Re: DMAR-IR: IRQ remapping was enabled on dmar6 but we are not in kdump mode
From: Paul Menzel
Date: Sat Jun 08 2024 - 07:08:11 EST
Dear Linux folks,
Am 15.05.24 um 08:02 schrieb Paul Menzel:
Am 15.05.24 um 04:13 schrieb Baolu Lu:
On 5/15/24 3:46 AM, Paul Menzel wrote:
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?
How did you reproduce this?
On a “server” (with Intel Xeon?), in my case Dell PowerEdge T640 and
Dell PowerEdge R930 (Intel E7-8891 v3), run
kexec /boot/bzImage --initrd=/boot/grub/initramfs.igz --reuse-cmdline
Were you able to fit some cycles into reproducing/analyzing this issue?
Kind regards,
Paul