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From: Eric Auger <eric.auger@redhat.com>
To: eric.auger.pro@gmail.com, eric.auger@redhat.com, joro@8bytes.org,
	iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
	dwmw2@infradead.org, robin.murphy@arm.com
Cc: alex.williamson@redhat.com, shameerali.kolothum.thodi@huawei.com,
	jean-philippe.brucker@arm.com
Subject: [PATCH v5 7/7] iommu/vt-d: Differentiate relaxable and non relaxable RMRRs
Date: Tue, 28 May 2019 13:50:25 +0200	[thread overview]
Message-ID: <20190528115025.17194-8-eric.auger@redhat.com> (raw)
In-Reply-To: <20190528115025.17194-1-eric.auger@redhat.com>

Now we have a new IOMMU_RESV_DIRECT_RELAXABLE reserved memory
region type, let's report USB and GFX RMRRs as relaxable ones.

We introduce a new device_rmrr_is_relaxable() helper to check
whether the rmrr belongs to the relaxable category.

This allows to have a finer reporting at IOMMU API level of
reserved memory regions. This will be exploitable by VFIO to
define the usable IOVA range and detect potential conflicts
between the guest physical address space and host reserved
regions.

Signed-off-by: Eric Auger <eric.auger@redhat.com>

---

v3 -> v4:
- introduce device_rmrr_is_relaxable and reshuffle the comments
---
 drivers/iommu/intel-iommu.c | 55 +++++++++++++++++++++++++++----------
 1 file changed, 40 insertions(+), 15 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 9302351818ab..01c82f848470 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -2920,6 +2920,36 @@ static bool device_has_rmrr(struct device *dev)
 	return false;
 }
 
+/*
+ * device_rmrr_is_relaxable - Test whether the RMRR of this device
+ * is relaxable (ie. is allowed to be not enforced under some conditions)
+ *
+ * @dev: device handle
+ *
+ * We assume that PCI USB devices with RMRRs have them largely
+ * for historical reasons and that the RMRR space is not actively used post
+ * boot.  This exclusion may change if vendors begin to abuse it.
+ *
+ * The same exception is made for graphics devices, with the requirement that
+ * any use of the RMRR regions will be torn down before assigning the device
+ * to a guest.
+ *
+ * Return: true if the RMRR is relaxable
+ */
+static bool device_rmrr_is_relaxable(struct device *dev)
+{
+	struct pci_dev *pdev;
+
+	if (!dev_is_pci(dev))
+		return false;
+
+	pdev = to_pci_dev(dev);
+	if (IS_USB_DEVICE(pdev) || IS_GFX_DEVICE(pdev))
+		return true;
+	else
+		return false;
+}
+
 /*
  * There are a couple cases where we need to restrict the functionality of
  * devices associated with RMRRs.  The first is when evaluating a device for
@@ -2934,25 +2964,16 @@ static bool device_has_rmrr(struct device *dev)
  * We therefore prevent devices associated with an RMRR from participating in
  * the IOMMU API, which eliminates them from device assignment.
  *
- * In both cases we assume that PCI USB devices with RMRRs have them largely
- * for historical reasons and that the RMRR space is not actively used post
- * boot.  This exclusion may change if vendors begin to abuse it.
- *
- * The same exception is made for graphics devices, with the requirement that
- * any use of the RMRR regions will be torn down before assigning the device
- * to a guest.
+ * In both cases, devices which have relaxable RMRRs are not concerned by this
+ * restriction. See device_rmrr_is_relaxable comment.
  */
 static bool device_is_rmrr_locked(struct device *dev)
 {
 	if (!device_has_rmrr(dev))
 		return false;
 
-	if (dev_is_pci(dev)) {
-		struct pci_dev *pdev = to_pci_dev(dev);
-
-		if (IS_USB_DEVICE(pdev) || IS_GFX_DEVICE(pdev))
-			return false;
-	}
+	if (device_rmrr_is_relaxable(dev))
+		return false;
 
 	return true;
 }
@@ -5494,6 +5515,7 @@ static void intel_iommu_get_resv_regions(struct device *device,
 		for_each_active_dev_scope(rmrr->devices, rmrr->devices_cnt,
 					  i, i_dev) {
 			struct iommu_resv_region *resv;
+			enum iommu_resv_type type;
 			size_t length;
 
 			if (i_dev != device &&
@@ -5501,9 +5523,12 @@ static void intel_iommu_get_resv_regions(struct device *device,
 				continue;
 
 			length = rmrr->end_address - rmrr->base_address + 1;
+
+			type = device_rmrr_is_relaxable(device) ?
+				IOMMU_RESV_DIRECT_RELAXABLE : IOMMU_RESV_DIRECT;
+
 			resv = iommu_alloc_resv_region(rmrr->base_address,
-						       length, prot,
-						       IOMMU_RESV_DIRECT);
+						       length, prot, type);
 			if (!resv)
 				break;
 
-- 
2.20.1


  parent reply	other threads:[~2019-05-28 11:51 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-28 11:50 [PATCH v5 0/7] RMRR related fixes and enhancements Eric Auger
2019-05-28 11:50 ` [PATCH v5 1/7] iommu: Fix a leak in iommu_insert_resv_region Eric Auger
2019-05-29  6:17   ` Christoph Hellwig
2019-05-29 15:38     ` Auger Eric
2019-05-28 11:50 ` [PATCH v5 2/7] iommu/vt-d: Duplicate iommu_resv_region objects per device list Eric Auger
2019-05-29  2:04   ` Lu Baolu
2019-05-29 15:40     ` Auger Eric
2019-05-28 11:50 ` [PATCH v5 3/7] iommu/vt-d: Introduce is_downstream_to_pci_bridge helper Eric Auger
2019-05-29  2:11   ` Lu Baolu
2019-05-29  6:21   ` Christoph Hellwig
2019-05-29 15:43     ` Auger Eric
2019-05-28 11:50 ` [PATCH v5 4/7] iommu/vt-d: Handle RMRR with PCI bridge device scopes Eric Auger
2019-05-29  2:12   ` Lu Baolu
2019-05-28 11:50 ` [PATCH v5 5/7] iommu/vt-d: Handle PCI bridge RMRR device scopes in intel_iommu_get_resv_regions Eric Auger
2019-05-29  2:13   ` Lu Baolu
2019-05-28 11:50 ` [PATCH v5 6/7] iommu: Introduce IOMMU_RESV_DIRECT_RELAXABLE reserved memory regions Eric Auger
2019-05-28 11:50 ` Eric Auger [this message]
2019-05-29  2:34   ` [PATCH v5 7/7] iommu/vt-d: Differentiate relaxable and non relaxable RMRRs Lu Baolu
2019-05-29 15:43     ` Auger Eric

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