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ArmPkg/ArmV7Mmu: prefer non shareable memory on non-coherent hardware 

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 <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19285 6f19259b-4bc3-4df7-8a09-765794883524
This commit is contained in:
Ard Biesheuvel 2015-12-15 17:31:56 +00:00 committed by abiesheuvel
parent b9f7890c47
commit 46ff196fde
2 changed files with 53 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
ArmPkg/Library/ArmLib/ArmV7/ArmV7Lib.h
View File

@ -15,6 +15,20 @@
#ifndef __ARM_V7_LIB_H__
#define __ARM_V7_LIB_H__
#define ID_MMFR0_SHARELVL_SHIFT 12
#define ID_MMFR0_SHARELVL_MASK 0xf
#define ID_MMFR0_SHARELVL_ONE 0
#define ID_MMFR0_SHARELVL_TWO 1
#define ID_MMFR0_INNERSHR_SHIFT 28
#define ID_MMFR0_INNERSHR_MASK 0xf
#define ID_MMFR0_OUTERSHR_SHIFT 8
#define ID_MMFR0_OUTERSHR_MASK 0xf
#define ID_MMFR0_SHR_IMP_UNCACHED 0
#define ID_MMFR0_SHR_IMP_HW_COHERENT 1
#define ID_MMFR0_SHR_IGNORED 0xf
typedef VOID (*ARM_V7_CACHE_OPERATION)(UINT32);
VOID

42
ArmPkg/Library/ArmLib/ArmV7/ArmV7Mmu.c
View File

@ -41,6 +41,42 @@ ConvertSectionAttributesToPageAttributes (
return PageAttributes;
}
STATIC
BOOLEAN
PreferNonshareableMemory (
VOID
)
{
UINTN Mmfr;
UINTN Val;
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 >> ID_MMFR0_SHARELVL_SHIFT) & ID_MMFR0_SHARELVL_MASK) {
case ID_MMFR0_SHARELVL_ONE:
// one level of shareability
Val = (Mmfr >> ID_MMFR0_OUTERSHR_SHIFT) & ID_MMFR0_OUTERSHR_MASK;
break;
case ID_MMFR0_SHARELVL_TWO:
// two levels of shareability
Val = (Mmfr >> ID_MMFR0_INNERSHR_SHIFT) & ID_MMFR0_INNERSHR_MASK;
break;
default:
// unexpected value -> shareable is the safe option
ASSERT (FALSE);
return FALSE;
}
return Val != ID_MMFR0_SHR_IMP_HW_COHERENT;
}
STATIC
VOID
PopulateLevel2PageTable (
@ -80,7 +116,7 @@ PopulateLevel2PageTable (
break;
}
if (FeaturePcdGet(PcdNormalMemoryNonshareableOverride)) {
if (PreferNonshareableMemory ()) {
PageAttributes &= ~TT_DESCRIPTOR_PAGE_S_SHARED;
}
@ -189,7 +225,7 @@ FillTranslationTable (
break;
}
if (FeaturePcdGet(PcdNormalMemoryNonshareableOverride)) {
if (PreferNonshareableMemory ()) {
Attributes &= ~TT_DESCRIPTOR_SECTION_S_SHARED;
}
@ -281,7 +317,7 @@ ArmConfigureMmu (
}
if (TTBRAttributes & TTBR_SHAREABLE) {
if (FeaturePcdGet(PcdNormalMemoryNonshareableOverride)) {
if (PreferNonshareableMemory ()) {
TTBRAttributes ^= TTBR_SHAREABLE;
} else {
//