Re: [PATCH v3 08/16] ArmPkg/ArmMmuLib: take the CPU supported maximum PA space into account

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

On 28/11/18 15:33, Ard Biesheuvel wrote:
> In preparation of dropping PcdPrePiCpuMemorySize entirely, base the
> maximum size of the identity map on the capabilities of the CPU.
> Since that may exceed what is architecturally permitted when using
> 4 KB pages, take MAX_ADDRESS into account as well.
> 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

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

> ---
>  ArmPkg/Library/ArmMmuLib/ArmMmuBaseLib.inf       |  3 ---
>  ArmPkg/Library/ArmMmuLib/ArmMmuPeiLib.inf        |  3 ---
>  ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c | 11 +++++++++--
>  3 files changed, 9 insertions(+), 8 deletions(-)
> 
> diff --git a/ArmPkg/Library/ArmMmuLib/ArmMmuBaseLib.inf b/ArmPkg/Library/ArmMmuLib/ArmMmuBaseLib.inf
> index b9f264de8d26..246963361e45 100644
> --- a/ArmPkg/Library/ArmMmuLib/ArmMmuBaseLib.inf
> +++ b/ArmPkg/Library/ArmMmuLib/ArmMmuBaseLib.inf
> @@ -40,8 +40,5 @@ [LibraryClasses]
>    CacheMaintenanceLib
>    MemoryAllocationLib
>  
> -[Pcd.AARCH64]
> -  gEmbeddedTokenSpaceGuid.PcdPrePiCpuMemorySize
> -
>  [Pcd.ARM]
>    gArmTokenSpaceGuid.PcdNormalMemoryNonshareableOverride
> diff --git a/ArmPkg/Library/ArmMmuLib/ArmMmuPeiLib.inf b/ArmPkg/Library/ArmMmuLib/ArmMmuPeiLib.inf
> index ecf13f790734..f689c193b862 100644
> --- a/ArmPkg/Library/ArmMmuLib/ArmMmuPeiLib.inf
> +++ b/ArmPkg/Library/ArmMmuLib/ArmMmuPeiLib.inf
> @@ -35,6 +35,3 @@ [LibraryClasses]
>    ArmLib
>    CacheMaintenanceLib
>    MemoryAllocationLib
> -
> -[Pcd.AARCH64]
> -  gEmbeddedTokenSpaceGuid.PcdPrePiCpuMemorySize
> diff --git a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
> index 4b62ecb6a476..5403b8d4070e 100644
> --- a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
> +++ b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
> @@ -604,8 +604,15 @@ ArmConfigureMmu (
>      return EFI_INVALID_PARAMETER;
>    }
>  
> -  // Cover the entire GCD memory space
> -  MaxAddress = (1UL << PcdGet8 (PcdPrePiCpuMemorySize)) - 1;
> +  //
> +  // Limit the virtual address space to what we can actually use: UEFI
> +  // mandates a 1:1 mapping, so no point in making the virtual address
> +  // space larger than the physical address space. We also have to take
> +  // into account the architectural limitations that result from UEFI's
> +  // use of 4 KB pages.
> +  //
> +  MaxAddress = MIN (LShiftU64 (1ULL, ArmGetPhysicalAddressBits ()) - 1,
> +                    MAX_ADDRESS);
>  
>    // Lookup the Table Level to get the information
>    LookupAddresstoRootTable (MaxAddress, &T0SZ, &RootTableEntryCount);
>