Enabling KVM with recent QEMU builds from GIT hang at boot on Ubuntu Precise AMD64 kernel 3.8.0

Bug #1212402 reported by Julius Schwartzenberg on 2013-08-14
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
QEMU
Undecided
Unassigned

Bug Description

When I compile QEMU from GIT and run it with './x86_64-softmmu/qemu-system-x86_64 -enable-kvm' it just hangs, the QEMU screen stays black. (Everything else in the GTK UI is responsive though, I can use the QEMU console as well.)
I'm running Ubuntu Precise with kernel 3.8.0-27-generic on an Intel Core2 Duo P9500.

With bisecting, I found this commit caused the problem:

235e8982ad393e5611cb892df54881c872eea9e1 is the first bad commit
commit 235e8982ad393e5611cb892df54881c872eea9e1
Author: Jordan Justen <email address hidden>
Date: Wed May 29 01:27:26 2013 -0700

    kvm: support using KVM_MEM_READONLY flag for regions

    For readonly memory regions and rom devices in romd_mode,
    we make use of the KVM_MEM_READONLY. A slot that uses
    KVM_MEM_READONLY can be read from and code can execute from the
    region, but writes will exit to qemu.

    For rom devices with !romd_mode, we force the slot to be
    removed so reads or writes to the region will exit to qemu.
    (Note that a memory region in this state is not executable
    within kvm.)

    v7:
     * Update for readable => romd_mode rename (5f9a5ea1)

    Signed-off-by: Jordan Justen <email address hidden>
    Reviewed-by: Xiao Guangrong <email address hidden> (v4)
    Reviewed-by: Paolo Bonzini <email address hidden> (v5)
    Message-id: <email address hidden>
    Signed-off-by: Anthony Liguori <email address hidden>

:100644 100644 327ae12f08b9dddc796d753d8adfb1f70c78b2c1 8e7bbf8698f6bcaa5ae945ef86e7b51effde06fe M kvm-all.c

Download full text (4.1 KiB)

We have discussed this issue in this mail:
http://<email address hidden>/msg174932.html (VM can
not boot after commit 235e898)

You can upgrade your kernel to 3.9.x to work around.

On Thu, Aug 15, 2013 at 3:23 AM, Julius Schwartzenberg <
<email address hidden>> wrote:

> Public bug reported:
>
> When I compile QEMU from GIT and run it with
> './x86_64-softmmu/qemu-system-x86_64 -enable-kvm' it just hangs, the QEMU
> screen stays black. (Everything else in the GTK UI is responsive though, I
> can use the QEMU console as well.)
> I'm running Ubuntu Precise with kernel 3.8.0-27-generic on an Intel Core2
> Duo P9500.
>
> With bisecting, I found this commit caused the problem:
>
> 235e8982ad393e5611cb892df54881c872eea9e1 is the first bad commit
> commit 235e8982ad393e5611cb892df54881c872eea9e1
> Author: Jordan Justen <email address hidden>
> Date: Wed May 29 01:27:26 2013 -0700
>
> kvm: support using KVM_MEM_READONLY flag for regions
>
> For readonly memory regions and rom devices in romd_mode,
> we make use of the KVM_MEM_READONLY. A slot that uses
> KVM_MEM_READONLY can be read from and code can execute from the
> region, but writes will exit to qemu.
>
> For rom devices with !romd_mode, we force the slot to be
> removed so reads or writes to the region will exit to qemu.
> (Note that a memory region in this state is not executable
> within kvm.)
>
> v7:
> * Update for readable => romd_mode rename (5f9a5ea1)
>
> Signed-off-by: Jordan Justen <email address hidden>
> Reviewed-by: Xiao Guangrong <email address hidden> (v4)
> Reviewed-by: Paolo Bonzini <email address hidden> (v5)
> Message-id:
> <email address hidden>
> Signed-off-by: Anthony Liguori <email address hidden>
>
> :100644 100644 327ae12f08b9dddc796d753d8adfb1f70c78b2c1
> 8e7bbf8698f6bcaa5ae945ef86e7b51effde06fe M kvm-all.c
>
> ** Affects: qemu
> Importance: Undecided
> Status: New
>
> --
> You received this bug notification because you are a member of qemu-
> devel-ml, which is subscribed to QEMU.
> https://bugs.launchpad.net/bugs/1212402
>
> Title:
> Enabling KVM with recent QEMU builds from GIT hang at boot on Ubuntu
> Precise AMD64 kernel 3.8.0
>
> Status in QEMU:
> New
>
> Bug description:
> When I compile QEMU from GIT and run it with
> './x86_64-softmmu/qemu-system-x86_64 -enable-kvm' it just hangs, the QEMU
> screen stays black. (Everything else in the GTK UI is responsive though, I
> can use the QEMU console as well.)
> I'm running Ubuntu Precise with kernel 3.8.0-27-generic on an Intel
> Core2 Duo P9500.
>
> With bisecting, I found this commit caused the problem:
>
> 235e8982ad393e5611cb892df54881c872eea9e1 is the first bad commit
> commit 235e8982ad393e5611cb892df54881c872eea9e1
> Author: Jordan Justen <email address hidden>
> Date: Wed May 29 01:27:26 2013 -0700
>
> kvm: support using KVM_MEM_READONLY flag for regions
>
> For readonly memory regions and rom devices in romd_mode,
> we make use of the KVM_MEM_READONLY. A slot that uses
> KVM_MEM_READONLY ca...

Read more...

It seems reverting this exact commit also works around the problem. I have attached a patch against current head.

Thomas Huth (th-huth) wrote :

According to comment #1, this has been fixed with kernel 3.9, so setting the status to "Fix released" now.

Changed in qemu:
status: New → Fix Released
To post a comment you must log in.
This report contains Public information  Edit
Everyone can see this information.

Other bug subscribers