From: John Garry <john.garry@huawei.com>
To: <joro@8bytes.org>, <will@kernel.org>, <dwmw2@infradead.org>,
<baolu.lu@linux.intel.com>, <robin.murphy@arm.com>,
<corbet@lwn.net>
Cc: <linux-kernel@vger.kernel.org>,
<iommu@lists.linux-foundation.org>, <linuxarm@huawei.com>,
<thunder.leizhen@huawei.com>, <chenxiang66@hisilicon.com>,
<linux-doc@vger.kernel.org>, John Garry <john.garry@huawei.com>
Subject: [PATCH v13 3/6] iommu: Enhance IOMMU default DMA mode build options
Date: Wed, 16 Jun 2021 19:03:54 +0800 [thread overview]
Message-ID: <1623841437-211832-4-git-send-email-john.garry@huawei.com> (raw)
In-Reply-To: <1623841437-211832-1-git-send-email-john.garry@huawei.com>
From: Zhen Lei <thunder.leizhen@huawei.com>
First, add build options IOMMU_DEFAULT_{LAZY|STRICT}, so that we have the
opportunity to set {lazy|strict} mode as default at build time. Then put
the two config options in an choice, as they are mutually exclusive.
[jpg: Make choice between strict and lazy only (and not passthrough)]
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
---
.../admin-guide/kernel-parameters.txt | 3 +-
drivers/iommu/Kconfig | 40 +++++++++++++++++++
drivers/iommu/iommu.c | 2 +-
3 files changed, 43 insertions(+), 2 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index fcbb36d6eea7..d8fb36363be0 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2052,9 +2052,10 @@
throughput at the cost of reduced device isolation.
Will fall back to strict mode if not supported by
the relevant IOMMU driver.
- 1 - Strict mode (default).
+ 1 - Strict mode.
DMA unmap operations invalidate IOMMU hardware TLBs
synchronously.
+ unset - Use value of CONFIG_IOMMU_DEFAULT_{LAZY,STRICT}.
Note: on x86, the default behaviour depends on the
equivalent driver-specific parameters, but a strict
mode explicitly specified by either method takes
diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index 1f111b399bca..0327a942fdb7 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -90,6 +90,46 @@ config IOMMU_DEFAULT_PASSTHROUGH
If unsure, say N here.
+choice
+ prompt "IOMMU default DMA IOTLB invalidation mode"
+ depends on IOMMU_DMA
+
+ default IOMMU_DEFAULT_STRICT
+ help
+ This option allows an IOMMU DMA IOTLB invalidation mode to be
+ chosen at build time, to override the default mode of each ARCH,
+ removing the need to pass in kernel parameters through command line.
+ It is still possible to provide common boot params to override this
+ config.
+
+ If unsure, keep the default.
+
+config IOMMU_DEFAULT_STRICT
+ bool "strict"
+ help
+ For every IOMMU DMA unmap operation, the flush operation of IOTLB and
+ the free operation of IOVA are guaranteed to be done in the unmap
+ function.
+
+config IOMMU_DEFAULT_LAZY
+ bool "lazy"
+ help
+ Support lazy mode, where for every IOMMU DMA unmap operation, the
+ flush operation of IOTLB and the free operation of IOVA are deferred.
+ They are only guaranteed to be done before the related IOVA will be
+ reused.
+
+ The isolation provided in this mode is not as secure as STRICT mode,
+ such that a vulnerable time window may be created between the DMA
+ unmap and the mappings cached in the IOMMU IOTLB or device TLB
+ finally being invalidated, where the device could still access the
+ memory which has already been unmapped by the device driver.
+ However this mode may provide better performance in high throughput
+ scenarios, and is still considerably more secure than passthrough
+ mode or no IOMMU.
+
+endchoice
+
config OF_IOMMU
def_bool y
depends on OF && IOMMU_API
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index cf58949cc2f3..60b1ec42e73b 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -29,7 +29,7 @@ static struct kset *iommu_group_kset;
static DEFINE_IDA(iommu_group_ida);
static unsigned int iommu_def_domain_type __read_mostly;
-static bool iommu_dma_strict __read_mostly = true;
+static bool iommu_dma_strict __read_mostly = IS_ENABLED(CONFIG_IOMMU_DEFAULT_STRICT);
static u32 iommu_cmd_line __read_mostly;
struct iommu_group {
--
2.26.2
next prev parent reply other threads:[~2021-06-16 11:08 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-16 11:03 [PATCH v13 0/6] iommu: Enhance IOMMU default DMA mode build options John Garry
2021-06-16 11:03 ` [PATCH v13 1/6] iommu: Deprecate Intel and AMD cmdline methods to enable strict mode John Garry
2021-06-17 19:01 ` Robin Murphy
2021-06-18 7:43 ` John Garry
2021-06-16 11:03 ` [PATCH v13 2/6] iommu: Print strict or lazy mode at init time John Garry
2021-06-16 11:03 ` John Garry [this message]
2021-06-16 11:03 ` [PATCH v13 4/6] iommu/vt-d: Add support for IOMMU default DMA mode build options John Garry
2021-06-17 7:32 ` Lu Baolu
2021-06-17 8:00 ` John Garry
2021-06-17 19:03 ` Robin Murphy
2021-06-18 1:46 ` Lu Baolu
2021-06-18 7:31 ` John Garry
2021-06-16 11:03 ` [PATCH v13 5/6] iommu/amd: " John Garry
2021-06-16 11:03 ` [PATCH v13 6/6] iommu: Remove mode argument from iommu_set_dma_strict() John Garry
2021-06-17 7:36 ` Lu Baolu
2021-06-17 7:41 ` John Garry
2021-06-18 1:52 ` Lu Baolu
2021-06-17 18:56 ` Robin Murphy
2021-06-18 1:51 ` Lu Baolu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1623841437-211832-4-git-send-email-john.garry@huawei.com \
--to=john.garry@huawei.com \
--cc=baolu.lu@linux.intel.com \
--cc=chenxiang66@hisilicon.com \
--cc=corbet@lwn.net \
--cc=dwmw2@infradead.org \
--cc=iommu@lists.linux-foundation.org \
--cc=joro@8bytes.org \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxarm@huawei.com \
--cc=robin.murphy@arm.com \
--cc=thunder.leizhen@huawei.com \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).