[PATCH v6 0/7] Add safe unaccepted memory behavior

Dionna Glaze

These seven patches build on the lazy-accept patch series

"Introduce Lazy-accept for Tdx guest"

by adding SEV-SNP support for the MemoryAccept protocol, and
importantly making eager memory acceptance the default behavior.

We add a new protocol, ExitBootServicesCallbackProtocol, with a single
interface: TerminateMemoryMapPrehook(). We invoke all prehooks in
CoreExitBootServices after disabling the timer and before
TerminateMemoryMap. This gives hooks the chance to change the memory
map and cause ExitBootServices to fail with EFI_INVALID_PARAMETER.
The failure is specified to require the caller to update their view
of the MemoryMap and call ExitBootServices again.

To make use of this new protocol, we add a new driver that is meant to
carry behavior that is needed for all confidential compute technologies,
not just specific platforms, CocoDxe. In CocoDxe we implement the
default safe behavior to accept all unaccepted memory and invalidate
the MemoryMap on ExitBootServices.

To allow the OS loader to prevent the eager acceptance, add another
protocol, up for standardization, AcceptAllUnacceptedMemoryProtocol.
This protocol has one interface, Disable(). The OS loader can inform the
UEFI that it supports the unaccepted memory type and accepts the
responsibility to accept it.

All images that support unaccepted memory must now locate and call this

Changes since v5:
- Generic callback protocol moved to MdeModulePkg
- Removed use of EFI_WARN_STALE_DATA and added comment that the callback
- Removed errant log statement and fixed formatting.

Changes since v4:
- Commit message wording
- Replaced direct change to DxeMain with a more generic callback
- Implemented the direct change as an instance of the callback protocol
from a new CocoDxe driver.
- Replaced "enable" protocol with a "disable" protocol, since the name
was confusing. The AcceptAllUnacceptedMemory protocol directly names
the behavior that is disabling.

Changes since v3:
- "DxeMain accepts all memory" patch split into 3 to make each patch
affect only one package at a time.

Changes since v2:
- Removed the redundant memory accept interface and added the accept
behavior to the DXE implementation of
- Fixed missing #include in >=4GB patch.

Changes since v1:
- Added a patch to classify SEV-SNP memory above 4GB unaccepted.
- Fixed style problems in EfiMemoryAcceptProtocol implementation.

Cc: Ard Biescheuvel <ardb@...>
Cc: "Min M. Xu" <min.m.xu@...>
Cc: Gerd Hoffmann <kraxel@...>
Cc: James Bottomley <jejb@...>
Cc: Tom Lendacky <Thomas.Lendacky@...>
Cc: Jiewen Yao <jiewen.yao@...>
Cc: Erdem Aktas <erdemaktas@...>
Cc: Andrew Fish <afish@...>
Cc: "Michael D. Kinney" <michael.d.kinney@...>

Dionna Glaze (7):
OvmfPkg: Realize EfiMemoryAcceptProtocol in AmdSevDxe
MdeModulePkg: Introduce ExitBootServicesCallbackProtocol
MdeModulePkg: Invoke all ExitBootServicesCallback instances at
OvmfPkg: Introduce CocoDxe driver
MdePkg: Introduce the AcceptAllUnacceptedMemory protocol
OvmfPkg: Implement AcceptAllUnacceptedMemory in CocoDxe
OvmfPkg/PlatformPei: SEV-SNP make >=4GB unaccepted

MdeModulePkg/Core/Dxe/DxeMain.h | 1 +
MdeModulePkg/Core/Dxe/DxeMain.inf | 1 +
MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c | 41 +++++
MdeModulePkg/Include/Protocol/ExitBootServicesCallback.h | 40 +++++
MdeModulePkg/MdeModulePkg.dec | 3 +
MdePkg/Include/Protocol/Bz3987AcceptAllUnacceptedMemory.h | 40 +++++
MdePkg/MdePkg.dec | 3 +
OvmfPkg/AmdSev/AmdSevX64.dsc | 1 +
OvmfPkg/AmdSev/AmdSevX64.fdf | 1 +
OvmfPkg/AmdSevDxe/AmdSevDxe.c | 55 ++++++-
OvmfPkg/AmdSevDxe/AmdSevDxe.inf | 3 +
OvmfPkg/CocoDxe/CocoDxe.c | 169 ++++++++++++++++++++
OvmfPkg/CocoDxe/CocoDxe.inf | 44 +++++
OvmfPkg/IntelTdx/IntelTdxX64.dsc | 1 +
OvmfPkg/IntelTdx/IntelTdxX64.fdf | 1 +
OvmfPkg/Library/BaseMemEncryptSevLib/X64/DxeSnpSystemRamValidate.c | 24 ++-
OvmfPkg/OvmfPkgIa32X64.dsc | 1 +
OvmfPkg/OvmfPkgIa32X64.fdf | 1 +
OvmfPkg/OvmfPkgX64.dsc | 1 +
OvmfPkg/OvmfPkgX64.fdf | 1 +
OvmfPkg/PlatformPei/AmdSev.c | 5 +
21 files changed, 429 insertions(+), 8 deletions(-)
create mode 100644 MdeModulePkg/Include/Protocol/ExitBootServicesCallback.h
create mode 100644 MdePkg/Include/Protocol/Bz3987AcceptAllUnacceptedMemory.h
create mode 100644 OvmfPkg/CocoDxe/CocoDxe.c
create mode 100644 OvmfPkg/CocoDxe/CocoDxe.inf