Re: [edk2-devel] [PATCH v4 4/6] MdeModulePkg: DxeMain accepts all memory at EBS if needed

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

Can you explain a bit more why this PCD is needed?

> -----Original Message-----
> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Dionna Glaze via groups.io
> Sent: Wednesday, September 28, 2022 11:33 PM
> To: devel@edk2.groups.io
> Cc: Dionna Glaze <dionnaglaze@google.com>; Gerd Hoffmann <kraxel@redhat.com>; James Bottomley
> <jejb@linux.ibm.com>; Yao, Jiewen <jiewen.yao@intel.com>; Tom Lendacky <thomas.lendacky@amd.com>; Ard
> Biesheuvel <ardb@kernel.org>
> Subject: [edk2-devel] [PATCH v4 4/6] MdeModulePkg: DxeMain accepts all memory at EBS if needed
> 
> With the addition of the EfiUnacceptedMemory memory type, it is possible
> the EFI-enlightened guests do not themselves support the new memory
> type. This commit uses the new PcdEnableUnacceptedMemory to enable
> unaccepted memory support before ExitBootServices is called by not
> accepting all unaccepted memory at EBS.
> 
> The expected usage is to set the new Pcd with a protocol that is usable
> by bootloaders and directly-booted OSes when they can determine that the
> OS does indeed support unaccepted memory.
> 
> Cc: Gerd Hoffmann <kraxel@redhat.com>
> Cc: James Bottomley <jejb@linux.ibm.com>
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Cc: Tom Lendacky <thomas.lendacky@amd.com>
> Cc: Ard Biesheuvel <ardb@kernel.org>
> 
> Signed-off-by: Dionna Glaze <dionnaglaze@google.com>
> ---
>  MdeModulePkg/Core/Dxe/DxeMain.h         | 10 +++
>  MdeModulePkg/Core/Dxe/DxeMain.inf       |  2 +
>  MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c | 14 +++-
>  MdeModulePkg/Core/Dxe/Mem/Page.c        | 87 ++++++++++++++++++++
>  4 files changed, 112 insertions(+), 1 deletion(-)
> 
> diff --git a/MdeModulePkg/Core/Dxe/DxeMain.h b/MdeModulePkg/Core/Dxe/DxeMain.h
> index 815a6b4bd8..ac943c87a3 100644
> --- a/MdeModulePkg/Core/Dxe/DxeMain.h
> +++ b/MdeModulePkg/Core/Dxe/DxeMain.h
> @@ -2698,6 +2698,16 @@ CoreInitializeMemoryProtection (
>    VOID
>    );
> 
> +/**
> +   Accept and convert unaccepted memory to conventional memory if unaccepted
> +   memory is not enabled and there is an implementation of MemoryAcceptProtocol
> +   installed.
> + **/
> +EFI_STATUS
> +CoreResolveUnacceptedMemory (
> +  VOID
> +  );
> +
>  /**
>    Install MemoryAttributesTable on memory allocation.
> 
> diff --git a/MdeModulePkg/Core/Dxe/DxeMain.inf b/MdeModulePkg/Core/Dxe/DxeMain.inf
> index e4bca89577..deb8bb2ba8 100644
> --- a/MdeModulePkg/Core/Dxe/DxeMain.inf
> +++ b/MdeModulePkg/Core/Dxe/DxeMain.inf
> @@ -153,6 +153,7 @@
>    gEfiHiiPackageListProtocolGuid                ## SOMETIMES_PRODUCES
>    gEfiSmmBase2ProtocolGuid                      ## SOMETIMES_CONSUMES
>    gEdkiiPeCoffImageEmulatorProtocolGuid         ## SOMETIMES_CONSUMES
> +  gEfiMemoryAcceptProtocolGuid                  ## SOMETIMES_CONSUMES
> 
>    # Arch Protocols
>    gEfiBdsArchProtocolGuid                       ## CONSUMES
> @@ -186,6 +187,7 @@
>    gEfiMdeModulePkgTokenSpaceGuid.PcdHeapGuardPropertyMask                   ## CONSUMES
>    gEfiMdeModulePkgTokenSpaceGuid.PcdCpuStackGuard                           ## CONSUMES
>    gEfiMdeModulePkgTokenSpaceGuid.PcdFwVolDxeMaxEncapsulationDepth           ## CONSUMES
> +  gEfiMdeModulePkgTokenSpaceGuid.PcdEnableUnacceptedMemory                  ## CONSUMES
> 
>  # [Hob]
>  # RESOURCE_DESCRIPTOR   ## CONSUMES
> diff --git a/MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c b/MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c
> index 5733f0c8ec..8d1de32fe7 100644
> --- a/MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c
> +++ b/MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c
> @@ -768,13 +768,25 @@ CoreExitBootServices (
>    //
>    gTimer->SetTimerPeriod (gTimer, 0);
> 
> +  //
> +  // Accept all memory if unaccepted memory isn't enabled.
> +  //
> +  Status = CoreResolveUnacceptedMemory();
> +  if (EFI_ERROR (Status)) {
> +    //
> +    // Notify other drivers that ExitBootServices failed
> +    //
> +    CoreNotifySignalList (&gEventExitBootServicesFailedGuid);
> +    return Status;
> +  }
> +
>    //
>    // Terminate memory services if the MapKey matches
>    //
>    Status = CoreTerminateMemoryMap (MapKey);
>    if (EFI_ERROR (Status)) {
>      //
> -    // Notify other drivers that ExitBootServices fail
> +    // Notify other drivers that ExitBootServices failed
>      //
>      CoreNotifySignalList (&gEventExitBootServicesFailedGuid);
>      return Status;
> diff --git a/MdeModulePkg/Core/Dxe/Mem/Page.c b/MdeModulePkg/Core/Dxe/Mem/Page.c
> index ffe79dcca9..cbebe62a28 100644
> --- a/MdeModulePkg/Core/Dxe/Mem/Page.c
> +++ b/MdeModulePkg/Core/Dxe/Mem/Page.c
> @@ -9,6 +9,8 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
>  #include "DxeMain.h"
>  #include "Imem.h"
>  #include "HeapGuard.h"
> +#include <Library/PcdLib.h>
> +#include <Protocol/MemoryAccept.h>
> 
>  //
>  // Entry for tracking the memory regions for each memory type to coalesce similar memory types
> @@ -2118,6 +2120,91 @@ CoreFreePoolPages (
>    CoreConvertPages (Memory, NumberOfPages, EfiConventionalMemory);
>  }
> 
> +EFI_EVENT gExitBootServiceEvent = NULL;
> +
> +STATIC
> +EFI_STATUS
> +AcceptAllUnacceptedMemory (
> +  IN EFI_MEMORY_ACCEPT_PROTOCOL *AcceptMemory
> +  )
> +{
> +  EFI_GCD_MEMORY_SPACE_DESCRIPTOR  *AllDescMap;
> +  UINTN                            NumEntries;
> +  UINTN                            Index;
> +  EFI_STATUS                       Status;
> +
> +  /*
> +   * Get a copy of the memory space map to iterate over while
> +   * changing the map.
> +   */
> +  Status = CoreGetMemorySpaceMap (&NumEntries, &AllDescMap);
> +  if (EFI_ERROR (Status)) {
> +    return Status;
> +  }
> +  for (Index = 0; Index < NumEntries; Index++) {
> +    CONST EFI_GCD_MEMORY_SPACE_DESCRIPTOR  *Desc;
> +
> +    Desc = &AllDescMap[Index];
> +    if (Desc->GcdMemoryType != EfiGcdMemoryTypeUnaccepted) {
> +      continue;
> +    }
> +
> +    Status = AcceptMemory->AcceptMemory (
> +      AcceptMemory,
> +      Desc->BaseAddress,
> +      Desc->Length
> +      );
> +    if (EFI_ERROR(Status)) {
> +      goto done;
> +    }
> +
> +    Status = CoreRemoveMemorySpace(Desc->BaseAddress, Desc->Length);
> +    if (EFI_ERROR(Status)) {
> +      goto done;
> +    }
> +
> +    Status = CoreAddMemorySpace (
> +      EfiGcdMemoryTypeSystemMemory,
> +      Desc->BaseAddress,
> +      Desc->Length,
> +      EFI_MEMORY_CPU_CRYPTO | EFI_MEMORY_XP | EFI_MEMORY_RO | EFI_MEMORY_RP
> +      );
> +    if (EFI_ERROR(Status)) {
> +      goto done;
> +    }
> +  }
> +
> +done:
> +  FreePool (AllDescMap);
> +  return Status;
> +}
> +
> +EFI_STATUS
> +CoreResolveUnacceptedMemory (
> +  VOID
> +  )
> +{
> +  EFI_MEMORY_ACCEPT_PROTOCOL *AcceptMemory;
> +  EFI_STATUS                 Status;
> +
> +  // No need to accept anything. Unaccepted memory is enabled.
> +  if (PcdGetBool(PcdEnableUnacceptedMemory)) {
> +    return EFI_SUCCESS;
> +  }
> +
> +  Status = gBS->LocateProtocol (&gEfiMemoryAcceptProtocolGuid, NULL,
> +    (VOID **)&AcceptMemory);
> +  if (Status == EFI_NOT_FOUND) {
> +    return EFI_SUCCESS;
> +  }
> +  if (Status != EFI_SUCCESS) {
> +    DEBUG ((DEBUG_ERROR, "Error locating MemoryAcceptProtocol: %d\n", Status));
> +    return Status;
> +  }
> +
> +  return AcceptAllUnacceptedMemory(AcceptMemory);
> +}
> +
>  /**
>    Make sure the memory map is following all the construction rules,
>    it is the last time to check memory map error before exit boot services.
> --
> 2.37.3.998.g577e59143f-goog
> 
> 
> 
> 
>