linux-kernel - [Intel IOMMU PATCH] Re-evaluate RMRR info for devices removed from si domain

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Message-ID: <9774516974AF5F4C8A2C3C69CD3412332034C987@G9W0755.americas.hpqcorp.net>
Date:	Tue, 28 Feb 2012 17:58:30 +0000
From:	"Mingarelli, Thomas" <Thomas.Mingarelli@...com>
To:	"dwmw2@...radead.org" <dwmw2@...radead.org>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"ddutile@...hat.com" <ddutile@...hat.com>,
	Alex Williamson <alex.williamson@...hat.com>
Subject: [Intel IOMMU PATCH] Re-evaluate RMRR info for devices removed from
 si domain

This patch is being submitted to handle the case where a pci device is
placed into the si domain, when booting in iommu passthrough mode, 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
device's context entry.
Signed-off-by: Thomas Mingarelli <thomas.mingarelli@...com>

diff -up linux-3.2.4/drivers/iommu/intel-iommu.c.ORIG linux-3.2.4/drivers/iommu/intel-iommu.c
--- linux-3.2.4/drivers/iommu/intel-iommu.c.ORIG	2012-02-22 16:10:07.105254130 -0600
+++ linux-3.2.4/drivers/iommu/intel-iommu.c	2012-02-28 12:49:38.537694065 -0600
@@ -2676,7 +2676,8 @@ static int iommu_dummy(struct pci_dev *p
 static int iommu_no_mapping(struct device *dev)
 {
 	struct pci_dev *pdev;
-	int found;
+	struct dmar_rmrr_unit *rmrr;
+	int i, ret, found;
 
 	if (unlikely(dev->bus != &pci_bus_type))
 		return 1;
@@ -2699,7 +2700,24 @@ static int iommu_no_mapping(struct devic
 			 */
 			domain_remove_one_dev_info(si_domain, pdev);
 			printk(KERN_INFO "32bit %s uses non-identity mapping\n",
-			       pci_name(pdev));
+				pci_name(pdev));
+			printk(KERN_INFO "IOMMU: Re-processing RMRR information for device %s:\n",
+				pci_name(pdev));
+			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;
+					ret = iommu_prepare_rmrr_dev(rmrr, pdev);
+					if (ret)
+						printk(KERN_ERR
+							"IOMMU: mapping reserved region failed for device.\n");
+				}
+			}
 			return 0;
 		}
 	} else {
--
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