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>
---
v2:
- Drop "in the guest" in intremap entry [Jason]
- Explain how the default value of intremap is chosen [Eric]
- Add r-bs for Jason and Yi
Signed-off-by: Peter Xu <peterx@redhat.com>
---
qemu-options.hx | 33 +++++++++++++++++++++++++++++++++
1 file changed, 33 insertions(+)
diff --git a/qemu-options.hx b/qemu-options.hx
index 8965dabc83..0fcc8973dd 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -926,6 +926,39 @@ 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,
--
2.31.1
Hi Peter, On 7/7/21 5:41 PM, Peter Xu wrote: > 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> Reviewed-by: Eric Auger <eric.auger@redhat.com> Thanks Eric > --- > v2: > - Drop "in the guest" in intremap entry [Jason] > - Explain how the default value of intremap is chosen [Eric] > - Add r-bs for Jason and Yi > Signed-off-by: Peter Xu <peterx@redhat.com> > --- > qemu-options.hx | 33 +++++++++++++++++++++++++++++++++ > 1 file changed, 33 insertions(+) > > diff --git a/qemu-options.hx b/qemu-options.hx > index 8965dabc83..0fcc8973dd 100644 > --- a/qemu-options.hx > +++ b/qemu-options.hx > @@ -926,6 +926,39 @@ 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, >
On Wed, 2021-07-07 at 11:41 -0400, Peter Xu wrote: > 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> > --- > v2: > - Drop "in the guest" in intremap entry [Jason] > - Explain how the default value of intremap is chosen [Eric] > - Add r-bs for Jason and Yi > Signed-off-by: Peter Xu <peterx@redhat.com> > --- > qemu-options.hx | 33 +++++++++++++++++++++++++++++++++ > 1 file changed, 33 insertions(+) > > diff --git a/qemu-options.hx b/qemu-options.hx > index 8965dabc83..0fcc8973dd 100644 > --- a/qemu-options.hx > +++ b/qemu-options.hx > @@ -926,6 +926,39 @@ 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, As far as I know this looks very good. Thanks for doing this! Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Best regards, Maxim Levitsky
On Thu, Jul 08, 2021 at 01:17:50AM +0300, Maxim Levitsky wrote: > As far as I know this looks very good. > Thanks for doing this! > > Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Thanks! Michael - I just saw a pull req sent, so I wanted to double check: should this patch go through your tree at last? Thanks, -- Peter Xu
On Thu, Jul 08, 2021 at 04:28:01PM -0400, Peter Xu wrote: > On Thu, Jul 08, 2021 at 01:17:50AM +0300, Maxim Levitsky wrote: > > As far as I know this looks very good. > > Thanks for doing this! > > > > Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> > > Thanks! > > Michael - I just saw a pull req sent, so I wanted to double check: should this > patch go through your tree at last? Thanks, Sure. Will be in the next one. > -- > Peter Xu
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