Date: Tue, 19 Dec 2023 14:37:31 +0800
From: Ethan Zhao <haifeng.zhao@...ux.intel.com>
To: Baolu Lu <baolu.lu@...ux.intel.com>, bhelgaas@...gle.com,
 dwmw2@...radead.org, will@...nel.org, robin.murphy@....com, lukas@...ner.de
Cc: linux-pci@...r.kernel.org, iommu@...ts.linux.dev,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/2] iommu/vt-d: don's issue devTLB flush request when
 device is disconnected


On 12/19/2023 2:09 PM, Baolu Lu wrote:
> On 2023/12/17 19:49, Ethan Zhao wrote:
>> For those endpoint devices connect to system via hotplug capable ports,
>> users could request a warm reset to the device by flapping device's link
>> through setting the slot's link control register, as pciehpt_ist() DLLSC
>> interrupt sequence response, pciehp will unload the device driver and
>> then power it off. thus cause an IOMMU devTLB flush request for 
>> device to
>> be sent and a long time completion/timeout waiting in interrupt context.
>>
>> That would cause following continuous hard lockup warning and system 
>> hang
>>
>> [ 4211.433662] pcieport 0000:17:01.0: pciehp: Slot(108): Link Down
>> [ 4211.433664] pcieport 0000:17:01.0: pciehp: Slot(108): Card not 
>> present
>> [ 4223.822591] NMI watchdog: Watchdog detected hard LOCKUP on cpu 144
>> [ 4223.822622] CPU: 144 PID: 1422 Comm: irq/57-pciehp Kdump: loaded 
>> Tainted: G S
>>           OE    kernel version xxxx
>> [ 4223.822623] Hardware name: vendorname xxxx 666-106,
>> BIOS 01.01.02.03.01 05/15/2023
>> [ 4223.822623] RIP: 0010:qi_submit_sync+0x2c0/0x490
>> [ 4223.822624] Code: 48 be 00 00 00 00 00 08 00 00 49 85 74 24 20 0f 
>> 95 c1 48 8b
>>   57 10 83 c1 04 83 3c 1a 03 0f 84 a2 01 00 00 49 8b 04 24 8b 70 34 
>> <40> f6 c6 1
>> 0 74 17 49 8b 04 24 8b 80 80 00 00 00 89 c2 d3 fa 41 39
>> [ 4223.822624] RSP: 0018:ffffc4f074f0bbb8 EFLAGS: 00000093
>> [ 4223.822625] RAX: ffffc4f040059000 RBX: 0000000000000014 RCX: 
>> 0000000000000005
>> [ 4223.822625] RDX: ffff9f3841315800 RSI: 0000000000000000 RDI: 
>> ffff9f38401a8340
>> [ 4223.822625] RBP: ffff9f38401a8340 R08: ffffc4f074f0bc00 R09: 
>> 0000000000000000
>> [ 4223.822626] R10: 0000000000000010 R11: 0000000000000018 R12: 
>> ffff9f384005e200
>> [ 4223.822626] R13: 0000000000000004 R14: 0000000000000046 R15: 
>> 0000000000000004
>> [ 4223.822626] FS:  0000000000000000(0000) GS:ffffa237ae400000(0000)
>> knlGS:0000000000000000
>> [ 4223.822627] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> [ 4223.822627] CR2: 00007ffe86515d80 CR3: 000002fd3000a001 CR4: 
>> 0000000000770ee0
>> [ 4223.822627] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 
>> 0000000000000000
>> [ 4223.822628] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: 
>> 0000000000000400
>> [ 4223.822628] PKRU: 55555554
>> [ 4223.822628] Call Trace:
>> [ 4223.822628]  qi_flush_dev_iotlb+0xb1/0xd0
>> [ 4223.822628]  __dmar_remove_one_dev_info+0x224/0x250
>> [ 4223.822629]  dmar_remove_one_dev_info+0x3e/0x50
>> [ 4223.822629]  intel_iommu_release_device+0x1f/0x30
>> [ 4223.822629]  iommu_release_device+0x33/0x60
>> [ 4223.822629]  iommu_bus_notifier+0x7f/0x90
>> [ 4223.822630]  blocking_notifier_call_chain+0x60/0x90
>> [ 4223.822630]  device_del+0x2e5/0x420
>> [ 4223.822630]  pci_remove_bus_device+0x70/0x110
>> [ 4223.822630]  pciehp_unconfigure_device+0x7c/0x130
>> [ 4223.822631]  pciehp_disable_slot+0x6b/0x100
>> [ 4223.822631]  pciehp_handle_presence_or_link_change+0xd8/0x320
>> [ 4223.822631]  pciehp_ist+0x176/0x180
>> [ 4223.822631]  ? irq_finalize_oneshot.part.50+0x110/0x110
>> [ 4223.822632]  irq_thread_fn+0x19/0x50
>> [ 4223.822632]  irq_thread+0x104/0x190
>> [ 4223.822632]  ? irq_forced_thread_fn+0x90/0x90
>> [ 4223.822632]  ? irq_thread_check_affinity+0xe0/0xe0
>> [ 4223.822633]  kthread+0x114/0x130
>> [ 4223.822633]  ? __kthread_cancel_work+0x40/0x40
>> [ 4223.822633]  ret_from_fork+0x1f/0x30
>> [ 4223.822633] Kernel panic - not syncing: Hard LOCKUP
>> [ 4223.822634] CPU: 144 PID: 1422 Comm: irq/57-pciehp Kdump: loaded 
>> Tainted: G S
>>           OE     kernel version xxxx
>> [ 4223.822634] Hardware name: vendorname xxxx 666-106,
>> BIOS 01.01.02.03.01 05/15/2023
>> [ 4223.822634] Call Trace:
>> [ 4223.822634]  <NMI>
>> [ 4223.822635]  dump_stack+0x6d/0x88
>> [ 4223.822635]  panic+0x101/0x2d0
>> [ 4223.822635]  ? ret_from_fork+0x11/0x30
>> [ 4223.822635]  nmi_panic.cold.14+0xc/0xc
>> [ 4223.822636]  watchdog_overflow_callback.cold.8+0x6d/0x81
>> [ 4223.822636]  __perf_event_overflow+0x4f/0xf0
>> [ 4223.822636]  handle_pmi_common+0x1ef/0x290
>> [ 4223.822636]  ? __set_pte_vaddr+0x28/0x40
>> [ 4223.822637]  ? flush_tlb_one_kernel+0xa/0x20
>> [ 4223.822637]  ? __native_set_fixmap+0x24/0x30
>> [ 4223.822637]  ? ghes_copy_tofrom_phys+0x70/0x100
>> [ 4223.822637]  ? __ghes_peek_estatus.isra.16+0x49/0xa0
>> [ 4223.822637]  intel_pmu_handle_irq+0xba/0x2b0
>> [ 4223.822638]  perf_event_nmi_handler+0x24/0x40
>> [ 4223.822638]  nmi_handle+0x4d/0xf0
>> [ 4223.822638]  default_do_nmi+0x49/0x100
>> [ 4223.822638]  exc_nmi+0x134/0x180
>> [ 4223.822639]  end_repeat_nmi+0x16/0x67
>> [ 4223.822639] RIP: 0010:qi_submit_sync+0x2c0/0x490
>> [ 4223.822639] Code: 48 be 00 00 00 00 00 08 00 00 49 85 74 24 20 0f 
>> 95 c1 48 8b
>>   57 10 83 c1 04 83 3c 1a 03 0f 84 a2 01 00 00 49 8b 04 24 8b 70 34 
>> <40> f6 c6 10
>>   74 17 49 8b 04 24 8b 80 80 00 00 00 89 c2 d3 fa 41 39
>> [ 4223.822640] RSP: 0018:ffffc4f074f0bbb8 EFLAGS: 00000093
>> [ 4223.822640] RAX: ffffc4f040059000 RBX: 0000000000000014 RCX: 
>> 0000000000000005
>> [ 4223.822640] RDX: ffff9f3841315800 RSI: 0000000000000000 RDI: 
>> ffff9f38401a8340
>> [ 4223.822641] RBP: ffff9f38401a8340 R08: ffffc4f074f0bc00 R09: 
>> 0000000000000000
>> [ 4223.822641] R10: 0000000000000010 R11: 0000000000000018 R12: 
>> ffff9f384005e200
>> [ 4223.822641] R13: 0000000000000004 R14: 0000000000000046 R15: 
>> 0000000000000004
>> [ 4223.822641]  ? qi_submit_sync+0x2c0/0x490
>> [ 4223.822642]  ? qi_submit_sync+0x2c0/0x490
>> [ 4223.822642]  </NMI>
>> [ 4223.822642]  qi_flush_dev_iotlb+0xb1/0xd0
>> [ 4223.822642]  __dmar_remove_one_dev_info+0x224/0x250
>> [ 4223.822643]  dmar_remove_one_dev_info+0x3e/0x50
>> [ 4223.822643]  intel_iommu_release_device+0x1f/0x30
>> [ 4223.822643]  iommu_release_device+0x33/0x60
>> [ 4223.822643]  iommu_bus_notifier+0x7f/0x90
>> [ 4223.822644]  blocking_notifier_call_chain+0x60/0x90
>> [ 4223.822644]  device_del+0x2e5/0x420
>> [ 4223.822644]  pci_remove_bus_device+0x70/0x110
>> [ 4223.822644]  pciehp_unconfigure_device+0x7c/0x130
>> [ 4223.822644]  pciehp_disable_slot+0x6b/0x100
>> [ 4223.822645]  pciehp_handle_presence_or_link_change+0xd8/0x320
>> [ 4223.822645]  pciehp_ist+0x176/0x180
>> [ 4223.822645]  ? irq_finalize_oneshot.part.50+0x110/0x110
>> [ 4223.822645]  irq_thread_fn+0x19/0x50
>> [ 4223.822646]  irq_thread+0x104/0x190
>> [ 4223.822646]  ? irq_forced_thread_fn+0x90/0x90
>> [ 4223.822646]  ? irq_thread_check_affinity+0xe0/0xe0
>> [ 4223.822646]  kthread+0x114/0x130
>> [ 4223.822647]  ? __kthread_cancel_work+0x40/0x40
>> [ 4223.822647]  ret_from_fork+0x1f/0x30
>> [ 4223.822647] Kernel Offset: 0x6400000 from 0xffffffff81000000 
>> (relocation
>> range: 0xffffffff80000000-0xffffffffbfffffff)
>>
>> Fix it by checking the device's error_state in
>> devtlb_invalidation_with_pasid() to avoid sending meaningless devTLB 
>> flush
>> request to link down device that is set to 
>> pci_channel_io_perm_failure and
>> then powered off in
>>
>> pciehp_ist()
>>     pciehp_handle_presence_or_link_change()
>>       pciehp_disable_slot()
>>         remove_board()
>>           pciehp_unconfigure_device()
>>
>> For SAFE_REMOVAL unplug, link is alive when iommu releases device and
>> issues devTLB invalidate request, wouldn't trigger such issue.
>>
>> This patch works for all kinds of SURPPRISE_REMOVAL unplug operation.
>>
>> Tested-by: Haorong Ye <yehaorong@...edance.com>
>> Signed-off-by: Ethan Zhao <haifeng.zhao@...ux.intel.com>
>> ---
>>   drivers/iommu/intel/pasid.c | 17 +++++++++++++++++
>>   1 file changed, 17 insertions(+)
>>
>> diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c
>> index 74e8e4c17e81..182eb5df244d 100644
>> --- a/drivers/iommu/intel/pasid.c
>> +++ b/drivers/iommu/intel/pasid.c
>> @@ -476,6 +476,23 @@ devtlb_invalidation_with_pasid(struct 
>> intel_iommu *iommu,
>>   {
>>       struct device_domain_info *info;
>>       u16 sid, qdep, pfsid;
>> +    struct pci_dev *pdev;
>> +
>> +    pdev = to_pci_dev(dev);
>> +    if (!pdev)
>> +        return;
>> +
>> +    /*
>> +     * If endpoint device's link was brough down by user's pci 
>> configuration
>> +     * access to it's hotplug capable slot link control register, as 
>> sequence
>> +     * response for DLLSC, pciehp_ist() will set the device 
>> error_state to
>> +     * pci_channel_io_perm_failure. Checking device's state here to 
>> avoid
>> +     * issuing meaningless devTLB flush request to it, that might 
>> cause lockup
>> +     * warning or deadlock because too long time waiting in 
>> interrupt context.
>> +     */
>> +
>> +    if (pci_dev_is_disconnected(pdev))
>> +        return;
>>         info = dev_iommu_priv_get(dev);
>>       if (!info || !info->ats_enabled)
>
> It's likely better to check the device status after verifying
> ats_enabled. How about below change?
>
> diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c
> index 74e8e4c17e81..fa19c6cdfd8b 100644
> --- a/drivers/iommu/intel/pasid.c
> +++ b/drivers/iommu/intel/pasid.c
> @@ -481,6 +481,9 @@ devtlb_invalidation_with_pasid(struct intel_iommu 
> *iommu,
>         if (!info || !info->ats_enabled)
>                 return;
>
> +       if (pci_dev_is_disconnected(to_pci_dev(dev)))
> +               return
> +

I did this in the first version, but I thought seconds, changed it.

Anyway, not performance critical path, I am okay with them.


Thanks,

Ethan

> sid = info->bus << 8 | info->devfn;
>         qdep = info->ats_qdep;
>         pfsid = info->pfsid;
>
> Best regards,
> baolu

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