linux-kernel - [PATCH 1/1] iommu/vt-d: Downgrade warning for pre-enabled IR

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Date: Tue, 25 Jun 2024 12:39:12 +0800
From: Lu Baolu <baolu.lu@...ux.intel.com>
To: Joerg Roedel <joro@...tes.org>,
	Kevin Tian <kevin.tian@...el.com>,
	Yi Liu <yi.l.liu@...el.com>,
	Jacob Pan <jacob.jun.pan@...ux.intel.com>
Cc: Will Deacon <will@...nel.org>,
	Robin Murphy <robin.murphy@....com>,
	iommu@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	Lu Baolu <baolu.lu@...ux.intel.com>,
	Paul Menzel <pmenzel@...gen.mpg.de>
Subject: [PATCH 1/1] iommu/vt-d: Downgrade warning for pre-enabled IR

Emitting a warning is overkill in intel_setup_irq_remapping() since the
interrupt remapping is pre-enabled. For example, there's no guarantee
that kexec will explicitly disable interrupt remapping before booting a
new kernel. As a result, users are seeing warning messages like below
when they kexec boot a kernel, though there is nothing wrong:

 DMAR-IR: IRQ remapping was enabled on dmar18 but we are not in kdump mode
 DMAR-IR: IRQ remapping was enabled on dmar17 but we are not in kdump mode
 DMAR-IR: IRQ remapping was enabled on dmar16 but we are not in kdump mode
 ... ...

Downgrade the severity of this message to avoid user confusion.

CC: Paul Menzel <pmenzel@...gen.mpg.de>
Link: https://lore.kernel.org/linux-iommu/5517f76a-94ad-452c-bae6-34ecc0ec4831@molgen.mpg.de/
Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
---
 drivers/iommu/intel/irq_remapping.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/intel/irq_remapping.c b/drivers/iommu/intel/irq_remapping.c
index e4a70886678c..e090ca07364b 100644
--- a/drivers/iommu/intel/irq_remapping.c
+++ b/drivers/iommu/intel/irq_remapping.c
@@ -597,8 +597,8 @@ static int intel_setup_irq_remapping(struct intel_iommu *iommu)

 	if (ir_pre_enabled(iommu)) {
 		if (!is_kdump_kernel()) {
-			pr_warn("IRQ remapping was enabled on %s but we are not in kdump mode\n",
-				iommu->name);
+			pr_info_once("IRQ remapping was enabled on %s but we are not in kdump mode\n",
+				     iommu->name);
 			clear_ir_pre_enabled(iommu);
 			iommu_disable_irq_remapping(iommu);
 		} else if (iommu_load_old_irte(iommu))
-- 
2.34.1