Commit SVN r18778 made all mappings of normal memory (inner) shareable, even on hardware that implements shareability as uncached accesses. The original concerns that prompted the change, regarding coherent DMA and virt guests migrating between CPUs, do not apply to such hardware, so revert to the original behavior in that case.
Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Ard Biesheuvel <[email protected]> --- ArmPkg/Library/ArmLib/ArmV7/ArmV7Mmu.c | 38 ++++++++++++++++++-- 1 file changed, 35 insertions(+), 3 deletions(-) diff --git a/ArmPkg/Library/ArmLib/ArmV7/ArmV7Mmu.c b/ArmPkg/Library/ArmLib/ArmV7/ArmV7Mmu.c index 23d2e43beba0..8aecbe8cc354 100644 --- a/ArmPkg/Library/ArmLib/ArmV7/ArmV7Mmu.c +++ b/ArmPkg/Library/ArmLib/ArmV7/ArmV7Mmu.c @@ -42,6 +42,38 @@ ConvertSectionAttributesToPageAttributes ( } STATIC +BOOLEAN +PreferNonshareableMemory ( + VOID + ) +{ + UINTN Mmfr; + BOOLEAN Result; + + if (FeaturePcdGet (PcdNormalMemoryNonshareableOverride)) { + return TRUE; + } + + // + // Check whether the innermost level of shareability (the level we will use + // by default to map normal memory) is implemented with hardware coherency + // support. Otherwise, revert to mapping as non-shareable. + // + Mmfr = ArmReadIdMmfr0 (); + switch ((Mmfr >> 12) & 0xf) { + case 0x1: + // two levels of shareability + Result = ((Mmfr >> 28) & 0xf) != 1; + break; + default: + // one level of shareability + Result = ((Mmfr >> 8) & 0xf) != 1; + break; + } + return Result; +} + +STATIC VOID PopulateLevel2PageTable ( IN UINT32 *SectionEntry, @@ -80,7 +112,7 @@ PopulateLevel2PageTable ( break; } - if (FeaturePcdGet(PcdNormalMemoryNonshareableOverride)) { + if (PreferNonshareableMemory ()) { PageAttributes &= ~TT_DESCRIPTOR_PAGE_S_SHARED; } @@ -189,7 +221,7 @@ FillTranslationTable ( break; } - if (FeaturePcdGet(PcdNormalMemoryNonshareableOverride)) { + if (PreferNonshareableMemory ()) { Attributes &= ~TT_DESCRIPTOR_SECTION_S_SHARED; } @@ -281,7 +313,7 @@ ArmConfigureMmu ( } if (TTBRAttributes & TTBR_SHAREABLE) { - if (FeaturePcdGet(PcdNormalMemoryNonshareableOverride)) { + if (PreferNonshareableMemory ()) { TTBRAttributes ^= TTBR_SHAREABLE; } else { // -- 1.9.1 _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
