Re: [RFC PATCH v9 2/5] iommu/vt-d: break out ATS Invalidation if target device is gone

Ethan Zhao
2023-12-28T13:03:21Z

On 12/28/2023 4:30 PM, Tian, Kevin wrote:
>> From: Ethan Zhao <haifeng.zhao@linux.intel.com>
>> Sent: Thursday, December 28, 2023 8:17 AM
>>
>> 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 pciehp_ist() DLLSC
>> interrupt sequence response, pciehp will unload the device driver and
>> then power it off. thus cause an IOMMU device-TLB invalidation (Intel
>> VT-d spec, or ATS Invalidation in PCIe spec r6.1) request for device to
>> be sent and a long time completion/timeout waiting in interrupt context.
> is above describing the behavior of safe removal or surprise removal?

bring the link down is a kind of surprise removal for hotplug capable

device.

>
>> 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)
>>
>> Furthermore even an in-process safe removal unplugged device could be
>> surprise removed anytime, thus need to check the ATS Invalidation target
> I don't understand what this sentence is trying to say. what is "in-process
> safe removal unplugged device"? Are following words about safe removal
> or surprise removal?

That is to say surprise removal unplug action happens when the safe

removal is in the middle of handling process.

>
>> device state to see if it is gone, and don't wait for the completion/
>> timeout blindly, thus avoid the up to 1min+50% (see Implementation Note
>> in PCIe spec r6.1 sec 10.3.1) waiting and cause hard lockup or system
>> hang.
>>
>> Signed-off-by: Ethan Zhao <haifeng.zhao@linux.intel.com>
>> ---
>> drivers/iommu/intel/dmar.c | 12 ++++++++++++
>> 1 file changed, 12 insertions(+)
>>
>> diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c
>> index 23cb80d62a9a..76903a8bf963 100644
>> --- a/drivers/iommu/intel/dmar.c
>> +++ b/drivers/iommu/intel/dmar.c
>> @@ -1347,6 +1347,7 @@ int qi_submit_sync(struct intel_iommu *iommu,
>> struct qi_desc *desc,
>> unsigned int count, unsigned long options)
>> {
>> struct q_inval *qi = iommu->qi;
>> + struct pci_dev *pdev = NULL;
>> s64 devtlb_start_ktime = 0;
>> s64 iotlb_start_ktime = 0;
>> s64 iec_start_ktime = 0;
>> @@ -1360,6 +1361,9 @@ int qi_submit_sync(struct intel_iommu *iommu,
>> struct qi_desc *desc,
>> if (!qi)
>> return 0;
>>
>> + if (iommu->flush_target_dev && dev_is_pci(iommu-
>>> flush_target_dev))
>> + pdev = to_pci_dev(iommu->flush_target_dev);
>> +
>> type = desc->qw0 & GENMASK_ULL(3, 0);
>>
>> if ((type == QI_IOTLB_TYPE || type == QI_EIOTLB_TYPE) &&
>> @@ -1423,6 +1427,14 @@ int qi_submit_sync(struct intel_iommu *iommu,
>> struct qi_desc *desc,
>> writel(qi->free_head << shift, iommu->reg + DMAR_IQT_REG);
>>
>> while (qi->desc_status[wait_index] != QI_DONE) {
>> + /*
>> + * if the device-TLB invalidation target device is gone, don't
>> + * wait anymore, it might take up to 1min+50%, causes
>> system
>> + * hang. (see Implementation Note in PCIe spec r6.1 sec
>> 10.3.1)
>> + */
>> + if ((type == QI_DIOTLB_TYPE || type == QI_DEIOTLB_TYPE)
>> && pdev)
>> + if (!pci_device_is_present(pdev))
>> + break;
> I'm not sure it's the right thing to do. Such check should be put in the
> caller which has the device pointer and can already know it's absent
> to not call those cache invalidation helpers.

Here is to handle such case, the invalidation request is sent, but the

device is just pulled out at that moment.

Thanks,

Ethan

>> /*
>> * We will leave the interrupts disabled, to prevent interrupt
>> * context to queue another cmd while a cmd is already
>> submitted
>> --
>> 2.31.1
>>
>