[Qemu-devel] [Bug 1826422] [NEW] Regression: QEMU 4.0 hangs the host (*bisect included*)

[Qemu-devel] [Bug 1826422] [NEW] Regression: QEMU 4.0 hangs the host (*bisect included*)

[Saverio Miroddi]

Public bug reported:

The commit b2fc91db84470a78f8e93f5b5f913c17188792c8 seemingly introduced
a regression on my system.

When I start QEMU, the guest and the host hang (I need a hard reset to
get back to a working system), before anything shows on the guest.

I use QEMU with GPU passthrough (which worked perfectly until the commit
above). This is the command I use:

```
/path/to/qemu-system-x86_64
  -drive if=pflash,format=raw,readonly,file=/path/to/OVMF_CODE.fd
  -drive if=pflash,format=raw,file=/tmp/OVMF_VARS.fd.tmp
  -enable-kvm
  -machine q35,accel=kvm,mem-merge=off
  -cpu host,kvm=off,hv_vendor_id=vgaptrocks,hv_relaxed,hv_spinlocks=0x1fff,hv_vapic,hv_time
  -smp 4,cores=4,sockets=1,threads=1
  -m 10240
  -vga none
  -rtc base=localtime
  -serial none
  -parallel none
  -usb
  -device usb-tablet
  -device vfio-pci,host=01:00.0,multifunction=on
  -device vfio-pci,host=01:00.1
  -device usb-host,vendorid=<vid>,productid=<pid>
  -device usb-host,vendorid=<vid>,productid=<pid>
  -device usb-host,vendorid=<vid>,productid=<pid>
  -device usb-host,vendorid=<vid>,productid=<pid>
  -device usb-host,vendorid=<vid>,productid=<pid>
  -device usb-host,vendorid=<vid>,productid=<pid>
  -device virtio-scsi-pci,id=scsi
  -drive file=/path/to/guest.img,id=hdd1,format=qcow2,if=none,cache=writeback
  -device scsi-hd,drive=hdd1
  -net nic,model=virtio
  -net user,smb=/path/to/shared
```

If I run QEMU without GPU passthrough, it runs fine.

Some details about my system:

- O/S: Mint 19.1 x86-64 (it's based on Ubuntu 18.04)
- Kernel: 4.15
- `configure` options: `--target-list=x86_64-softmmu --enable-gtk --enable-spice --audio-drv-list=pa`
- EDK2 version: 1a734ed85fda71630c795832e6d24ea560caf739 (20/Apr/2019)
- CPU: i7-6700k
- Motherboard: ASRock Z170 Gaming-ITX/ac
- VGA: Gigabyte GTX 960 Mini-ITX

** Affects: qemu
     Importance: Undecided
         Status: New

-- 
You received this bug notification because you are a member of qemu-
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https://bugs.launchpad.net/bugs/1826422

Title:
  Regression: QEMU 4.0 hangs the host (*bisect included*)

Status in QEMU:
  New

Bug description:
  The commit b2fc91db84470a78f8e93f5b5f913c17188792c8 seemingly
  introduced a regression on my system.

  When I start QEMU, the guest and the host hang (I need a hard reset to
  get back to a working system), before anything shows on the guest.

  I use QEMU with GPU passthrough (which worked perfectly until the
  commit above). This is the command I use:

  ```
  /path/to/qemu-system-x86_64
    -drive if=pflash,format=raw,readonly,file=/path/to/OVMF_CODE.fd
    -drive if=pflash,format=raw,file=/tmp/OVMF_VARS.fd.tmp
    -enable-kvm
    -machine q35,accel=kvm,mem-merge=off
    -cpu host,kvm=off,hv_vendor_id=vgaptrocks,hv_relaxed,hv_spinlocks=0x1fff,hv_vapic,hv_time
    -smp 4,cores=4,sockets=1,threads=1
    -m 10240
    -vga none
    -rtc base=localtime
    -serial none
    -parallel none
    -usb
    -device usb-tablet
    -device vfio-pci,host=01:00.0,multifunction=on
    -device vfio-pci,host=01:00.1
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device virtio-scsi-pci,id=scsi
    -drive file=/path/to/guest.img,id=hdd1,format=qcow2,if=none,cache=writeback
    -device scsi-hd,drive=hdd1
    -net nic,model=virtio
    -net user,smb=/path/to/shared
  ```

  If I run QEMU without GPU passthrough, it runs fine.

  Some details about my system:

  - O/S: Mint 19.1 x86-64 (it's based on Ubuntu 18.04)
  - Kernel: 4.15
  - `configure` options: `--target-list=x86_64-softmmu --enable-gtk --enable-spice --audio-drv-list=pa`
  - EDK2 version: 1a734ed85fda71630c795832e6d24ea560caf739 (20/Apr/2019)
  - CPU: i7-6700k
  - Motherboard: ASRock Z170 Gaming-ITX/ac
  - VGA: Gigabyte GTX 960 Mini-ITX

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1826422/+subscriptions

[Qemu-devel] [Bug 1826422] Re: Regression: QEMU 4.0 hangs the host (*bisect included*)

[Alex Williamson]

Does adding "kernel_irqchip=on" to the comma separated list of options
for -machine resolve it?

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1826422

Title:
  Regression: QEMU 4.0 hangs the host (*bisect included*)

Status in QEMU:
  New

Bug description:
  The commit b2fc91db84470a78f8e93f5b5f913c17188792c8 seemingly
  introduced a regression on my system.

  When I start QEMU, the guest and the host hang (I need a hard reset to
  get back to a working system), before anything shows on the guest.

  I use QEMU with GPU passthrough (which worked perfectly until the
  commit above). This is the command I use:

  ```
  /path/to/qemu-system-x86_64
    -drive if=pflash,format=raw,readonly,file=/path/to/OVMF_CODE.fd
    -drive if=pflash,format=raw,file=/tmp/OVMF_VARS.fd.tmp
    -enable-kvm
    -machine q35,accel=kvm,mem-merge=off
    -cpu host,kvm=off,hv_vendor_id=vgaptrocks,hv_relaxed,hv_spinlocks=0x1fff,hv_vapic,hv_time
    -smp 4,cores=4,sockets=1,threads=1
    -m 10240
    -vga none
    -rtc base=localtime
    -serial none
    -parallel none
    -usb
    -device usb-tablet
    -device vfio-pci,host=01:00.0,multifunction=on
    -device vfio-pci,host=01:00.1
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device virtio-scsi-pci,id=scsi
    -drive file=/path/to/guest.img,id=hdd1,format=qcow2,if=none,cache=writeback
    -device scsi-hd,drive=hdd1
    -net nic,model=virtio
    -net user,smb=/path/to/shared
  ```

  If I run QEMU without GPU passthrough, it runs fine.

  Some details about my system:

  - O/S: Mint 19.1 x86-64 (it's based on Ubuntu 18.04)
  - Kernel: 4.15
  - `configure` options: `--target-list=x86_64-softmmu --enable-gtk --enable-spice --audio-drv-list=pa`
  - EDK2 version: 1a734ed85fda71630c795832e6d24ea560caf739 (20/Apr/2019)
  - CPU: i7-6700k
  - Motherboard: ASRock Z170 Gaming-ITX/ac
  - VGA: Gigabyte GTX 960 Mini-ITX

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1826422/+subscriptions

[Qemu-devel] [Bug 1826422] Re: Regression: QEMU 4.0 hangs the host (*bisect included*)

[Saverio Miroddi]

> Does adding "kernel_irqchip=on" to the comma separated list of options
for -machine resolve it?

Yes, that solved it, thanks!

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1826422

Title:
  Regression: QEMU 4.0 hangs the host (*bisect included*)

Status in QEMU:
  New

Bug description:
  The commit b2fc91db84470a78f8e93f5b5f913c17188792c8 seemingly
  introduced a regression on my system.

  When I start QEMU, the guest and the host hang (I need a hard reset to
  get back to a working system), before anything shows on the guest.

  I use QEMU with GPU passthrough (which worked perfectly until the
  commit above). This is the command I use:

  ```
  /path/to/qemu-system-x86_64
    -drive if=pflash,format=raw,readonly,file=/path/to/OVMF_CODE.fd
    -drive if=pflash,format=raw,file=/tmp/OVMF_VARS.fd.tmp
    -enable-kvm
    -machine q35,accel=kvm,mem-merge=off
    -cpu host,kvm=off,hv_vendor_id=vgaptrocks,hv_relaxed,hv_spinlocks=0x1fff,hv_vapic,hv_time
    -smp 4,cores=4,sockets=1,threads=1
    -m 10240
    -vga none
    -rtc base=localtime
    -serial none
    -parallel none
    -usb
    -device usb-tablet
    -device vfio-pci,host=01:00.0,multifunction=on
    -device vfio-pci,host=01:00.1
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device virtio-scsi-pci,id=scsi
    -drive file=/path/to/guest.img,id=hdd1,format=qcow2,if=none,cache=writeback
    -device scsi-hd,drive=hdd1
    -net nic,model=virtio
    -net user,smb=/path/to/shared
  ```

  If I run QEMU without GPU passthrough, it runs fine.

  Some details about my system:

  - O/S: Mint 19.1 x86-64 (it's based on Ubuntu 18.04)
  - Kernel: 4.15
  - `configure` options: `--target-list=x86_64-softmmu --enable-gtk --enable-spice --audio-drv-list=pa`
  - EDK2 version: 1a734ed85fda71630c795832e6d24ea560caf739 (20/Apr/2019)
  - CPU: i7-6700k
  - Motherboard: ASRock Z170 Gaming-ITX/ac
  - VGA: Gigabyte GTX 960 Mini-ITX

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1826422/+subscriptions

[Qemu-devel] [Bug 1826422] Re: Regression: QEMU 4.0 hangs the host (*bisect included*)

[Alex Williamson]

This seems related to INTx (legacy) interrupt mode, which NVIDIA GeForce
will use by default.  Using regedit in a Windows VM or adjusting
nvidia.ko module parameters of a Linux VM can enable the driver to use
MSI, which seems unaffected.  We also have the vfio-pci device option x
-no-kvm-intx=on, which is probably a good compliment to configuring the
driver to use MSI until we get this figured out, as the Windows driver
likes to occasional switch MSI off, which would leave you in a bad
state.  Routing INTx through QEMU would be a performance regression
though, so while a workaround, having it routed through QEMU and not
using MSI, is not a great combination.

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1826422

Title:
  Regression: QEMU 4.0 hangs the host (*bisect included*)

Status in QEMU:
  New

Bug description:
  The commit b2fc91db84470a78f8e93f5b5f913c17188792c8 seemingly
  introduced a regression on my system.

  When I start QEMU, the guest and the host hang (I need a hard reset to
  get back to a working system), before anything shows on the guest.

  I use QEMU with GPU passthrough (which worked perfectly until the
  commit above). This is the command I use:

  ```
  /path/to/qemu-system-x86_64
    -drive if=pflash,format=raw,readonly,file=/path/to/OVMF_CODE.fd
    -drive if=pflash,format=raw,file=/tmp/OVMF_VARS.fd.tmp
    -enable-kvm
    -machine q35,accel=kvm,mem-merge=off
    -cpu host,kvm=off,hv_vendor_id=vgaptrocks,hv_relaxed,hv_spinlocks=0x1fff,hv_vapic,hv_time
    -smp 4,cores=4,sockets=1,threads=1
    -m 10240
    -vga none
    -rtc base=localtime
    -serial none
    -parallel none
    -usb
    -device usb-tablet
    -device vfio-pci,host=01:00.0,multifunction=on
    -device vfio-pci,host=01:00.1
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device virtio-scsi-pci,id=scsi
    -drive file=/path/to/guest.img,id=hdd1,format=qcow2,if=none,cache=writeback
    -device scsi-hd,drive=hdd1
    -net nic,model=virtio
    -net user,smb=/path/to/shared
  ```

  If I run QEMU without GPU passthrough, it runs fine.

  Some details about my system:

  - O/S: Mint 19.1 x86-64 (it's based on Ubuntu 18.04)
  - Kernel: 4.15
  - `configure` options: `--target-list=x86_64-softmmu --enable-gtk --enable-spice --audio-drv-list=pa`
  - EDK2 version: 1a734ed85fda71630c795832e6d24ea560caf739 (20/Apr/2019)
  - CPU: i7-6700k
  - Motherboard: ASRock Z170 Gaming-ITX/ac
  - VGA: Gigabyte GTX 960 Mini-ITX

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1826422/+subscriptions

[Qemu-devel] [Bug 1826422] Re: Regression: QEMU 4.0 hangs the host (*bisect included*)

[Alex Williamson]

Not just NVIDIA, forcing a NIC to use INTx also fails and it's apparent
from the host that the device is stuck with DisINTx+.  Looks like the
resampling mechanism that allows KVM to unmask the interrupt is broken
with split irqchip.

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1826422

Title:
  Regression: QEMU 4.0 hangs the host (*bisect included*)

Status in QEMU:
  New

Bug description:
  The commit b2fc91db84470a78f8e93f5b5f913c17188792c8 seemingly
  introduced a regression on my system.

  When I start QEMU, the guest and the host hang (I need a hard reset to
  get back to a working system), before anything shows on the guest.

  I use QEMU with GPU passthrough (which worked perfectly until the
  commit above). This is the command I use:

  ```
  /path/to/qemu-system-x86_64
    -drive if=pflash,format=raw,readonly,file=/path/to/OVMF_CODE.fd
    -drive if=pflash,format=raw,file=/tmp/OVMF_VARS.fd.tmp
    -enable-kvm
    -machine q35,accel=kvm,mem-merge=off
    -cpu host,kvm=off,hv_vendor_id=vgaptrocks,hv_relaxed,hv_spinlocks=0x1fff,hv_vapic,hv_time
    -smp 4,cores=4,sockets=1,threads=1
    -m 10240
    -vga none
    -rtc base=localtime
    -serial none
    -parallel none
    -usb
    -device usb-tablet
    -device vfio-pci,host=01:00.0,multifunction=on
    -device vfio-pci,host=01:00.1
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device virtio-scsi-pci,id=scsi
    -drive file=/path/to/guest.img,id=hdd1,format=qcow2,if=none,cache=writeback
    -device scsi-hd,drive=hdd1
    -net nic,model=virtio
    -net user,smb=/path/to/shared
  ```

  If I run QEMU without GPU passthrough, it runs fine.

  Some details about my system:

  - O/S: Mint 19.1 x86-64 (it's based on Ubuntu 18.04)
  - Kernel: 4.15
  - `configure` options: `--target-list=x86_64-softmmu --enable-gtk --enable-spice --audio-drv-list=pa`
  - EDK2 version: 1a734ed85fda71630c795832e6d24ea560caf739 (20/Apr/2019)
  - CPU: i7-6700k
  - Motherboard: ASRock Z170 Gaming-ITX/ac
  - VGA: Gigabyte GTX 960 Mini-ITX

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1826422/+subscriptions

[Qemu-devel] [Bug 1826422] Re: Regression: QEMU 4.0 hangs the host (*bisect included*)

[Saverio Miroddi]

ok, so, if I understand correctly, the workaround is:

- set `x-no-kvm-intx=on` and enable MSI in the guest (via regedit or
module params)

which may lead to a performance regression (at least under certain
circumstances).

Is it therefore preferrable, performance and configuration-wise, to use
QEMU 3.1.0, if there are no 4.0.0 feature requirements, until this issue
is sorted out?

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1826422

Title:
  Regression: QEMU 4.0 hangs the host (*bisect included*)

Status in QEMU:
  New

Bug description:
  The commit b2fc91db84470a78f8e93f5b5f913c17188792c8 seemingly
  introduced a regression on my system.

  When I start QEMU, the guest and the host hang (I need a hard reset to
  get back to a working system), before anything shows on the guest.

  I use QEMU with GPU passthrough (which worked perfectly until the
  commit above). This is the command I use:

  ```
  /path/to/qemu-system-x86_64
    -drive if=pflash,format=raw,readonly,file=/path/to/OVMF_CODE.fd
    -drive if=pflash,format=raw,file=/tmp/OVMF_VARS.fd.tmp
    -enable-kvm
    -machine q35,accel=kvm,mem-merge=off
    -cpu host,kvm=off,hv_vendor_id=vgaptrocks,hv_relaxed,hv_spinlocks=0x1fff,hv_vapic,hv_time
    -smp 4,cores=4,sockets=1,threads=1
    -m 10240
    -vga none
    -rtc base=localtime
    -serial none
    -parallel none
    -usb
    -device usb-tablet
    -device vfio-pci,host=01:00.0,multifunction=on
    -device vfio-pci,host=01:00.1
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device virtio-scsi-pci,id=scsi
    -drive file=/path/to/guest.img,id=hdd1,format=qcow2,if=none,cache=writeback
    -device scsi-hd,drive=hdd1
    -net nic,model=virtio
    -net user,smb=/path/to/shared
  ```

  If I run QEMU without GPU passthrough, it runs fine.

  Some details about my system:

  - O/S: Mint 19.1 x86-64 (it's based on Ubuntu 18.04)
  - Kernel: 4.15
  - `configure` options: `--target-list=x86_64-softmmu --enable-gtk --enable-spice --audio-drv-list=pa`
  - EDK2 version: 1a734ed85fda71630c795832e6d24ea560caf739 (20/Apr/2019)
  - CPU: i7-6700k
  - Motherboard: ASRock Z170 Gaming-ITX/ac
  - VGA: Gigabyte GTX 960 Mini-ITX

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1826422/+subscriptions

[Qemu-devel] [Bug 1826422] Re: Regression: QEMU 4.0 hangs the host (*bisect included*)

[Alex Williamson]

The change in QEMU 4.0 is only a change in defaults of the machine type,
it can be entirely reverted in the VM config with kernel_irqchip=on or
<ioapic driver='kvm'/> with libvirt.  Using a machine type prior to the
q35 4.0 machine type would also avoid it.  There are no performance
issues with these configurations that would favor using 3.1 over 4.0.

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1826422

Title:
  Regression: QEMU 4.0 hangs the host (*bisect included*)

Status in QEMU:
  New

Bug description:
  The commit b2fc91db84470a78f8e93f5b5f913c17188792c8 seemingly
  introduced a regression on my system.

  When I start QEMU, the guest and the host hang (I need a hard reset to
  get back to a working system), before anything shows on the guest.

  I use QEMU with GPU passthrough (which worked perfectly until the
  commit above). This is the command I use:

  ```
  /path/to/qemu-system-x86_64
    -drive if=pflash,format=raw,readonly,file=/path/to/OVMF_CODE.fd
    -drive if=pflash,format=raw,file=/tmp/OVMF_VARS.fd.tmp
    -enable-kvm
    -machine q35,accel=kvm,mem-merge=off
    -cpu host,kvm=off,hv_vendor_id=vgaptrocks,hv_relaxed,hv_spinlocks=0x1fff,hv_vapic,hv_time
    -smp 4,cores=4,sockets=1,threads=1
    -m 10240
    -vga none
    -rtc base=localtime
    -serial none
    -parallel none
    -usb
    -device usb-tablet
    -device vfio-pci,host=01:00.0,multifunction=on
    -device vfio-pci,host=01:00.1
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device virtio-scsi-pci,id=scsi
    -drive file=/path/to/guest.img,id=hdd1,format=qcow2,if=none,cache=writeback
    -device scsi-hd,drive=hdd1
    -net nic,model=virtio
    -net user,smb=/path/to/shared
  ```

  If I run QEMU without GPU passthrough, it runs fine.

  Some details about my system:

  - O/S: Mint 19.1 x86-64 (it's based on Ubuntu 18.04)
  - Kernel: 4.15
  - `configure` options: `--target-list=x86_64-softmmu --enable-gtk --enable-spice --audio-drv-list=pa`
  - EDK2 version: 1a734ed85fda71630c795832e6d24ea560caf739 (20/Apr/2019)
  - CPU: i7-6700k
  - Motherboard: ASRock Z170 Gaming-ITX/ac
  - VGA: Gigabyte GTX 960 Mini-ITX

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1826422/+subscriptions

[Qemu-devel] [Bug 1826422] Re: Regression: QEMU 4.0 hangs the host (*bisect included*)

[Saverio Miroddi]

> The change in QEMU 4.0 is only a change in defaults of the machine
type, it can be entirely reverted in the VM config with
kernel_irqchip=on or <ioapic driver='kvm'/> with libvirt. Using a
machine type prior to the q35 4.0 machine type would also avoid it.
There are no performance issues with these configurations that would
favor using 3.1 over 4.0.

Thanks for the detailed answer :-)

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https://bugs.launchpad.net/bugs/1826422

Title:
  Regression: QEMU 4.0 hangs the host (*bisect included*)

Status in QEMU:
  New

Bug description:
  The commit b2fc91db84470a78f8e93f5b5f913c17188792c8 seemingly
  introduced a regression on my system.

  When I start QEMU, the guest and the host hang (I need a hard reset to
  get back to a working system), before anything shows on the guest.

  I use QEMU with GPU passthrough (which worked perfectly until the
  commit above). This is the command I use:

  ```
  /path/to/qemu-system-x86_64
    -drive if=pflash,format=raw,readonly,file=/path/to/OVMF_CODE.fd
    -drive if=pflash,format=raw,file=/tmp/OVMF_VARS.fd.tmp
    -enable-kvm
    -machine q35,accel=kvm,mem-merge=off
    -cpu host,kvm=off,hv_vendor_id=vgaptrocks,hv_relaxed,hv_spinlocks=0x1fff,hv_vapic,hv_time
    -smp 4,cores=4,sockets=1,threads=1
    -m 10240
    -vga none
    -rtc base=localtime
    -serial none
    -parallel none
    -usb
    -device usb-tablet
    -device vfio-pci,host=01:00.0,multifunction=on
    -device vfio-pci,host=01:00.1
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device virtio-scsi-pci,id=scsi
    -drive file=/path/to/guest.img,id=hdd1,format=qcow2,if=none,cache=writeback
    -device scsi-hd,drive=hdd1
    -net nic,model=virtio
    -net user,smb=/path/to/shared
  ```

  If I run QEMU without GPU passthrough, it runs fine.

  Some details about my system:

  - O/S: Mint 19.1 x86-64 (it's based on Ubuntu 18.04)
  - Kernel: 4.15
  - `configure` options: `--target-list=x86_64-softmmu --enable-gtk --enable-spice --audio-drv-list=pa`
  - EDK2 version: 1a734ed85fda71630c795832e6d24ea560caf739 (20/Apr/2019)
  - CPU: i7-6700k
  - Motherboard: ASRock Z170 Gaming-ITX/ac
  - VGA: Gigabyte GTX 960 Mini-ITX

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[Qemu-devel] [Bug 1826422] Re: Regression: QEMU 4.0 hangs the host (*bisect included*)

[Alex Williamson]

Just to provide an update, patches are posted to revert this change in
both the q35 4.1 machine type for the next release as well as introduce
a q35 4.0.1 machine type making the same change for 4.0-stable.
References:

https://patchwork.ozlabs.org/patch/1099695/
https://patchwork.ozlabs.org/patch/1099659/

** Changed in: qemu
       Status: New => In Progress

** Changed in: qemu
     Assignee: (unassigned) => Alex Williamson (alex-l-williamson)

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1826422

Title:
  Regression: QEMU 4.0 hangs the host (*bisect included*)

Status in QEMU:
  In Progress

Bug description:
  The commit b2fc91db84470a78f8e93f5b5f913c17188792c8 seemingly
  introduced a regression on my system.

  When I start QEMU, the guest and the host hang (I need a hard reset to
  get back to a working system), before anything shows on the guest.

  I use QEMU with GPU passthrough (which worked perfectly until the
  commit above). This is the command I use:

  ```
  /path/to/qemu-system-x86_64
    -drive if=pflash,format=raw,readonly,file=/path/to/OVMF_CODE.fd
    -drive if=pflash,format=raw,file=/tmp/OVMF_VARS.fd.tmp
    -enable-kvm
    -machine q35,accel=kvm,mem-merge=off
    -cpu host,kvm=off,hv_vendor_id=vgaptrocks,hv_relaxed,hv_spinlocks=0x1fff,hv_vapic,hv_time
    -smp 4,cores=4,sockets=1,threads=1
    -m 10240
    -vga none
    -rtc base=localtime
    -serial none
    -parallel none
    -usb
    -device usb-tablet
    -device vfio-pci,host=01:00.0,multifunction=on
    -device vfio-pci,host=01:00.1
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device virtio-scsi-pci,id=scsi
    -drive file=/path/to/guest.img,id=hdd1,format=qcow2,if=none,cache=writeback
    -device scsi-hd,drive=hdd1
    -net nic,model=virtio
    -net user,smb=/path/to/shared
  ```

  If I run QEMU without GPU passthrough, it runs fine.

  Some details about my system:

  - O/S: Mint 19.1 x86-64 (it's based on Ubuntu 18.04)
  - Kernel: 4.15
  - `configure` options: `--target-list=x86_64-softmmu --enable-gtk --enable-spice --audio-drv-list=pa`
  - EDK2 version: 1a734ed85fda71630c795832e6d24ea560caf739 (20/Apr/2019)
  - CPU: i7-6700k
  - Motherboard: ASRock Z170 Gaming-ITX/ac
  - VGA: Gigabyte GTX 960 Mini-ITX

To manage notifications about this bug go to:
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[Qemu-devel] [Bug 1826422] Re: Regression: QEMU 4.0 hangs the host (*bisect included*)

[Thomas Huth]

Fix has been included here:
https://git.qemu.org/?p=qemu.git;a=commitdiff;h=c87759ce876a7a0b17c2b

** Changed in: qemu
       Status: In Progress => Fix Released

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1826422

Title:
  Regression: QEMU 4.0 hangs the host (*bisect included*)

Status in QEMU:
  Fix Released

Bug description:
  The commit b2fc91db84470a78f8e93f5b5f913c17188792c8 seemingly
  introduced a regression on my system.

  When I start QEMU, the guest and the host hang (I need a hard reset to
  get back to a working system), before anything shows on the guest.

  I use QEMU with GPU passthrough (which worked perfectly until the
  commit above). This is the command I use:

  ```
  /path/to/qemu-system-x86_64
    -drive if=pflash,format=raw,readonly,file=/path/to/OVMF_CODE.fd
    -drive if=pflash,format=raw,file=/tmp/OVMF_VARS.fd.tmp
    -enable-kvm
    -machine q35,accel=kvm,mem-merge=off
    -cpu host,kvm=off,hv_vendor_id=vgaptrocks,hv_relaxed,hv_spinlocks=0x1fff,hv_vapic,hv_time
    -smp 4,cores=4,sockets=1,threads=1
    -m 10240
    -vga none
    -rtc base=localtime
    -serial none
    -parallel none
    -usb
    -device usb-tablet
    -device vfio-pci,host=01:00.0,multifunction=on
    -device vfio-pci,host=01:00.1
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device usb-host,vendorid=<vid>,productid=<pid>
    -device virtio-scsi-pci,id=scsi
    -drive file=/path/to/guest.img,id=hdd1,format=qcow2,if=none,cache=writeback
    -device scsi-hd,drive=hdd1
    -net nic,model=virtio
    -net user,smb=/path/to/shared
  ```

  If I run QEMU without GPU passthrough, it runs fine.

  Some details about my system:

  - O/S: Mint 19.1 x86-64 (it's based on Ubuntu 18.04)
  - Kernel: 4.15
  - `configure` options: `--target-list=x86_64-softmmu --enable-gtk --enable-spice --audio-drv-list=pa`
  - EDK2 version: 1a734ed85fda71630c795832e6d24ea560caf739 (20/Apr/2019)
  - CPU: i7-6700k
  - Motherboard: ASRock Z170 Gaming-ITX/ac
  - VGA: Gigabyte GTX 960 Mini-ITX

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1826422/+subscriptions