On Tue, Jun 05, 2018 at 01:05:43PM +0200, 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 instead, let's reimplement IoLib in a KVM safe manner. > > Contributed-under: TianoCore Contribution Agreement 1.1 > Signed-off-by: Ard Biesheuvel <ard.biesheu...@linaro.org> > --- > Yet another approach for the KVM MMIO emulation issue. Note that this one > (as well as the MdePkg) affect both AArch64 and ARM. This is deliberate, > given that there is no reason AArch64 should be immune to this: we simply > haven't triggered the issue yet.
I'm happier with this version (at the same time as I'm sad we're splitting this out). Reviewed-by: Leif Lindholm <leif.lindh...@linaro.org> > ArmVirtPkg/Library/ArmVirtIoLib/AArch64/ArmVirtMmio.S | 164 ++ > ArmVirtPkg/Library/ArmVirtIoLib/Arm/ArmVirtMmio.S | 154 ++ > ArmVirtPkg/Library/ArmVirtIoLib/Arm/ArmVirtMmio.asm | 165 ++ > ArmVirtPkg/Library/ArmVirtIoLib/ArmVirtIoLib.c | 589 +++++ > ArmVirtPkg/Library/ArmVirtIoLib/ArmVirtIoLib.h | 188 ++ > ArmVirtPkg/Library/ArmVirtIoLib/ArmVirtIoLib.inf | 49 + > ArmVirtPkg/Library/ArmVirtIoLib/IoHighLevel.c | 2358 > ++++++++++++++++++++ > ArmVirtPkg/Library/ArmVirtIoLib/IoLibMmioBuffer.c | 413 ++++ > 8 files changed, 4080 insertions(+) _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
