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From: Jacob Pan <jacob.jun.pan@linux.intel.com>
To: iommu@lists.linux-foundation.org,
	LKML <linux-kernel@vger.kernel.org>,
	Joerg Roedel <joro@8bytes.org>,
	David Woodhouse <dwmw2@infradead.org>,
	Eric Auger <eric.auger@redhat.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Cc: "Tian, Kevin" <kevin.tian@intel.com>,
	Raj Ashok <ashok.raj@intel.com>,
	Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Subject: [PATCH v4 05/22] iommu: Add a timeout parameter for PRQ response
Date: Sun,  9 Jun 2019 06:44:05 -0700
Message-ID: <1560087862-57608-6-git-send-email-jacob.jun.pan@linux.intel.com> (raw)
In-Reply-To: <1560087862-57608-1-git-send-email-jacob.jun.pan@linux.intel.com>

When an IO page request is processed outside IOMMU subsystem, response
can be delayed or lost. Add a tunable setup parameter such that user can
choose the timeout for IOMMU to track pending page requests.

This timeout mechanism is a basic safety net which can be implemented in
conjunction with credit based or device level page response exception
handling.

Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
---
 Documentation/admin-guide/kernel-parameters.txt |  8 +++++++
 drivers/iommu/iommu.c                           | 29 +++++++++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 138f666..b43f089 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1813,6 +1813,14 @@
 			1 - Bypass the IOMMU for DMA.
 			unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH.
 
+	iommu.prq_timeout=
+			Timeout in seconds to wait for page response
+			of a pending page request.
+			Format: <integer>
+			Default: 10
+			0 - no timeout tracking
+			1 to 100 - allowed range
+
 	io7=		[HW] IO7 for Marvel based alpha systems
 			See comment before marvel_specify_io7 in
 			arch/alpha/kernel/core_marvel.c.
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 13b301c..64e87d5 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -45,6 +45,19 @@ static unsigned int iommu_def_domain_type = IOMMU_DOMAIN_DMA;
 #endif
 static bool iommu_dma_strict __read_mostly = true;
 
+/*
+ * Timeout to wait for page response of a pending page request. This is
+ * intended as a basic safty net in case a pending page request is not
+ * responded for an exceptionally long time. Device may also implement
+ * its own protection mechanism against this exception.
+ * Units are in jiffies with a range between 1 - 100 seconds equivalent.
+ * Default to 10 seconds.
+ * Setting 0 means no timeout tracking.
+ */
+#define IOMMU_PAGE_RESPONSE_MAX_TIMEOUT (HZ * 100)
+#define IOMMU_PAGE_RESPONSE_DEF_TIMEOUT (HZ * 10)
+static unsigned long prq_timeout = IOMMU_PAGE_RESPONSE_DEF_TIMEOUT;
+
 struct iommu_group {
 	struct kobject kobj;
 	struct kobject *devices_kobj;
@@ -157,6 +170,22 @@ static int __init iommu_dma_setup(char *str)
 }
 early_param("iommu.strict", iommu_dma_setup);
 
+static int __init iommu_set_prq_timeout(char *str)
+{
+	unsigned long timeout;
+
+	if (!str)
+		return -EINVAL;
+	timeout = simple_strtoul(str, NULL, 0);
+	timeout = timeout * HZ;
+	if (timeout > IOMMU_PAGE_RESPONSE_MAX_TIMEOUT)
+		return -EINVAL;
+	prq_timeout = timeout;
+
+	return 0;
+}
+early_param("iommu.prq_timeout", iommu_set_prq_timeout);
+
 static ssize_t iommu_group_attr_show(struct kobject *kobj,
 				     struct attribute *__attr, char *buf)
 {
-- 
2.7.4

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  parent reply index

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-09 13:44 [PATCH v4 00/22] Shared virtual address IOMMU and VT-d support Jacob Pan
2019-06-09 13:44 ` [PATCH v4 01/22] driver core: Add per device iommu param Jacob Pan
2019-06-09 13:44 ` [PATCH v4 02/22] iommu: Introduce device fault data Jacob Pan
2019-06-18 15:42   ` Jonathan Cameron
2019-06-09 13:44 ` [PATCH v4 03/22] iommu: Introduce device fault report API Jacob Pan
2019-06-18 15:41   ` Jonathan Cameron
2019-06-09 13:44 ` [PATCH v4 04/22] iommu: Add recoverable fault reporting Jacob Pan
2019-06-18 15:44   ` Jonathan Cameron
2019-06-09 13:44 ` Jacob Pan [this message]
2019-06-09 13:44 ` [PATCH v4 06/22] trace/iommu: Add sva trace events Jacob Pan
2019-06-09 13:44 ` [PATCH v4 07/22] iommu: Use device fault trace event Jacob Pan
2019-06-09 13:44 ` [PATCH v4 08/22] iommu: Introduce attach/detach_pasid_table API Jacob Pan
2019-06-18 15:41   ` Jonathan Cameron
2019-06-24 15:06     ` Auger Eric
2019-06-24 15:23       ` Jean-Philippe Brucker
2019-06-09 13:44 ` [PATCH v4 09/22] iommu: Introduce cache_invalidate API Jacob Pan
2019-06-18 15:41   ` Jonathan Cameron
2019-06-09 13:44 ` [PATCH v4 10/22] iommu: Fix compile error without IOMMU_API Jacob Pan
2019-06-18 14:10   ` Jonathan Cameron
2019-06-24 22:28     ` Jacob Pan
2019-06-09 13:44 ` [PATCH v4 11/22] iommu: Introduce guest PASID bind function Jacob Pan
2019-06-18 15:36   ` Jean-Philippe Brucker
2019-06-24 22:24     ` Jacob Pan
2019-07-16 16:44   ` Auger Eric
2019-08-05 21:02     ` Jacob Pan
2019-08-05 23:13     ` Jacob Pan
2019-06-09 13:44 ` [PATCH v4 12/22] iommu: Add I/O ASID allocator Jacob Pan
2019-06-18 16:50   ` Jonathan Cameron
2019-06-25 18:55     ` Jacob Pan
2019-06-09 13:44 ` [PATCH v4 13/22] iommu/vt-d: Enlightened PASID allocation Jacob Pan
2019-07-16  9:29   ` Auger Eric
2019-08-13 16:57     ` Jacob Pan
2019-06-09 13:44 ` [PATCH v4 14/22] iommu/vt-d: Add custom allocator for IOASID Jacob Pan
2019-07-16  9:30   ` Auger Eric
2019-08-05 20:02     ` Jacob Pan
2019-06-09 13:44 ` [PATCH v4 15/22] iommu/vt-d: Replace Intel specific PASID allocator with IOASID Jacob Pan
2019-06-18 15:57   ` Jonathan Cameron
2019-06-24 21:36     ` Jacob Pan
2019-06-27  1:53   ` Lu Baolu
2019-06-27 15:40     ` Jacob Pan
2019-06-09 13:44 ` [PATCH v4 16/22] iommu/vt-d: Move domain helper to header Jacob Pan
2019-07-16  9:33   ` Auger Eric
2019-06-09 13:44 ` [PATCH v4 17/22] iommu/vt-d: Avoid duplicated code for PASID setup Jacob Pan
2019-06-18 16:03   ` Jonathan Cameron
2019-06-24 23:44     ` Jacob Pan
2019-07-16  9:52   ` Auger Eric
2019-06-09 13:44 ` [PATCH v4 18/22] iommu/vt-d: Add nested translation helper function Jacob Pan
2019-06-09 13:44 ` [PATCH v4 19/22] iommu/vt-d: Clean up for SVM device list Jacob Pan
2019-06-18 16:42   ` Jonathan Cameron
2019-06-24 23:59     ` Jacob Pan
2019-06-09 13:44 ` [PATCH v4 20/22] iommu/vt-d: Add bind guest PASID support Jacob Pan
2019-06-18 16:44   ` Jonathan Cameron
2019-06-24 22:41     ` Jacob Pan
2019-06-27  2:50   ` Lu Baolu
2019-06-27 20:22     ` Jacob Pan
2019-07-05  2:21       ` Lu Baolu
2019-08-14 17:20         ` Jacob Pan
2019-07-16 16:45   ` Auger Eric
2019-07-16 17:04     ` Raj, Ashok
2019-07-18  7:47       ` Auger Eric
2019-06-09 13:44 ` [PATCH v4 21/22] iommu/vt-d: Support flushing more translation cache types Jacob Pan
2019-07-18  8:35   ` Auger Eric
2019-08-14 20:17     ` Jacob Pan
2019-06-09 13:44 ` [PATCH v4 22/22] iommu/vt-d: Add svm/sva invalidate function Jacob Pan

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