+), 38 deletions(-)
create mode 100644 OvmfPkg/Library/GhcbRegisterLib/GhcbRegisterLib.inf
create mode 100644 OvmfPkg/Include/Library/GhcbRegisterLib.h
create mode 100644 OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChange.h
create mode 100644 OvmfPkg/Library/BaseMemEncryptSevLib/X64/DxeSnpSystemRamValidate.c
create mode 100644 OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiSnpSystemRamValidate.c
create mode 100644 OvmfPkg/Library/BaseMemEncryptSevLib/X64/SecSnpSystemRamValidate.c
create mode 100644 OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChangeInternal.c
create mode 100644 OvmfPkg/Library/GhcbRegisterLib/GhcbRegisterLib.c
create mode 100644 UefiCpuPkg/Library/MpInitLib/Ia32/SevSnpRmpAdjustInternal.c
create mode 100644 UefiCpuPkg/Library/MpInitLib/X64/SevSnpRmpAdjustInternal.c
On 05/27/21 01:10, Brijesh Singh wrote:
(I missed adding firstname.lastname@example.org, resending the series)I'm confirming that this series is in my review queue.
However, I may need unusually long time to get to it. Thanks for your
On 05/27/21 11:42, Laszlo Ersek wrote:
On 05/27/21 01:10, Brijesh Singh wrote:
Changes since v2:
I'm confirming that this series is in my review queue.My hope is that I can at least start reviewing this series tomorrow.
Sorry about the delay, I've been working on my todo list the best I can.
On 05/27/21 01:10, Brijesh Singh wrote:
(I missed adding email@example.com, resending the series)That series ("[PATCH v3 00/13] Add GHCBv2 macro and helpers") has been
merged at this point, as commit range dbc22a178546..adfa3327d4fc. [*]
So, I'm having trouble applying this series. I attempted to apply it in
preparation for reviewing patch#2 with a larger context, but I failed,
- When I try applying the series with git-am, upon current master
(c410ad4da4b7), patch#21 ("UefiCpuPkg/MpInitLib: Use SEV-SNP AP
Creation NAE event to launch APs") does not apply.
AFAICT, that's because your modification of GetApResetVectorSize() did
not (could not) take into account Tom's commit dbc22a178546
("UefiCpuPkg/MpInitLib: Allocate a separate SEV-ES AP reset stack
- Your remote branch (with HEAD @ 2dbd79823402) is based on upstream
commit 01c0ab90beb3 ("AzurePipelines: Add support for ArmPlatformPkg",
2021-04-28). If I try to rebase the branch from there to current
master (c410ad4da4b7), I get the following rebase action list:
1 pick 570829c5a0d6 MdePkg: Expand the SEV MSR to include the SNP definition
2 pick b9247f69bdfe MdePkg: Define the GHCB Hypervisor features
3 pick d09ed6d44ffd MdePkg: Define the Page State Change VMGEXIT structures
4 pick 7148b2684f87 MdePkg: Add AsmPvalidate() support
5 pick d6a2c2a0d625 OvmfPkg/BaseMemEncryptSevLib: Introduce MemEncryptSevClearMmioPageEncMask()
6 pick 9b1037d0d9ac OvmfPkg: Use MemEncryptSevClearMmioPageEncMask() to clear EncMask from Mmio
7 pick 556e8fc40179 OvmfPkg/BaseMemEncryptSevLib: Remove CacheFlush parameter
8 pick 03e27af79c61 OvmfPkg/VmgExitLib: Allow PMBASE register access in Dxe phase
9 pick a81925eeb1c6 OvmfPkg/MemEncryptSevLib: add MemEncryptSevSnpEnabled()
10 pick 3d443240f91c OvmfPkg: Reserve Secrets page in MEMFD
11 pick 94dad29970b0 OvmfPkg: Reserve CPUID page for the SEV-SNP guest
12 pick b3e3faa12b0f OvmfPkg: Validate the data pages used in the Reset vector and SEC phase
13 pick 62290e03c79a UefiCpuPkg: Define the SEV-SNP specific dynamic PCDs
14 pick c04e71dabf63 OvmfPkg/MemEncryptSevLib: extend the workarea to include SNP enabled field
15 pick 76072671f367 OvmfPkg/MemEncryptSevLib: Extend Es Workarea to include hv features
16 pick 2bf0eaf2beea OvmfPkg/ResetVector: Invalidate the GHCB page
17 pick 2f050b2a1033 OvmfPkg: Add a library to support registering GHCB GPA
18 pick b2681bdfbebc OvmfPkg: register GHCB gpa for the SEV-SNP guest
19 pick d9f1abb1ff35 UefiCpuPkg/MpLib: add support to register GHCB GPA when SEV-SNP is enabled
20 pick 814084815108 OvmfPkg/MemEncryptSevLib: Add support to validate system RAM
21 pick ec34893c46ab OvmfPkg/BaseMemEncryptSevLib: Skip the pre-validated system RAM
22 pick 37af54f86c3a OvmfPkg/MemEncryptSevLib: Add support to validate > 4GB memory in PEI phase
23 pick 25891f51499e OvmfPkg/SecMain: Pre-validate the memory used for decompressing Fv
24 pick f2f55135b562 OvmfPkg/PlatformPei: Validate the system RAM when SNP is active
25 pick a28b66462eae OvmfPkg/MemEncryptSevLib: Change the page state in the RMP table
26 pick b10c0e61913b OvmfPkg/AmdSev: Expose the SNP reserved pages through configuration table
27 pick 2dbd79823402 MdePkg/GHCB: Increase the GHCB protocol max version
This is 27 patches, while your series contains 22 patches. It *seems*
like some of these 27 patches have been merged via [*] already, but it's
not easy to say which ones. In particular, I can't just drop a
contiguous *prefix* of this rebase action list, because your *posted*
patch#1 is "UefiCpuPkg: Define the SEV-SNP specific dynamic PCDs", but
on your topic branch, that's patch#13! And if I dropped the 12 patches
before that, then we'd be left with 27-12=15 patches, which obviously
doesn't match your posted series consisting of 22 patches. I assume some
of the patches may have been reordered, but I wouldn't like to guess.
I believe we have two problems here: (1) the patch set does not apply to
current master, (2) the posted patch set doesn't even match your remote
Problem (1) is somewhat expected (the master branch is expected to
diverge over time), but problem (2) should never occur. Please never do
this. If you provide a fetch URL + branch reference in your cover
letter, then that remote topic branch must match the posted patches
*forver*. It effectively becomes read only, same as your posted emails
are read-only. If you need to modify the branch, please create a brand
new topic branch (possibly with a new version number in the name), and
rebase that branch.
(It's also possible that you modified your local branch just before
posting, without pushing it to the <https://github.com/AMDESE/ovmf>
repository afterwards, but that's quite disruptive too.)
So... what do you want me to do?
- Are at least patches 01 through 20 (as posted to the list)
authoritative? Should I review those?
- Or would you like to rebase and repost the entire series (this time
keeping the posted version and the fetchable topic branch in sync)?
On 6/4/21 4:32 AM, Laszlo Ersek wrote:
Hi Brijesh,The main issue is I typed wrong branch name in the cover letter. The
branch name should be "sev-snp-rfc-3" and not "sev-snp-rfc-2". I
apologies for it :(. Ray asked the branch name and I replied him with
the correct branch.
This branch was based on commit 5531fd48ded1271b8775725355ab83994e4bc77c
from the upstream.
On 06/04/21 13:50, Brijesh Singh wrote:
Hi Laszlo,Hmmm... indeed, but that discussion happened off-list, namely under the
original posting of this v3 RFC set that did not reach the list. And now
I was working with my list folder.
Right, this branch indeed averts problem (2); it is in sync with the
posted series. Thanks!
Problem (1) stays the same -- git-rebase reports the same issue as
git-am above, for patch#21. So, I'm going to review this version on the
list, but I'll skip patch#21 (or perhaps I'll attempt to make useful
comments there too, if I can).
On 06/04/21 15:09, Laszlo Ersek wrote:
On 06/04/21 13:50, Brijesh Singh wrote:
I re-reviewed patch #3 today, and reviewed patch #4 as well.The main issue is I typed wrong branch name in the cover letter. TheHmmm... indeed, but that discussion happened off-list, namely under the
Because the data flow was not explained in advance, regarding the
"SevSnpEnabled" and "HypervisorFeatures" fields, I wasted a huge amount
of time reviewing ResetVector details that ultimately proved irrelevant.
Additionally, I've found that several patches modify multiple modules in
one step, typically ResetVector and PlatformPei. Honestly, this is
inexplicable to me, given the edk2 coding style. The edk2 style permits
multi-module patches only in the most exceptional cases. In a typical
producer/consumer setup, the producer module patch comes first, the
consumer module patch comes second. Breaking this edk2 rule is very
detrimental to my efficiency as a reviewer.
Either way, I'm done reviewing RFCv3; primarily because tomorrow and the
day after I have some time-sensitive work to do, and afterwards, I'm
going to disapper for a good while, to salvage the shreds of my brain
that I've been left with, after the last two weeks.
In the meantime, assuming no other reviewer wishes to comment RFCv3,
please rework this series carefully -- even if it has "RFC" status,
that's not a license to break edk2 coding style, structure patches
incorrectly, diverge from spec-dictated constants, omit detailed
explanations in commit messages (data flow!), duplicate code (assembly
code!) mindlessly, and so on.