Re: [RFC PATCH 05/10] MdeModulePkg: Define memory attribute PPI

["Ni, Ray" <ray.ni@intel.com>]

1. 
The PPI interface supports to set and clear any attributes with single invocation.
That's much better than the existing UEFI protocol prototype which requires caller to call the interfaces
twice to set and clear some attributes.

So far I see two patterns for attributes setting:
*. The patten in this patch: SetMask/ClearMask
*. The pattern I used in PageTableLib: Attribute/Mask.

I think from caller side, they provide the same capabilities.
The difference is SetMask/ClearMask expects callers to not set the same BIT in both
SetMask/ClearMask.

(I thought there would be similar existing interfaces as pattern 2. But I didn't find any now.)
Do you mind to align to pattern #2?


2.
When a memory region is marked from not-present to present, PageTableLib expects
caller to supply all memory attributes (including RW, NX, etc.) as the lib implementation doesn't
want to carry any default attributes..
Do you think the MemoryAttribute PPI should expect the same to caller?


Thanks,
Ray


> -----Original Message-----
> From: Ard Biesheuvel <ardb@kernel.org>
> Sent: Thursday, May 25, 2023 10:31 PM
> To: devel@edk2.groups.io
> Cc: Ard Biesheuvel <ardb@kernel.org>; Ni, Ray <ray.ni@intel.com>; Yao, Jiewen
> <jiewen.yao@intel.com>; Gerd Hoffmann <kraxel@redhat.com>; Taylor Beebe
> <t@taylorbeebe.com>; Oliver Smith-Denny <osd@smith-denny.com>; Bi, Dandan
> <dandan.bi@intel.com>; Gao, Liming <gaoliming@byosoft.com.cn>; Kinney,
> Michael D <michael.d.kinney@intel.com>; Leif Lindholm
> <quic_llindhol@quicinc.com>; Sunil V L <sunilvl@ventanamicro.com>; Warkentin,
> Andrei <andrei.warkentin@intel.com>
> Subject: [RFC PATCH 05/10] MdeModulePkg: Define memory attribute PPI
> 
> Define a PPI interface that may be used by the PEI core or other PEIMs
> to manage permissions on memory ranges. This is primarily intended for
> restricting permissions to what is actually needed for correct execution
> by the code in question, and for limiting the use of memory mappings
> that are both writable and executable at the same time.
> 
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> ---
>  MdeModulePkg/Include/Ppi/MemoryAttribute.h | 78 ++++++++++++++++++++
>  MdeModulePkg/MdeModulePkg.dec              |  3 +
>  2 files changed, 81 insertions(+)
> 
> diff --git a/MdeModulePkg/Include/Ppi/MemoryAttribute.h
> b/MdeModulePkg/Include/Ppi/MemoryAttribute.h
> new file mode 100644
> index 0000000000000000..5ff31185ab4183f8
> --- /dev/null
> +++ b/MdeModulePkg/Include/Ppi/MemoryAttribute.h
> @@ -0,0 +1,78 @@
> +/** @file
> 
> +
> 
> +Copyright (c) 2023, Google LLC. All rights reserved.<BR>
> 
> +
> 
> +SPDX-License-Identifier: BSD-2-Clause-Patent
> 
> +
> 
> +**/
> 
> +
> 
> +#ifndef EDKII_MEMORY_ATTRIBUTE_PPI_H_
> 
> +#define EDKII_MEMORY_ATTRIBUTE_PPI_H_
> 
> +
> 
> +#include <Uefi/UefiSpec.h>
> 
> +
> 
> +///
> 
> +/// Global ID for the EDKII_MEMORY_ATTRIBUTE_PPI.
> 
> +///
> 
> +#define EDKII_MEMORY_ATTRIBUTE_PPI_GUID \
> 
> +  { \
> 
> +    0x1be840de, 0x2d92, 0x41ec, { 0xb6, 0xd3, 0x19, 0x64, 0x13, 0x50, 0x51,
> 0xfb } \
> 
> +  }
> 
> +
> 
> +///
> 
> +/// Forward declaration for the EDKII_MEMORY_ATTRIBUTE_PPI.
> 
> +///
> 
> +typedef struct _EDKII_MEMORY_ATTRIBUTE_PPI
> EDKII_MEMORY_ATTRIBUTE_PPI;
> 
> +
> 
> +/**
> 
> +  Set the requested memory permission attributes on a region of memory.
> 
> +
> 
> +  BaseAddress and Length must be aligned to EFI_PAGE_SIZE.
> 
> +
> 
> +  Both SetMask and ClearMask may contain any combination of
> EFI_MEMORY_RP,
> 
> +  EFI_MEMORY_RO and EFI_MEMORY_XP, with the following restrictions:
> 
> +  - each constant may appear in either SetMask or ClearMask, but not in both;
> 
> +  - SetMask or ClearMask may be 0x0, but not both.
> 
> +
> 
> +  @param[in]  This            The protocol instance pointer.
> 
> +  @param[in]  BaseAddress     The physical address that is the start address of
> 
> +                              a memory region.
> 
> +  @param[in]  Length          The size in bytes of the memory region.
> 
> +  @param[in]  SetMask         Mask of memory attributes to set.
> 
> +  @param[in]  ClearMask       Mask of memory attributes to clear.
> 
> +
> 
> +  @retval EFI_SUCCESS           The attributes were set for the memory region.
> 
> +  @retval EFI_INVALID_PARAMETER Length is zero.
> 
> +                                Invalid combination of SetMask and ClearMask.
> 
> +                                BaseAddress or Length is not suitably aligned.
> 
> +  @retval EFI_UNSUPPORTED       The processor does not support one or more
> 
> +                                bytes of the memory resource range specified
> 
> +                                by BaseAddress and Length.
> 
> +                                The bit mask of attributes is not supported for
> 
> +                                the memory resource range specified by
> 
> +                                BaseAddress and Length.
> 
> +  @retval EFI_OUT_OF_RESOURCES  Requested attributes cannot be applied
> due to
> 
> +                                lack of system resources.
> 
> +
> 
> +**/
> 
> +typedef
> 
> +EFI_STATUS
> 
> +(EFIAPI *EDKII_MEMORY_ATTRIBUTE_SET_PERMISSIONS)(
> 
> +  IN  EDKII_MEMORY_ATTRIBUTE_PPI  *This,
> 
> +  IN  EFI_PHYSICAL_ADDRESS        BaseAddress,
> 
> +  IN  UINT64                      Length,
> 
> +  IN  UINT64                      SetMask,
> 
> +  IN  UINT64                      ClearMask
> 
> +  );
> 
> +
> 
> +///
> 
> +/// This PPI contains a set of services to manage memory permission attributes.
> 
> +///
> 
> +struct _EDKII_MEMORY_ATTRIBUTE_PPI {
> 
> +  EDKII_MEMORY_ATTRIBUTE_SET_PERMISSIONS    SetPermissions;
> 
> +};
> 
> +
> 
> +extern EFI_GUID  gEdkiiMemoryAttributePpiGuid;
> 
> +
> 
> +#endif
> 
> +
> 
> diff --git a/MdeModulePkg/MdeModulePkg.dec
> b/MdeModulePkg/MdeModulePkg.dec
> index 95dd077e19b3a901..d65dae18aa81e569 100644
> --- a/MdeModulePkg/MdeModulePkg.dec
> +++ b/MdeModulePkg/MdeModulePkg.dec
> @@ -528,6 +528,9 @@ [Ppis]
>    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/MemoryAttribute.h
> 
> +  gEdkiiMemoryAttributePpiGuid              = { 0x1be840de, 0x2d92, 0x41ec, { 0xb6,
> 0xd3, 0x19, 0x64, 0x13, 0x50, 0x51, 0xfb } }
> 
> +
> 
>  [Protocols]
> 
>    ## Load File protocol provides capability to load and unload EFI image into
> memory and execute it.
> 
>    #  Include/Protocol/LoadPe32Image.h
> 
> --
> 2.39.2