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authorPeter Xu <peterx@redhat.com>2021-07-07 11:41:14 -0400
committerMichael S. Tsirkin <mst@redhat.com>2021-07-16 11:10:45 -0400
commit7395b3e3e70031b1efff7941cbef6a1ceb6f2ffd (patch)
treef84fa62ac95d6440256d976ab8a3bbaf02179418 /qemu-options.hx
parent538bb6f1219c1711538d73143f005e62c3d20f7b (diff)
docs: Add '-device intel-iommu' entry
The parameters of intel-iommu device are non-trivial to understand. Add an entry for it so that people can reference to it when using. There're actually a few more options there, but I hide them explicitly because they shouldn't be used by normal QEMU users. Cc: Chao Yang <chayang@redhat.com> Cc: Lei Yang <leiyang@redhat.com> Cc: Jing Zhao <jinzhao@redhat.com> Cc: Jason Wang <jasowang@redhat.com> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Alex Williamson <alex.williamson@redhat.com> Reviewed-by: Jason Wang <jasowang@redhat.com> Reviewed-by: Yi Liu <yi.l.liu@intel.com> Signed-off-by: Peter Xu <peterx@redhat.com> Message-Id: <20210707154114.197580-1-peterx@redhat.com> Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Reviewed-by: Eric Auger <eric.auger@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'qemu-options.hx')
-rw-r--r--qemu-options.hx33
1 files changed, 33 insertions, 0 deletions
diff --git a/qemu-options.hx b/qemu-options.hx
index 214c477dcc..0c9ddc0274 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -939,6 +939,39 @@ SRST
``-device pci-ipmi-bt,bmc=id``
Like the KCS interface, but defines a BT interface on the PCI bus.
+
+``-device intel-iommu[,option=...]``
+ This is only supported by ``-machine q35``, which will enable Intel VT-d
+ emulation within the guest. It supports below options:
+
+ ``intremap=on|off`` (default: auto)
+ This enables interrupt remapping feature. It's required to enable
+ complete x2apic. Currently it only supports kvm kernel-irqchip modes
+ ``off`` or ``split``, while full kernel-irqchip is not yet supported.
+ The default value is "auto", which will be decided by the mode of
+ kernel-irqchip.
+
+ ``caching-mode=on|off`` (default: off)
+ This enables caching mode for the VT-d emulated device. When
+ caching-mode is enabled, each guest DMA buffer mapping will generate an
+ IOTLB invalidation from the guest IOMMU driver to the vIOMMU device in
+ a synchronous way. It is required for ``-device vfio-pci`` to work
+ with the VT-d device, because host assigned devices requires to setup
+ the DMA mapping on the host before guest DMA starts.
+
+ ``device-iotlb=on|off`` (default: off)
+ This enables device-iotlb capability for the emulated VT-d device. So
+ far virtio/vhost should be the only real user for this parameter,
+ paired with ats=on configured for the device.
+
+ ``aw-bits=39|48`` (default: 39)
+ This decides the address width of IOVA address space. The address
+ space has 39 bits width for 3-level IOMMU page tables, and 48 bits for
+ 4-level IOMMU page tables.
+
+ Please also refer to the wiki page for general scenarios of VT-d
+ emulation in QEMU: https://wiki.qemu.org/Features/VT-d.
+
ERST
DEF("name", HAS_ARG, QEMU_OPTION_name,