On Fri, Nov 23, 2018 at 01:14:28PM +0100, Ard Biesheuvel wrote:
> In preparation of permitting the virt code to define a larger PA space
> size via gEmbeddedTokenSpaceGuid.PcdPrePiCpuMemorySize than what the
> CPU actually supports, take the CPU's capabilities into account when
> setting up the page tables. This is necessary because KVM will shortly
> support variable PA space sizes, and to support running the same UEFI
> binaries regardless of that limit, PcdPrePiCpuMemorySize needs to be
> treated as an upper bound rather than a fixed size.
Why do we keep PcdPrePiCpuMemorySize at all? (I.e., rather than just
using the probed value?
Mainly for the purpose of being able to restrict ourselves to 32/48
bits?
If we keep it, should we rename
PcdPrePiCpuMemorySize -> PcdPrePiCpuMemoryBits
and
PcdPrePiCpuIoSize -> PcdPrePiCpuIoBits
?
Argument against this would be that later consumers still refer to
the value extracted from the HOB as SizeOf*Space, and happily shifts
1s around by it :|
/
Leif
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Ard Biesheuvel <[email protected]>
> ---
> ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
> b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
> index 4b62ecb6a476..a4fde9b59383 100644
> --- a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
> +++ b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
> @@ -593,6 +593,7 @@ ArmConfigureMmu (
> {
> VOID* TranslationTable;
> UINT32 TranslationTableAttribute;
> + UINTN MaxAddressBits;
> UINT64 MaxAddress;
> UINTN T0SZ;
> UINTN RootTableEntryCount;
> @@ -605,7 +606,9 @@ ArmConfigureMmu (
> }
>
> // Cover the entire GCD memory space
> - MaxAddress = (1UL << PcdGet8 (PcdPrePiCpuMemorySize)) - 1;
> + MaxAddressBits = MIN (ArmGetPhysicalAddressBits (),
> + PcdGet8 (PcdPrePiCpuMemorySize));
> + MaxAddress = (1UL << MaxAddressBits) - 1;
>
> // Lookup the Table Level to get the information
> LookupAddresstoRootTable (MaxAddress, &T0SZ, &RootTableEntryCount);
> --
> 2.17.1
>
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