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From: "Dirk Müller" <dmueller@suse.com>
To: Paolo Bonzini <pbonzini@redhat.com>, kvm@vger.kernel.org
Cc: Joerg Roedel <joro@8bytes.org>
Subject: Re: [PATCH] Use WARN_ON_ONCE for missing X86_FEATURE_NRIPS
Date: Thu, 1 Oct 2015 14:45:32 +0200	[thread overview]
Message-ID: <560D2AEC.1060605@suse.com> (raw)
In-Reply-To: <560D2622.4090906@redhat.com>

On 01.10.2015 14:25, Paolo Bonzini wrote:

Hi Paolo,

 > Applied.  Do you also know what caused the warning, and/or would you
> like me to take a look?

The trace we're getting is this:

  [<ffffffff8100471d>] dump_trace+0x7d/0x2d0
  [<ffffffff81004a04>] show_stack_log_lvl+0x94/0x170
  [<ffffffff81005cc1>] show_stack+0x21/0x50
  [<ffffffff81510f42>] dump_stack+0x41/0x51
  [<ffffffff81055362>] warn_slowpath_common+0x82/0xc0
  [<ffffffffa0388cc1>] skip_emulated_instruction+0xe1/0x160 [kvm_amd]
  [<ffffffffa038908b>] io_interception+0x3b/0x80 [kvm_amd]
  [<ffffffffa031667c>] vcpu_enter_guest+0x6bc/0xc70 [kvm]
  [<ffffffffa031aa08>] kvm_arch_vcpu_ioctl_run+0x1d8/0x450 [kvm]
  [<ffffffffa0305ec1>] kvm_vcpu_ioctl+0x2e1/0x580 [kvm]
  [<ffffffff811b3f24>] do_vfs_ioctl+0x2d4/0x4b0
  [<ffffffff811b4188>] SyS_ioctl+0x88/0xa0
  [<ffffffff8151f209>] system_call_fastpath+0x16/0x1b
  [<00007f8f7b5fabe7>] 0x7f8f7b5fabe6


The colleague who was investigating this is not here today, but from 
what I remember it seems to only happen when nested virtualisation is 
being used. I don't know more about it right now, bisecting pointed out 
f104765b4f81fd74d69e0eb161e89096deade2db . Since it was logging so 
rapidly on our autotester machines (which are running 200-250 VMs 
nested) that we are continuously run out of disk space I just tried to 
come up with a stop-gap fix until this has been properly analyzed.

Thanks,
Dirk


  reply	other threads:[~2015-10-01 12:46 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-10-01 11:43 [PATCH] Use WARN_ON_ONCE for missing X86_FEATURE_NRIPS Dirk Müller
2015-10-01 12:25 ` Paolo Bonzini
2015-10-01 12:45   ` Dirk Müller [this message]
2015-10-01 12:31 ` Paolo Bonzini
2015-10-01 22:31   ` Bandan Das
2015-10-02  6:43     ` Dirk Müller
2015-10-05  1:15       ` Bandan Das
2015-10-05  9:50     ` Joerg Roedel
2015-10-05 16:54       ` Bandan Das
2015-10-05 17:15         ` Joerg Roedel
2015-10-05 17:42           ` Bandan Das
2015-10-06 10:23             ` Joerg Roedel
2015-10-06 18:02               ` Bandan Das
2015-10-05 20:12           ` Dirk Müller
2015-10-05 22:00             ` Bandan Das
2015-10-06 10:28     ` Joerg Roedel
2015-10-06 17:59       ` Bandan Das
2015-10-07 11:03         ` Joerg Roedel
2015-10-07 12:47           ` [PATCH] kvm: svm: Only propagate next_rip when guest supports it Joerg Roedel
2015-10-07 12:57             ` kbuild test robot
2015-10-07 15:48             ` Bandan Das
2015-10-07 16:14               ` Joerg Roedel
2015-10-07 17:03                 ` Dirk Müller
2015-10-07 14:58           ` [PATCH] Use WARN_ON_ONCE for missing X86_FEATURE_NRIPS Bandan Das
2015-10-07 15:24             ` Joerg Roedel

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