Re: [patch V3 00/35] genirq/msi, PCI/MSI: Spring cleaning - Part 2

Re: [patch V3 00/35] genirq/msi, PCI/MSI: Spring cleaning - Part 2

[Thomas Gleixner]

On Mon, Dec 13 2021 at 12:29, Nishanth Menon wrote:
> On 23:18-20211210, Thomas Gleixner wrote:
> Also while testing on TI K3 platforms, I noticed:
>
> msi_device_data_release/msi_device_destroy_sysfs in am64xx-evm / j7200

The warning complains about a device being released with MSI descriptors
still attached to the device. This was added by:

  5b012cede0f7 ("device: Add device::msi_data pointer and struct msi_device_data")

That's not a regression caused by this commit. The warning is just
exposing an already existing problem in the iwlwifi driver, which seems
to do:

   probe()
     setup_pci_msi[x]_interrupts()
     start_drv()
       if (try_to_load_firmware() == FAIL)
       	   device_release_driver()
                ...
                msi_device_data_release()
                    WARN()

Thanks,

        tglx

Re: [patch V3 00/35] genirq/msi, PCI/MSI: Spring cleaning - Part 2

[Nishanth Menon]

On 10:41-20211214, Thomas Gleixner wrote:
> On Mon, Dec 13 2021 at 12:29, Nishanth Menon wrote:
> > On 23:18-20211210, Thomas Gleixner wrote:
> > Also while testing on TI K3 platforms, I noticed:
> >
> > msi_device_data_release/msi_device_destroy_sysfs in am64xx-evm / j7200
> 
> The warning complains about a device being released with MSI descriptors
> still attached to the device. This was added by:
> 
>   5b012cede0f7 ("device: Add device::msi_data pointer and struct msi_device_data")
> 
> That's not a regression caused by this commit. The warning is just
> exposing an already existing problem in the iwlwifi driver, which seems
> to do:
> 
>    probe()
>      setup_pci_msi[x]_interrupts()
>      start_drv()
>        if (try_to_load_firmware() == FAIL)
>        	   device_release_driver()
>                 ...
>                 msi_device_data_release()
>                     WARN()
> 

Agreed that the warning is fine, the null pointer exception that follows
[1] [2] it however does'nt look right and it can be trivially fixed with the
following fixup for ee90787487bc ("genirq/msi: Provide
msi_device_populate/destroy_sysfs()") below, with that the log looks
like [3] - the warn is good, the null pointer exception and resultant
crash could be avoided (not saying this is the best solution):

diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
index ab5e83f41188..24edb870c66f 100644
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -252,11 +252,14 @@ int msi_device_populate_sysfs(struct device *dev)
  */
 void msi_device_destroy_sysfs(struct device *dev)
 {
-	const struct attribute_group **msi_irq_groups = dev->msi.data->attrs;
+	const struct attribute_group **msi_irq_groups;
 	struct device_attribute *dev_attr;
 	struct attribute **msi_attrs;
 	int count = 0;
 
+	if (!dev->msi.data)
+		return;
+	msi_irq_groups = dev->msi.data->attrs;
 	dev->msi.data->attrs = NULL;
 	if (!msi_irq_groups)
 		return;

[1] https://gist.github.com/nmenon/36899c7819681026cfe1ef185fb95f33#file-am64xx-evm-txt-L1049
[2] https://gist.github.com/nmenon/36899c7819681026cfe1ef185fb95f33#file-j7200-evm-txt-L1111

[3] https://gist.github.com/nmenon/575afe7d04463026a7e420a76c2c1c5b
	https://gist.github.com/nmenon/575afe7d04463026a7e420a76c2c1c5b#file-am64xx-evm-txt-L1018
	https://gist.github.com/nmenon/575afe7d04463026a7e420a76c2c1c5b#file-j7200-evm-txt-L1053
-- 
Regards,
Nishanth Menon
Key (0xDDB5849D1736249D)/Fingerprint: F8A2 8693 54EB 8232 17A3  1A34 DDB5 849D 1736 249D

Re: [patch V3 00/35] genirq/msi, PCI/MSI: Spring cleaning - Part 2

[Thomas Gleixner]

On Tue, Dec 14 2021 at 10:22, Nishanth Menon wrote:
> On 10:41-20211214, Thomas Gleixner wrote:
> Agreed that the warning is fine, the null pointer exception that follows
> [1] [2] it however does'nt look right and it can be trivially fixed with the
> following fixup for ee90787487bc ("genirq/msi: Provide
> msi_device_populate/destroy_sysfs()") below, with that the log looks
> like [3] - the warn is good, the null pointer exception and resultant
> crash could be avoided (not saying this is the best solution):

Aaargh.

[   13.478122] Call trace:
[   13.509042]  msi_device_destroy_sysfs+0x18/0x88
[   13.509058]  msi_domain_free_irqs+0x34/0x58
[   13.509064]  pci_msi_teardown_msi_irqs+0x30/0x3c
[   13.509072]  free_msi_irqs+0x78/0xd4
[   13.509077]  pci_disable_msix+0x138/0x164
[   13.529930]  pcim_release+0x70/0x238
[   13.529942]  devres_release_all+0x9c/0xfc
[   13.529951]  device_release_driver_internal+0x1a0/0x244
[   13.542725]  device_release_driver+0x18/0x24
[   13.542741]  iwl_req_fw_callback+0x1a28/0x1ddc [iwlwifi]
[   13.552308]  request_firmware_work_func+0x50/0x9c
[   13.552320]  process_one_work+0x194/0x25c

That's not a driver problem, that's an ordering issue vs. the devres
muck. Let me go back to the drawing board. Sigh...

Thanks,

        tglx

Re: [patch V3 00/35] genirq/msi, PCI/MSI: Spring cleaning - Part 2

[Thomas Gleixner]

On Tue, Dec 14 2021 at 17:36, Thomas Gleixner wrote:
> On Tue, Dec 14 2021 at 10:22, Nishanth Menon wrote:
>> On 10:41-20211214, Thomas Gleixner wrote:
> [   13.478122] Call trace:
> [   13.509042]  msi_device_destroy_sysfs+0x18/0x88
> [   13.509058]  msi_domain_free_irqs+0x34/0x58
> [   13.509064]  pci_msi_teardown_msi_irqs+0x30/0x3c
> [   13.509072]  free_msi_irqs+0x78/0xd4
> [   13.509077]  pci_disable_msix+0x138/0x164
> [   13.529930]  pcim_release+0x70/0x238
> [   13.529942]  devres_release_all+0x9c/0xfc
> [   13.529951]  device_release_driver_internal+0x1a0/0x244
> [   13.542725]  device_release_driver+0x18/0x24
> [   13.542741]  iwl_req_fw_callback+0x1a28/0x1ddc [iwlwifi]
> [   13.552308]  request_firmware_work_func+0x50/0x9c
> [   13.552320]  process_one_work+0x194/0x25c
>
> That's not a driver problem, that's an ordering issue vs. the devres
> muck. Let me go back to the drawing board. Sigh...

Which is pretty obvious why:

   pcim_enable_device()
        devres_alloc(pcim_release...);
        ...
        pci_irq_alloc()
          msi_setup_device_data()
             devres_alloc(msi_device_data_release, ...)

and once the device is released:

    msi_device_data_release()
    ...
    pcim_release()
       pci_disable_msi[x]()

Groan....

Re: [patch V3 00/35] genirq/msi, PCI/MSI: Spring cleaning - Part 2

[Thomas Gleixner]

Nishanth,

On Tue, Dec 14 2021 at 18:03, Thomas Gleixner wrote:
>     msi_device_data_release()
>     ...
>     pcim_release()
>        pci_disable_msi[x]()
>
> Groan....

I think I managed to distangle this. Can you please give:

   git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git msi-v4-part-2

and/or the full pile:

   git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git msi-v4-part-3

a test ride?

Thanks,

        tglx

Re: [patch V3 00/35] genirq/msi, PCI/MSI: Spring cleaning - Part 2

[Nishanth Menon]

On 21:15-20211214, Thomas Gleixner wrote:
> Nishanth,
> 
> On Tue, Dec 14 2021 at 18:03, Thomas Gleixner wrote:
> >     msi_device_data_release()
> >     ...
> >     pcim_release()
> >        pci_disable_msi[x]()
> >
> > Groan....
> 
> I think I managed to distangle this. Can you please give:
> 
>    git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git msi-v4-part-2


Umm.. I am not entirely sure what is going on.. but all kinds of weird
corruption seems to occur with msi-v4-part-2 that does'nt seem to be
present in v5.16-rc5. (I use NFS since ethernet in K3 platforms use
inta/intr and dma that is impacted by this series).

I will try and rebase your patches on v5.16-rc4 to be sure as well and
report back later today once i get some time.

[1] https://gist.github.com/nmenon/a66e022926c4c15313c45d44313d860c msi-v4-part-2
[2] https://gist.github.com/nmenon/43085664d69ad846d596e76a06ed0656  v5.16-rc5
-- 
Regards,
Nishanth Menon
Key (0xDDB5849D1736249D) / Fingerprint: F8A2 8693 54EB 8232 17A3  1A34 DDB5 849D 1736 249D

Re: [patch V3 00/35] genirq/msi, PCI/MSI: Spring cleaning - Part 2

[Thomas Gleixner]

Nishanth,

On Tue, Dec 14 2021 at 14:56, Nishanth Menon wrote:
> On 21:15-20211214, Thomas Gleixner wrote:
>> I think I managed to distangle this. Can you please give:
>> 
>>    git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git msi-v4-part-2
>
>
> Umm.. I am not entirely sure what is going on.. but all kinds of weird
> corruption seems to occur with msi-v4-part-2 that does'nt seem to be
> present in v5.16-rc5. (I use NFS since ethernet in K3 platforms use
> inta/intr and dma that is impacted by this series).
>
> I will try and rebase your patches on v5.16-rc4 to be sure as well and
> report back later today once i get some time.
>
> [1] https://gist.github.com/nmenon/a66e022926c4c15313c45d44313d860c msi-v4-part-2
> [2] https://gist.github.com/nmenon/43085664d69ad846d596e76a06ed0656  v5.16-rc5

thanks for trying. I'll have a look again with brain awake tomorrow
morning.

Thanks,

        tglx

Re: [patch V3 00/35] genirq/msi, PCI/MSI: Spring cleaning - Part 2

[Thomas Gleixner]

On Tue, Dec 14 2021 at 22:19, Thomas Gleixner wrote:
> On Tue, Dec 14 2021 at 14:56, Nishanth Menon wrote:
>
> thanks for trying. I'll have a look again with brain awake tomorrow
> morning.

Morning was busy with other things, but I found what my sleepy brain
managed to do wrong yesterday evening.

Let me reintegrate the pile and I'll send you an update.

Thanks,

        tglx

Re: [patch V3 00/35] genirq/msi, PCI/MSI: Spring cleaning - Part 2

[Thomas Gleixner]

On Wed, Dec 15 2021 at 17:18, Thomas Gleixner wrote:

> On Tue, Dec 14 2021 at 22:19, Thomas Gleixner wrote:
>> On Tue, Dec 14 2021 at 14:56, Nishanth Menon wrote:
>>
>> thanks for trying. I'll have a look again with brain awake tomorrow
>> morning.
>
> Morning was busy with other things, but I found what my sleepy brain
> managed to do wrong yesterday evening.
>
> Let me reintegrate the pile and I'll send you an update.

   git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git msi-v4.1-part-2
   git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git msi-v4.2-part-3

That should cure the problem.

Re: [patch V3 00/35] genirq/msi, PCI/MSI: Spring cleaning - Part 2

[Nishanth Menon]

On 17:35-20211215, Thomas Gleixner wrote:
>    git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git msi-v4.1-part-2
[...]

> That should cure the problem.

And it sure does. Thanks for looking closer and providing a fix.

https://gist.github.com/nmenon/9862a1c31b17fd6dfe0a30c54d396187
(msi-v4.1-part-2) looks clean

Also while I had detected pointer corruption in the previous v4
https://gist.github.com/nmenon/ce4d12f460db5cd511185c047d5d35d0

Running it again on v4.1 does indicate the fix is in place.
https://gist.github.com/nmenon/3231fbb0faa1b9c827b40d1ae6160626


please feel free to add:

Tested-by: Nishanth Menon <nm@ti.com>

-- 
Regards,
Nishanth Menon
Key (0xDDB5849D1736249D)/Fingerprint: F8A2 8693 54EB 8232 17A3  1A34 DDB5 849D 1736 249D

Re: [patch V3 00/35] genirq/msi, PCI/MSI: Spring cleaning - Part 2

[Nishanth Menon]

Hi Thomas,

On 17:35-20211215, Thomas Gleixner wrote:
>    git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git msi-v4.2-part-3

As you helped offline, summarizing the details on part3 of the series:

I was seeing failure[1] of NFS(DMA) on all TI K3 platforms:

[    1.013258] ti-bcdma 485c0100.dma-controller: Number of rings: 68
[    1.019963] ti-bcdma 485c0100.dma-controller: Failed to allocate IRQs -28
[    1.026938] ti-bcdma 485c0100.dma-controller: Failed to allocate MSI interrupts

Rationale as you explained:
"
-28 is ENOSPC, which is returned when the interrupt allocation in the
 MSI domain fails. Fix below.
"

Which turned out to be the fixup[2] you suggested and I confirm that
fixes the problem for me.

With the fixup in place:

Tested-by: Nishanth Menon <nm@ti.com>

for part 3 of the series as well.

Thanks once again for your help. Hope we can roll in the fixes for
part3.

[1] https://gist.github.com/nmenon/5971ab27aa626c022e276cc946e4b6c3
[2]
--- a/drivers/soc/ti/ti_sci_inta_msi.c
+++ b/drivers/soc/ti/ti_sci_inta_msi.c
@@ -68,6 +68,7 @@ static int ti_sci_inta_msi_alloc_descs(s
 	int set, i, count = 0;
 
 	memset(&msi_desc, 0, sizeof(msi_desc));
+	msi_desc.nvec_used = 1;
 
 	for (set = 0; set < res->sets; set++) {
 		for (i = 0; i < res->desc[set].num; i++, count++) {
-- 
Regards,
Nishanth Menon
Key (0xDDB5849D1736249D)/Fingerprint: F8A2 8693 54EB 8232 17A3  1A34 DDB5 849D 1736 249D

RE: [patch V3 00/35] genirq/msi, PCI/MSI: Spring cleaning - Part 2

[Michael Kelley (LINUX)]

From: Thomas Gleixner <tglx@linutronix.de> Sent: Wednesday, December 15, 2021 8:36 AM
> 
> On Wed, Dec 15 2021 at 17:18, Thomas Gleixner wrote:
> 
> > On Tue, Dec 14 2021 at 22:19, Thomas Gleixner wrote:
> >> On Tue, Dec 14 2021 at 14:56, Nishanth Menon wrote:
> >>
> >> thanks for trying. I'll have a look again with brain awake tomorrow
> >> morning.
> >
> > Morning was busy with other things, but I found what my sleepy brain
> > managed to do wrong yesterday evening.
> >
> > Let me reintegrate the pile and I'll send you an update.
> 
>    git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git msi-v4.1-part-2
>    git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git msi-v4.2-part-3
> 
> That should cure the problem.

Tested the msi-v4.2-part-3 tag in two different Azure/Hyper-V VMs.  One
is a Generation 1 VM that has legacy PCI devices and one is a Generation 2
VM with no legacy PCI devices.   Tested hot add and remove of Mellanox
CX-3 and CX-4 SR-IOV NIC virtual functions that are directly mapped into the
VM.  Also tested local NVMe devices directly mapped into one of the VMs.

No issues encountered.  So for Azure/Hyper-V specifically,

Tested-by: Michael Kelley <mikelley@microsoft.com>

Re: [patch V3 00/35] genirq/msi, PCI/MSI: Spring cleaning - Part 2

[Thomas Gleixner]

Nishanth,

On Wed, Dec 15 2021 at 19:45, Nishanth Menon wrote:
> On 17:35-20211215, Thomas Gleixner wrote:
> Thanks once again for your help. Hope we can roll in the fixes for
> part3.

Sure, it's only the one-liner for ti sci. Got it folded already.

Thanks for your help and testing!

       tglx