Re: [PATCH] docs: Add '-device intel-iommu' entry
Hi Peter,
On 7/7/21 5:35 PM, Peter Xu wrote:
> On Wed, Jul 07, 2021 at 11:29:47AM +0200, Eric Auger wrote:
>> Hi Peter,
>
> Hi, Eric,
>
>>
>> On 6/11/21 8:55 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
>>> Cc: Lei Yang
>>> Cc: Jing Zhao
>>> Cc: Jason Wang
>>> Cc: Michael S. Tsirkin
>>> Cc: Alex Williamson
>>> Signed-off-by: Peter Xu
>>> ---
>>> qemu-options.hx | 32
>>> 1 file changed, 32 insertions(+)
>>>
>>> diff --git a/qemu-options.hx b/qemu-options.hx
>>> index 14258784b3a..4bb04243907 100644
>>> --- a/qemu-options.hx
>>> +++ b/qemu-options.hx
>>> @@ -926,6 +926,38 @@ 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 in the guest. It's
>>> required
>>> +to enable complete x2apic. Currently it only supports kvm
>>> +kernel-irqchip modes ``off`` or ``split``. Full kernel-irqchip is
>>> not
>>> +yet supported.
>> maybe explain how the default is chosen (based on kernel-irqhcip mode?)
>
> Will do.
>
>>> +
>>> +``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,
>> I thought if was needed for vhost. What is the usage for virtio?
>
> I used "virtio/vhost" because vhost is only one type of virtio backend, so
> normally they should be used in pair. Also, the "ats=on" parameter should be
> an option to virtio frontend rather than vhost, hence I mentioned both.
OK makes sense.
>
>>> +paired with ats=on configured for the device.
>> What is not obvious to me is whether there is a kind of diagnosis
>> whether device-iotlb and caching mode settings are consistent with
>> vfio/vhost usage. Does qemu exit if there is inconsistency?
>
> Caching mode check is done in vtd_machine_done_notify_one().
>
> I think there's no such check for vhost, however iirc vhost should work
> with/without ats=on; I did't check deeper.
OK
>
>>> +
>>> +``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,
>>>
>> Besides, it is quite useful.
>
> Thanks for taking a look!
>
Besides,
Reviewed-by: Eric Auger
Eric
Re: [PATCH] docs: Add '-device intel-iommu' entry
On Wed, Jul 07, 2021 at 11:29:47AM +0200, Eric Auger wrote:
> Hi Peter,
Hi, Eric,
>
> On 6/11/21 8:55 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
> > Cc: Lei Yang
> > Cc: Jing Zhao
> > Cc: Jason Wang
> > Cc: Michael S. Tsirkin
> > Cc: Alex Williamson
> > Signed-off-by: Peter Xu
> > ---
> > qemu-options.hx | 32
> > 1 file changed, 32 insertions(+)
> >
> > diff --git a/qemu-options.hx b/qemu-options.hx
> > index 14258784b3a..4bb04243907 100644
> > --- a/qemu-options.hx
> > +++ b/qemu-options.hx
> > @@ -926,6 +926,38 @@ 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 in the guest. It's
> > required
> > +to enable complete x2apic. Currently it only supports kvm
> > +kernel-irqchip modes ``off`` or ``split``. Full kernel-irqchip is
> > not
> > +yet supported.
> maybe explain how the default is chosen (based on kernel-irqhcip mode?)
Will do.
> > +
> > +``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,
> I thought if was needed for vhost. What is the usage for virtio?
I used "virtio/vhost" because vhost is only one type of virtio backend, so
normally they should be used in pair. Also, the "ats=on" parameter should be
an option to virtio frontend rather than vhost, hence I mentioned both.
> > +paired with ats=on configured for the device.
> What is not obvious to me is whether there is a kind of diagnosis
> whether device-iotlb and caching mode settings are consistent with
> vfio/vhost usage. Does qemu exit if there is inconsistency?
Caching mode check is done in vtd_machine_done_notify_one().
I think there's no such check for vhost, however iirc vhost should work
with/without ats=on; I did't check deeper.
> > +
> > +``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,
> >
> Besides, it is quite useful.
Thanks for taking a look!
--
Peter Xu
Re: [PATCH] docs: Add '-device intel-iommu' entry
On Wed, Jul 07, 2021 at 11:35:43AM +0800, Jason Wang wrote: > > 在 2021/6/12 上午2:55, Peter Xu 写道: > > 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 > > Cc: Lei Yang > > Cc: Jing Zhao > > Cc: Jason Wang > > Cc: Michael S. Tsirkin > > Cc: Alex Williamson > > Signed-off-by: Peter Xu > > --- > > qemu-options.hx | 32 > > 1 file changed, 32 insertions(+) > > > > diff --git a/qemu-options.hx b/qemu-options.hx > > index 14258784b3a..4bb04243907 100644 > > --- a/qemu-options.hx > > +++ b/qemu-options.hx > > @@ -926,6 +926,38 @@ 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 in the guest. > > > I think we don't need "in the guest" here. Sure. > > Other than this: > > Reviewed-by: Jason Wang Thanks, -- Peter Xu
RE: [PATCH] docs: Add '-device intel-iommu' entry
> From: Peter Xu < pet...@redhat.com >
> Sent: Saturday, June 12, 2021 2:55 AM
>
> 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.
yes, it's a good start.
Looks good to me.
Reviewed-by: Liu Yi L
Regards,
Yi Liu
>
> Cc: Chao Yang
> Cc: Lei Yang
> Cc: Jing Zhao
> Cc: Jason Wang
> Cc: Michael S. Tsirkin
> Cc: Alex Williamson
> Signed-off-by: Peter Xu
> ---
> qemu-options.hx | 32
> 1 file changed, 32 insertions(+)
>
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 14258784b3a..4bb04243907 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -926,6 +926,38 @@ 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 in the guest. It's required
> +to enable complete x2apic. Currently it only supports kvm
> +kernel-irqchip modes ``off`` or ``split``. Full kernel-irqchip is
> not
> +yet supported.
> +
> +``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
>
Re: [PATCH] docs: Add '-device intel-iommu' entry
Hi Peter,
On 6/11/21 8:55 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
> Cc: Lei Yang
> Cc: Jing Zhao
> Cc: Jason Wang
> Cc: Michael S. Tsirkin
> Cc: Alex Williamson
> Signed-off-by: Peter Xu
> ---
> qemu-options.hx | 32
> 1 file changed, 32 insertions(+)
>
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 14258784b3a..4bb04243907 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -926,6 +926,38 @@ 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 in the guest. It's required
> +to enable complete x2apic. Currently it only supports kvm
> +kernel-irqchip modes ``off`` or ``split``. Full kernel-irqchip is
> not
> +yet supported.
maybe explain how the default is chosen (based on kernel-irqhcip mode?)
> +
> +``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,
I thought if was needed for vhost. What is the usage for virtio?
> +paired with ats=on configured for the device.
What is not obvious to me is whether there is a kind of diagnosis
whether device-iotlb and caching mode settings are consistent with
vfio/vhost usage. Does qemu exit if there is inconsistency?
> +
> +``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,
>
Besides, it is quite useful.
Thanks
Eric
Re: [PATCH] docs: Add '-device intel-iommu' entry
在 2021/6/12 上午2:55, Peter Xu 写道:
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
Cc: Lei Yang
Cc: Jing Zhao
Cc: Jason Wang
Cc: Michael S. Tsirkin
Cc: Alex Williamson
Signed-off-by: Peter Xu
---
qemu-options.hx | 32
1 file changed, 32 insertions(+)
diff --git a/qemu-options.hx b/qemu-options.hx
index 14258784b3a..4bb04243907 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -926,6 +926,38 @@ 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 in the guest.
I think we don't need "in the guest" here.
Other than this:
Reviewed-by: Jason Wang
Thanks
It's required
+to enable complete x2apic. Currently it only supports kvm
+kernel-irqchip modes ``off`` or ``split``. Full kernel-irqchip is not
+yet supported.
+
+``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,
Re: [PATCH] docs: Add '-device intel-iommu' entry
On Fri, Jun 11, 2021 at 02:55:00PM -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 > Cc: Lei Yang > Cc: Jing Zhao > Cc: Jason Wang > Cc: Michael S. Tsirkin > Cc: Alex Williamson > Signed-off-by: Peter Xu > --- > qemu-options.hx | 32 > 1 file changed, 32 insertions(+) Ping.. -- Peter Xu
[PATCH] 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
Cc: Lei Yang
Cc: Jing Zhao
Cc: Jason Wang
Cc: Michael S. Tsirkin
Cc: Alex Williamson
Signed-off-by: Peter Xu
---
qemu-options.hx | 32
1 file changed, 32 insertions(+)
diff --git a/qemu-options.hx b/qemu-options.hx
index 14258784b3a..4bb04243907 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -926,6 +926,38 @@ 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 in the guest. It's required
+to enable complete x2apic. Currently it only supports kvm
+kernel-irqchip modes ``off`` or ``split``. Full kernel-irqchip is not
+yet supported.
+
+``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
