On Tue, Feb 24, 2015 at 12:29:25PM +0000, Richard W.M. Jones wrote: > 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? Shouldn't be, I don't think aarch64 does any register write-back here. This is an aarch64 userspace process, right? You can try adding some more debugging info to the print to get us the IPA it is failing on: diff --git a/arch/arm/kvm/mmio.c b/arch/arm/kvm/mmio.c index 5d3bfc0..e468937 100644 --- a/arch/arm/kvm/mmio.c +++ b/arch/arm/kvm/mmio.c @@ -182,7 +182,8 @@ int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run, if (ret) return ret; } else { - kvm_err("load/store instruction decoding not implemented\n"); + kvm_err("load/store instruction decoding not implemented (HSR: 0x%x, IPA: 0x%llx)\n", + kvm_vcpu_get_hsr(vcpu), fault_ipa); return -ENOSYS; } I wonder why you're faulting on an address that your guest kernel is doing __copy_to_user() on in the first place though, hmmm. -Christoffer _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
