[Bug 195813] New: intel gvt/kvmgt: BUG: unable to handle kernel NULL pointer dereference at (null)

[Bug 195813] New: intel gvt/kvmgt: BUG: unable to handle kernel NULL pointer dereference at (null)

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=195813

            Bug ID: 195813
           Summary: intel gvt/kvmgt: BUG: unable to handle kernel NULL
                    pointer dereference at (null)
           Product: Virtualization
           Version: unspecified
    Kernel Version: linux-4.11.1
          Hardware: All
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: kvm
          Assignee: virtualization_kvm@kernel-bugs.osdl.org
          Reporter: bu9zilla@gmail.com
        Regression: No

Hi,

trying out intel gvt/kvmgt on a i7-6700 CPU with a Intel Corporation HD
Graphics 530 onboard gpu.
I've followed following guide to try it out:
https://github.com/01org/gvt-linux/wiki/GVTg_Setup_Guide
However, even though i can generate the VGPU on the host, as soon i try to boot
the guest, kvmgt/i915 crashes with following error:

May 18 20:44:24 tunafix kernel: vfio_pin_page_external: Task qemu-system-x86
(4636) RLIMIT_MEMLOCK (65536) exceeded
May 18 20:44:24 tunafix kernel: vfio_pin_page_external: Task qemu-system-x86
(4633) RLIMIT_MEMLOCK (65536) exceeded
May 18 20:44:25 tunafix kernel: vfio_pin_page_external: Task qemu-system-x86
(4636) RLIMIT_MEMLOCK (65536) exceeded
May 18 20:44:25 tunafix kernel: vfio_pin_page_external: Task qemu-system-x86
(4633) RLIMIT_MEMLOCK (65536) exceeded
May 18 20:44:25 tunafix kernel: BUG: unable to handle kernel NULL pointer
dereference at           (null)
May 18 20:44:25 tunafix kernel: IP: __wake_up_common+0x20/0x80
May 18 20:44:25 tunafix kernel: PGD 0 
May 18 20:44:25 tunafix kernel: 
May 18 20:44:25 tunafix kernel: Oops: 0000 [#1] SMP
May 18 20:44:25 tunafix kernel: CPU: 3 PID: 4636 Comm: qemu-system-x86 Not
tainted 4.11.1-gentoo #1
May 18 20:44:25 tunafix kernel: Hardware name: FUJITSU D3401-H1/D3401-H1, BIOS
V5.0.0.11 R1.13.0.SR.1 for D3401-H1x               02/29/2016
May 18 20:44:25 tunafix kernel: vfio_pin_page_external: Task qemu-system-x86
(4636) RLIMIT_MEMLOCK (65536) exceeded
May 18 20:44:25 tunafix kernel: vfio_pin_page_external: Task qemu-system-x86
(4633) RLIMIT_MEMLOCK (65536) exceeded
May 18 20:44:25 tunafix kernel: BUG: unable to handle kernel NULL pointer
dereference at           (null)
May 18 20:44:25 tunafix kernel: IP: __wake_up_common+0x20/0x80
May 18 20:44:25 tunafix kernel: PGD 0 
May 18 20:44:25 tunafix kernel: 
May 18 20:44:25 tunafix kernel: Oops: 0000 [#1] SMP
May 18 20:44:25 tunafix kernel: CPU: 3 PID: 4636 Comm: qemu-system-x86 Not
tainted 4.11.1-gentoo #1
May 18 20:44:25 tunafix kernel: Hardware name: FUJITSU D3401-H1/D3401-H1, BIOS
V5.0.0.11 R1.13.0.SR.1 for D3401-H1x               02/29/2016
May 18 20:44:25 tunafix kernel: task: ffff9436caec8000 task.stack:
ffff9f000d4b8000
May 18 20:44:25 tunafix kernel: RIP: 0010:__wake_up_common+0x20/0x80
May 18 20:44:25 tunafix kernel: RSP: 0018:ffff9f000d4bbc58 EFLAGS: 00010082
May 18 20:44:25 tunafix kernel: RAX: 0000000000000246 RBX: ffff943720211ac8
RCX: 0000000000000000
May 18 20:44:25 tunafix kernel: RDX: 0000000000000000 RSI: 0000000000000003
RDI: ffff943720211ac8
May 18 20:44:25 tunafix kernel: RBP: ffff943720211ad0 R08: 0000000000000000
R09: 0000000000000000
May 18 20:44:25 tunafix kernel: R10: 0000000179143000 R11: 0000000179146000
R12: 0000000000000003
May 18 20:44:25 tunafix kernel: R13: 0000000000000001 R14: 0000000000000003
R15: ffff9436c8c97300
May 18 20:44:25 tunafix kernel: FS:  00007fb128586700(0000)
GS:ffff94376e4c0000(0000) knlGS:0000000000000000
May 18 20:44:25 tunafix kernel: CS:  0010 DS: 0000 ES: 0000 CR0:
0000000080050033
May 18 20:44:25 tunafix kernel: task: ffff9436caec8000 task.stack:
ffff9f000d4b8000
May 18 20:44:25 tunafix kernel: RIP: 0010:__wake_up_common+0x20/0x80
May 18 20:44:25 tunafix kernel: RSP: 0018:ffff9f000d4bbc58 EFLAGS: 00010082
May 18 20:44:25 tunafix kernel: RAX: 0000000000000246 RBX: ffff943720211ac8
RCX: 0000000000000000
May 18 20:44:25 tunafix kernel: RDX: 0000000000000000 RSI: 0000000000000003
RDI: ffff943720211ac8
May 18 20:44:25 tunafix kernel: RBP: ffff943720211ad0 R08: 0000000000000000
R09: 0000000000000000
May 18 20:44:25 tunafix kernel: R10: 0000000179143000 R11: 0000000179146000
R12: 0000000000000003
May 18 20:44:25 tunafix kernel: R13: 0000000000000001 R14: 0000000000000003
R15: ffff9436c8c97300
May 18 20:44:25 tunafix kernel: FS:  00007fb128586700(0000)
GS:ffff94376e4c0000(0000) knlGS:0000000000000000
May 18 20:44:25 tunafix kernel: CS:  0010 DS: 0000 ES: 0000 CR0:
0000000080050033
May 18 20:44:25 tunafix kernel: CR2: 0000000000000000 CR3: 0000000f8ac6c000
CR4: 00000000003426e0
May 18 20:44:25 tunafix kernel: DR0: 0000000000000000 DR1: 0000000000000000
DR2: 0000000000000000
May 18 20:44:25 tunafix kernel: DR3: 0000000000000000 DR6: 00000000fffe0ff0
DR7: 0000000000000400
May 18 20:44:25 tunafix kernel: Call Trace:
May 18 20:44:25 tunafix kernel: ? __wake_up+0x2f/0x50
May 18 20:44:25 tunafix kernel: ? intel_vgpu_submit_execlist+0x6e3/0x890 [i915]
May 18 20:44:25 tunafix kernel: ? elsp_mmio_write+0xc8/0x150 [i915]
May 18 20:44:25 tunafix kernel: ? intel_vgpu_emulate_mmio_write+0x42d/0x660
[i915]
May 18 20:44:25 tunafix kernel: ? __kernel_fpu_end+0x48/0xb0
May 18 20:44:25 tunafix kernel: ? intel_vgpu_rw+0x147/0x1c0 [kvmgt]
May 18 20:44:25 tunafix kernel: CR2: 0000000000000000 CR3: 0000000f8ac6c000
CR4: 00000000003426e0
May 18 20:44:25 tunafix kernel: DR0: 0000000000000000 DR1: 0000000000000000
DR2: 0000000000000000
May 18 20:44:25 tunafix kernel: DR3: 0000000000000000 DR6: 00000000fffe0ff0
DR7: 0000000000000400
May 18 20:44:25 tunafix kernel: Call Trace:
May 18 20:44:25 tunafix kernel: ? __wake_up+0x2f/0x50
May 18 20:44:25 tunafix kernel: ? intel_vgpu_submit_execlist+0x6e3/0x890 [i915]
May 18 20:44:25 tunafix kernel: ? elsp_mmio_write+0xc8/0x150 [i915]
May 18 20:44:25 tunafix kernel: ? intel_vgpu_emulate_mmio_write+0x42d/0x660
[i915]
May 18 20:44:25 tunafix kernel: ? __kernel_fpu_end+0x48/0xb0
May 18 20:44:25 tunafix kernel: ? intel_vgpu_rw+0x147/0x1c0 [kvmgt]
May 18 20:44:25 tunafix kernel: ? intel_vgpu_write+0x136/0x160 [kvmgt]
May 18 20:44:25 tunafix kernel: ? __vfs_write+0x1e/0x120
May 18 20:44:25 tunafix kernel: ? do_vfs_ioctl+0x8a/0x5a0
May 18 20:44:25 tunafix kernel: ? vfs_write+0xaf/0x1b0
May 18 20:44:25 tunafix kernel: ? kvm_on_user_return+0x5a/0x90
May 18 20:44:25 tunafix kernel: ? SyS_pwrite64+0x6c/0x80
May 18 20:44:25 tunafix kernel: ? entry_SYSCALL_64_fastpath+0x1a/0xa9
May 18 20:44:25 tunafix kernel: Code: 90 66 2e 0f 1f 84 00 00 00 00 00 41 57 41
56 41 89 f6 41 55 41 54 55 53 48 8d 6f 08 48 83 ec 08 89 54 24 04 48 8b 57 08
48 39 d5 <48> 8b 32 74 48 41 89 cd 4d 89 c4 48 8d 42 e8 4c 8d 7e e8 eb 03 
May 18 20:44:25 tunafix kernel: RIP: __wake_up_common+0x20/0x80 RSP:
ffff9f000d4bbc58
May 18 20:44:25 tunafix kernel: ? intel_vgpu_write+0x136/0x160 [kvmgt]
May 18 20:44:25 tunafix kernel: ? __vfs_write+0x1e/0x120
May 18 20:44:25 tunafix kernel: ? do_vfs_ioctl+0x8a/0x5a0
May 18 20:44:25 tunafix kernel: ? vfs_write+0xaf/0x1b0
May 18 20:44:25 tunafix kernel: ? kvm_on_user_return+0x5a/0x90
May 18 20:44:25 tunafix kernel: ? SyS_pwrite64+0x6c/0x80
May 18 20:44:25 tunafix kernel: ? entry_SYSCALL_64_fastpath+0x1a/0xa9
May 18 20:44:25 tunafix kernel: Code: 90 66 2e 0f 1f 84 00 00 00 00 00 41 57 41
56 41 89 f6 41 55 41 54 55 53 48 8d 6f 08 48 83 ec 08 89 54 24 04 48 8b 57 08
48 39 d5 <48> 8b 32 74 48 41 89 cd 4d 89 c4 48 8d 42 e8 4c 8d 7e e8 eb 03 
May 18 20:44:25 tunafix kernel: RIP: __wake_up_common+0x20/0x80 RSP:
ffff9f000d4bbc58
May 18 20:44:25 tunafix kernel: CR2: 0000000000000000
May 18 20:44:25 tunafix kernel: ---[ end trace c1c0ee8078d3b02f ]---
May 18 20:44:25 tunafix kernel: CR2: 0000000000000000
May 18 20:44:25 tunafix kernel: ---[ end trace c1c0ee8078d3b02f ]---




vfio_pin_page_external: Task qemu-system-x86 (4636) RLIMIT_MEMLOCK (65536)
exceeded errors are cut, as there are even more of the same message.


The VM gets started as followed:
/usr/bin/qemu-system-x86_64 
    -name panoramix 
    -monitor unix:/run/kvm/kvm.panoramix.sock,server,nowait 
    -balloon virtio -pidfile /run/kvm/kvm.panoramix.pid 
    -runas qemu 
    -m 4096 
    -smp cores=2,threads=1,sockets=1 
    -machine q35 -k de -cpu host 
    -kernel /media/vms/kernel/gentoo-4.11-r2 
    -initrd /media/vms/kernel/initrd-v2.cpio.gz 
    -append root=/dev/vda2 quiet video=1920x1200@60 
    -enable-kvm 
    -daemonize 
    -device virtio-serial -chardev spicevmc,id=vdagent,name=vdagent -device
virtserialport,chardev=vdagent,name=com.redhat.spice.0 
    -device virtio-serial -chardev
socket,path=/run/kvm/kvm.panoramix.qga.sock,server,nowait,id=panoramix-qga 
    -device virtserialport,chardev=panoramix-qga,name=org.qemu.guest_agent.0
-chardev spicevmc,name=usbredir,id=usbredirchardev2 
    -device usb-redir,chardev=usbredirchardev2,id=usbredirdev2,debug=3 
    -chardev spicevmc,name=usbredir,id=usbredirchardev1 -device
usb-redir,chardev=usbredirchardev1,id=usbredirdev1,debug=3 
    -spice port=5811,addr=192.168.2.30 
    -drive
file=/media/vms/hds/panoramix_hd1.qcow2,if=virtio,cache=writethrough,aio=threads 
    -netdev tap,id=panoramix_4,ifname=qtap4,script=no,downscript=no 
    -device virtio-net-pci,netdev=panoramix_4,mac=AA:6E:17:00:80:05 
    -fsdev local,id=panoramix_9p_0,path=/usr/portage,security_model=none 
    -device virtio-9p-pci,fsdev=panoramix_9p_0,mount_tag=portage 
    -usb -usbdevice tablet -vga qxl
    -device
vfio-pci,sysfsdev=/sys/bus/pci/devices/0000:00:02.0/487405b5-e2fb-462c-8631-7000490f426f,rombar=0


Hostkernel: 4.11.1
Guestkernel: 4.11

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[Bug 195813] intel gvt/kvmgt: BUG: unable to handle kernel NULL pointer dereference at (null)

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=195813

Alex Williamson (alex.williamson@redhat.com) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |alex.williamson@redhat.com

--- Comment #1 from Alex Williamson (alex.williamson@redhat.com) ---
While I agree that this should not result in a host oops (a bug remains in the
intel kvmgt driver), it is necessary to allow the vfio user sufficient locked
memory limits.  libvirt would do this for you if you used it, otherwise you
should configure the user running the VM with a locked memory limit at least
equal to the VM memory size (4G, the default is 64k).

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[Bug 195813] intel gvt/kvmgt: BUG: unable to handle kernel NULL pointer dereference at (null)

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=195813

--- Comment #2 from Alex Williamson (alex.williamson@redhat.com) ---
Also, the remaining bug is in the Intel kvmgt mdev driver, there is no kvm bug
here.

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[Bug 195813] intel gvt/kvmgt: BUG: unable to handle kernel NULL pointer dereference at (null)

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=195813

changbin.du@hotmail.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |changbin.du@hotmail.com

--- Comment #3 from changbin.du@hotmail.com ---
Agree with Alex that is is a bug of GVTg device model. This looks like a
syncronazation issue. We have many GVTg fixes these months. Please retry using
latest kernel. Thanks.

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