[ovs-dev] [PATCH V2 2/2] netdev-dpdk: vHost IOMMU support
Mark Kavanagh
mark.b.kavanagh at intel.com
Thu Nov 30 10:03:18 UTC 2017
DPDK v17.11 introduces support for the vHost IOMMU feature.
This is a security feature, which restricts the vhost memory
that a virtio device may access.
This feature also enables the vhost REPLY_ACK protocol, the
implementation of which is known to work in newer versions of
QEMU (i.e. v2.10.0), but is buggy in older versions (v2.7.0 -
v2.9.0, inclusive). As such, the feature is disabled by default
in (and should remain so), for the aforementioned older QEMU
verions. Starting with QEMU v2.9.1, vhost-iommu-support can
safely be enabled, even without having an IOMMU device, with
no performance penalty.
This patch adds a new global config option, vhost-iommu-support,
that controls enablement of the vhost IOMMU feature:
ovs-vsctl set Open_vSwitch . other_config:vhost-iommu-support=true
Note that changing this value after guest devices have already been
initialized will not toggle IOMMU support. To that end, if IOMMU
support is required, this field should be set to true when setting
other global parameters on init (such as "dpdk-socket-mem", for
example).
Signed-off-by: Mark Kavanagh <mark.b.kavanagh at intel.com>
---
v2->v1:
- rebase to HEAD of master
- refactor vHost IOMMU enablement mechanism (use a global
config option, instead of the previous per-port approach).
---
Documentation/topics/dpdk/vhost-user.rst | 29 +++++++++++++++++++++++++++++
NEWS | 1 +
lib/dpdk.c | 16 ++++++++++++++++
lib/dpdk.h | 3 +++
lib/netdev-dpdk.c | 19 +++++++++++++------
vswitchd/vswitch.xml | 19 +++++++++++++++++++
6 files changed, 81 insertions(+), 6 deletions(-)
diff --git a/Documentation/topics/dpdk/vhost-user.rst b/Documentation/topics/dpdk/vhost-user.rst
index 5347995..814c50b 100644
--- a/Documentation/topics/dpdk/vhost-user.rst
+++ b/Documentation/topics/dpdk/vhost-user.rst
@@ -273,6 +273,35 @@ One benefit of using this mode is the ability for vHost ports to 'reconnect' in
event of the switch crashing or being brought down. Once it is brought back up,
the vHost ports will reconnect automatically and normal service will resume.
+vhost IOMMU Support
+-------------------
+
+vhost IOMMU is a feature which restricts the vhost memory that a virtio device
+can access, and as such is useful in deployments in which security is a concern.
+
+IOMMU support may be enabled via a global config value, ```vhost-iommu-support```.
+Setting this to true enables vhost IOMMU support for all vhost ports when/where
+available::
+
+ $ ovs-vsctl set Open_vSwitch.other_config:vhost-iommu-support=true
+
+.. important::
+
+ Changing this value after guest devices have already been initialized
+ will not toggle vHost IOMMU support. To that end, if vHost IOMMU
+ support is required, this field should be set to ```true```
+ when setting other global parameters on init (such as ```dpdk-socket-mem```,
+ for example).
+
+.. important::
+
+ Enabling the IOMMU feature also enables the vhost user reply-ack protocol;
+ this is known to work on QEMU v2.10.0, but is buggy on older versions
+ (2.7.0 - 2.9.0, inclusive). Consequently, the IOMMU feaure is disabled by
+ default (and should remain so if using the aforementioned versions of QEMU).
+ Starting with QEMU v2.9.1, vhost-iommu-support can safely be enabled, even
+ without having an IOMMU device, with no performance penalty.
+
.. _dpdk-testpmd:
DPDK in the Guest
diff --git a/NEWS b/NEWS
index 74e59bf..3e1a073 100644
--- a/NEWS
+++ b/NEWS
@@ -14,6 +14,7 @@ Post-v2.8.0
* Add support for compiling OVS with the latest Linux 4.13 kernel
- DPDK:
* Add support for DPDK v17.11
+ * Add support for vHost IOMMU
v2.8.0 - 31 Aug 2017
--------------------
diff --git a/lib/dpdk.c b/lib/dpdk.c
index 8da6c32..c5120f7 100644
--- a/lib/dpdk.c
+++ b/lib/dpdk.c
@@ -41,6 +41,7 @@ VLOG_DEFINE_THIS_MODULE(dpdk);
static FILE *log_stream = NULL; /* Stream for DPDK log redirection */
static char *vhost_sock_dir = NULL; /* Location of vhost-user sockets */
+static bool vhost_iommu_enabled = false; /* Status of vHost IOMMU support */
static int
process_vhost_flags(char *flag, const char *default_val, int size,
@@ -312,6 +313,7 @@ dpdk_init__(const struct smap *ovs_other_config)
int err = 0;
cpu_set_t cpuset;
char *sock_dir_subcomponent;
+ char *enable_vhost_iommu;
log_stream = fopencookie(NULL, "w+", dpdk_log_func);
if (log_stream == NULL) {
@@ -345,6 +347,14 @@ dpdk_init__(const struct smap *ovs_other_config)
vhost_sock_dir = sock_dir_subcomponent;
}
+ if (process_vhost_flags("vhost-iommu-support", "false",
+ strlen("vhost-iommu-support"), ovs_other_config,
+ &enable_vhost_iommu)) {
+ vhost_iommu_enabled = (strncmp(enable_vhost_iommu, "true",
+ strlen("true")) == 0) ?
+ true : false;
+ }
+
argv = grow_argv(&argv, 0, 1);
argc = 1;
argv[0] = xstrdup(ovs_get_program_name());
@@ -482,6 +492,12 @@ dpdk_get_vhost_sock_dir(void)
return vhost_sock_dir;
}
+bool
+dpdk_vhost_iommu_enabled(void)
+{
+ return vhost_iommu_enabled;
+}
+
void
dpdk_set_lcore_id(unsigned cpu)
{
diff --git a/lib/dpdk.h b/lib/dpdk.h
index 673a1f1..83f0fac 100644
--- a/lib/dpdk.h
+++ b/lib/dpdk.h
@@ -19,6 +19,8 @@
#ifdef DPDK_NETDEV
+#include <stdbool.h>
+
#include <rte_config.h>
#include <rte_lcore.h>
@@ -35,5 +37,6 @@ struct smap;
void dpdk_init(const struct smap *ovs_other_config);
void dpdk_set_lcore_id(unsigned cpu);
const char *dpdk_get_vhost_sock_dir(void);
+bool dpdk_vhost_iommu_enabled(void);
#endif /* dpdk.h */
diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
index f552444..e190e0c 100644
--- a/lib/netdev-dpdk.c
+++ b/lib/netdev-dpdk.c
@@ -3253,6 +3253,7 @@ netdev_dpdk_vhost_client_reconfigure(struct netdev *netdev)
{
struct netdev_dpdk *dev = netdev_dpdk_cast(netdev);
int err;
+ uint64_t vhost_flags = 0;
ovs_mutex_lock(&dev->mutex);
@@ -3263,19 +3264,25 @@ netdev_dpdk_vhost_client_reconfigure(struct netdev *netdev)
*/
if (!(dev->vhost_driver_flags & RTE_VHOST_USER_CLIENT)
&& strlen(dev->vhost_id)) {
- /* Register client-mode device */
- err = rte_vhost_driver_register(dev->vhost_id,
- RTE_VHOST_USER_CLIENT);
+ /* Register client-mode device. */
+ vhost_flags |= RTE_VHOST_USER_CLIENT;
+
+ /* Enable IOMMU support, if explicitly requested. */
+ if (dpdk_vhost_iommu_enabled()) {
+ vhost_flags |= RTE_VHOST_USER_IOMMU_SUPPORT;
+ }
+ err = rte_vhost_driver_register(dev->vhost_id, vhost_flags);
if (err) {
VLOG_ERR("vhost-user device setup failure for device %s\n",
dev->vhost_id);
goto unlock;
} else {
/* Configuration successful */
- dev->vhost_driver_flags |= RTE_VHOST_USER_CLIENT;
+ dev->vhost_driver_flags |= vhost_flags;
VLOG_INFO("vHost User device '%s' created in 'client' mode, "
- "using client socket '%s'",
- dev->up.name, dev->vhost_id);
+ "using client socket '%s'. vHost IOMMU support is %s.",
+ dev->up.name, dev->vhost_id, dpdk_vhost_iommu_enabled() ?
+ "enabled" : "disabled");
}
err = rte_vhost_driver_callback_register(dev->vhost_id,
diff --git a/vswitchd/vswitch.xml b/vswitchd/vswitch.xml
index c145e1a..d8e767b 100644
--- a/vswitchd/vswitch.xml
+++ b/vswitchd/vswitch.xml
@@ -344,6 +344,25 @@
</p>
</column>
+ <column name="other_config" key="vhost-iommu-support"
+ type='{"type": "boolean"}'>
+ <p>
+ vHost IOMMU is a security feature, which restricts the vhost memory
+ that a virtio device may access. vHost IOMMU support is disabled by
+ default, due to a bug in QEMU implementations of the vhost REPLY_ACK
+ protocol, (on which vHost IOMMU relies) prior to v2.9.1. Setting this
+ value to <code>true</code> enables vHost IOMMU support for vHost User
+ Client ports in OvS-DPDK, starting from DPDK v17.11.
+ </p>
+ <p>
+ Changing this value after guest devices have already been initialized
+ does not toggle vHost IOMMU support. To that end, if vHost IOMMU
+ support is required, this field should be set to <code>true</code>
+ when setting other global parameters on init (such as
+ <ref column="other_config" key="dpdk-socket-mem"/>, for example).
+ </p>
+ </column>
+
<column name="other_config" key="n-handler-threads"
type='{"type": "integer", "minInteger": 1}'>
<p>
--
1.9.3
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