On 06/07/18 12:46, Ard Biesheuvel wrote: > KVM on ARM refuses to decode load/store instructions used to perform > I/O to emulated devices, and instead relies on the exception syndrome > information to describe the operand register, access size, etc. > This is only possible for instructions that have a single input/output > register (as opposed to ones that increment the offset register, or > load/store pair instructions, etc). Otherwise, QEMU crashes with the > following error > > error: kvm run failed Function not implemented > R00=01010101 R01=00000008 R02=00000048 R03=08000820 > R04=00000120 R05=7faaa0e0 R06=7faaa0dc R07=7faaa0e8 > R08=7faaa0ec R09=7faaa088 R10=000000ff R11=00000080 > R12=ff000000 R13=7fccfe08 R14=7faa835f R15=7faa887c > PSR=800001f3 N--- T svc32 > QEMU: Terminated > > and KVM produces a warning such as the following in the kernel log > > kvm [17646]: load/store instruction decoding not implemented > > The IoLib implementation provided by MdePkg/Library/BaseIoLibIntrinsic > is based on C code, and when LTO is in effect, the MMIO accesses could > be merged with, e.g., manipulations of the loop counter, producing > opcodes that KVM does not support for emulated MMIO. > > So let's add a special ArmVirt flavor of this library that implements > that actual load/store operations in assembler, ensuring that the > instructions involved can be emulated by KVM. > > Contributed-under: TianoCore Contribution Agreement 1.1 > Signed-off-by: Ard Biesheuvel <ard.biesheu...@linaro.org> > --- > ArmVirtPkg/ArmVirt.dsc.inc | 2 +- > MdePkg/Library/BaseIoLibIntrinsic/AArch64/ArmVirtMmio.S | 164 +++++ > MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S | 161 +++++ > MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm | 165 +++++ > MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf | 50 ++ > MdePkg/Library/BaseIoLibIntrinsic/IoLibArmVirt.c | 641 > ++++++++++++++++++++ > 6 files changed, 1182 insertions(+), 1 deletion(-)
Assuming Liming is OK with this patch for MdePkg, I have some comments (specific to adding this package to MdePkg): (1) ArmVirtPkg and MdePkg should likely not be modified in the same patch. (2) The library instance should be added as a standalone component to MdePkg.dsc (so it can be built without any client modules): [Components.ARM, Components.AARCH64] MdePkg/Library/BaseStackCheckLib/BaseStackCheckLib.inf MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf <-HERE (3) Library instances under MdePkg are supposed to have MODULE_UNI_FILEs. I think customizing "BaseIoLibIntrinsic.uni" shouldn't be hard; it's basically a different format for re-stating the blurb of the new INF file. (Obviously, don't do anything about these until Liming follows up.) The rest looks OK to me! Thank you for this! Laszlo _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
