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From: Lennert Buytenhek <buytenh@wantstofly.org>
To: iommu@lists.linux-foundation.org, Joerg Roedel <joro@8bytes.org>,
	Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Subject: [PATCH] iommu/amd: Fix I/O page fault logging ratelimit test
Date: Mon, 19 Jul 2021 03:47:19 +0300	[thread overview]
Message-ID: <YPTLl7XHOGp5NiVH@wantstofly.org> (raw)

On an AMD system, I/O page faults are usually logged like this:

	drvname 0000:05:00.0: Event logged [IO_PAGE_FAULT domain=0x0000 address=0x0000000092050da0 flags=0x0020]

But sometimes they are logged like this instead, even for the exact
same PCI device:

	AMD-Vi: Event logged [IO_PAGE_FAULT device=05:00.0 domain=0x0000 address=0x0000000092050de0 flags=0x0020]

This discrepancy appears to be caused by this code:

	if (dev_data && __ratelimit(&dev_data->rs)) {
		pci_err(pdev, "Event logged [IO_PAGE_FAULT domain=0x%04x address=0x%llx flags=0x%04x]\n",
			domain_id, address, flags);
	} else if (printk_ratelimit()) {
		pr_err("Event logged [IO_PAGE_FAULT device=%02x:%02x.%x domain=0x%04x address=0x%llx flags=0x%04x]\n",
			PCI_BUS_NUM(devid), PCI_SLOT(devid), PCI_FUNC(devid),
			domain_id, address, flags);
	}

If an I/O page fault occurs for a PCI device with associated
iommu_dev_data, but for which the __ratelimit(&dev_data->rs) check fails,
we'll give it a second chance with printk_ratelimit(), and if that check
succeeds, we will log the fault anyway, but in a different format.

Change this to only check printk_ratelimit() if !dev_data, which seems to
be what had been originally intended.

Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
---
 drivers/iommu/amd/iommu.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 811a49a95d04..7ae426b092f2 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -483,7 +483,7 @@ static void amd_iommu_report_page_fault(u16 devid, u16 domain_id,
 	if (dev_data && __ratelimit(&dev_data->rs)) {
 		pci_err(pdev, "Event logged [IO_PAGE_FAULT domain=0x%04x address=0x%llx flags=0x%04x]\n",
 			domain_id, address, flags);
-	} else if (printk_ratelimit()) {
+	} else if (!dev_data && printk_ratelimit()) {
 		pr_err("Event logged [IO_PAGE_FAULT device=%02x:%02x.%x domain=0x%04x address=0x%llx flags=0x%04x]\n",
 			PCI_BUS_NUM(devid), PCI_SLOT(devid), PCI_FUNC(devid),
 			domain_id, address, flags);
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             reply	other threads:[~2021-07-19  0:56 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-19  0:47 Lennert Buytenhek [this message]
2021-07-21  0:05 ` [PATCH] iommu/amd: Fix I/O page fault logging ratelimit test Suthikulpanit, Suravee via iommu
2021-07-21 13:46   ` Lennert Buytenhek

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