mirror of https://github.com/acidanthera/audk.git
51bb05c795
QEMU/mach-virt is rather unhelpful when it comes to tracking down NULL pointer dereferences that occur while running in UEFI: since we have NOR flash mapped at address 0x0, inadvertent reads go unnoticed, and even most writes are silently dropped, unless you're unlucky and the instruction in question is one that KVM cannot emulate, in which case you end up with a QEMU crash like this: error: kvm run failed Function not implemented PC=000000013f7ff804 X00=000000013f7ab108 X01=0000000000000064 X02=000000013f801988 X03=00000000800003c4 X04=0000000000000000 X05=0000000096000044 X06=fffffffffffd8270 X07=000000013f7ab4a0 X08=0000000000000001 X09=000000013f803b88 X10=000000013f7e88d0 X11=0000000000000009 X12=000000013f7ab554 X13=0000000000000008 X14=0000000000000002 X15=0000000000000000 X16=0000000000000000 X17=0000000000000000 X18=0000000000000000 X19=0000000000000000 X20=000000013f81c000 X21=000000013f7ab170 X22=000000013f81c000 X23=0000000009000018 X24=000000013f407020 X25=000000013f81c000 X26=000000013f803530 X27=000000013f802000 X28=000000013f7ab270 X29=000000013f7ab0d0 X30=000000013f7fee10 SP=000000013f7a6f30 PSTATE=800003c5 N--- EL1h and a warning in the host kernel log that load/store instruction decoding is not supported by KVM. Given that the first page of the flash device is not actually used anyway, let's reduce the mappings of the peripheral space and the flash device (both of which cover page #0) to only cover what is actually required: ArmVirtQemu.fdf: > 0x00001000|0x001ff000 > gArmTokenSpaceGuid.PcdFvBaseAddress|gArmTokenSpaceGuid.PcdFvSize ArmVirtQemuKernel.fdf: > 0x00008000|0x001f8000 > gArmTokenSpaceGuid.PcdFvBaseAddress|gArmTokenSpaceGuid.PcdFvSize For ArmVirtQemu, the resulting virtual mapping looks roughly like: - [0, 4K) : flash, unmapped - [4K, 2M) : flash, mapped as WB+X RAM - [2M, 64M) : flash, unmapped - [64M, 128M) : varstore flash, will be mapped by the NOR flash driver - [128M, 256M) : peripherals, mapped as device - [256M, 1GB) : 32-bit MMIO aperture, translated IO aperture, ECAM, will be mapped by the PCI host bridge driver - [1GB, ...) : RAM, mapped. After this change, any inadvertent read or write from/to the first physical page will trigger a translation fault inside the guest, regardless of the nature of the instruction, without crashing QEMU. Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Laszlo Ersek <lersek@redhat.com> |
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| .. | ||
| QemuVirtMemInfoLib.c | ||
| QemuVirtMemInfoLib.inf | ||
| QemuVirtMemInfoPeiLib.inf | ||
| QemuVirtMemInfoPeiLibConstructor.c | ||