[edk2-devel] [PATCH for-edk2-stable201905 2/6] Revert "OvmfPkg/PlatformPei: reorder the 32-bit PCI window vs. the PCIEXBAR on q35"
Laszlo Ersek
lersek at redhat.com
Wed May 29 15:12:05 UTC 2019
This reverts commit 75136b29541b0e093a51d2e2c2af8d19855c2b60.
The original fix for <https://bugzilla.tianocore.org/show_bug.cgi?id=1814>
triggered a bug / incorrect assumption in QEMU.
QEMU assumes that the PCIEXBAR is below the 32-bit PCI window, not above
it. When the firmware doesn't satisfy this assumption, QEMU generates an
\_SB.PCI0._CRS object in the ACPI DSDT that does not reflect the
firmware's 32-bit MMIO BAR assignments. This causes OSes to re-assign
32-bit MMIO BARs.
Working around the problem in the firmware looks less problematic than
fixing QEMU. Revert the original changes first, before implementing an
alternative fix.
Cc: Ard Biesheuvel <ard.biesheuvel at linaro.org>
Cc: Gerd Hoffmann <kraxel at redhat.com>
Cc: Jordan Justen <jordan.l.justen at intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1859
Signed-off-by: Laszlo Ersek <lersek at redhat.com>
---
OvmfPkg/OvmfPkgIa32.dsc | 5 ++++-
OvmfPkg/OvmfPkgIa32X64.dsc | 5 ++++-
OvmfPkg/OvmfPkgX64.dsc | 5 ++++-
OvmfPkg/PlatformPei/Platform.c | 9 +++++----
4 files changed, 17 insertions(+), 7 deletions(-)
diff --git a/OvmfPkg/OvmfPkgIa32.dsc b/OvmfPkg/OvmfPkgIa32.dsc
index b3446ece311a..578fc6c98ec8 100644
--- a/OvmfPkg/OvmfPkgIa32.dsc
+++ b/OvmfPkg/OvmfPkgIa32.dsc
@@ -490,7 +490,10 @@ [PcdsFixedAtBuild]
# This PCD is used to set the base address of the PCI express hierarchy. It
# is only consulted when OVMF runs on Q35. In that case it is programmed into
# the PCIEXBAR register.
- gEfiMdePkgTokenSpaceGuid.PcdPciExpressBaseAddress|0xE0000000
+ #
+ # On Q35 machine types that QEMU intends to support in the long term, QEMU
+ # never lets the RAM below 4 GB exceed 2 GB.
+ gEfiMdePkgTokenSpaceGuid.PcdPciExpressBaseAddress|0x80000000
!ifdef $(SOURCE_DEBUG_ENABLE)
gEfiSourceLevelDebugPkgTokenSpaceGuid.PcdDebugLoadImageMethod|0x2
diff --git a/OvmfPkg/OvmfPkgIa32X64.dsc b/OvmfPkg/OvmfPkgIa32X64.dsc
index 679d4eb8dd36..eade8f62d3de 100644
--- a/OvmfPkg/OvmfPkgIa32X64.dsc
+++ b/OvmfPkg/OvmfPkgIa32X64.dsc
@@ -495,7 +495,10 @@ [PcdsFixedAtBuild]
# This PCD is used to set the base address of the PCI express hierarchy. It
# is only consulted when OVMF runs on Q35. In that case it is programmed into
# the PCIEXBAR register.
- gEfiMdePkgTokenSpaceGuid.PcdPciExpressBaseAddress|0xE0000000
+ #
+ # On Q35 machine types that QEMU intends to support in the long term, QEMU
+ # never lets the RAM below 4 GB exceed 2 GB.
+ gEfiMdePkgTokenSpaceGuid.PcdPciExpressBaseAddress|0x80000000
!ifdef $(SOURCE_DEBUG_ENABLE)
gEfiSourceLevelDebugPkgTokenSpaceGuid.PcdDebugLoadImageMethod|0x2
diff --git a/OvmfPkg/OvmfPkgX64.dsc b/OvmfPkg/OvmfPkgX64.dsc
index 56a9560262aa..733a4c9d8a43 100644
--- a/OvmfPkg/OvmfPkgX64.dsc
+++ b/OvmfPkg/OvmfPkgX64.dsc
@@ -495,7 +495,10 @@ [PcdsFixedAtBuild]
# This PCD is used to set the base address of the PCI express hierarchy. It
# is only consulted when OVMF runs on Q35. In that case it is programmed into
# the PCIEXBAR register.
- gEfiMdePkgTokenSpaceGuid.PcdPciExpressBaseAddress|0xE0000000
+ #
+ # On Q35 machine types that QEMU intends to support in the long term, QEMU
+ # never lets the RAM below 4 GB exceed 2 GB.
+ gEfiMdePkgTokenSpaceGuid.PcdPciExpressBaseAddress|0x80000000
!ifdef $(SOURCE_DEBUG_ENABLE)
gEfiSourceLevelDebugPkgTokenSpaceGuid.PcdDebugLoadImageMethod|0x2
diff --git a/OvmfPkg/PlatformPei/Platform.c b/OvmfPkg/PlatformPei/Platform.c
index fd8eccaf3e50..9c013613a1a0 100644
--- a/OvmfPkg/PlatformPei/Platform.c
+++ b/OvmfPkg/PlatformPei/Platform.c
@@ -184,13 +184,14 @@ MemMapInitialization (
PciBase = (TopOfLowRam < BASE_2GB) ? BASE_2GB : TopOfLowRam;
if (mHostBridgeDevId == INTEL_Q35_MCH_DEVICE_ID) {
//
- // The 32-bit PCI host aperture is expected to fall between the top of
- // low RAM and the base of the MMCONFIG area.
+ // The MMCONFIG area is expected to fall between the top of low RAM and
+ // the base of the 32-bit PCI host aperture.
//
PciExBarBase = FixedPcdGet64 (PcdPciExpressBaseAddress);
- ASSERT (PciBase < PciExBarBase);
+ ASSERT (TopOfLowRam <= PciExBarBase);
ASSERT (PciExBarBase <= MAX_UINT32 - SIZE_256MB);
- PciSize = (UINT32)(PciExBarBase - PciBase);
+ PciBase = (UINT32)(PciExBarBase + SIZE_256MB);
+ PciSize = 0xFC000000 - PciBase;
} else {
PciSize = 0xFC000000 - PciBase;
}
--
2.19.1.3.g30247aa5d201
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