tyler.durden/audk
1
0
Fork 0
mirror of https://github.com/acidanthera/audk.git synced 2025-04-08 17:05:09 +02:00
Code Issues Packages Projects Releases Wiki Activity

OvmfPkg/QemuVideoDxe: add feature PCD to remap framebuffer W/C

Browse Source 
Some platforms (such as SBSA-QEMU on recent builds of the emulator) only
tolerate misaligned accesses to normal memory, and raise alignment
faults on such accesses to device memory, which is the default for PCIe
MMIO BARs.

When emulating a PCIe graphics controller, the framebuffer is typically
exposed via a MMIO BAR, while the disposition of the region is closer to
memory (no side effects on reads or writes, except for the changing
picture on the screen; direct random access to any pixel in the image).

In order to permit the use of such controllers on platforms that only
tolerate these types of accesses for normal memory, it is necessary to
remap the memory. Use the DXE services to set the desired capabilities
and attributes.

Hide this behavior under a feature PCD so only platforms that really
need it can enable it. (OVMF on x86 has no need for this)

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
This commit is contained in:
Ard Biesheuvel 2024-06-17 17:07:41 +02:00 committed by mergify[bot]
parent ffce430d2b
commit c1d1910be6
4 changed files with 29 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
OvmfPkg/OvmfPkg.dec
View File

@ -449,3 +449,8 @@
## This feature flag indicates the firmware build supports secure boot.
gUefiOvmfPkgTokenSpaceGuid.PcdSecureBootSupported|FALSE|BOOLEAN|0x6d
## Whether QemuVideoDxe should perform a EFI_MEMORY_WC remap of the PCI
# framebuffer. This might be required on platforms that do not tolerate
# misaligned accesses otherwise.
gUefiOvmfPkgTokenSpaceGuid.PcdRemapFrameBufferWriteCombine|FALSE|BOOLEAN|0x75

19
OvmfPkg/QemuVideoDxe/Gop.c
View File

@ -9,6 +9,8 @@
#include "Qemu.h"
#include <Library/DxeServicesTableLib.h>
STATIC
VOID
QemuVideoCompleteModeInfo (
@ -54,6 +56,7 @@ QemuVideoCompleteModeData (
EFI_GRAPHICS_OUTPUT_MODE_INFORMATION *Info;
EFI_ACPI_ADDRESS_SPACE_DESCRIPTOR *FrameBufDesc;
QEMU_VIDEO_MODE_DATA *ModeData;
EFI_STATUS Status;
ModeData = &Private->ModeData[Mode->Mode];
Info = Mode->Info;
@ -79,6 +82,22 @@ QemuVideoCompleteModeData (
(UINT64)Mode->FrameBufferSize
));
if (FeaturePcdGet (PcdRemapFrameBufferWriteCombine)) {
Status = gDS->SetMemorySpaceCapabilities (
FrameBufDesc->AddrRangeMin,
FrameBufDesc->AddrLen,
EFI_MEMORY_UC | EFI_MEMORY_WC | EFI_MEMORY_XP
);
ASSERT_EFI_ERROR (Status);
Status = gDS->SetMemorySpaceAttributes (
FrameBufDesc->AddrRangeMin,
FrameBufDesc->AddrLen,
EFI_MEMORY_WC | EFI_MEMORY_XP
);
ASSERT_EFI_ERROR (Status);
}
FreePool (FrameBufDesc);
return EFI_SUCCESS;
}

2
OvmfPkg/QemuVideoDxe/Qemu.h
View File

@ -13,7 +13,7 @@
#ifndef _QEMU_H_
#define _QEMU_H_
#include <Uefi.h>
#include <PiDxe.h>
#include <Protocol/GraphicsOutput.h>
#include <Protocol/PciIo.h>
#include <Protocol/DriverSupportedEfiVersion.h>

4
OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
View File

@ -40,6 +40,7 @@
[LibraryClasses]
BaseMemoryLib
DxeServicesTableLib
FrameBufferBltLib
DebugLib
DevicePathLib
@ -57,6 +58,9 @@
gEfiDevicePathProtocolGuid # PROTOCOL BY_START
gEfiPciIoProtocolGuid # PROTOCOL TO_START
[FeaturePcd]
gUefiOvmfPkgTokenSpaceGuid.PcdRemapFrameBufferWriteCombine
[Pcd]
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfHostBridgePciDevId
gUefiOvmfPkgTokenSpaceGuid.PcdVideoResolutionSource