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

Wed Mar 29 12:09:06 PDT 2017

On 3/29/2017 1:27 PM, Patel, Mayurkumar wrote:
> 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 think you have a mixture of old and new patches or a mixture of old/new object files.
pci_function_0() is no longer getting called from pci_aspm_init(). This was done in V4 of the patch.

> 
> 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.
> 

I think you have a mixture of old and new patches or a mixture of old/new object files.

> [    2.339374]  pcie_get_aspm_reg+0x39/0x1a0
> [    2.387312]  pcie_aspm_init_link_state+0x2aa/0x900
> [    2.444611]  ? pci_device_add+0x20a/0x300

This was also done in V4 of the patch. This was replaced by pci_aspm_init() in V5 and
there is no call from device_add path into pci_aspm_init() function. The 
pcie_aspm_init_link_state() gets called from the pci_scan_slot() as it used to be.

Can you try it on a clean tree with the following patches?

https://patchwork.codeaurora.org/patch/207667/
https://patchwork.codeaurora.org/patch/207653/
https://patchwork.codeaurora.org/patch/207669/
https://patchwork.codeaurora.org/patch/207651/

The only change you should need on top of this is this.

--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -847,6 +847,9 @@ int pci_aspm_init(struct pci_dev *pdev)
        if (!pdev->has_secondary_link)
                return 0;

+       if (!pci_is_pcie(pdev))
+               return -EINVAL;
+
        link = alloc_pcie_link_state(pdev);
        if (!link)
                return -ENOMEM;



> [    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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> 


-- 
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.

