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

[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?

Best regards,
baolu