On Fri, Feb 13, 2015 at 07:21:20AM +0100, Jan Kiszka wrote: > Hi Christoffer, > > On 2015-02-13 05:46, Christoffer Dall wrote: > > Hi Jan, > > > > On Sun, Feb 08, 2015 at 08:48:09AM +0100, Jan Kiszka wrote: > >> Hi, > >> > >> after fixing the VM_BUG_ON, my QEMU guest on the Jetson TK1 generally > >> refuses to boot. Once in a while it does, but quickly gets stuck again. > >> In one case I found this in the kernel log (never happened again so > >> far): > >> > >> [ 762.022874] WARNING: CPU: 1 PID: 972 at ../arch/arm/kvm/../../../virt/kvm/arm/vgic.c:1468 kvm_vgic_sync_hwstate+0x314/0x344() > >> [ 762.022884] Modules linked in: > >> [ 762.022902] CPU: 1 PID: 972 Comm: qemu-system-arm Not tainted 3.19.0-rc7-00221-gfd7a168-dirty #13 > >> [ 762.022911] Hardware name: NVIDIA Tegra SoC (Flattened Device Tree) > >> [ 762.022937] [<c0025d80>] (unwind_backtrace) from [<c00215d8>] (show_stack+0x10/0x14) > >> [ 762.022958] [<c00215d8>] (show_stack) from [<c065f494>] (dump_stack+0x98/0xd8) > >> [ 762.022976] [<c065f494>] (dump_stack) from [<c0035f38>] (warn_slowpath_common+0x80/0xb0) > >> [ 762.022991] [<c0035f38>] (warn_slowpath_common) from [<c0036004>] (warn_slowpath_null+0x1c/0x24) > >> [ 762.023007] [<c0036004>] (warn_slowpath_null) from [<c001c3c4>] (kvm_vgic_sync_hwstate+0x314/0x344) > >> [ 762.023024] [<c001c3c4>] (kvm_vgic_sync_hwstate) from [<c00147c0>] (kvm_arch_vcpu_ioctl_run+0x210/0x400) > >> [ 762.023041] [<c00147c0>] (kvm_arch_vcpu_ioctl_run) from [<c001063c>] (kvm_vcpu_ioctl+0x2e4/0x6ec) > >> [ 762.023059] [<c001063c>] (kvm_vcpu_ioctl) from [<c01098a4>] (do_vfs_ioctl+0x40c/0x600) > >> [ 762.023076] [<c01098a4>] (do_vfs_ioctl) from [<c0109acc>] (SyS_ioctl+0x34/0x5c) > >> [ 762.023091] [<c0109acc>] (SyS_ioctl) from [<c001e320>] (ret_fast_syscall+0x0/0x34) > > > > so this means your guest caused a maintenance interrupt and the bit is > > set in the GICH_EISR for the LR in question but the link register state > > is not 0, which is in direct violation of the GIC spec. Hmmmm. > > > > You're not doing any IRQ forwarding stuff or device passthrough here are > > you? > > No, just boring emulation. The command line is > > qemu-system-ar -machine vexpress-a15 -kernel zImage -serial mon:stdio > -append 'console=ttyAMA0 root=/dev/mmcblk0 rw' -snapshot -sd > OpenSuse13-1_arm.img -dtb vexpress-v2p-ca15-tc1.dtb -s -enable-kvm > > > > >> > >> > >> BTW, KVM tracing support on ARM seems like it requires some care. E.g.: > >> kvm_exit does not report an exit reason. The in-kernel vgic also seems > >> to lack instrumentation. Unfortunate. Tracing is usually the first stop > >> when KVM is stuck on a guest. > > > > I know, the exit reason is on my todo list, and Alex B is sitting on > > trace patches for the gic. Coming soon to a git repo near your. > > Cool, looking forward. > > Next thing I noticed is that guest debugging via qemu causes troubles in > kvm mode. For some reason, qemu is unable to write soft-breakpoints, > thus not even a single-step works. Also known? > Yes, Alex Bennee is working on this. -Christoffer
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