[PATCH V2 0/1] Add EDKII_PEI_VARIABLE_PPI

[PATCH V2 0/1] Add EDKII_PEI_VARIABLE_PPI

[Nate DeSimone]

Changes in V2:
  - Fixed instances where the new PPI was incorrectly reffered to as
    "EDKII PEI Variable Protocol"
  - Added OPTIONAL to the Attributes argument of GetVariable()
  - Added description of initial calling conditions to GetNextVariableName()
  - Clarified the function and format of EFI_AUTHENTICATED_VARIABLE_HOB

This patch series proposes a new architectural PPI: EDKII_PEI_VARIABLE_PPI
This PPI provides services to read and write to UEFI variables during the PEI
environment. While an implementation of this PPI does not exist yet, Intel is
working on a new implementation of the PEI variable services that includes write
support.

As this is essentially a PEI version of the EFI_SMM_VARIABLE_PROTOCOL, I don't
expect it to be immensely controversial. Regardless, before this implementation
is done, we would like to provide the community with an opportunity to provide
input the on new architectural PPI.

Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Isaac Oram <isaac.w.oram@intel.com>
Cc: Chasel Chiu <chasel.chiu@intel.com>
Cc: Gao Cheng <gao.cheng@intel.com>
Cc: Di Zhang <di.zhang@intel.com>
Cc: Daocheng Bu <daocheng.bu@intel.com>
Cc: Michael Kubacki <michael.kubacki@microsoft.com>
Signed-off-by: Nate DeSimone <nathaniel.l.desimone@intel.com>

Nathaniel L Desimone (1):
  MdeModulePkg: Add Definition of EDKII_PEI_VARIABLE_PPI

 MdeModulePkg/Include/Ppi/Variable.h | 195 ++++++++++++++++++++++++++++
 MdeModulePkg/MdeModulePkg.dec       |   3 +
 2 files changed, 198 insertions(+)
 create mode 100644 MdeModulePkg/Include/Ppi/Variable.h

-- 
2.27.0.windows.1

[PATCH V2 1/1] MdeModulePkg: Add Definition of EDKII_PEI_VARIABLE_PPI

[Nate DeSimone]

Adds definition of EDKII_PEI_VARIABLE_PPI, a pre-cursor
to enabling variable writes in the PEI environment.

Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Isaac Oram <isaac.w.oram@intel.com>
Cc: Chasel Chiu <chasel.chiu@intel.com>
Cc: Gao Cheng <gao.cheng@intel.com>
Cc: Di Zhang <di.zhang@intel.com>
Cc: Daocheng Bu <daocheng.bu@intel.com>
Cc: Michael Kubacki <michael.kubacki@microsoft.com>
Signed-off-by: Nate DeSimone <nathaniel.l.desimone@intel.com>
---
 MdeModulePkg/Include/Ppi/Variable.h | 195 ++++++++++++++++++++++++++++
 MdeModulePkg/MdeModulePkg.dec       |   3 +
 2 files changed, 198 insertions(+)
 create mode 100644 MdeModulePkg/Include/Ppi/Variable.h

diff --git a/MdeModulePkg/Include/Ppi/Variable.h b/MdeModulePkg/Include/Ppi/Variable.h
new file mode 100644
index 0000000000..b4b120d2ba
--- /dev/null
+++ b/MdeModulePkg/Include/Ppi/Variable.h
@@ -0,0 +1,195 @@
+/** @file
+  EDKII PEI Variable PPI provides an implementation of variables
+  intended for use as a means to store data in the PEI environment.
+
+  Copyright (c) 2022, Intel Corporation. All rights reserved.<BR>
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#ifndef PEI_VARIABLE_PPI_H_
+#define PEI_VARIABLE_PPI_H_
+
+#define EDKII_PEI_VARIABLE_PPI_GUID \
+  { \
+    0xe7b2cd04, 0x4b14, 0x44c2, { 0xb7, 0x48, 0xce, 0xaf, 0x2b, 0x66, 0x4a, 0xb0 } \
+  }
+
+typedef struct _EDKII_PEI_VARIABLE_PPI EDKII_PEI_VARIABLE_PPI;
+
+/**
+  This service retrieves a variable's value using its name and GUID.
+
+  Read the specified variable from the UEFI variable store. If the Data
+  buffer is too small to hold the contents of the variable,
+  the error EFI_BUFFER_TOO_SMALL is returned and DataSize is set to the
+  required buffer size to obtain the data.
+
+  @param[in]        This              A pointer to this instance of the EDKII_PEI_VARIABLE_PPI.
+  @param[in]        VariableName      A pointer to a null-terminated string that is the variable's name.
+  @param[in]        VariableGuid      A pointer to an EFI_GUID that is the variable's GUID. The combination of
+                                      VariableGuid and VariableName must be unique.
+  @param[out]       Attributes        If non-NULL, on return, points to the variable's attributes.
+  @param[in, out]   DataSize          On entry, points to the size in bytes of the Data buffer.
+                                      On return, points to the size of the data returned in Data.
+  @param[out]       Data              Points to the buffer which will hold the returned variable value.
+                                      May be NULL with a zero DataSize in order to determine the size of the
+                                      buffer needed.
+
+  @retval EFI_SUCCESS                 The variable was read successfully.
+  @retval EFI_NOT_FOUND               The variable was not found.
+  @retval EFI_BUFFER_TOO_SMALL        The DataSize is too small for the resulting data.
+                                      DataSize is updated with the size required for
+                                      the specified variable.
+  @retval EFI_INVALID_PARAMETER       VariableName, VariableGuid, DataSize or Data is NULL.
+  @retval EFI_DEVICE_ERROR            The variable could not be retrieved because of a device error.
+
+**/
+typedef
+EFI_STATUS
+(EFIAPI *EDKII_PEI_GET_VARIABLE)(
+  IN CONST  EDKII_PEI_VARIABLE_PPI    *This,
+  IN CONST  CHAR16                    *VariableName,
+  IN CONST  EFI_GUID                  *VariableGuid,
+  OUT       UINT32                    *Attributes   OPTIONAL,
+  IN OUT    UINTN                     *DataSize,
+  OUT       VOID                      *Data         OPTIONAL
+  );
+
+/**
+  Return the next variable name and GUID.
+
+  This function is called multiple times to retrieve the VariableName
+  and VariableGuid of all variables currently available in the system.
+  On each call, the previous results are passed into the interface,
+  and, on return, the interface returns the data for the next
+  interface. To get started, VariableName should initially contain L"\0"
+  and VariableNameSize should be sizeof(CHAR16). When the entire
+  variable list has been returned, EFI_NOT_FOUND is returned.
+
+  @param[in]        This              A pointer to this instance of the EDKII_PEI_VARIABLE_PPI.
+  @param[in, out]   VariableNameSize  On entry, points to the size of the buffer pointed to by VariableName.
+                                      On return, the size of the variable name buffer.
+  @param[in, out]   VariableName      On entry, a pointer to a null-terminated string that is the variable's name.
+                                      On return, points to the next variable's null-terminated name string.
+  @param[in, out]   VariableGuid      On entry, a pointer to an EFI_GUID that is the variable's GUID.
+                                      On return, a pointer to the next variable's GUID.
+
+  @retval EFI_SUCCESS                 The variable was read successfully.
+  @retval EFI_NOT_FOUND               The variable could not be found.
+  @retval EFI_BUFFER_TOO_SMALL        The VariableNameSize is too small for the resulting
+                                      data. VariableNameSize is updated with the size
+                                      required for the specified variable.
+  @retval EFI_INVALID_PARAMETER       VariableName, VariableGuid or
+                                      VariableNameSize is NULL.
+  @retval EFI_DEVICE_ERROR            The variable could not be retrieved because of a device error.
+
+**/
+typedef
+EFI_STATUS
+(EFIAPI *EDKII_PEI_GET_NEXT_VARIABLE_NAME)(
+  IN CONST  EDKII_PEI_VARIABLE_PPI    *This,
+  IN OUT    UINTN                     *VariableNameSize,
+  IN OUT    CHAR16                    *VariableName,
+  IN OUT    EFI_GUID                  *VariableGuid
+  );
+
+/**
+  Sets the value of a variable.
+
+  @param[in]        This              A pointer to this instance of the EDKII_PEI_VARIABLE_PPI.
+  @param[in]        VariableName      A Null-terminated string that is the name of the vendor's variable.
+                                      Each VariableName is unique for each VendorGuid. VariableName must
+                                      contain 1 or more characters. If VariableName is an empty string,
+                                      then EFI_INVALID_PARAMETER is returned.
+  @param[in]        VendorGuid        A unique identifier for the vendor.
+  @param[in]        Attributes        Attributes bitmask to set for the variable.
+  @param[in]        DataSize          The size in bytes of the Data buffer. Unless the EFI_VARIABLE_APPEND_WRITE
+                                      attribute is set, a size of zero causes the variable to be deleted. When the
+                                      EFI_VARIABLE_APPEND_WRITE attribute is set, then a SetVariable() call with a
+                                      DataSize of zero will not cause any change to the variable value.
+  @param[in]        Data              The contents for the variable.
+
+  @retval EFI_SUCCESS                 The firmware has successfully stored the variable and its data as
+                                      defined by the Attributes.
+  @retval EFI_INVALID_PARAMETER       An invalid combination of attribute bits, name, and GUID was supplied, or the
+                                      DataSize exceeds the maximum allowed.
+  @retval EFI_INVALID_PARAMETER       VariableName is an empty string.
+  @retval EFI_OUT_OF_RESOURCES        Not enough storage is available to hold the variable and its data.
+  @retval EFI_DEVICE_ERROR            The variable could not be retrieved due to a hardware error.
+  @retval EFI_WRITE_PROTECTED         The variable in question is read-only.
+  @retval EFI_WRITE_PROTECTED         The variable in question cannot be deleted.
+  @retval EFI_SECURITY_VIOLATION      The variable could not be written due to EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS,
+                                      or EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS, or
+                                      EFI_VARIABLE_ENHANCED_AUTHENTICATED_ACCESS being set. Writing to authenticated
+                                      variables is not supported in the PEI environment. Updates to authenticated
+                                      variables can be requested during PEI via the EFI_AUTHENTICATED_VARIABLE_HOB, but
+                                      these updates won't be written to non-volatile storage until later in DXE.
+                                      The EFI_AUTHENTICATED_VARIABLE_HOB is a HOB with the GUID
+                                      gEfiAuthenticatedVariableGuid. This HOB contains a VARIABLE_STORE_HEADER followed
+                                      by one or more UEFI variables, which are stored as DWORD aligned tuples of
+                                      (VARIABLE_HEADER + CHAR16 VariableName + VariableData).
+                                      See MdeModulePkg/Include/Guid/VariableFormat.h for these data structure
+                                      definitions and MdeModulePkg/Universal/Variable/RuntimeDxe/VariableParsing.c for
+                                      an example of how to parse these data structures.
+  @retval EFI_NOT_FOUND               The variable trying to be updated or deleted was not found.
+
+**/
+typedef
+EFI_STATUS
+(EFIAPI *EDKII_PEI_SET_VARIABLE)(
+  IN CONST  EDKII_PEI_VARIABLE_PPI    *This,
+  IN        CHAR16                    *VariableName,
+  IN        EFI_GUID                  *VendorGuid,
+  IN        UINT32                    Attributes,
+  IN        UINTN                     DataSize,
+  IN        VOID                      *Data
+  );
+
+/**
+  Returns information about the UEFI variables.
+
+  @param[in]        This                          A pointer to this instance of the EDKII_PEI_VARIABLE_PPI.
+  @param[in]        Attributes                    Attributes bitmask to specify the type of variables on
+                                                  which to return information.
+  @param[out]       MaximumVariableStorageSize    On output the maximum size of the storage space
+                                                  available for the EFI variables associated with the
+                                                  attributes specified.
+  @param[out]       RemainingVariableStorageSize  Returns the remaining size of the storage space
+                                                  available for the EFI variables associated with the
+                                                  attributes specified.
+  @param[out]       MaximumVariableSize           Returns the maximum size of the individual EFI
+                                                  variables associated with the attributes specified.
+
+  @retval EFI_SUCCESS                             Valid answer returned.
+  @retval EFI_INVALID_PARAMETER                   An invalid combination of attribute bits was supplied
+  @retval EFI_UNSUPPORTED                         The attribute is not supported on this platform, and the
+                                                  MaximumVariableStorageSize,
+                                                  RemainingVariableStorageSize, MaximumVariableSize
+                                                  are undefined.
+
+**/
+typedef
+EFI_STATUS
+(EFIAPI *EDKII_PEI_QUERY_VARIABLE_INFO)(
+  IN CONST  EDKII_PEI_VARIABLE_PPI    *This,
+  IN        UINT32                    Attributes,
+  OUT       UINT64                    *MaximumVariableStorageSize,
+  OUT       UINT64                    *RemainingVariableStorageSize,
+  OUT       UINT64                    *MaximumVariableSize
+  );
+
+///
+/// PEI Variable PPI is intended for use as a means
+/// to store data in the PEI environment.
+///
+struct _EDKII_PEI_VARIABLE_PPI {
+  EDKII_PEI_GET_VARIABLE            GetVariable;
+  EDKII_PEI_GET_NEXT_VARIABLE_NAME  GetNextVariableName;
+  EDKII_PEI_SET_VARIABLE            SetVariable;
+  EDKII_PEI_QUERY_VARIABLE_INFO     QueryVariableInfo;
+};
+
+extern EFI_GUID  gEdkiiPeiVariablePpiGuid;
+
+#endif
diff --git a/MdeModulePkg/MdeModulePkg.dec b/MdeModulePkg/MdeModulePkg.dec
index 2bcb9f9453..4f4c48b81f 100644
--- a/MdeModulePkg/MdeModulePkg.dec
+++ b/MdeModulePkg/MdeModulePkg.dec
@@ -513,6 +513,9 @@
   gEdkiiPeiCapsuleOnDiskPpiGuid             = { 0x71a9ea61, 0x5a35, 0x4a5d, { 0xac, 0xef, 0x9c, 0xf8, 0x6d, 0x6d, 0x67, 0xe0 } }
   gEdkiiPeiBootInCapsuleOnDiskModePpiGuid   = { 0xb08a11e4, 0xe2b7, 0x4b75, { 0xb5, 0x15, 0xaf, 0x61, 0x6, 0x68, 0xbf, 0xd1  } }
 
+  ## Include/Ppi/Variable.h
+  gEdkiiPeiVariablePpiGuid                  = { 0xe7b2cd04, 0x4b14, 0x44c2, { 0xb7, 0x48, 0xce, 0xaf, 0x2b, 0x66, 0x4a, 0xb0 } }
+
 [Protocols]
   ## Load File protocol provides capability to load and unload EFI image into memory and execute it.
   #  Include/Protocol/LoadPe32Image.h
-- 
2.27.0.windows.1

Re: [edk2-devel] [PATCH V2 0/1] Add EDKII_PEI_VARIABLE_PPI

[Michael Kubacki]

Acked-by: Michael Kubacki <michael.kubacki@microsoft.com>

On 6/10/2022 5:20 PM, Nate DeSimone wrote:
> Changes in V2:
>    - Fixed instances where the new PPI was incorrectly reffered to as
>      "EDKII PEI Variable Protocol"
>    - Added OPTIONAL to the Attributes argument of GetVariable()
>    - Added description of initial calling conditions to GetNextVariableName()
>    - Clarified the function and format of EFI_AUTHENTICATED_VARIABLE_HOB
> 
> This patch series proposes a new architectural PPI: EDKII_PEI_VARIABLE_PPI
> This PPI provides services to read and write to UEFI variables during the PEI
> environment. While an implementation of this PPI does not exist yet, Intel is
> working on a new implementation of the PEI variable services that includes write
> support.
> 
> As this is essentially a PEI version of the EFI_SMM_VARIABLE_PROTOCOL, I don't
> expect it to be immensely controversial. Regardless, before this implementation
> is done, we would like to provide the community with an opportunity to provide
> input the on new architectural PPI.
> 
> Cc: Jian J Wang <jian.j.wang@intel.com>
> Cc: Liming Gao <gaoliming@byosoft.com.cn>
> Cc: Michael D Kinney <michael.d.kinney@intel.com>
> Cc: Isaac Oram <isaac.w.oram@intel.com>
> Cc: Chasel Chiu <chasel.chiu@intel.com>
> Cc: Gao Cheng <gao.cheng@intel.com>
> Cc: Di Zhang <di.zhang@intel.com>
> Cc: Daocheng Bu <daocheng.bu@intel.com>
> Cc: Michael Kubacki <michael.kubacki@microsoft.com>
> Signed-off-by: Nate DeSimone <nathaniel.l.desimone@intel.com>
> 
> Nathaniel L Desimone (1):
>    MdeModulePkg: Add Definition of EDKII_PEI_VARIABLE_PPI
> 
>   MdeModulePkg/Include/Ppi/Variable.h | 195 ++++++++++++++++++++++++++++
>   MdeModulePkg/MdeModulePkg.dec       |   3 +
>   2 files changed, 198 insertions(+)
>   create mode 100644 MdeModulePkg/Include/Ppi/Variable.h
>