[PATCH V5 0/4] PCI/ASPM: reconfigure ASPM following hotplug for POLICY_DEFAULT

[Patel, Mayurkumar]

Hi Kaya

>
>On 3/28/2017 9:04 AM, Sinan Kaya wrote:
>> On 3/28/2017 8:52 AM, Sinan Kaya wrote:
>>> On 3/28/2017 2:02 AM, Patel, Mayurkumar wrote:
>>>> Thanks for your patches. I am seeing kernel panic after applying
>>>> these patches (on top of latest kernel) each time during early boot in pci_aspm_init() (any hints already?) function.
>>>> Need to check if it's something related to my local setup or it's because of these changes.
>>>> For now I don't have more details why it crashes but I will dig in further and I will provide
>>>> you more data as soon as I have it.
>>>>
>>>
>>> Interesting, I retested Qemu and I don't see an issue.
>>> Can you share your bootlog when you see the crash?
>>>
>> Thinking more...
>>
>> Can you add this to the top of pci_aspm_init() and try again?
>>
>> if (!pci_is_pcie(pdev))
>>           return -EINVAL;
>>
>
>Did this help?

No, It did not helped. I tested without your patches and no panic seen.

I found with your patch in pci_aspm_init() call, pdev->subordinate is not valid which causes a crash in
pci_function_0().
I tentatively started validating pdev->subordinate pointer and proceeding pci_aspm_init()  without allocating link->downstream pointer,
then I got another following issue during boot. I will further debug it but if you have any other suggestion or some other clicks in your mind
what this could be I could try that too.

[    0.835443] BUG: unable to handle kernel NULL pointer dereference at 000000000000003e
[    0.929138] IP: pcie_capability_read_dword+0x82/0x1a0
[    0.989555] PGD 0
[    0.989556]
[    1.031360] Oops: 0000 [#1] SMP
[    1.068901] Modules linked in:
[    1.105403] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.11.0-rc4-aspmtestv6 #24
[    1.192861] Hardware name:    /IC97, BIOS IV97R903 02/25/2016
[    1.261600] task: ffff9141435c8000 task.stack: ffffa6b8418c0000
[    1.332419] RIP: 0010:pcie_capability_read_dword+0x82/0x1a0
[    1.399077] RSP: 0000:ffffa6b8418c39b0 EFLAGS: 00010246
[    1.461575] RAX: 0000000000000000 RBX: 000000000000000c RCX: ffffffff85e5be08
[    1.546954] RDX: ffffa6b8418c39ec RSI: 000000000000000c RDI: 0000000000000000
[    1.632332] RBP: ffffa6b8418c39d8 R08: 0000000000000001 R09: 0000000000000171
[    1.717707] R10: 0000000000000000 R11: 0000000000000170 R12: 0000000000000000
[    1.803085] R13: ffffa6b8418c39ec R14: ffff914142e370c0 R15: 0000000000000000
[    1.888462] FS:  0000000000000000(0000) GS:ffff914155c80000(0000) knlGS:0000000000000000
[    1.985278] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    2.054017] CR2: 000000000000003e CR3: 0000000300e09000 CR4: 00000000003406e0
[    2.139396] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[    2.224772] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[    2.310150] Call Trace:
[    2.339374]  pcie_get_aspm_reg+0x39/0x1a0
[    2.387312]  pcie_aspm_init_link_state+0x2aa/0x900
[    2.444611]  ? pci_device_add+0x20a/0x300
[    2.492554]  pci_scan_slot+0xd7/0x110
[    2.536335]  pci_scan_child_bus+0x30/0x180
[    2.585313]  pci_scan_bridge+0x3f0/0x670
[    2.632215]  ? pci_scan_single_device+0x6d/0xd0
[    2.686394]  pci_scan_child_bus+0x9f/0x180
[    2.735375]  acpi_pci_root_create+0x182/0x1de
[    2.787475]  pci_acpi_scan_root+0x15f/0x1b0
[    2.837493]  acpi_pci_root_add+0x3bf/0x4c4
[    2.886474]  acpi_bus_attach+0xdf/0x18e
[    2.932336]  acpi_bus_attach+0x135/0x18e
[    2.979234]  acpi_bus_attach+0x135/0x18e
[    3.026135]  acpi_bus_scan+0x6e/0x8d
[    3.068877]  ? acpi_sleep_proc_init+0x28/0x28
[    3.120976]  acpi_scan_init+0xda/0x237
[    3.165795]  ? acpi_sleep_proc_init+0x28/0x28
[    3.217895]  acpi_init+0x2be/0x347

>
>--
>Sinan Kaya
>Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
>Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
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