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ArmVirtualizationPkg/PciHostBridgeDxe: MMIO aperture must not be uncached

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Quite non-intuitively, we must allow guest-side writes to emulated PCI
MMIO regions to go through the CPU cache, otherwise QEMU, whose accesses
always go through the cache, may see stale data in the region.

This change makes no difference for QEMU/TCG, but it is important for
QEMU/KVM, at the moment.

Because gDS->SetMemorySpaceAttributes() is ultimately implemented by
EFI_CPU_ARCH_PROTOCOL.SetMemoryAttributes() -- see
"MdeModulePkg/Core/Dxe/Gcd/Gcd.c" and "ArmPkg/Drivers/CpuDxe/" -- we add
the CPU architectural protocol to the module's DepEx.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Olivier Martin <olivier.martin@arm.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16904 6f19259b-4bc3-4df7-8a09-765794883524
This commit is contained in:
Laszlo Ersek
2015-02-23 16:03:42 +00:00
committed by lersek
parent 807c26d306
commit f9a8be423c
4 changed files with 50 additions and 2 deletions
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3
ArmPlatformPkg/ArmVirtualizationPkg/ArmVirtualizationQemu.dsc
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@@ -86,6 +86,9 @@
# It could be set FALSE to save size.
gEfiMdeModulePkgTokenSpaceGuid.PcdConOutGopSupport|FALSE
# Activate KVM workaround for now.
gArmVirtualizationTokenSpaceGuid.PcdKludgeMapPciMmioAsCached|TRUE
[PcdsFixedAtBuild.common]
gEfiMdePkgTokenSpaceGuid.PcdDebugPrintErrorLevel|0x8000004F