linux-kernel - [PATCH] Intel IOMMU patch to reprocess RMRR info

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Date:	Fri, 15 Jun 2012 08:58:58 -0400
From:	Tom Mingarelli <thomas.mingarelli@...com>
To:	David Woodhouse <dwm2@...radead.org>,
	Joerg Roedel <joerg.roedel@....com>
Cc:	Tom Mingarelli <thomas.mingarelli@...com>,
	iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: [PATCH] Intel IOMMU patch to reprocess RMRR info

This patch is being submitted to handle the case where a pci device is
placed into the si domain, but then removed. The RMRR information for
such devices need to be re-processed to avoid DMA Read errors due to
the Present Bit being cleared in the context entry.
----
drivers/iommu/intel-iommu.c |   32 ++++++++++++++++++++++++++++++++
1 files changed, 32 insertions(+), 0 deletions(-)
    
Signed-off-by: Tom Mingarelli <thomas.mingarelli@...com>
Tested-by: Tony Camuso <tony.camuso@...com>

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index f93d5ac..5ae57c5 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -2696,6 +2696,37 @@ static int iommu_dummy(struct pci_dev *pdev)
 	return pdev->dev.archdata.iommu == DUMMY_DEVICE_DOMAIN_INFO;
 }
 
+static int reprocess_rmrr(struct device *dev)
+{
+	struct dmar_rmrr_unit *rmrr;
+	struct pci_dev *pdev;
+	int i, ret;
+
+	pdev = to_pci_dev(dev);
+
+	for_each_rmrr_units(rmrr) {
+		for (i = 0; i < rmrr->devices_cnt; i++) {
+			/*
+			 * Here we are just concerned with
+			 * finding the one device that was
+			 * removed from the si_domain and
+			 * re-evaluating its RMRR info.
+			 */
+			if (rmrr->devices[i] != pdev)
+				continue;
+			pr_info("%s %s\n",
+				"IOMMU: Reprocess RMRR information for device",
+				pci_name(pdev));
+			ret = iommu_prepare_rmrr_dev(rmrr, pdev);
+			if (ret)
+				pr_err("%s %s\n",
+					"IOMMU: Reprocessing RMRR reserved",
+					"region for device failed");
+		}
+	}
+	return 0;
+}
+
 /* Check if the pdev needs to go through non-identity map and unmap process.*/
 static int iommu_no_mapping(struct device *dev)
 {
@@ -2724,6 +2755,7 @@ static int iommu_no_mapping(struct device *dev)
 			domain_remove_one_dev_info(si_domain, pdev);
 			printk(KERN_INFO "32bit %s uses non-identity mapping\n",
 			       pci_name(pdev));
+			reprocess_rmrr(dev);
 			return 0;
 		}
 	} else {
--
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