linux-kernel - Re: DMAR-IR: IRQ remapping was enabled on dmar6 but we are not in kdump mode

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Date: Tue, 14 May 2024 21:46:47 +0200
From: Paul Menzel <pmenzel@...gen.mpg.de>
To: Baolu Lu <baolu.lu@...ux.intel.com>
Cc: Jörg Rödel <joro@...tes.org>,
 Will Deacon <will@...nel.org>, iommu@...ts.linux.dev,
 linux-kernel@...r.kernel.org
Subject: Re: DMAR-IR: IRQ remapping was enabled on dmar6 but we are not in
 kdump mode

Dear Baolu,


Am 23.01.24 um 01:55 schrieb Baolu Lu:
> On 2024/1/22 22:53, Paul Menzel wrote:
>> Am 22.01.24 um 13:38 schrieb Baolu Lu:
>>> On 2024/1/19 22:45, Paul Menzel wrote:
>>>>
>>>> On a Dell PowerEdge T640, Linux 5.9 and 6.6.12 warn about kdump:
>>>>
>>>>      [    2.728445] DMAR-IR: IRQ remapping was enabled on dmar6 but we are not in kdump mode
>>>>      [    2.736544] DMAR-IR: IRQ remapping was enabled on dmar5 but we are not in kdump mode
>>>>      [    2.744620] DMAR-IR: IRQ remapping was enabled on dmar4 but we are not in kdump mode
>>>>      [    2.752695] DMAR-IR: IRQ remapping was enabled on dmar3 but we are not in kdump mode
>>>>      [    2.760774] DMAR-IR: IRQ remapping was enabled on dmar2 but we are not in kdump mode
>>>>      [    2.768847] DMAR-IR: IRQ remapping was enabled on dmar1 but we are not in kdump mode
>>>>      [    2.776922] DMAR-IR: IRQ remapping was enabled on dmar0 but we are not in kdump mode
>>>>      [    2.784999] DMAR-IR: IRQ remapping was enabled on dmar7 but we are not in kdump mode
>>>>
>>>> Looking through the logs, this only happens when using kexec to 
>>>> restart the system.
>>>
>>> The code that warned this is,
>>>
>>>   599         if (ir_pre_enabled(iommu)) {
>>>   600                 if (!is_kdump_kernel()) {
>>>   601                         pr_warn("IRQ remapping was enabled on %s but we are not in kdump mode\n",
>>>   602                                 iommu->name);
>>>   603                         clear_ir_pre_enabled(iommu);
>>>   604                         iommu_disable_irq_remapping(iommu);
>>>   605                 }
>>>
>>> The VT-d interrupt remapping is enabled during boot, but this is not a
>>> kdump kernel.
>>>
>>> Do you mind checking whether the disable interrupt remapping callback
>>> was called during kexec reboot?
>>>
>>> 1121 struct irq_remap_ops intel_irq_remap_ops = {
>>> 1122         .prepare                = intel_prepare_irq_remapping,
>>> 1123         .enable                 = intel_enable_irq_remapping,
>>> 1124         .disable                = disable_irq_remapping,
>>> 1125         .reenable               = reenable_irq_remapping,
>>> 1126         .enable_faulting        = enable_drhd_fault_handling,
>>> 1127 };
>>
>> Is there a way to check this without rebuilding the Linux kernel?
> 
> I am not sure, but you can check whether any messages are dumped in the
> path of .disable callback? or try to use ftrace?

With

```
diff --git a/drivers/iommu/intel/irq_remapping.c 
b/drivers/iommu/intel/irq_remapping.c
index 712ebfc9870c6..146f19ae5b5f1 100644
--- a/drivers/iommu/intel/irq_remapping.c
+++ b/drivers/iommu/intel/irq_remapping.c
@@ -1030,6 +1030,7 @@ static void disable_irq_remapping(void)
  	struct dmar_drhd_unit *drhd;
  	struct intel_iommu *iommu = NULL;

+	pr_warn("XXX: Called %s\n", __func__);
  	/*
  	 * Disable Interrupt-remapping for all the DRHD's now.
  	 */
```

I can’t see anything in the logs, so it does not seem to be called.

Can you reproduce the issue?


Kind regards,

Paul
View attachment "20240514--linux-6.9+-messages--kexec.log" of type "text/x-log" (575591 bytes)