Re: [PATCH v3 04/16] ArmVirtPkg/QemuVirtMemInfoLib: remove 1:1 mapping of top of PA range

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 28/11/18 15:33, Ard Biesheuvel wrote:
> Currently, we map DRAM as EFI_MEMORY_WB, and the remainder of the
> entire virtual address space is mapped with EFI_MEMORY_UC attributes,
> regardless of whether any devices actually reside there.
> 
> Now that we are relaxing the address space limit to more than 40 bits,
> mapping all that address space actually takes up more space in page
> tables than we have so far made available as temporary RAM. So let's
> get rid of the mapping rather than increasing the available RAM, given
> that the mapping is not particularly useful anyway.
> 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

> ---
>  ArmVirtPkg/Library/QemuVirtMemInfoLib/QemuVirtMemInfoLib.inf    |  7 ----
>  ArmVirtPkg/Library/QemuVirtMemInfoLib/QemuVirtMemInfoPeiLib.inf |  7 ----
>  ArmVirtPkg/Library/QemuVirtMemInfoLib/QemuVirtMemInfoLib.c      | 25 +++----------
>  ArmVirtPkg/Library/QemuVirtMemInfoLib/AArch64/PhysAddrTop.S     | 39 --------------------
>  ArmVirtPkg/Library/QemuVirtMemInfoLib/Arm/PhysAddrTop.S         | 24 ------------
>  5 files changed, 5 insertions(+), 97 deletions(-)
> 
> diff --git a/ArmVirtPkg/Library/QemuVirtMemInfoLib/QemuVirtMemInfoLib.inf b/ArmVirtPkg/Library/QemuVirtMemInfoLib/QemuVirtMemInfoLib.inf
> index c72a97f9e78a..5c5b841051ad 100644
> --- a/ArmVirtPkg/Library/QemuVirtMemInfoLib/QemuVirtMemInfoLib.inf
> +++ b/ArmVirtPkg/Library/QemuVirtMemInfoLib/QemuVirtMemInfoLib.inf
> @@ -24,12 +24,6 @@ [Defines]
>  [Sources]
>    QemuVirtMemInfoLib.c
>  
> -[Sources.ARM]
> -  Arm/PhysAddrTop.S
> -
> -[Sources.AARCH64]
> -  AArch64/PhysAddrTop.S
> -
>  [Packages]
>    ArmPkg/ArmPkg.dec
>    ArmVirtPkg/ArmVirtPkg.dec
> @@ -51,4 +45,3 @@ [Pcd]
>  
>  [FixedPcd]
>    gArmTokenSpaceGuid.PcdFdSize
> -  gEmbeddedTokenSpaceGuid.PcdPrePiCpuMemorySize
> diff --git a/ArmVirtPkg/Library/QemuVirtMemInfoLib/QemuVirtMemInfoPeiLib.inf b/ArmVirtPkg/Library/QemuVirtMemInfoLib/QemuVirtMemInfoPeiLib.inf
> index e4032d3efb53..d12089760b22 100644
> --- a/ArmVirtPkg/Library/QemuVirtMemInfoLib/QemuVirtMemInfoPeiLib.inf
> +++ b/ArmVirtPkg/Library/QemuVirtMemInfoLib/QemuVirtMemInfoPeiLib.inf
> @@ -26,12 +26,6 @@ [Sources]
>    QemuVirtMemInfoLib.c
>    QemuVirtMemInfoPeiLibConstructor.c
>  
> -[Sources.ARM]
> -  Arm/PhysAddrTop.S
> -
> -[Sources.AARCH64]
> -  AArch64/PhysAddrTop.S
> -
>  [Packages]
>    ArmPkg/ArmPkg.dec
>    ArmVirtPkg/ArmVirtPkg.dec
> @@ -55,4 +49,3 @@ [Pcd]
>  [FixedPcd]
>    gArmTokenSpaceGuid.PcdFdSize
>    gArmVirtTokenSpaceGuid.PcdDeviceTreeInitialBaseAddress
> -  gEmbeddedTokenSpaceGuid.PcdPrePiCpuMemorySize
> diff --git a/ArmVirtPkg/Library/QemuVirtMemInfoLib/QemuVirtMemInfoLib.c b/ArmVirtPkg/Library/QemuVirtMemInfoLib/QemuVirtMemInfoLib.c
> index 760bcc169cf4..0285a11b1d77 100644
> --- a/ArmVirtPkg/Library/QemuVirtMemInfoLib/QemuVirtMemInfoLib.c
> +++ b/ArmVirtPkg/Library/QemuVirtMemInfoLib/QemuVirtMemInfoLib.c
> @@ -21,11 +21,6 @@
>  // Number of Virtual Memory Map Descriptors
>  #define MAX_VIRTUAL_MEMORY_MAP_DESCRIPTORS          5
>  
> -EFI_PHYSICAL_ADDRESS
> -ArmGetPhysAddrTop (
> -  VOID
> -  );
> -
>  /**
>    Return the Virtual Memory Map of your platform
>  
> @@ -45,7 +40,6 @@ ArmVirtGetMemoryMap (
>    )
>  {
>    ARM_MEMORY_REGION_DESCRIPTOR  *VirtualMemoryTable;
> -  UINT64                        TopOfMemory;
>  
>    ASSERT (VirtualMemoryMap != NULL);
>  
> @@ -78,23 +72,14 @@ ArmVirtGetMemoryMap (
>    VirtualMemoryTable[1].Length       = VirtualMemoryTable[0].PhysicalBase;
>    VirtualMemoryTable[1].Attributes   = ARM_MEMORY_REGION_ATTRIBUTE_DEVICE;
>  
> -  // Peripheral space after DRAM
> -  TopOfMemory = MIN (1ULL << FixedPcdGet8 (PcdPrePiCpuMemorySize),
> -                     ArmGetPhysAddrTop ());
> -  VirtualMemoryTable[2].PhysicalBase = VirtualMemoryTable[0].Length + VirtualMemoryTable[1].Length;
> -  VirtualMemoryTable[2].VirtualBase  = VirtualMemoryTable[2].PhysicalBase;
> -  VirtualMemoryTable[2].Length       = TopOfMemory -
> -                                       VirtualMemoryTable[2].PhysicalBase;
> -  VirtualMemoryTable[2].Attributes   = ARM_MEMORY_REGION_ATTRIBUTE_DEVICE;
> -
>    // Remap the FD region as normal executable memory
> -  VirtualMemoryTable[3].PhysicalBase = PcdGet64 (PcdFdBaseAddress);
> -  VirtualMemoryTable[3].VirtualBase  = VirtualMemoryTable[3].PhysicalBase;
> -  VirtualMemoryTable[3].Length       = FixedPcdGet32 (PcdFdSize);
> -  VirtualMemoryTable[3].Attributes   = ARM_MEMORY_REGION_ATTRIBUTE_WRITE_BACK;
> +  VirtualMemoryTable[2].PhysicalBase = PcdGet64 (PcdFdBaseAddress);
> +  VirtualMemoryTable[2].VirtualBase  = VirtualMemoryTable[2].PhysicalBase;
> +  VirtualMemoryTable[2].Length       = FixedPcdGet32 (PcdFdSize);
> +  VirtualMemoryTable[2].Attributes   = ARM_MEMORY_REGION_ATTRIBUTE_WRITE_BACK;
>  
>    // End of Table
> -  ZeroMem (&VirtualMemoryTable[4], sizeof (ARM_MEMORY_REGION_DESCRIPTOR));
> +  ZeroMem (&VirtualMemoryTable[3], sizeof (ARM_MEMORY_REGION_DESCRIPTOR));
>  
>    *VirtualMemoryMap = VirtualMemoryTable;
>  }
> diff --git a/ArmVirtPkg/Library/QemuVirtMemInfoLib/AArch64/PhysAddrTop.S b/ArmVirtPkg/Library/QemuVirtMemInfoLib/AArch64/PhysAddrTop.S
> deleted file mode 100644
> index a1f6a194d59b..000000000000
> --- a/ArmVirtPkg/Library/QemuVirtMemInfoLib/AArch64/PhysAddrTop.S
> +++ /dev/null
> @@ -1,39 +0,0 @@
> -#
> -#  Copyright (c) 2011-2013, ARM Limited. All rights reserved.
> -#  Copyright (c) 2016-2017, Linaro Limited. All rights reserved.
> -#
> -#  This program and the accompanying materials
> -#  are licensed and made available under the terms and conditions of the BSD License
> -#  which accompanies this distribution.  The full text of the license may be found at
> -#  http://opensource.org/licenses/bsd-license.php
> -#
> -#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
> -#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> -#
> -#
> -
> -#include <AsmMacroIoLibV8.h>
> -
> -//EFI_PHYSICAL_ADDRESS
> -//GetPhysAddrTop (
> -//  VOID
> -//  );
> -ASM_FUNC(ArmGetPhysAddrTop)
> -  mrs   x0, id_aa64mmfr0_el1
> -  adr   x1, .LPARanges
> -  and   x0, x0, #7
> -  ldrb  w1, [x1, x0]
> -  mov   x0, #1
> -  lsl   x0, x0, x1
> -  ret
> -
> -//
> -// Bits 0..2 of the AA64MFR0_EL1 system register encode the size of the
> -// physical address space support on this CPU:
> -// 0 == 32 bits, 1 == 36 bits, etc etc
> -// 6 and 7 are reserved
> -//
> -.LPARanges:
> -  .byte 32, 36, 40, 42, 44, 48, -1, -1
> -
> -ASM_FUNCTION_REMOVE_IF_UNREFERENCED
> diff --git a/ArmVirtPkg/Library/QemuVirtMemInfoLib/Arm/PhysAddrTop.S b/ArmVirtPkg/Library/QemuVirtMemInfoLib/Arm/PhysAddrTop.S
> deleted file mode 100644
> index 9cd81529fb3d..000000000000
> --- a/ArmVirtPkg/Library/QemuVirtMemInfoLib/Arm/PhysAddrTop.S
> +++ /dev/null
> @@ -1,24 +0,0 @@
> -#
> -#  Copyright (c) 2011-2013, ARM Limited. All rights reserved.
> -#  Copyright (c) 2014-2017, Linaro Limited. All rights reserved.
> -#
> -#  This program and the accompanying materials
> -#  are licensed and made available under the terms and conditions of the BSD License
> -#  which accompanies this distribution.  The full text of the license may be found at
> -#  http://opensource.org/licenses/bsd-license.php
> -#
> -#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
> -#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> -#
> -#
> -
> -#include <AsmMacroIoLib.h>
> -
> -//EFI_PHYSICAL_ADDRESS
> -//GetPhysAddrTop (
> -//  VOID
> -//  );
> -ASM_FUNC(ArmGetPhysAddrTop)
> -  mov   r0, #0x00000000
> -  mov   r1, #0x10000
> -  bx    lr
>