Hi Bjorn,
On Fri, May 22, 2020 at 4:19 AM Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote:
>
> On Thu, May 21, 2020 at 09:28:20AM +0530, Prabhakar Kushwaha wrote:
> > On Wed, May 20, 2020 at 4:52 AM Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote:
> > > On Thu, May 14, 2020 at 12:47:02PM +0530, Prabhakar Kushwaha wrote:
> > > > On Wed, May 13, 2020 at 3:33 AM Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote:
> > > > > On Mon, May 11, 2020 at 07:46:06PM -0700, Prabhakar Kushwaha wrote:
> > > > > > An SMMU Stream table is created by the primary kernel. This table is
> > > > > > used by the SMMU to perform address translations for device-originated
> > > > > > transactions. Any crash (if happened) launches the kdump kernel which
> > > > > > re-creates the SMMU Stream table. New transactions will be translated
> > > > > > via this new table..
> > > > > >
> > > > > > There are scenarios, where devices are still having old pending
> > > > > > transactions (configured in the primary kernel). These transactions
> > > > > > come in-between Stream table creation and device-driver probe.
> > > > > > As new stream table does not have entry for older transactions,
> > > > > > it will be aborted by SMMU.
> > > > > >
> > > > > > Similar observations were found with PCIe-Intel 82576 Gigabit
> > > > > > Network card. It sends old Memory Read transaction in kdump kernel.
> > > > > > Transactions configured for older Stream table entries, that do not
> > > > > > exist any longer in the new table, will cause a PCIe Completion Abort.
> > > > >
> > > > > That sounds like exactly what we want, doesn't it?
> > > > >
> > > > > Or do you *want* DMA from the previous kernel to complete? That will
> > > > > read or scribble on something, but maybe that's not terrible as long
> > > > > as it's not memory used by the kdump kernel.
> > > >
> > > > Yes, Abort should happen. But it should happen in context of driver.
> > > > But current abort is happening because of SMMU and no driver/pcie
> > > > setup present at this moment.
> > >
> > > I don't understand what you mean by "in context of driver." The whole
> > > problem is that we can't control *when* the abort happens, so it may
> > > happen in *any* context. It may happen when a NIC receives a packet
> > > or at some other unpredictable time.
> > >
> > > > Solution of this issue should be at 2 place
> > > > a) SMMU level: I still believe, this patch has potential to overcome
> > > > issue till finally driver's probe takeover.
> > > > b) Device level: Even if something goes wrong. Driver/device should
> > > > able to recover.
> > > >
> > > > > > Returned PCIe completion abort further leads to AER Errors from APEI
> > > > > > Generic Hardware Error Source (GHES) with completion timeout.
> > > > > > A network device hang is observed even after continuous
> > > > > > reset/recovery from driver, Hence device is no more usable.
> > > > >
> > > > > The fact that the device is no longer usable is definitely a problem.
> > > > > But in principle we *should* be able to recover from these errors. If
> > > > > we could recover and reliably use the device after the error, that
> > > > > seems like it would be a more robust solution that having to add
> > > > > special cases in every IOMMU driver.
> > > > >
> > > > > If you have details about this sort of error, I'd like to try to fix
> > > > > it because we want to recover from that sort of error in normal
> > > > > (non-crash) situations as well.
> > > > >
> > > > Completion abort case should be gracefully handled. And device should
> > > > always remain usable.
> > > >
> > > > There are 2 scenario which I am testing with Ethernet card PCIe-Intel
> > > > 82576 Gigabit Network card.
> > > >
> > > > I) Crash testing using kdump root file system: De-facto scenario
> > > > - kdump file system does not have Ethernet driver
> > > > - A lot of AER prints [1], making it impossible to work on shell
> > > > of kdump root file system.
> > >
> > > In this case, I think report_error_detected() is deciding that because
> > > the device has no driver, we can't do anything. The flow is like
> > > this:
> > >
> > > aer_recover_work_func # aer_recover_work
> > > kfifo_get(aer_recover_ring, entry)
> > > dev = pci_get_domain_bus_and_slot
> > > cper_print_aer(dev, ...)
> > > pci_err("AER: aer_status:")
> > > pci_err("AER: [14] CmpltTO")
> > > pci_err("AER: aer_layer=")
> > > if (AER_NONFATAL)
> > > pcie_do_recovery(dev, pci_channel_io_normal)
> > > status = CAN_RECOVER
> > > pci_walk_bus(report_normal_detected)
> > > report_error_detected
> > > if (!dev->driver)
> > > vote = NO_AER_DRIVER
> > > pci_info("can't recover (no error_detected callback)")
> > > *result = merge_result(*, NO_AER_DRIVER)
> > > # always NO_AER_DRIVER
> > > status is now NO_AER_DRIVER
> > >
> > > So pcie_do_recovery() does not call .report_mmio_enabled() or .slot_reset(),
> > > and status is not RECOVERED, so it skips .resume().
> > >
> > > I don't remember the history there, but if a device has no driver and
> > > the device generates errors, it seems like we ought to be able to
> > > reset it.
> >
> > But how to reset the device considering there is no driver.
> > Hypothetically, this case should be taken care by PCIe subsystem to
> > perform reset at PCIe level.
>
> I don't understand your question. The PCI core (not the device
> driver) already does the reset. When pcie_do_recovery() calls
> reset_link(), all devices on the other side of the link are reset.
>
> > > We should be able to field one (or a few) AER errors, reset the
> > > device, and you should be able to use the shell in the kdump kernel.
> > >
> > here kdump shell is usable only problem is a "lot of AER Errors". One
> > cannot see what they are typing.
>
> Right, that's what I expect. If the PCI core resets the device, you
> should get just a few AER errors, and they should stop after the
> device is reset.
>
> > > > - Note kdump shell allows to use makedumpfile, vmcore-dmesg applications.
> > > >
> > > > II) Crash testing using default root file system: Specific case to
> > > > test Ethernet driver in second kernel
> > > > - Default root file system have Ethernet driver
> > > > - AER error comes even before the driver probe starts.
> > > > - Driver does reset Ethernet card as part of probe but no success.
> > > > - AER also tries to recover. but no success. [2]
> > > > - I also tries to remove AER errors by using "pci=noaer" bootargs
> > > > and commenting ghes_handle_aer() from GHES driver..
> > > > than different set of errors come which also never able to recover [3]
> > > >
> >
> > Please suggest your view on this case. Here driver is preset.
> > (driver/net/ethernet/intel/igb/igb_main.c)
> > In this case AER errors starts even before driver probe starts.
> > After probe, driver does the device reset with no success and even AER
> > recovery does not work.
>
> This case should be the same as the one above. If we can change the
> PCI core so it can reset the device when there's no driver, that would
> apply to case I (where there will never be a driver) and to case II
> (where there is no driver now, but a driver will probe the device
> later).
>
Does this means change are required in PCI core.
I tried following changes in pcie_do_recovery() but it did not help.
Same error as before.
-- a/drivers/pci/pcie/err.c
+++ b/drivers/pci/pcie/err.c
pci_info(dev, "broadcast resume message\n");
pci_walk_bus(bus, report_resume, &status);
@@ -203,7 +207,12 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
return status;
failed:
pci_uevent_ers(dev, PCI_ERS_RESULT_DISCONNECT);
+ pci_reset_function(dev);
+ pci_aer_clear_device_status(dev);
+ pci_aer_clear_nonfatal_status(dev);
--pk
> > Problem mentioned in case I and II goes away if do pci_reset_function
> > during enumeration phase of kdump kernel.
> > can we thought of doing pci_reset_function for all devices in kdump
> > kernel or device specific quirk.
> >
> > --pk
> >
> >
> > > > As per my understanding, possible solutions are
> > > > - Copy SMMU table i.e. this patch
> > > > OR
> > > > - Doing pci_reset_function() during enumeration phase.
> > > > I also tried clearing "M" bit using pci_clear_master during
> > > > enumeration but it did not help. Because driver re-set M bit causing
> > > > same AER error again.
> > > >
> > > >
> > > > -pk
> > > >
> > > > ---------------------------------------------------------------------------------------------------------------------------
> > > > [1] with bootargs having pci=noaer
> > > >
> > > > [ 22.494648] {4}[Hardware Error]: Hardware error from APEI Generic
> > > > Hardware Error Source: 1
> > > > [ 22.512773] {4}[Hardware Error]: event severity: recoverable
> > > > [ 22.518419] {4}[Hardware Error]: Error 0, type: recoverable
> > > > [ 22.544804] {4}[Hardware Error]: section_type: PCIe error
> > > > [ 22.550363] {4}[Hardware Error]: port_type: 0, PCIe end point
> > > > [ 22.556268] {4}[Hardware Error]: version: 3.0
> > > > [ 22.560785] {4}[Hardware Error]: command: 0x0507, status: 0x4010
> > > > [ 22.576852] {4}[Hardware Error]: device_id: 0000:09:00.1
> > > > [ 22.582323] {4}[Hardware Error]: slot: 0
> > > > [ 22.586406] {4}[Hardware Error]: secondary_bus: 0x00
> > > > [ 22.591530] {4}[Hardware Error]: vendor_id: 0x8086, device_id: 0x10c9
> > > > [ 22.608900] {4}[Hardware Error]: class_code: 000002
> > > > [ 22.613938] {4}[Hardware Error]: serial number: 0xff1b4580, 0x90e2baff
> > > > [ 22.803534] pci 0000:09:00.1: AER: aer_status: 0x00004000,
> > > > aer_mask: 0x00000000
> > > > [ 22.810838] pci 0000:09:00.1: AER: [14] CmpltTO (First)
> > > > [ 22.817613] pci 0000:09:00.1: AER: aer_layer=Transaction Layer,
> > > > aer_agent=Requester ID
> > > > [ 22.847374] pci 0000:09:00.1: AER: aer_uncor_severity: 0x00062011
> > > > [ 22.866161] mpt3sas_cm0: 63 BIT PCI BUS DMA ADDRESSING SUPPORTED,
> > > > total mem (8153768 kB)
> > > > [ 22.946178] pci 0000:09:00.0: AER: can't recover (no error_detected callback)
> > > > [ 22.995142] pci 0000:09:00.1: AER: can't recover (no error_detected callback)
> > > > [ 23.002300] pcieport 0000:00:09.0: AER: device recovery failed
> > > > [ 23.027607] pci 0000:09:00.1: AER: aer_status: 0x00004000,
> > > > aer_mask: 0x00000000
> > > > [ 23.044109] pci 0000:09:00.1: AER: [14] CmpltTO (First)
> > > > [ 23.060713] pci 0000:09:00.1: AER: aer_layer=Transaction Layer,
> > > > aer_agent=Requester ID
> > > > [ 23.068616] pci 0000:09:00.1: AER: aer_uncor_severity: 0x00062011
> > > > [ 23.122056] pci 0000:09:00.0: AER: can't recover (no error_detected callback)
> > > >
> > > >
> > > > ----------------------------------------------------------------------------------------------------------------------------
> > > > [2] Normal bootargs.
> > > >
> > > > [ 54.252454] {6}[Hardware Error]: Hardware error from APEI Generic
> > > > Hardware Error Source: 1
> > > > [ 54.265827] {6}[Hardware Error]: event severity: recoverable
> > > > [ 54.271473] {6}[Hardware Error]: Error 0, type: recoverable
> > > > [ 54.281605] {6}[Hardware Error]: section_type: PCIe error
> > > > [ 54.287163] {6}[Hardware Error]: port_type: 0, PCIe end point
> > > > [ 54.296955] {6}[Hardware Error]: version: 3.0
> > > > [ 54.301471] {6}[Hardware Error]: command: 0x0507, status: 0x4010
> > > > [ 54.312520] {6}[Hardware Error]: device_id: 0000:09:00.1
> > > > [ 54.317991] {6}[Hardware Error]: slot: 0
> > > > [ 54.322074] {6}[Hardware Error]: secondary_bus: 0x00
> > > > [ 54.327197] {6}[Hardware Error]: vendor_id: 0x8086, device_id: 0x10c9
> > > > [ 54.333797] {6}[Hardware Error]: class_code: 000002
> > > > [ 54.351312] {6}[Hardware Error]: serial number: 0xff1b4580, 0x90e2baff
> > > > [ 54.358001] AER: AER recover: Buffer overflow when recovering AER
> > > > for 0000:09:00:1
> > > > [ 54.376852] pcieport 0000:00:09.0: AER: device recovery successful
> > > > [ 54.383034] igb 0000:09:00.1: AER: aer_status: 0x00004000,
> > > > aer_mask: 0x00000000
> > > > [ 54.390348] igb 0000:09:00.1: AER: [14] CmpltTO (First)
> > > > [ 54.397144] igb 0000:09:00.1: AER: aer_layer=Transaction Layer,
> > > > aer_agent=Requester ID
> > > > [ 54.409555] igb 0000:09:00.1: AER: aer_uncor_severity: 0x00062011
> > > > [ 54.551370] AER: AER recover: Buffer overflow when recovering AER
> > > > for 0000:09:00:1
> > > > [ 54.705214] AER: AER recover: Buffer overflow when recovering AER
> > > > for 0000:09:00:1
> > > > [ 54.758703] AER: AER recover: Buffer overflow when recovering AER
> > > > for 0000:09:00:1
> > > > [ 54.865445] AER: AER recover: Buffer overflow when recovering AER
> > > > for 0000:09:00:1
> > > > [ 54.888751] pcieport 0000:00:09.0: AER: device recovery successful
> > > > [ 54.894933] igb 0000:09:00.1: AER: aer_status: 0x00004000,
> > > > aer_mask: 0x00000000
> > > > [ 54.902228] igb 0000:09:00.1: AER: [14] CmpltTO (First)
> > > > [ 54.916059] igb 0000:09:00.1: AER: aer_layer=Transaction Layer,
> > > > aer_agent=Requester ID
> > > > [ 54.923972] igb 0000:09:00.1: AER: aer_uncor_severity: 0x00062011
> > > > [ 55.057272] AER: AER recover: Buffer overflow when recovering AER
> > > > for 0000:09:00:1
> > > > [ 274.571401] AER: AER recover: Buffer overflow when recovering AER
> > > > for 0000:09:00:1
> > > > [ 274.686138] AER: AER recover: Buffer overflow when recovering AER
> > > > for 0000:09:00:1
> > > > [ 274.786134] AER: AER recover: Buffer overflow when recovering AER
> > > > for 0000:09:00:1
> > > > [ 274.886141] AER: AER recover: Buffer overflow when recovering AER
> > > > for 0000:09:00:1
> > > > [ 397.792897] Workqueue: events aer_recover_work_func
> > > > [ 397.797760] Call trace:
> > > > [ 397.800199] __switch_to+0xcc/0x108
> > > > [ 397.803675] __schedule+0x2c0/0x700
> > > > [ 397.807150] schedule+0x58/0xe8
> > > > [ 397.810283] schedule_preempt_disabled+0x18/0x28
> > > > [ 397.810788] AER: AER recover: Buffer overflow when recovering AER
> > > > for 0000:09:00:1
> > > > [ 397.814887] __mutex_lock.isra.9+0x288/0x5c8
> > > > [ 397.814890] __mutex_lock_slowpath+0x1c/0x28
> > > > [ 397.830962] mutex_lock+0x4c/0x68
> > > > [ 397.834264] report_slot_reset+0x30/0xa0
> > > > [ 397.838178] pci_walk_bus+0x68/0xc0
> > > > [ 397.841653] pcie_do_recovery+0xe8/0x248
> > > > [ 397.845562] aer_recover_work_func+0x100/0x138
> > > > [ 397.849995] process_one_work+0x1bc/0x458
> > > > [ 397.853991] worker_thread+0x150/0x500
> > > > [ 397.857727] kthread+0x114/0x118
> > > > [ 397.860945] ret_from_fork+0x10/0x18
> > > > [ 397.864525] INFO: task kworker/223:2:2939 blocked for more than 122 seconds.
> > > > [ 397.871564] Not tainted 5.7.0-rc3+ #68
> > > > [ 397.875819] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs"
> > > > disables this message.
> > > > [ 397.883638] kworker/223:2 D 0 2939 2 0x00000228
> > > > [ 397.889121] Workqueue: ipv6_addrconf addrconf_verify_work
> > > > [ 397.894505] Call trace:
> > > > [ 397.896940] __switch_to+0xcc/0x108
> > > > [ 397.900419] __schedule+0x2c0/0x700
> > > > [ 397.903894] schedule+0x58/0xe8
> > > > [ 397.907023] schedule_preempt_disabled+0x18/0x28
> > > > [ 397.910798] AER: AER recover: Buffer overflow when recovering AER
> > > > for 0000:09:00:1
> > > > [ 397.911630] __mutex_lock.isra.9+0x288/0x5c8
> > > > [ 397.923440] __mutex_lock_slowpath+0x1c/0x28
> > > > [ 397.927696] mutex_lock+0x4c/0x68
> > > > [ 397.931005] rtnl_lock+0x24/0x30
> > > > [ 397.934220] addrconf_verify_work+0x18/0x30
> > > > [ 397.938394] process_one_work+0x1bc/0x458
> > > > [ 397.942390] worker_thread+0x150/0x500
> > > > [ 397.946126] kthread+0x114/0x118
> > > > [ 397.949345] ret_from_fork+0x10/0x18
> > > >
> > > > ---------------------------------------------------------------------------------------------------------------------------------
> > > > [3] with bootargs as pci=noaer and comment ghes_halder_aer() from AER driver
> > > >
> > > > [ 69.037035] igb 0000:09:00.1 enp9s0f1: Reset adapter
> > > > [ 69.348446] {9}[Hardware Error]: Hardware error from APEI Generic
> > > > Hardware Error Source: 0
> > > > [ 69.356698] {9}[Hardware Error]: It has been corrected by h/w and
> > > > requires no further action
> > > > [ 69.365121] {9}[Hardware Error]: event severity: corrected
> > > > [ 69.370593] {9}[Hardware Error]: Error 0, type: corrected
> > > > [ 69.376064] {9}[Hardware Error]: section_type: PCIe error
> > > > [ 69.381623] {9}[Hardware Error]: port_type: 4, root port
> > > > [ 69.387094] {9}[Hardware Error]: version: 3.0
> > > > [ 69.391611] {9}[Hardware Error]: command: 0x0106, status: 0x4010
> > > > [ 69.397777] {9}[Hardware Error]: device_id: 0000:00:09.0
> > > > [ 69.403248] {9}[Hardware Error]: slot: 0
> > > > [ 69.407331] {9}[Hardware Error]: secondary_bus: 0x09
> > > > [ 69.412455] {9}[Hardware Error]: vendor_id: 0x177d, device_id: 0xaf84
> > > > [ 69.419055] {9}[Hardware Error]: class_code: 000406
> > > > [ 69.424093] {9}[Hardware Error]: bridge: secondary_status:
> > > > 0x6000, control: 0x0002
> > > > [ 72.118132] igb 0000:09:00.1 enp9s0f1: igb: enp9s0f1 NIC Link is Up
> > > > 1000 Mbps Full Duplex, Flow Control: RX
> > > > [ 73.995068] igb 0000:09:00.1: Detected Tx Unit Hang
> > > > [ 73.995068] Tx Queue <2>
> > > > [ 73.995068] TDH <0>
> > > > [ 73.995068] TDT <1>
> > > > [ 73.995068] next_to_use <1>
> > > > [ 73.995068] next_to_clean <0>
> > > > [ 73.995068] buffer_info[next_to_clean]
> > > > [ 73.995068] time_stamp <ffff9c1a>
> > > > [ 73.995068] next_to_watch <0000000097d42934>
> > > > [ 73.995068] jiffies <ffff9cd0>
> > > > [ 73.995068] desc.status <168000>
> > > > [ 75.987323] igb 0000:09:00.1: Detected Tx Unit Hang
> > > > [ 75.987323] Tx Queue <2>
> > > > [ 75.987323] TDH <0>
> > > > [ 75.987323] TDT <1>
> > > > [ 75.987323] next_to_use <1>
> > > > [ 75.987323] next_to_clean <0>
> > > > [ 75.987323] buffer_info[next_to_clean]
> > > > [ 75.987323] time_stamp <ffff9c1a>
> > > > [ 75.987323] next_to_watch <0000000097d42934>
> > > > [ 75.987323] jiffies <ffff9d98>
> > > > [ 75.987323] desc.status <168000>
> > > > [ 77.952661] {10}[Hardware Error]: Hardware error from APEI Generic
> > > > Hardware Error Source: 1
> > > > [ 77.971790] {10}[Hardware Error]: event severity: recoverable
> > > > [ 77.977522] {10}[Hardware Error]: Error 0, type: recoverable
> > > > [ 77.983254] {10}[Hardware Error]: section_type: PCIe error
> > > > [ 77.999930] {10}[Hardware Error]: port_type: 0, PCIe end point
> > > > [ 78.005922] {10}[Hardware Error]: version: 3.0
> > > > [ 78.010526] {10}[Hardware Error]: command: 0x0507, status: 0x4010
> > > > [ 78.016779] {10}[Hardware Error]: device_id: 0000:09:00.1
> > > > [ 78.033107] {10}[Hardware Error]: slot: 0
> > > > [ 78.037276] {10}[Hardware Error]: secondary_bus: 0x00
> > > > [ 78.066253] {10}[Hardware Error]: vendor_id: 0x8086, device_id: 0x10c9
> > > > [ 78.072940] {10}[Hardware Error]: class_code: 000002
> > > > [ 78.078064] {10}[Hardware Error]: serial number: 0xff1b4580, 0x90e2baff
> > > > [ 78.096202] igb 0000:09:00.1: Detected Tx Unit Hang
> > > > [ 78.096202] Tx Queue <2>
> > > > [ 78.096202] TDH <0>
> > > > [ 78.096202] TDT <1>
> > > > [ 78.096202] next_to_use <1>
> > > > [ 78.096202] next_to_clean <0>
> > > > [ 78.096202] buffer_info[next_to_clean]
> > > > [ 78.096202] time_stamp <ffff9c1a>
> > > > [ 78.096202] next_to_watch <0000000097d42934>
> > > > [ 78.096202] jiffies <ffff9e6a>
> > > > [ 78.096202] desc.status <168000>
> > > > [ 79.587406] {11}[Hardware Error]: Hardware error from APEI Generic
> > > > Hardware Error Source: 0
> > > > [ 79.595744] {11}[Hardware Error]: It has been corrected by h/w and
> > > > requires no further action
> > > > [ 79.604254] {11}[Hardware Error]: event severity: corrected
> > > > [ 79.609813] {11}[Hardware Error]: Error 0, type: corrected
> > > > [ 79.615371] {11}[Hardware Error]: section_type: PCIe error
> > > > [ 79.621016] {11}[Hardware Error]: port_type: 4, root port
> > > > [ 79.626574] {11}[Hardware Error]: version: 3.0
> > > > [ 79.631177] {11}[Hardware Error]: command: 0x0106, status: 0x4010
> > > > [ 79.637430] {11}[Hardware Error]: device_id: 0000:00:09.0
> > > > [ 79.642988] {11}[Hardware Error]: slot: 0
> > > > [ 79.647157] {11}[Hardware Error]: secondary_bus: 0x09
> > > > [ 79.652368] {11}[Hardware Error]: vendor_id: 0x177d, device_id: 0xaf84
> > > > [ 79.659055] {11}[Hardware Error]: class_code: 000406
> > > > [ 79.664180] {11}[Hardware Error]: bridge: secondary_status:
> > > > 0x6000, control: 0x0002
> > > > [ 79.987052] igb 0000:09:00.1: Detected Tx Unit Hang
> > > > [ 79.987052] Tx Queue <2>
> > > > [ 79.987052] TDH <0>
> > > > [ 79.987052] TDT <1>
> > > > [ 79.987052] next_to_use <1>
> > > > [ 79.987052] next_to_clean <0>
> > > > [ 79.987052] buffer_info[next_to_clean]
> > > > [ 79.987052] time_stamp <ffff9c1a>
> > > > [ 79.987052] next_to_watch <0000000097d42934>
> > > > [ 79.987052] jiffies <ffff9f28>
> > > > [ 79.987052] desc.status <168000>
> > > > [ 79.987056] igb 0000:09:00.1: Detected Tx Unit Hang
> > > > [ 79.987056] Tx Queue <3>
> > > > [ 79.987056] TDH <0>
> > > > [ 79.987056] TDT <1>
> > > > [ 79.987056] next_to_use <1>
> > > > [ 79.987056] next_to_clean <0>
> > > > [ 79.987056] buffer_info[next_to_clean]
> > > > [ 79.987056] time_stamp <ffff9e43>
> > > > [ 79.987056] next_to_watch <000000008da33deb>
> > > > [ 79.987056] jiffies <ffff9f28>
> > > > [ 79.987056] desc.status <514000>
> > > > [ 81.986688] igb 0000:09:00.1 enp9s0f1: Reset adapter
> > > > [ 81.986842] igb 0000:09:00.1: Detected Tx Unit Hang
> > > > [ 81.986842] Tx Queue <2>
> > > > [ 81.986842] TDH <0>
> > > > [ 81.986842] TDT <1>
> > > > [ 81.986842] next_to_use <1>
> > > > [ 81.986842] next_to_clean <0>
> > > > [ 81.986842] buffer_info[next_to_clean]
> > > > [ 81.986842] time_stamp <ffff9c1a>
> > > > [ 81.986842] next_to_watch <0000000097d42934>
> > > > [ 81.986842] jiffies <ffff9ff0>
> > > > [ 81.986842] desc.status <168000>
> > > > [ 81.986844] igb 0000:09:00.1: Detected Tx Unit Hang
> > > > [ 81.986844] Tx Queue <3>
> > > > [ 81.986844] TDH <0>
> > > > [ 81.986844] TDT <1>
> > > > [ 81.986844] next_to_use <1>
> > > > [ 81.986844] next_to_clean <0>
> > > > [ 81.986844] buffer_info[next_to_clean]
> > > > [ 81.986844] time_stamp <ffff9e43>
> > > > [ 81.986844] next_to_watch <000000008da33deb>
> > > > [ 81.986844] jiffies <ffff9ff0>
> > > > [ 81.986844] desc.status <514000>
> > > > [ 85.346515] {12}[Hardware Error]: Hardware error from APEI Generic
> > > > Hardware Error Source: 0
> > > > [ 85.354854] {12}[Hardware Error]: It has been corrected by h/w and
> > > > requires no further action
> > > > [ 85.363365] {12}[Hardware Error]: event severity: corrected
> > > > [ 85.368924] {12}[Hardware Error]: Error 0, type: corrected
> > > > [ 85.374483] {12}[Hardware Error]: section_type: PCIe error
> > > > [ 85.380129] {12}[Hardware Error]: port_type: 0, PCIe end point
> > > > [ 85.386121] {12}[Hardware Error]: version: 3.0
> > > > [ 85.390725] {12}[Hardware Error]: command: 0x0507, status: 0x0010
> > > > [ 85.396980] {12}[Hardware Error]: device_id: 0000:09:00.0
> > > > [ 85.402540] {12}[Hardware Error]: slot: 0
> > > > [ 85.406710] {12}[Hardware Error]: secondary_bus: 0x00
> > > > [ 85.411921] {12}[Hardware Error]: vendor_id: 0x8086, device_id: 0x10c9
> > > > [ 85.418609] {12}[Hardware Error]: class_code: 000002
> > > > [ 85.423733] {12}[Hardware Error]: serial number: 0xff1b4580, 0x90e2baff
> > > > [ 85.826695] igb 0000:09:00.1 enp9s0f1: igb: enp9s0f1 NIC Link is Up
> > > > 1000 Mbps Full Duplex, Flow Control: RX
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > > > So, If we are in a kdump kernel try to copy SMMU Stream table from
> > > > > > primary/old kernel to preserve the mappings until the device driver
> > > > > > takes over.
> > > > > >
> > > > > > Signed-off-by: Prabhakar Kushwaha <pkushwaha@xxxxxxxxxxx>
> > > > > > ---
> > > > > > Changes for v2: Used memremap in-place of ioremap
> > > > > >
> > > > > > V2 patch has been sanity tested.
> > > > > >
> > > > > > V1 patch has been tested with
> > > > > > A) PCIe-Intel 82576 Gigabit Network card in following
> > > > > > configurations with "no AER error". Each iteration has
> > > > > > been tested on both Suse kdump rfs And default Centos distro rfs.
> > > > > >
> > > > > > 1) with 2 level stream table
> > > > > > ----------------------------------------------------
> > > > > > SMMU | Normal Ping | Flood Ping
> > > > > > -----------------------------------------------------
> > > > > > Default Operation | 100 times | 10 times
> > > > > > -----------------------------------------------------
> > > > > > IOMMU bypass | 41 times | 10 times
> > > > > > -----------------------------------------------------
> > > > > >
> > > > > > 2) with Linear stream table.
> > > > > > -----------------------------------------------------
> > > > > > SMMU | Normal Ping | Flood Ping
> > > > > > ------------------------------------------------------
> > > > > > Default Operation | 100 times | 10 times
> > > > > > ------------------------------------------------------
> > > > > > IOMMU bypass | 55 times | 10 times
> > > > > > -------------------------------------------------------
> > > > > >
> > > > > > B) This patch is also tested with Micron Technology Inc 9200 PRO NVMe
> > > > > > SSD card with 2 level stream table using "fio" in mixed read/write and
> > > > > > only read configurations. It is tested for both Default Operation and
> > > > > > IOMMU bypass mode for minimum 10 iterations across Centos kdump rfs and
> > > > > > default Centos ditstro rfs.
> > > > > >
> > > > > > This patch is not full proof solution. Issue can still come
> > > > > > from the point device is discovered and driver probe called.
> > > > > > This patch has reduced window of scenario from "SMMU Stream table
> > > > > > creation - device-driver" to "device discovery - device-driver".
> > > > > > Usually, device discovery to device-driver is very small time. So
> > > > > > the probability is very low.
> > > > > >
> > > > > > Note: device-discovery will overwrite existing stream table entries
> > > > > > with both SMMU stage as by-pass.
> > > > > >
> > > > > >
> > > > > > drivers/iommu/arm-smmu-v3.c | 36 +++++++++++++++++++++++++++++++++++-
> > > > > > 1 file changed, 35 insertions(+), 1 deletion(-)
> > > > > >
> > > > > > diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
> > > > > > index 82508730feb7..d492d92c2dd7 100644
> > > > > > --- a/drivers/iommu/arm-smmu-v3.c
> > > > > > +++ b/drivers/iommu/arm-smmu-v3.c
> > > > > > @@ -1847,7 +1847,13 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_master *master, u32 sid,
> > > > > > break;
> > > > > > case STRTAB_STE_0_CFG_S1_TRANS:
> > > > > > case STRTAB_STE_0_CFG_S2_TRANS:
> > > > > > - ste_live = true;
> > > > > > + /*
> > > > > > + * As kdump kernel copy STE table from previous
> > > > > > + * kernel. It still may have valid stream table entries.
> > > > > > + * Forcing entry as false to allow overwrite.
> > > > > > + */
> > > > > > + if (!is_kdump_kernel())
> > > > > > + ste_live = true;
> > > > > > break;
> > > > > > case STRTAB_STE_0_CFG_ABORT:
> > > > > > BUG_ON(!disable_bypass);
> > > > > > @@ -3264,6 +3270,9 @@ static int arm_smmu_init_l1_strtab(struct arm_smmu_device *smmu)
> > > > > > return -ENOMEM;
> > > > > > }
> > > > > >
> > > > > > + if (is_kdump_kernel())
> > > > > > + return 0;
> > > > > > +
> > > > > > for (i = 0; i < cfg->num_l1_ents; ++i) {
> > > > > > arm_smmu_write_strtab_l1_desc(strtab, &cfg->l1_desc[i]);
> > > > > > strtab += STRTAB_L1_DESC_DWORDS << 3;
> > > > > > @@ -3272,6 +3281,23 @@ static int arm_smmu_init_l1_strtab(struct arm_smmu_device *smmu)
> > > > > > return 0;
> > > > > > }
> > > > > >
> > > > > > +static void arm_smmu_copy_table(struct arm_smmu_device *smmu,
> > > > > > + struct arm_smmu_strtab_cfg *cfg, u32 size)
> > > > > > +{
> > > > > > + struct arm_smmu_strtab_cfg rdcfg;
> > > > > > +
> > > > > > + rdcfg.strtab_dma = readq_relaxed(smmu->base + ARM_SMMU_STRTAB_BASE);
> > > > > > + rdcfg.strtab_base_cfg = readq_relaxed(smmu->base
> > > > > > + + ARM_SMMU_STRTAB_BASE_CFG);
> > > > > > +
> > > > > > + rdcfg.strtab_dma &= STRTAB_BASE_ADDR_MASK;
> > > > > > + rdcfg.strtab = memremap(rdcfg.strtab_dma, size, MEMREMAP_WB);
> > > > > > +
> > > > > > + memcpy_fromio(cfg->strtab, rdcfg.strtab, size);
> > > > > > +
> > > > > > + cfg->strtab_base_cfg = rdcfg.strtab_base_cfg;
> > > > > > +}
> > > > > > +
> > > > > > static int arm_smmu_init_strtab_2lvl(struct arm_smmu_device *smmu)
> > > > > > {
> > > > > > void *strtab;
> > > > > > @@ -3307,6 +3333,9 @@ static int arm_smmu_init_strtab_2lvl(struct arm_smmu_device *smmu)
> > > > > > reg |= FIELD_PREP(STRTAB_BASE_CFG_SPLIT, STRTAB_SPLIT);
> > > > > > cfg->strtab_base_cfg = reg;
> > > > > >
> > > > > > + if (is_kdump_kernel())
> > > > > > + arm_smmu_copy_table(smmu, cfg, l1size);
> > > > > > +
> > > > > > return arm_smmu_init_l1_strtab(smmu);
> > > > > > }
> > > > > >
> > > > > > @@ -3334,6 +3363,11 @@ static int arm_smmu_init_strtab_linear(struct arm_smmu_device *smmu)
> > > > > > reg |= FIELD_PREP(STRTAB_BASE_CFG_LOG2SIZE, smmu->sid_bits);
> > > > > > cfg->strtab_base_cfg = reg;
> > > > > >
> > > > > > + if (is_kdump_kernel()) {
> > > > > > + arm_smmu_copy_table(smmu, cfg, size);
> > > > > > + return 0;
> > > > > > + }
> > > > > > +
> > > > > > arm_smmu_init_bypass_stes(strtab, cfg->num_l1_ents);
> > > > > > return 0;
> > > > > > }
> > > > > > --
> > > > > > 2.18.2
> > > > > >
