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Message-ID: <433452d0-589a-49c8-8044-dcc93d5be90a@linux.intel.com>
Date: Mon, 22 Jan 2024 20:38:41 +0800
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Cc: baolu.lu@linux.intel.com, iommu@lists.linux.dev,
 linux-kernel@vger.kernel.org
Subject: Re: DMAR-IR: IRQ remapping was enabled on dmar6 but we are not in
 kdump mode
To: Paul Menzel <pmenzel@molgen.mpg.de>, =?UTF-8?B?SsO2cmcgUsO2ZGVs?=
 <joro@8bytes.org>, Will Deacon <will@kernel.org>
References: <5517f76a-94ad-452c-bae6-34ecc0ec4831@molgen.mpg.de>
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From: Baolu Lu <baolu.lu@linux.intel.com>
In-Reply-To: <5517f76a-94ad-452c-bae6-34ecc0ec4831@molgen.mpg.de>
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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 };

Best regards,
baolu