On Tue, Feb 24, 2015 at 09:15:18PM +0900, Peter Maydell wrote: > On 24 February 2015 at 20:59, Richard W.M. Jones <rjones@xxxxxxxxxx> wrote: > > > > https://bugzilla.redhat.com/show_bug.cgi?id=1194366 > > > > Has anyone seen this KVM error? Or have suggestions how to debug it > > further? > > > > kvm [2028]: load/store instruction decoding not implemented > > This is a fairly common thing to run into and google is bound > to have references to past discussions. What has happened here > is that the guest has attempted a "complex" load/store instruction > to an area of RAM which is not mapped (ie not guest RAM). > For this class of instructions the hardware doesn't provide > syndrome information to allow us to figure out the address/size > etc of the access, so we would have to actually decode the > offending instruction and emulate it; this emulation isn't > implemented. > > Complex insns are things like load-multiple (there's a complete > list in the ARM ARM somewhere). Generally this indicates a guest > bug because you really shouldn't be accessing devices with > weird instructions like that (and you shouldn't be accessing > unmapped memory at all). I'm not super-familiar with the aarch64 instruction set, but according to qemu the instruction is: b8004403 str w3, [x0],#4 (in __copy_to_user). My interpretation is this is storing the lower 32 bits of x3 into the storage pointed to by x0 (+ 4 bytes?) Is that one of the complicated ones? > At some point we might actually implement the decoding, > which will probably just mean your guest crashes inside > the VM rather than outside it. > > > Qemu prints this before crashing: > > > > error: kvm run failed Function not implemented > > (followed by a register dump) > > That's not a QEMU crash, it's QEMU exiting noisily. You can > use the register dump info in combination with the kernel > address map to find out exactly what was trying the access > that failed. > > (Maybe we should add a line to that dump saying "this is not > a QEMU crash" because it's kinda misleading :-)) Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com Fedora Windows cross-compiler. Compile Windows programs, test, and build Windows installers. Over 100 libraries supported. http://fedoraproject.org/wiki/MinGW _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
