Hi Stefan,
On 22/07/16 06:57, Stefan Agner wrote:
> Hi,
>
> I tried KVM on a Cortex-A7 platform (i.MX 7Dual SoC) and encountered
> this stack trace immediately after invoking qemu-system-arm:
>
> Unable to handle kernel paging request at virtual address ffffffe4
> pgd = 8ca52740
> [ffffffe4] *pgd=80000080007003, *pmd=8ff7e003, *pte=00000000
> Internal error: Oops: 207 [#1] SMP ARM
> Modules linked in:
> CPU: 0 PID: 329 Comm: qemu-system-arm Tainted: G W
> 4.7.0-rc7-00094-gea3ed2c #109
> Hardware name: Freescale i.MX7 Dual (Device Tree)
> task: 8ca3ee40 ti: 8d2b0000 task.ti: 8d2b0000
> PC is at do_raw_spin_lock+0x8/0x1dc
> LR is at kvm_vgic_flush_hwstate+0x8c/0x224
> pc : [<8027c87c>] lr : [<802172d4>] psr: 60070013
> sp : 8d2b1e38 ip : 8d2b0000 fp : 00000001
> r10: 8d2b0000 r9 : 00010000 r8 : 8d2b8e54
> fec 30be0000.ethernet eth0: MDIO read timeout
> r7 : 8d2b8000 r6 : 8d2b8e74 r5 : 00000000 r4 : ffffffe0
> r3 : 00004ead r2 : 00000000 r1 : 00000000 r0 : ffffffe0
> Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user
> Control: 30c5387d Table: 8ca52740 DAC: fffffffd
> Process qemu-system-arm (pid: 329, stack limit = 0x8d2b0210)
> Stack: (0x8d2b1e38 to 0x8d2b2000)
> 1e20: ffffffe0
> 00000000
> 1e40: 8d2b8e74 8d2b8000 8d2b8e54 00010000 8d2b0000 802172d4 8d2b8000
> 810074f8
> 1e60: 81007508 8ca5f800 8d284000 00010000 8d2b0000 8020fbd4 8ce9a000
> 8ca5f800
> 1e80: 00000000 00010000 00000000 00ff0000 8d284000 00000000 00000000
> 7ffbfeff
> 1ea0: fffffffe 00000000 8d28b780 00000000 755fec6c 00000000 00000000
> ffffe000
> 1ec0: 8d2b8000 00000000 8d28b780 00000000 755fec6c 8020af90 00000000
> 8023f248
> 1ee0: 0000000a 755fe98c 8d2b1f08 00000008 8021aa84 ffffe000 00000000
> 00000000
> 1f00: 8a00d860 8d28b780 80334f94 00000000 8d2b0000 80334748 00000000
> 00000000
> 1f20: 00000000 8d28b780 00004000 00000009 8d28b500 00000024 8104ebee
> 80bc2ec4
> 1f40: 80bafa24 8034138c 00000000 00000000 80341248 00000000 755fec6c
> 007c1e70
> 1f60: 00000009 00004258 0000ae80 8d28b781 00000009 8d28b780 0000ae80
> 00000000
> 1f80: 8d2b0000 00000000 755fec6c 80334f94 007c1e70 322a7400 00004258
> 00000036
> 1fa0: 8021aa84 8021a900 007c1e70 322a7400 00000009 0000ae80 00000000
> 755feac0
> 1fc0: 007c1e70 322a7400 00004258 00000036 7e9aff58 01151da4 76f8b4c0
> 755fec6c
> 1fe0: 0038192c 755fea9c 00048ae7 7697d66c 60070010 00000009 00000000
> 00000000
> [<8027c87c>] (do_raw_spin_lock) from [<802172d4>]
> (kvm_vgic_flush_hwstate+0x8c/0x224)
> [<802172d4>] (kvm_vgic_flush_hwstate) from [<8020fbd4>]
> (kvm_arch_vcpu_ioctl_run+0x110/0x478)
> [<8020fbd4>] (kvm_arch_vcpu_ioctl_run) from [<8020af90>]
> (kvm_vcpu_ioctl+0x2e0/0x6d4)
> [<8020af90>] (kvm_vcpu_ioctl) from [<80334748>]
> (do_vfs_ioctl+0xa0/0x8b8)
> [<80334748>] (do_vfs_ioctl) from [<80334f94>] (SyS_ioctl+0x34/0x5c)
> [<80334f94>] (SyS_ioctl) from [<8021a900>] (ret_fast_syscall+0x0/0x1c)
> Code: e49de004 ea09ea24 e92d47f0 e3043ead (e5902004)
> ---[ end trace cb88537fdc8fa206 ]---
>
> I use CONFIG_KVM_NEW_VGIC=y. This happens to me with a rather minimal
> qemu invocation (qemu-system-arm -enable-kvm -M virt -cpu host
> -nographic -serial stdio -kernel zImage).
>
> Using a bit older Qemu version 2.4.0.
>
> Is there something missing on my platform or is this a general KVM ARM
> issue?
This looks like a genuine bug, and I suspect this is triggered by having
an older QEMU that predates the explicit vgic init, hence relying on the
"init at first run". But in the meantime, could you dump me the bit of
kernel log that shows the KVM initialization, just in case I spot
something odd there?
I'll try and dig a QEMU of that particular vintage to reproduce it.
Thanks for the heads up!
M.
--
Jazz is not dead. It just smells funny...
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