Re: [PATCH] s390: vfio-ap: disable IRQ in remove callback results in kernel OOPS

Pierre Morel
2019-10-30T18:02:25Z

On 10/30/19 5:51 PM, Tony Krowiak wrote:
> On 10/30/19 10:00 AM, Pierre Morel wrote:
>>
>>
>>
>> On 10/30/19 8:44 AM, Harald Freudenberger wrote:
>>> On 29.10.19 23:09, Tony Krowiak wrote:
>>>> From: aekrowia <akrowiak@linux.ibm.com>
>>>>
>>>> When an AP adapter card is configured off via the SE or the SCLP
>>>> Deconfigure Adjunct Processor command and the AP bus subsequently
>>>> detects
>>>> that the adapter card is no longer in the AP configuration, the card
>>>> device representing the adapter card as well as each of its associated
>>>> AP queue devices will be removed by the AP bus. If one or more of the
>>>> affected queue devices is bound to the VFIO AP device driver, its
>>>> remove
>>>> callback will be invoked for each queue to be removed. The remove
>>>> callback
>>>> resets the queue and disables IRQ processing. If interrupt
>>>> processing was
>>>> never enabled for the queue, disabling IRQ processing will fail
>>>> resulting
>>>> in a kernel OOPS.
>>>>
>>>> This patch verifies IRQ processing is enabled before attempting to
>>>> disable
>>>> interrupts for the queue.
>>>>
>>>> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
>>>> Signed-off-by: aekrowia <akrowiak@linux.ibm.com>
>>>> ---
>>>>   drivers/s390/crypto/vfio_ap_drv.c | 3 ++-
>>>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/s390/crypto/vfio_ap_drv.c
>>>> b/drivers/s390/crypto/vfio_ap_drv.c
>>>> index be2520cc010b..42d8308fd3a1 100644
>>>> --- a/drivers/s390/crypto/vfio_ap_drv.c
>>>> +++ b/drivers/s390/crypto/vfio_ap_drv.c
>>>> @@ -79,7 +79,8 @@ static void vfio_ap_queue_dev_remove(struct
>>>> ap_device *apdev)
>>>>       apid = AP_QID_CARD(q->apqn);
>>>>       apqi = AP_QID_QUEUE(q->apqn);
>>>>       vfio_ap_mdev_reset_queue(apid, apqi, 1);
>>>> -    vfio_ap_irq_disable(q);
>>>> +    if (q->saved_isc != VFIO_AP_ISC_INVALID)
>>>> +        vfio_ap_irq_disable(q);
>>>>       kfree(q);
>>>>       mutex_unlock(&matrix_dev->lock);
>>>>   }
>>> Reset of an APQN does also clear IRQ processing. I don't say that the
>>> resources associated with IRQ handling for the APQN are also cleared.
>>> But when you call PQAP(AQIC) after an PQAP(RAPQ) or PQAP(ZAPQ)
>>> it is superfluous. However, there should not appear any kernel OOPS.
>>> So can you please give me more details about this kernel oops - maybe
>>> I need to add exception handler code to the inline ap_aqic() function.
>>>
>>> regards, Harald Freudenberger
>>>
>>
>> Hi Tony,
>>
>> wasn't it already solved by the patch 5c4c2126  from Christian ?
>
> No, that patch merely sets the 'matrix_mdev' field of the
> 'struct vfio_ap_queue' to NULL in the vfio_ap_free_aqic_resources()
> function. Also, with the latest master branch which has 5c4c2126
> installed, the failure occurs.
>
>>
>> Can you send the trace to me please?
>
> [  266.989476] crw_info : CRW reports slct=0, oflw=0, chn=0, rsc=B,
> anc=0, erc=0, rsid=0
> [  266.989617] ------------[ cut here ]------------
> [  266.989622] vfio_ap_wait_for_irqclear: tapq rc 03: 0504
> [  266.989681] WARNING: CPU: 0 PID: 7 at
> drivers/s390/crypto/vfio_ap_ops.c:101 vfio_ap_irq_disable+0x13c/0x1b0
> [vfio_ap]

Hi Tony,

This is not a oops this is the warning written in
vfio_ap_wait_for_irqclear() because the AP has been deconfigured.

Note that, IIUC, this (the warning) does not happen for devices bound to
the vfio_ap driver but not currently assigned to a mediated device.

I do not think we should avoid sending a warning in this case because
this is not a normal administration good practice to forcefully take an
AP away like this without smoothly removing the device from the mediated
device.

Regards,

Pierre

> [ 266.989682] Modules linked in: xt_CHECKSUM xt_MASQUERADE tun bridge
> stp llc ip6t_rpfilter ip6t_REJECT nf_reject_ipv6 xt_conntrack
> ebtable_nat ip6table_nat ip6table_mangle ip6table_raw
> ip6table_security iptable_nat nf_nat iptable_mangle iptable_raw
> iptable_security nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 libcrc32c
> ip_set nfnetlink ebtable_filter ebtables ip6table_filter ip6_tables
> sunrpc ghash_s390 prng aes_s390 des_s390 libdes vfio_ccw sha512_s390
> sha1_s390 eadm_sch zcrypt_cex4 qeth_l2 crc32_vx_s390 dasd_eckd_mod
> sha256_s390 qeth sha_common dasd_mod ccwgroup qdio pkey zcrypt vfio_ap
> kvm
> [  266.989704] CPU: 0 PID: 7 Comm: kworker/0:1 Not tainted 5.4.0-rc5 #81
> [  266.989705] Hardware name: IBM 2964 NE1 749 (LPAR)
> [  266.989710] Workqueue: events_long ap_scan_bus
> [  266.989711] Krnl PSW : 0704c00180000000 000003ff8007d89c
> (vfio_ap_irq_disable+0x13c/0x1b0 [vfio_ap])
> [  266.989714]            R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3
> CC:0 PM:0 RI:0 EA:3
> [  266.989716] Krnl GPRS: 000000000000000a 0000000000000006
> 000000000000002b 0000000000000007
> [  266.989717]            0000000000000007 000000007fe06000
> 000003ff00000005 0000000000000000
> [  266.989718]            0000000100000504 0000000000000003
> 00000001f9d27e40 000003e00003bb5c
> [  266.989719]            00000001fe765d00 0000000000000504
> 000003ff8007d898 000003e00003ba60
> [  266.989724] Krnl Code: 000003ff8007d88c: c02000000ce6    larl
> %r2,3ff8007f258
>                           000003ff8007d892: c0e5fffff4c7    brasl
> %r14,3ff8007c220
>                          #000003ff8007d898: a7f40001        brc
> 15,3ff8007d89a
>                          >000003ff8007d89c: a7f4ff9d        brc
> 15,3ff8007d7d6
>                           000003ff8007d8a0: a7100100 tmlh    %r1,256
>                           000003ff8007d8a4: a784ff99        brc
> 8,3ff8007d7d6
>                           000003ff8007d8a8: a7290014 lghi    %r2,20
>                           000003ff8007d8ac: c0e5fffff4b0    brasl
> %r14,3ff8007c20c
> [  266.989772] Call Trace:
> [  266.989777] ([<000003ff8007d898>] vfio_ap_irq_disable+0x138/0x1b0
> [vfio_ap])
> [  266.989779]  [<000003ff8007c4d2>]
> vfio_ap_queue_dev_remove+0x6a/0x90 [vfio_ap]
> [  266.989782]  [<00000000bf0f24f0>] ap_device_remove+0x50/0x110
> [  266.989784]  [<00000000beffbaac>]
> device_release_driver_internal+0x114/0x1f0
> [  266.989787]  [<00000000beff9c88>] bus_remove_device+0x108/0x190
> [  266.989789]  [<00000000beff5418>] device_del+0x178/0x3a0
> [  266.989790]  [<00000000beff5670>] device_unregister+0x30/0x90
> [  266.989791]  [<00000000bf0f0f04>]
> __ap_queue_devices_with_id_unregister+0x44/0x50
> [  266.989793]  [<00000000beff86ea>] bus_for_each_dev+0x82/0xb0
> [  266.989794]  [<00000000bf0f2aba>] ap_scan_bus+0x262/0x878
> [  266.989798]  [<00000000beb4785c>] process_one_work+0x1e4/0x410
> [  266.989800]  [<00000000beb47ca8>] worker_thread+0x220/0x460
> [  266.989802]  [<00000000beb4e99a>] kthread+0x12a/0x160
> [  266.989805]  [<00000000bf2d8eb0>] ret_from_fork+0x28/0x2c
> [  266.989806]  [<00000000bf2d8eb4>] kernel_thread_starter+0x0/0xc
> [  266.989807] Last Breaking-Event-Address:
> [  266.989809]  [<000003ff8007d898>] vfio_ap_irq_disable+0x138/0x1b0
> [vfio_ap]
> [  266.989810] ---[ end trace 59b4020890dbd391 ]---
>
>
>>
>> Thanks,
>>
>> Pierre
>>
>>
>>
>
--
Pierre Morel
IBM Lab Boeblingen