From: Lu Baolu <baolu.lu@linux.intel.com>
To: David Woodhouse <dwmw2@infradead.org>,
Joerg Roedel <joro@8bytes.org>,
Bjorn Helgaas <bhelgaas@google.com>,
Christoph Hellwig <hch@lst.de>
Cc: Juergen Gross <jgross@suse.com>,
kevin.tian@intel.com, Stefano Stabellini <sstabellini@kernel.org>,
ashok.raj@intel.com,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
alan.cox@intel.com, Jonathan Corbet <corbet@lwn.net>,
Robin Murphy <robin.murphy@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
pengfei.xu@intel.com, Ingo Molnar <mingo@redhat.com>,
jacob.jun.pan@intel.com,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
mika.westerberg@linux.intel.com
Subject: [PATCH v9 2/5] iommu/vt-d: Check whether device requires bounce buffer
Date: Fri, 6 Sep 2019 14:14:49 +0800 [thread overview]
Message-ID: <20190906061452.30791-3-baolu.lu@linux.intel.com> (raw)
In-Reply-To: <20190906061452.30791-1-baolu.lu@linux.intel.com>
This adds a helper to check whether a device needs to
use bounce buffer. It also provides a boot time option
to disable the bounce buffer. Users can use this to
prevent the iommu driver from using the bounce buffer
for performance gain.
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Tested-by: Xu Pengfei <pengfei.xu@intel.com>
Tested-by: Mika Westerberg <mika.westerberg@intel.com>
---
Documentation/admin-guide/kernel-parameters.txt | 5 +++++
drivers/iommu/intel-iommu.c | 7 +++++++
2 files changed, 12 insertions(+)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 4c1971960afa..f441a9cea5bb 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1732,6 +1732,11 @@
Note that using this option lowers the security
provided by tboot because it makes the system
vulnerable to DMA attacks.
+ nobounce [Default off]
+ Disable bounce buffer for unstrusted devices such as
+ the Thunderbolt devices. This will treat the untrusted
+ devices as the trusted ones, hence might expose security
+ risks of DMA attacks.
intel_idle.max_cstate= [KNL,HW,ACPI,X86]
0 disables intel_idle and fall back on acpi_idle.
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index c4e0e4a9ee9e..e12aa73008df 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -362,6 +362,7 @@ static int dmar_forcedac;
static int intel_iommu_strict;
static int intel_iommu_superpage = 1;
static int iommu_identity_mapping;
+static int intel_no_bounce;
#define IDENTMAP_ALL 1
#define IDENTMAP_GFX 2
@@ -375,6 +376,9 @@ EXPORT_SYMBOL_GPL(intel_iommu_gfx_mapped);
static DEFINE_SPINLOCK(device_domain_lock);
static LIST_HEAD(device_domain_list);
+#define device_needs_bounce(d) (!intel_no_bounce && dev_is_pci(d) && \
+ to_pci_dev(d)->untrusted)
+
/*
* Iterate over elements in device_domain_list and call the specified
* callback @fn against each element.
@@ -457,6 +461,9 @@ static int __init intel_iommu_setup(char *str)
printk(KERN_INFO
"Intel-IOMMU: not forcing on after tboot. This could expose security risk for tboot\n");
intel_iommu_tboot_noforce = 1;
+ } else if (!strncmp(str, "nobounce", 8)) {
+ pr_info("Intel-IOMMU: No bounce buffer. This could expose security risks of DMA attacks\n");
+ intel_no_bounce = 1;
}
str += strcspn(str, ",");
--
2.17.1
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2019-09-06 6:16 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-06 6:14 [PATCH v9 0/5] iommu: Bounce page for untrusted devices Lu Baolu
2019-09-06 6:14 ` [PATCH v9 1/5] swiotlb: Split size parameter to map/unmap APIs Lu Baolu
2019-09-10 15:15 ` Konrad Rzeszutek Wilk
2019-09-11 6:16 ` Lu Baolu
2019-09-11 10:35 ` Joerg Roedel
2019-09-06 6:14 ` Lu Baolu [this message]
2019-09-06 6:14 ` [PATCH v9 3/5] iommu/vt-d: Don't switch off swiotlb if bounce page is used Lu Baolu
2019-09-06 6:14 ` [PATCH v9 4/5] iommu/vt-d: Add trace events for device dma map/unmap Lu Baolu
2019-09-06 6:14 ` [PATCH v9 5/5] iommu/vt-d: Use bounce buffer for untrusted devices Lu Baolu
2019-09-10 14:53 ` [PATCH v9 0/5] iommu: Bounce page " Joerg Roedel
2019-09-10 15:21 ` Konrad Rzeszutek Wilk
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