RE: [PATCH v2 1/2] vfio/xe: Reorganize the init to decouple migration from reset

[Tian, Kevin]

> From: Winiarski, Michal <michal.winiarski@xxxxxxxxx>
> Sent: Saturday, April 11, 2026 6:50 AM
> 
> Attempting to issue reset on VF devices that don't support migration
> leads to the following:
> 
>   BUG: unable to handle page fault for address: 00000000000011f8
>   #PF: supervisor read access in kernel mode
>   #PF: error_code(0x0000) - not-present page
>   PGD 0 P4D 0
>   Oops: Oops: 0000 [#1] SMP NOPTI
>   CPU: 2 UID: 0 PID: 7443 Comm: xe_sriov_flr Tainted: G S   U              7.0.0-rc1-
> lgci-xe-xe-4588-cec43d5c2696af219-nodebug+ #1 PREEMPT(lazy)
>   Tainted: [S]=CPU_OUT_OF_SPEC, [U]=USER
>   Hardware name: Intel Corporation Alder Lake Client Platform/AlderLake-P
> DDR4 RVP, BIOS RPLPFWI1.R00.4035.A00.2301200723 01/20/2023
>   RIP: 0010:xe_sriov_vfio_wait_flr_done+0xc/0x80 [xe]
>   Code: ff c3 cc cc cc cc 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90
> 90 90 90 90 90 0f 1f 44 00 00 55 48 89 e5 41 54 53 <83> bf f8 11 00 00 02 75 61
> 41 89 f4 85 f6 74 52 48 8b 47 08 48 89
>   RSP: 0018:ffffc9000f7c39b8 EFLAGS: 00010202
>   RAX: ffffffffa04d8660 RBX: ffff88813e3e4000 RCX: 0000000000000000
>   RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
>   RBP: ffffc9000f7c39c8 R08: 0000000000000000 R09: 0000000000000000
>   R10: 0000000000000000 R11: 0000000000000000 R12: ffff888101a48800
>   R13: ffff88813e3e4150 R14: ffff888130d0d008 R15: ffff88813e3e40d0
>   FS:  00007877d3d0d940(0000) GS:ffff88890b6d3000(0000)
> knlGS:0000000000000000
>   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>   CR2: 00000000000011f8 CR3: 000000015a762000 CR4: 0000000000f52ef0
>   PKRU: 55555554
>   Call Trace:
>    <TASK>
>    xe_vfio_pci_reset_done+0x49/0x120 [xe_vfio_pci]
>    pci_dev_restore+0x3b/0x80
>    pci_reset_function+0x109/0x140
>    reset_store+0x5c/0xb0
>    dev_attr_store+0x17/0x40
>    sysfs_kf_write+0x72/0x90
>    kernfs_fop_write_iter+0x161/0x1f0
>    vfs_write+0x261/0x440
>    ksys_write+0x69/0xf0
>    __x64_sys_write+0x19/0x30
>    x64_sys_call+0x259/0x26e0
>    do_syscall_64+0xcb/0x1500
>    ? __fput+0x1a2/0x2d0
>    ? fput_close_sync+0x3d/0xa0
>    ? __x64_sys_close+0x3e/0x90
>    ? x64_sys_call+0x1b7c/0x26e0
>    ? do_syscall_64+0x109/0x1500
>    ? __task_pid_nr_ns+0x68/0x100
>    ? __do_sys_getpid+0x1d/0x30
>    ? x64_sys_call+0x10b5/0x26e0
>    ? do_syscall_64+0x109/0x1500
>    ? putname+0x41/0x90
>    ? do_faccessat+0x1e8/0x300
>    ? __x64_sys_access+0x1c/0x30
>    ? x64_sys_call+0x1822/0x26e0
>    ? do_syscall_64+0x109/0x1500
>    ? tick_program_event+0x43/0xa0
>    ? hrtimer_interrupt+0x126/0x260
>    ? irqentry_exit+0xb2/0x710
>    entry_SYSCALL_64_after_hwframe+0x76/0x7e
>   RIP: 0033:0x7877d5f1c5a4
>   Code: c7 00 16 00 00 00 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e
> fa 80 3d a5 ea 0e 00 00 74 13 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 c3
> 0f 1f 00 55 48 89 e5 48 83 ec 20 48 89
>   RSP: 002b:00007fff48e5f908 EFLAGS: 00000202 ORIG_RAX:
> 0000000000000001
>   RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007877d5f1c5a4
>   RDX: 0000000000000001 RSI: 00007877d621b0c9 RDI: 0000000000000009
>   RBP: 0000000000000001 R08: 00005fb49113b010 R09: 0000000000000007
>   R10: 0000000000000000 R11: 0000000000000202 R12: 00007877d621b0c9
>   R13: 0000000000000009 R14: 00007fff48e5fac0 R15: 00007fff48e5fac0
>    </TASK>
> 
> This is caused by the fact that some of the xe_vfio_pci_core_device
> members needed for handling reset are only initialized as part of
> migration init.
> 
> Fix the problem by reorganizing the code to decouple VF init from
> migration init.
> 
> Fixes: 1f5556ec8b9ef ("vfio/xe: Add device specific vfio_pci driver variant for
> Intel graphics")
> Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/work_items/7352
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Michał Winiarski <michal.winiarski@xxxxxxxxx>

Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>