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From: Peter Lieven <pl@dlhnet.de>
To: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Jan Kiszka <jan.kiszka@web.de>,
	qemu-devel@nongnu.org, kvm@vger.kernel.org,
	Gleb Natapov <gleb@redhat.com>
Subject: Re: race between kvm-kmod-3.0 and kvm-kmod-3.3 // was: race condition in qemu-kvm-1.0.1
Date: Thu, 05 Jul 2012 14:42:42 +0200	[thread overview]
Message-ID: <4FF58BC2.3090303@dlhnet.de> (raw)
In-Reply-To: <4FF555A8.3000601@linux.vnet.ibm.com>

On 05.07.2012 10:51, Xiao Guangrong wrote:
> On 06/28/2012 05:11 PM, Peter Lieven wrote:
>
>> that here is bascially whats going on:
>>
>>    qemu-kvm-1.0-2506  [010] 60996.908000: kvm_mmio:             mmio read len 3 gpa 0xa0000 val 0x10ff
>>      qemu-kvm-1.0-2506  [010] 60996.908000: vcpu_match_mmio:      gva 0xa0000 gpa 0xa0000 Read GPA
>>      qemu-kvm-1.0-2506  [010] 60996.908000: kvm_mmio:             mmio unsatisfied-read len 1 gpa 0xa0000 val 0x0
>>      qemu-kvm-1.0-2506  [010] 60996.908000: kvm_userspace_exit:   reason KVM_EXIT_MMIO (6)
>>      qemu-kvm-1.0-2506  [010] 60996.908000: kvm_mmio:             mmio read len 3 gpa 0xa0000 val 0x10ff
>>      qemu-kvm-1.0-2506  [010] 60996.908000: vcpu_match_mmio:      gva 0xa0000 gpa 0xa0000 Read GPA
>>      qemu-kvm-1.0-2506  [010] 60996.908000: kvm_mmio:             mmio unsatisfied-read len 1 gpa 0xa0000 val 0x0
>>      qemu-kvm-1.0-2506  [010] 60996.908000: kvm_userspace_exit:   reason KVM_EXIT_MMIO (6)
>>      qemu-kvm-1.0-2506  [010] 60996.908000: kvm_mmio:             mmio read len 3 gpa 0xa0000 val 0x10ff
>>      qemu-kvm-1.0-2506  [010] 60996.908000: vcpu_match_mmio:      gva 0xa0000 gpa 0xa0000 Read GPA
>>      qemu-kvm-1.0-2506  [010] 60996.908000: kvm_mmio:             mmio unsatisfied-read len 1 gpa 0xa0000 val 0x0
>>      qemu-kvm-1.0-2506  [010] 60996.908000: kvm_userspace_exit:   reason KVM_EXIT_MMIO (6)
>>      qemu-kvm-1.0-2506  [010] 60996.908000: kvm_mmio:             mmio read len 3 gpa 0xa0000 val 0x10ff
>>      qemu-kvm-1.0-2506  [010] 60996.908000: vcpu_match_mmio:      gva 0xa0000 gpa 0xa0000 Read GPA
>>      qemu-kvm-1.0-2506  [010] 60996.908000: kvm_mmio:             mmio unsatisfied-read len 1 gpa 0xa0000 val 0x0
>>      qemu-kvm-1.0-2506  [010] 60996.908000: kvm_userspace_exit:   reason KVM_EXIT_MMIO (6)
>>
> There are two mmio emulation after user-space-exit, it is caused by mmio
> read access which spans two pages. But it should be fixed by:
>
> commit f78146b0f9230765c6315b2e14f56112513389ad
> Author: Avi Kivity<avi@redhat.com>
> Date:   Wed Apr 18 19:22:47 2012 +0300
>
>      KVM: Fix page-crossing MMIO
>
>      MMIO that are split across a page boundary are currently broken - the
>      code does not expect to be aborted by the exit to userspace for the
>      first MMIO fragment.
>
>      This patch fixes the problem by generalizing the current code for handling
>      16-byte MMIOs to handle a number of "fragments", and changes the MMIO
>      code to create those fragments.
>
>      Signed-off-by: Avi Kivity<avi@redhat.com>
>      Signed-off-by: Marcelo Tosatti<mtosatti@redhat.com>
>
> Could you please pull the code from:
> https://git.kernel.org/pub/scm/virt/kvm/kvm.git
> and trace it again?
Thank you very much, this fixes the issue I have seen.

Thanks,
Peter


WARNING: multiple messages have this Message-ID (diff)
From: Peter Lieven <pl@dlhnet.de>
To: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Gleb Natapov <gleb@redhat.com>, Jan Kiszka <jan.kiszka@web.de>,
	qemu-devel@nongnu.org, kvm@vger.kernel.org
Subject: Re: [Qemu-devel] race between kvm-kmod-3.0 and kvm-kmod-3.3 // was: race condition in qemu-kvm-1.0.1
Date: Thu, 05 Jul 2012 14:42:42 +0200	[thread overview]
Message-ID: <4FF58BC2.3090303@dlhnet.de> (raw)
In-Reply-To: <4FF555A8.3000601@linux.vnet.ibm.com>

On 05.07.2012 10:51, Xiao Guangrong wrote:
> On 06/28/2012 05:11 PM, Peter Lieven wrote:
>
>> that here is bascially whats going on:
>>
>>    qemu-kvm-1.0-2506  [010] 60996.908000: kvm_mmio:             mmio read len 3 gpa 0xa0000 val 0x10ff
>>      qemu-kvm-1.0-2506  [010] 60996.908000: vcpu_match_mmio:      gva 0xa0000 gpa 0xa0000 Read GPA
>>      qemu-kvm-1.0-2506  [010] 60996.908000: kvm_mmio:             mmio unsatisfied-read len 1 gpa 0xa0000 val 0x0
>>      qemu-kvm-1.0-2506  [010] 60996.908000: kvm_userspace_exit:   reason KVM_EXIT_MMIO (6)
>>      qemu-kvm-1.0-2506  [010] 60996.908000: kvm_mmio:             mmio read len 3 gpa 0xa0000 val 0x10ff
>>      qemu-kvm-1.0-2506  [010] 60996.908000: vcpu_match_mmio:      gva 0xa0000 gpa 0xa0000 Read GPA
>>      qemu-kvm-1.0-2506  [010] 60996.908000: kvm_mmio:             mmio unsatisfied-read len 1 gpa 0xa0000 val 0x0
>>      qemu-kvm-1.0-2506  [010] 60996.908000: kvm_userspace_exit:   reason KVM_EXIT_MMIO (6)
>>      qemu-kvm-1.0-2506  [010] 60996.908000: kvm_mmio:             mmio read len 3 gpa 0xa0000 val 0x10ff
>>      qemu-kvm-1.0-2506  [010] 60996.908000: vcpu_match_mmio:      gva 0xa0000 gpa 0xa0000 Read GPA
>>      qemu-kvm-1.0-2506  [010] 60996.908000: kvm_mmio:             mmio unsatisfied-read len 1 gpa 0xa0000 val 0x0
>>      qemu-kvm-1.0-2506  [010] 60996.908000: kvm_userspace_exit:   reason KVM_EXIT_MMIO (6)
>>      qemu-kvm-1.0-2506  [010] 60996.908000: kvm_mmio:             mmio read len 3 gpa 0xa0000 val 0x10ff
>>      qemu-kvm-1.0-2506  [010] 60996.908000: vcpu_match_mmio:      gva 0xa0000 gpa 0xa0000 Read GPA
>>      qemu-kvm-1.0-2506  [010] 60996.908000: kvm_mmio:             mmio unsatisfied-read len 1 gpa 0xa0000 val 0x0
>>      qemu-kvm-1.0-2506  [010] 60996.908000: kvm_userspace_exit:   reason KVM_EXIT_MMIO (6)
>>
> There are two mmio emulation after user-space-exit, it is caused by mmio
> read access which spans two pages. But it should be fixed by:
>
> commit f78146b0f9230765c6315b2e14f56112513389ad
> Author: Avi Kivity<avi@redhat.com>
> Date:   Wed Apr 18 19:22:47 2012 +0300
>
>      KVM: Fix page-crossing MMIO
>
>      MMIO that are split across a page boundary are currently broken - the
>      code does not expect to be aborted by the exit to userspace for the
>      first MMIO fragment.
>
>      This patch fixes the problem by generalizing the current code for handling
>      16-byte MMIOs to handle a number of "fragments", and changes the MMIO
>      code to create those fragments.
>
>      Signed-off-by: Avi Kivity<avi@redhat.com>
>      Signed-off-by: Marcelo Tosatti<mtosatti@redhat.com>
>
> Could you please pull the code from:
> https://git.kernel.org/pub/scm/virt/kvm/kvm.git
> and trace it again?
Thank you very much, this fixes the issue I have seen.

Thanks,
Peter

  reply	other threads:[~2012-07-05 12:42 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-06-27 15:39 race between kvm-kmod-3.0 and kvm-kmod-3.3 // was: race condition in qemu-kvm-1.0.1 Peter Lieven
2012-06-27 16:54 ` Jan Kiszka
2012-06-28  9:11   ` Peter Lieven
2012-06-28  9:21     ` Jan Kiszka
2012-06-28  9:31       ` Peter Lieven
2012-06-28  9:38         ` Peter Lieven
2012-07-02 15:05           ` Avi Kivity
2012-07-02 15:05             ` [Qemu-devel] " Avi Kivity
2012-07-02 15:57             ` Peter Lieven
2012-07-02 15:57               ` [Qemu-devel] " Peter Lieven
2012-07-03 13:01             ` Peter Lieven
2012-07-03 13:01               ` [Qemu-devel] " Peter Lieven
2012-07-03 13:13               ` Avi Kivity
2012-07-03 13:13                 ` [Qemu-devel] " Avi Kivity
2012-07-03 13:15                 ` Peter Lieven
2012-07-03 13:15                   ` [Qemu-devel] " Peter Lieven
2012-07-03 13:25                   ` Avi Kivity
2012-07-03 13:25                     ` [Qemu-devel] " Avi Kivity
2012-07-04 14:57                     ` Peter Lieven
2012-07-04 14:57                       ` [Qemu-devel] " Peter Lieven
2012-07-04 23:12                 ` Peter Lieven
2012-07-04 23:12                   ` [Qemu-devel] " Peter Lieven
2012-07-05  6:48                   ` Xiao Guangrong
2012-07-05  6:48                     ` [Qemu-devel] " Xiao Guangrong
2012-06-28  9:39         ` Jan Kiszka
2012-06-28 10:13           ` Peter Lieven
2012-06-28 10:34           ` Peter Lieven
2012-07-05  8:51     ` Xiao Guangrong
2012-07-05  8:51       ` [Qemu-devel] " Xiao Guangrong
2012-07-05 12:42       ` Peter Lieven [this message]
2012-07-05 12:42         ` Peter Lieven

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