[PATCH 4/5] iommu/amd: Rate limit INVALID_PPR_REQUEST error logging

[Vasant Hegde <vasant.hegde@amd.com>]

The amd_iommu_report_ppr_err() function logs an error message for every
INVALID_PPR_REQUEST event. Under certain fault conditions, a misbehaving
or malicious device can flood the IOMMU event log with PPR faults, causing
the kernel log to be overwhelmed with repeated error messages.

Switch from dev_err() to dev_err_ratelimited() to suppress duplicate
messages when INVALID_PPR_REQUEST events occur at a high rate.

Signed-off-by: Vasant Hegde <vasant.hegde@amd.com>
---
 drivers/iommu/amd/iommu.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 4372d3908e67..17df9b28ebaf 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -913,9 +913,10 @@ static void amd_iommu_report_ppr_err(struct amd_iommu *iommu, volatile u32 *even
 	u32 pasid = PPR_PASID(*((u64 *)event));
 	int tag = event[1] & 0x03FF;
 
-	dev_err(dev, "Event logged [INVALID_PPR_REQUEST device=%04x:%02x:%02x.%x pasid=0x%05x address=0x%llx flags=0x%04x tag=0x%03x]\n",
-		iommu->pci_seg->id, PCI_BUS_NUM(devid), PCI_SLOT(devid), PCI_FUNC(devid),
-		pasid, address, flags, tag);
+	dev_err_ratelimited(dev, "Event logged [INVALID_PPR_REQUEST device=%04x:%02x:%02x.%x "
+			    "pasid=0x%05x address=0x%llx flags=0x%04x tag=0x%03x]\n",
+			    iommu->pci_seg->id, PCI_BUS_NUM(devid), PCI_SLOT(devid),
+			    PCI_FUNC(devid), pasid, address, flags, tag);
 
 	/* Skip COMPLETE_PPR_REQUEST response if RX=1 */
 	if (flags & EVENT_FLAG_PPR_RX)
-- 
2.31.1