-----Original Message-----
From: Desimone, Nathaniel L <nathaniel.l.desim...@intel.com>
Sent: Saturday, June 11, 2022 5:49 AM
To: Yao, Jiewen <jiewen....@intel.com>; devel@edk2.groups.io;
michael.kuba...@outlook.com
Cc: Wang, Jian J <jian.j.w...@intel.com>; Gao, Liming
<gaolim...@byosoft.com.cn>; Kinney, Michael D
<michael.d.kin...@intel.com>; Oram, Isaac W <isaac.w.o...@intel.com>;
Chiu, Chasel <chasel.c...@intel.com>; Cheng, Gao <gao.ch...@intel.com>;
Zhang, Di <di.zh...@intel.com>; Bu, Daocheng <daocheng...@intel.com>;
Kubacki, Michael <michael.kuba...@microsoft.com>
Subject: RE: [edk2-devel] [PATCH V1 1/1] MdeModulePkg: Add Definition of
EDKII_PEI_VARIABLE_PPI
Hi Jiewen,
Thanks for the feedback, per your questions:
1. The primary use case for this is to enable UEFI variable writes before
permanent memory is available.
2. The implementation is a work in progress. We will provide it shortly. As this
will be a rather large patch set, I would like to get this piece in place
beforehand
so that the reviewers can focus on the implementation separate from the API
definition.
3. No impact to secure boot. We are not going to support writing to
authenticated variables in PEI. As mentioned in the comments, if a PEIM wishes
to update any of the authenticated variables it must use the existing HOB
mechanism to have a later DXE phase perform the update.
4. With regard to atomicity, we have a complete implementation of the fault
tolerant write services operational in Pre-Memory PEI.
5. Good point on the S3 resume, we will need to add an SMI to have the variable
services re-initialize the mNvVariableCache.
Hope that helps,
Nate
-----Original Message-----
From: Yao, Jiewen <jiewen....@intel.com>
Sent: Friday, June 10, 2022 9:56 AM
To: devel@edk2.groups.io; michael.kuba...@outlook.com; Desimone,
Nathaniel L <nathaniel.l.desim...@intel.com>
Cc: Wang, Jian J <jian.j.w...@intel.com>; Gao, Liming
<gaolim...@byosoft.com.cn>; Kinney, Michael D
<michael.d.kin...@intel.com>; Oram, Isaac W <isaac.w.o...@intel.com>;
Chiu, Chasel <chasel.c...@intel.com>; Cheng, Gao <gao.ch...@intel.com>;
Zhang, Di <di.zh...@intel.com>; Bu, Daocheng <daocheng...@intel.com>;
Kubacki, Michael <michael.kuba...@microsoft.com>
Subject: RE: [edk2-devel] [PATCH V1 1/1] MdeModulePkg: Add Definition of
EDKII_PEI_VARIABLE_PPI
Hi
I am curious why we need this interface. Why we need write variable capability
in PEI phase?
Where is the implementation of this? I prefer to see an implementation
submitted together with header file.
For example, what is the impact to secure boot related feature, how to write
auth variable in PEI, how PEI write variable cowork with SMM version in S3
resume phase, how to support variable atomicity, etc.
Thank you
Yao Jiewen
-----Original Message-----
From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Michael
Kubacki
Sent: Friday, June 10, 2022 10:00 AM
To: devel@edk2.groups.io; Desimone, Nathaniel L
<nathaniel.l.desim...@intel.com>
Cc: Wang, Jian J <jian.j.w...@intel.com>; Gao, Liming
<gaolim...@byosoft.com.cn>; Kinney, Michael D
<michael.d.kin...@intel.com>; Oram, Isaac W <isaac.w.o...@intel.com>;
Chiu, Chasel <chasel.c...@intel.com>; Cheng, Gao
<gao.ch...@intel.com>; Zhang, Di <di.zh...@intel.com>; Bu, Daocheng
<daocheng...@intel.com>; Kubacki, Michael
<michael.kuba...@microsoft.com>
Subject: Re: [edk2-devel] [PATCH V1 1/1] MdeModulePkg: Add Definition
of EDKII_PEI_VARIABLE_PPI
Is this change just adding the interface to Tianocore or is there
additional implementation planned as well?
---
I thought we were following this convention now:
"#ifndef __PEI_VARIABLE_PPI_H_" -> "#ifndef PEI_VARIABLE_PPI_H_"
Some other comments are inline.
Regards,
Michael
On 6/9/2022 9:17 PM, Nate DeSimone wrote:
Adds definition of EDKII_PEI_VARIABLE_PPI, a pre-cursor to enabling
variable writes in the PEI environment.
Cc: Jian J Wang <jian.j.w...@intel.com>
Cc: Liming Gao <gaolim...@byosoft.com.cn>
Cc: Michael D Kinney <michael.d.kin...@intel.com>
Cc: Isaac Oram <isaac.w.o...@intel.com>
Cc: Chasel Chiu <chasel.c...@intel.com>
Cc: Gao Cheng <gao.ch...@intel.com>
Cc: Di Zhang <di.zh...@intel.com>
Cc: Daocheng Bu <daocheng...@intel.com>
Cc: Michael Kubacki <michael.kuba...@microsoft.com>
Signed-off-by: Nate DeSimone <nathaniel.l.desim...@intel.com>
---
MdeModulePkg/Include/Ppi/Variable.h | 189
++++++++++++++++++++++++++++
MdeModulePkg/MdeModulePkg.dec | 3 +
2 files changed, 192 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..97dc7ceefa
--- /dev/null
+++ b/MdeModulePkg/Include/Ppi/Variable.h
@@ -0,0 +1,189 @@
+/** @file
+ EDKII PEI Variable Protocol provides an implementation of
+variables
[MK] Was "EDKII PEI Variable PPI" intended?
+ 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,
[MK] Based on the description, Attributes should be marked "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. When the entire variable list has been returned,
+ EFI_NOT_FOUND is returned.
+
[MK] I know other descriptions don't usually have it but it would be
nice to describe the initial calling values expected.
+ @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. See
+
+ MdeModulePkg/Include/Guid/VariableFormat.h for
more details on
+ EFI_AUTHENTICATED_VARIABLE_HOB.
[MK] I didn't see "EFI_AUTHENTICATED_VARIABLE_HOB" mentioned in
VariableFormat.h.
[MK] It seems that if a contract for producing and then consuming this
HOB is going to be defined between the HOB producer and consumer
phase, it should be described in something like the PI Spec.
+ @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 Protocol is intended for use as a means
[MK] Was "PEI Variable PPI" intended?
+/// 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
