Re: [PATCH v2 0/7] Implement forced unplug and forced activation

[Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>]

On Wed, Jul 23, 2025 at 01:58:27PM +0000, Tu Dinh wrote:
> The goal of these two features is to simplify driver servicing and avoid
> requiring storing driver state in Registry.
> 
> Forced unplug, as name implies, forcefully unplugs emulated devices when
> a driver is present, rather than when it's active. It defines a Registry
> key at CurrentControlSet\XEN\ForceUnplug. Drivers can opt into forced
> unplug by creating an appropriate value (DISKS/NICS) in this key.
> 
> Forced activation is the companion to forced unplug. It aims to make
> activation of Xenbus FDOs deterministic and stateless, using a
> precedence mapping based on device IDs, prioritizing the vendor device
> over the generic ones. This avoids situations where the wrong FDO is
> activated, which will prevent Windows Update from working.
> 
> With forced activation, Xenfilt is now installed via INF on top of the
> current installation routines. This means PV drivers can be injected
> offline without needing another reboot to be reconfigured.
> 
> To avoid affecting older drivers, the two features are conditioned
> behind new build variables FORCE_UNPLUG and FORCE_ACTIVATE.
> 
> The following scenarios have been successfully tested, both requiring
> only one reboot:
> * Offline driver installation via DISM
> * Toggling vendor device

Hi,

I tested this series (or rather
https://github.com/xcp-ng/win-xenbus/tree/emulated-v3 at
9424383b7c2f0b6d9f4a7fd554662c8679cc935f) and got the following failure:

    xen platform: xenbus|PdoQueryId: (ULONG_PTR)Buffer - (ULONG_PTR)Id.Buffer = 
1032
    xen platform: xenbus|PdoQueryId: REGSTR_VAL_MAX_HCID_LEN = 1024
    xen platform: xenbus|PdoQueryId: ASSERTION FAILED: ((ULONG_PTR)Buffer - 
(ULONG_PTR)Id.Buffer) < (1024)
    xen platform: XEN|DEBUG: ====> (xenbus.sys + 0000000000038990)
    xen platform: xenbus|SUSPEND: Count = 0
    xen platform: xenbus|SUSPEND: EARLY: xenbus.sys + 0000000000010910 
(FFFFC08B03CFF130)
    xen platform: xenbus|SUSPEND: EARLY: xenbus.sys + 000000000002F3D0 
(FFFFC08B03F11910)
    xen platform: xenbus|SUSPEND: EARLY: xenbus.sys + 0000000000026DA0 
(FFFFC08B04B63640)
    xen platform: xenbus|SUSPEND: EARLY: xenbus.sys + 00000000000373A0 
(FFFFC08B09393000)
    xen platform: xenbus|SUSPEND: LATE: xenbus.sys + 0000000000010B10 
(FFFFC08B03CFF130)
    xen platform: xenbus|SUSPEND: LATE: xenbus.sys + 0000000000037440 
(FFFFC08B09393000)
    xen platform: xenbus|SUSPEND: LATE: xenbus.sys + 0000000000004520 
(FFFFC08B09265260)
    xen platform: xenbus|SUSPEND: LATE: xenbus.sys + 0000000000021110 
(FFFFC08B092DA010)
    xen platform: XEN|DEBUG: <==== (xenbus.sys + 0000000000038990)
    xen platform: XEN|DEBUG: ====> (xenbus.sys + 000000000003C5C0)
    xen platform: xenbus|RANGE_SET: RANGE SETS:
    xen platform: xenbus|RANGE_SET:  - gnttab:
    xen platform: xenbus|RANGE_SET:    {20 - 1ff}*
    xen platform: xenbus|RANGE_SET:  - balloon:
    xen platform: xenbus|RANGE_SET:    EMPTY
    xen platform: XEN|DEBUG: <==== (xenbus.sys + 000000000003C5C0)
    xen platform: XEN|DEBUG: ====> (xenbus.sys + 000000000000D850)
    xen platform: xenbus|EVTCHN: EVENT CHANNELS:
    xen platform: xenbus|EVTCHN: - (0001) BY xenbus.sys + 0000000000034A41 
ACTIVE
    xen platform: xenbus|EVTCHN: FIXED
    xen platform: xenbus|EVTCHN: Count = 40
    xen platform: xenbus|EVTCHN: - (0002) BY xenbus.sys + 0000000000003AD6 
ACTIVE
    xen platform: xenbus|EVTCHN: FIXED
    xen platform: xenbus|EVTCHN: Count = 0
    xen platform: xenbus|EVTCHN: - (0006) BY xenbus.sys + 000000000002355B 
ACTIVE
    xen platform: xenbus|EVTCHN: VIRQ: Index = 1
    xen platform: xenbus|EVTCHN: Count = 0
    xen platform: XEN|DEBUG: <==== (xenbus.sys + 000000000000D850)
    xen platform: XEN|DEBUG: ====> (xenbus.sys + 000000000002E680)
    xen platform: xenbus|SHARED_INFO: Address = 00000000.7ee78000
    xen platform: XEN|DEBUG: <==== (xenbus.sys + 000000000002E680)
    xen platform: XEN|DEBUG: ====> (xenbus.sys + 0000000000042710)
    xen platform: XEN|DEBUG: <==== (xenbus.sys + 0000000000042710)
    xen platform: XEN|DEBUG: ====> (xenbus.sys + 0000000000025D60)
    xen platform: xenbus|GNTTAB: [0] Address = 7ee66000.884c0740
    xen platform: XEN|DEBUG: <==== (xenbus.sys + 0000000000025D60)
    xen platform: XEN|DEBUG: ====> (xenbus.sys + 00000000000341A0)
    xen platform: xenbus|STORE: Address = 00000000.feffc000
    xen platform: xenbus|STORE: Events = 40 Dpcs = 4 Polls = 44
    xen platform: xenbus|STORE: WATCHES:
    xen platform: xenbus|STORE: - (9255) ON device BY xenbus.sys + 
0000000000022879 [ACTIVE]
    xen platform: xenbus|STORE: - (9256) ON control/shutdown BY xenbus.sys + 
0000000000022908 [ACTIVE]
    xen platform: xenbus|STORE: - (9257) ON memory/target BY xenbus.sys + 
0000000000022A0A [ACTIVE]
    xen platform: XEN|DEBUG: <==== (xenbus.sys + 00000000000341A0)
    xen platform: XEN|DEBUG: ====> (xenbus.sys + 0000000000003680)
    xen platform: xenbus|CONSOLE: Address = 00000000.fefff000
    xen platform: xenbus|CONSOLE: Events = 0 Dpcs = 1
    xen platform: XEN|DEBUG: <==== (xenbus.sys + 0000000000003680)
    xen platform: XEN|DEBUG: ====> (xenbus.sys + 0000000000016F90)
    xen platform: xenbus|FDO: VIRQS:
    xen platform: xenbus|FDO: - DEBUG: (0:0) Count = 0
    xen platform: XEN|DEBUG: <==== (xenbus.sys + 0000000000016F90)
    xen platform: xen|BUGCHECK: ====>
    xen platform: xen|BUGCHECK: SYSTEM_THREAD_EXCEPTION_NOT_HANDLED: 
FFFFFFFFC0000420 FFFFF8028845B042 FFFFB0849D5E9178 FFFFB0849D5E89B0
    xen platform: xen|BUGCHECK: C0000420 AT xenbus.sys + 000000000002B042
    xen platform: xen|BUGCHECK: EXCEPTION (FFFFB0849D5E9178):
    xen platform: xen|BUGCHECK: - Code = C0000420
    xen platform: xen|BUGCHECK: - Flags = 00000000
    xen platform: xen|BUGCHECK: - Address = FFFFF8028845B042
    xen platform: xen|BUGCHECK: CONTEXT (FFFFB0849D5E89B0):
    xen platform: xen|BUGCHECK: - GS = 002B
    xen platform: xen|BUGCHECK: - FS = 0053
    xen platform: xen|BUGCHECK: - ES = 002B
    xen platform: xen|BUGCHECK: - DS = 002B
    xen platform: xen|BUGCHECK: - SS = 0018
    xen platform: xen|BUGCHECK: - CS = 0010
    xen platform: xen|BUGCHECK: - EFLAGS = 00040282
    xen platform: xen|BUGCHECK: - RDI = 00000000090FCA70
    xen platform: xen|BUGCHECK: - RSI = 000000009D5E9700
    xen platform: xen|BUGCHECK: - RBX = 0000000009389340
    xen platform: xen|BUGCHECK: - RDX = 0000000000000059
    xen platform: xen|BUGCHECK: - RCX = 00000000FD000000
    xen platform: xen|BUGCHECK: - RAX = 0000000000000001
    xen platform: xen|BUGCHECK: - RBP = 0000000000000000
    xen platform: xen|BUGCHECK: - RIP = 000000008845B042
    xen platform: xen|BUGCHECK: - RSP = 000000009D5E93B0
    xen platform: xen|BUGCHECK: - R8 = 000000000000004D
    xen platform: xen|BUGCHECK: - R9 = 0000000000000000
    xen platform: xen|BUGCHECK: - R10 = 00000000719679B0
    xen platform: xen|BUGCHECK: - R11 = 0000000000000000
    xen platform: xen|BUGCHECK: - R12 = 0000000080000FB4
    xen platform: xen|BUGCHECK: - R13 = 0000000000000001
    xen platform: xen|BUGCHECK: - R14 = 00000000C00000BB
    xen platform: xen|BUGCHECK: - R15 = 0000000009389340
    xen platform: xen|BUGCHECK: STACK:
    xen platform: xen|BUGCHECK: 000000009D5E9500: (00000000091AA140 
00000000090FCA70 0000000000000013 000000008847C370) xenbus.sys + 
0000000000028668
    xen platform: xen|BUGCHECK: 000000009D5E9560: (00000000091AA140 
00000000090FCA70 0000000000000518 0000000000000000) xenbus.sys + 
0000000000028408
    xen platform: xen|BUGCHECK: 000000009D5E95A0: (00000000091AA140 
00000000090FCA70 0000000000000000 000000007182E891) xenbus.sys + 
000000000000A3CC
    xen platform: xen|BUGCHECK: 000000009D5E9620: (0000000009389340 
00000000090FCA70 0000000000000001 0000000069706E04) ntoskrnl.exe + 
000000000022A6B5
    xen platform: xen|BUGCHECK: 000000009D5E9660: (0000000000000000 
0000000009389340 000000009D5E9700 0000000000000001) ntoskrnl.exe + 
0000000000694A88
    xen platform: xen|BUGCHECK: 000000009D5E96D0: (00000000C00000BB 
000000000938CC90 000000009D5E9878 0000000009389340) ntoskrnl.exe + 
0000000000733716
    xen platform: xen|BUGCHECK: 000000009D5E9760: (0000000000000000 
000000009D5E9878 0000000003D5A500 0000000000000000) ntoskrnl.exe + 
00000000007335F4
    xen platform: xen|BUGCHECK: 000000009D5E97C0: (0000000000000000 
000000009D5E98C0 0000000000020000 000000000938CC90) ntoskrnl.exe + 
0000000000730EC1


This is on fresh Windows 10 (22H2) domU, with opt-in patches for both xenvbd
and xennet.

The test was done on our CI system, more logs are available at
https://openqa.qubes-os.org/tests/147544#downloads. Especially it
includes tarball of the whole /var/log, where you can find
/var/log/xen/console/guest-windows-test-dm.log with messages before the
above failure.

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab

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