Re: regression bisected; KVM: entry failed, hardware error 0x80000021

[Paolo Bonzini]

On 24/12/2014 12:02, Jamie Heilman wrote:
> Running qemu-system-x86_64 -machine pc,accel=kvm -nodefaults works,
> my real (headless) kvm guests work, but this new patch makes running
> "qemu-system-x86_64 -machine pc,accel=kvm" fail again, this time with
> errors in the host to the tune of:
> 
> ------------[ cut here ]------------
> WARNING: CPU: 1 PID: 3901 at arch/x86/kvm/x86.c:6575 kvm_arch_vcpu_ioctl_run+0xd63/0xe5b [kvm]()
> Modules linked in: nfsv4 cpufreq_userspace cpufreq_stats cpufreq_powersave cpufreq_ondemand cpufreq_conservative autofs4 fan nfsd auth_rpcgss nfs lockd grace fscache sunrpc bridge stp llc vhost_net tun vhost macvtap macvlan fuse cbc dm_crypt usb_storage snd_hda_codec_analog snd_hda_codec_generic kvm_intel kvm tg3 ptp pps_core sr_mod snd_hda_intel snd_hda_controller snd_hda_codec snd_hwdep snd_pcm snd_timer snd sg dcdbas cdrom psmouse soundcore floppy evdev xfs dm_mod raid1 md_mod
> CPU: 1 PID: 3901 Comm: qemu-system-x86 Not tainted 3.19.0-rc1-00011-g53262d1-dirty #1
> Hardware name: Dell Inc. Precision WorkStation T3400  /0TP412, BIOS A14 04/30/2012
>  0000000000000000 000000007e052328 ffff8800c25ffcf8 ffffffff813defbe
>  0000000000000000 0000000000000000 ffff8800c25ffd38 ffffffff8103b517
>  ffff8800c25ffd28 ffffffffa019bdec ffff8800caf1d000 ffff8800c2774800
> Call Trace:
>  [<ffffffff813defbe>] dump_stack+0x4c/0x6e
>  [<ffffffff8103b517>] warn_slowpath_common+0x97/0xb1
>  [<ffffffffa019bdec>] ? kvm_arch_vcpu_ioctl_run+0xd63/0xe5b [kvm]
>  [<ffffffff8103b60b>] warn_slowpath_null+0x15/0x17
>  [<ffffffffa019bdec>] kvm_arch_vcpu_ioctl_run+0xd63/0xe5b [kvm]
>  [<ffffffffa02308b9>] ? vmcs_load+0x20/0x62 [kvm_intel]
>  [<ffffffffa0231e03>] ? vmx_vcpu_load+0x140/0x16a [kvm_intel]
>  [<ffffffffa0196ba3>] ? kvm_arch_vcpu_load+0x15c/0x161 [kvm]
>  [<ffffffffa018d8b1>] kvm_vcpu_ioctl+0x189/0x4bd [kvm]
>  [<ffffffff8104647a>] ? do_sigtimedwait+0x12f/0x189
>  [<ffffffff810ea316>] do_vfs_ioctl+0x370/0x436
>  [<ffffffff810f24f2>] ? __fget+0x67/0x72
>  [<ffffffff810ea41b>] SyS_ioctl+0x3f/0x5e
>  [<ffffffff813e34d2>] system_call_fastpath+0x12/0x17
> ---[ end trace 46abac932fb3b4a1 ]---
> ------------[ cut here ]------------
> WARNING: CPU: 1 PID: 3901 at arch/x86/kvm/x86.c:6575 kvm_arch_vcpu_ioctl_run+0xd63/0xe5b [kvm]()
> Modules linked in: nfsv4 cpufreq_userspace cpufreq_stats cpufreq_powersave cpufreq_ondemand cpufreq_conservative autofs4 fan nfsd auth_rpcgss nfs lockd grace fscache sunrpc bridge stp llc vhost_net tun vhost macvtap macvlan fuse cbc dm_crypt usb_storage snd_hda_codec_analog snd_hda_codec_generic kvm_intel kvm tg3 ptp pps_core sr_mod snd_hda_intel snd_hda_controller snd_hda_codec snd_hwdep snd_pcm snd_timer snd sg dcdbas cdrom psmouse soundcore floppy evdev xfs dm_mod raid1 md_mod
> CPU: 1 PID: 3901 Comm: qemu-system-x86 Tainted: G        W      3.19.0-rc1-00011-g53262d1-dirty #1
> Hardware name: Dell Inc. Precision WorkStation T3400  /0TP412, BIOS A14 04/30/2012
>  0000000000000000 000000007e052328 ffff8800c25ffcf8 ffffffff813defbe
>  0000000000000000 0000000000000000 ffff8800c25ffd38 ffffffff8103b517
>  ffff8800c25ffd28 ffffffffa019bdec ffff8800caf1d000 ffff8800c2774800
> Call Trace:
>  [<ffffffff813defbe>] dump_stack+0x4c/0x6e
>  [<ffffffff8103b517>] warn_slowpath_common+0x97/0xb1
>  [<ffffffffa019bdec>] ? kvm_arch_vcpu_ioctl_run+0xd63/0xe5b [kvm]
>  [<ffffffff8103b60b>] warn_slowpath_null+0x15/0x17
>  [<ffffffffa019bdec>] kvm_arch_vcpu_ioctl_run+0xd63/0xe5b [kvm]
>  [<ffffffffa02308b9>] ? vmcs_load+0x20/0x62 [kvm_intel]
>  [<ffffffffa0231e03>] ? vmx_vcpu_load+0x140/0x16a [kvm_intel]
>  [<ffffffffa0196ba3>] ? kvm_arch_vcpu_load+0x15c/0x161 [kvm]
>  [<ffffffffa018d8b1>] kvm_vcpu_ioctl+0x189/0x4bd [kvm]
>  [<ffffffff8104647a>] ? do_sigtimedwait+0x12f/0x189
>  [<ffffffff810ea316>] do_vfs_ioctl+0x370/0x436
>  [<ffffffff810f24f2>] ? __fget+0x67/0x72
>  [<ffffffff810ea41b>] SyS_ioctl+0x3f/0x5e
>  [<ffffffff813e34d2>] system_call_fastpath+0x12/0x17
> ---[ end trace 46abac932fb3b4a2 ]---
> 
> over and over and over ad nauseum, or until I kill the qemu command,
> it also eats a core's worth of cpu.

Yeah, I'm fairly sure that the second hunk of Tiejun's patch is not
correct, but he's on the right track.  I hope to post a fix today, else
on the 27th or 29th.

Paolo
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