linux-kernel - RE: [PATCH v2 11/13] Documentation: userspace-api: iommufd: Update EVENTQ_IOPF and EVENTQ

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Message-ID: <BN9PR11MB5276E09D5F2206804A7C15968C3E2@BN9PR11MB5276.namprd11.prod.outlook.com>
Date: Wed, 11 Dec 2024 08:11:03 +0000
From: "Tian, Kevin" <kevin.tian@...el.com>
To: Nicolin Chen <nicolinc@...dia.com>, "jgg@...dia.com" <jgg@...dia.com>,
	"will@...nel.org" <will@...nel.org>
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	<linux-kernel@...r.kernel.org>, "iommu@...ts.linux.dev"
	<iommu@...ts.linux.dev>, "linux-arm-kernel@...ts.infradead.org"
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	<smostafa@...gle.com>, "ddutile@...hat.com" <ddutile@...hat.com>, "Liu, Yi L"
	<yi.l.liu@...el.com>
Subject: RE: [PATCH v2 11/13] Documentation: userspace-api: iommufd: Update
 EVENTQ_IOPF and EVENTQ_VIRQ

> From: Nicolin Chen <nicolinc@...dia.com>
> Sent: Wednesday, December 4, 2024 6:10 AM
> 
> With the introduction of the new objects, update the doc to reflect that.
> 
> Signed-off-by: Nicolin Chen <nicolinc@...dia.com>
> ---
>  Documentation/userspace-api/iommufd.rst | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/Documentation/userspace-api/iommufd.rst
> b/Documentation/userspace-api/iommufd.rst
> index 70289d6815d2..798520d9344d 100644
> --- a/Documentation/userspace-api/iommufd.rst
> +++ b/Documentation/userspace-api/iommufd.rst
> @@ -63,6 +63,14 @@ Following IOMMUFD objects are exposed to userspace:
>    space usually has mappings from guest-level I/O virtual addresses to guest-
>    level physical addresses.
> 
> +- IOMMUFD_OBJ_EVENTQ_IOPF, representing a software queue for an
> HWPT_NESTED

now it can be used on paging hwpt too

> +  reporting IO Page Fault using the IOMMU HW's PRI (Page Request
> Interface).
> +  This queue object provides user space an FD to poll the page fault events
> +  and also to respond to those events. An EVENTQ_IOPF object must be
> created
> +  first to get a fault_id that could be then used to allocate an HWPT_NESTED
> +  via the IOMMU_HWPT_ALLOC command setting
> IOMMU_HWPT_FAULT_ID_VALID set in
> +  its flags field.
> +
>  - IOMMUFD_OBJ_VIOMMU, representing a slice of the physical IOMMU
> instance,
>    passed to or shared with a VM. It may be some HW-accelerated
> virtualization
>    features and some SW resources used by the VM. For examples:
> @@ -109,6 +117,15 @@ Following IOMMUFD objects are exposed to
> userspace:
>    vIOMMU, which is a separate ioctl call from attaching the same device to an
>    HWPT_PAGING that the vIOMMU holds.
> 
> +- IOMMUFD_OBJ_EVENTQ_VIRQ, representing a software queue for
> IOMMUFD_OBJ_VIOMMU
> +  reporting its non-affiliated events, such as translation faults occurred to a

non-affiliated is only mentioned here. It's not a standard term in this
area. Sticking to the later examples in 'such as' is straightforward.

> +  nested stage-1 and HW-specific events/irqs e.g. events to invalidation
> queues
> +  that are assigned to VMs via vIOMMUs. This queue object provides user

vcmdq is not supported yet. add it later.

> space an
> +  FD to poll the vIOMMU events. A vIOMMU object must be created first to
> get its
> +  viommu_id that could be then used to allocate an EVENTQ_VIRQ. Each
> vIOMMU can
> +  support multiple types of EVENTQ_VIRQs, but is confined to one
> EVENTQ_VIRQ per
> +  vIRQ type.
> +
>  All user-visible objects are destroyed via the IOMMU_DESTROY uAPI.
> 
>  The diagrams below show relationships between user-visible objects and
> kernel
> @@ -251,8 +268,10 @@ User visible objects are backed by following
> datastructures:
>  - iommufd_device for IOMMUFD_OBJ_DEVICE.
>  - iommufd_hwpt_paging for IOMMUFD_OBJ_HWPT_PAGING.
>  - iommufd_hwpt_nested for IOMMUFD_OBJ_HWPT_NESTED.
> +- iommufd_eventq_iopf for IOMMUFD_OBJ_EVENTQ_IOPF.
>  - iommufd_viommu for IOMMUFD_OBJ_VIOMMU.
>  - iommufd_vdevice for IOMMUFD_OBJ_VDEVICE.
> +- iommufd_eventq_virq for IOMMUFD_OBJ_EVENTQ_VIRQ.
> 
>  Several terminologies when looking at these datastructures:
> 
> --
> 2.43.0