linux-kernel - [PATCH v3 12/14] Documentation: userspace-api: iommufd: Update FAULT and VIRQ

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Message-ID: <9026d32c1ef46ca867e27777f653c736551ba692.1734477608.git.nicolinc@nvidia.com>
Date: Tue, 17 Dec 2024 21:00:25 -0800
From: Nicolin Chen <nicolinc@...dia.com>
To: <jgg@...dia.com>, <kevin.tian@...el.com>, <will@...nel.org>
CC: <corbet@....net>, <joro@...tes.org>, <suravee.suthikulpanit@....com>,
	<robin.murphy@....com>, <dwmw2@...radead.org>, <baolu.lu@...ux.intel.com>,
	<shuah@...nel.org>, <linux-kernel@...r.kernel.org>, <iommu@...ts.linux.dev>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-kselftest@...r.kernel.org>,
	<linux-doc@...r.kernel.org>, <eric.auger@...hat.com>,
	<jean-philippe@...aro.org>, <mdf@...nel.org>, <mshavit@...gle.com>,
	<shameerali.kolothum.thodi@...wei.com>, <smostafa@...gle.com>,
	<ddutile@...hat.com>, <yi.l.liu@...el.com>, <patches@...ts.linux.dev>
Subject: [PATCH v3 12/14] Documentation: userspace-api: iommufd: Update FAULT and VIRQ

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 | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/Documentation/userspace-api/iommufd.rst b/Documentation/userspace-api/iommufd.rst
index 70289d6815d2..5b4ef5d74fd1 100644
--- a/Documentation/userspace-api/iommufd.rst
+++ b/Documentation/userspace-api/iommufd.rst
@@ -63,6 +63,13 @@ Following IOMMUFD objects are exposed to userspace:
   space usually has mappings from guest-level I/O virtual addresses to guest-
   level physical addresses.
 
+- IOMMUFD_FAULT, representing a software queue for an HWPT reporting IO page
+  faults 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. A FAULT object must be created first to get a fault_id that
+  could be then used to allocate a fault-enabled HWPT via the IOMMU_HWPT_ALLOC
+  command by setting the IOMMU_HWPT_FAULT_ID_VALID bit 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 +116,13 @@ 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_VIRQ, representing a software queue for a vIOMMU reporting events
+  such as translation faults occurred to a nested stage-1 and HW-specific irqs.
+  This queue object provides user space an FD to poll the vIOMMU events/virqs.
+  A vIOMMU object must be created first to get its viommu_id that could be then
+  used to allocate a VIRQ. Each vIOMMU can support multiple types of VIRQs, but
+  is confined to one 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 +265,10 @@ 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_fault for IOMMUFD_OBJ_FAULT.
 - iommufd_viommu for IOMMUFD_OBJ_VIOMMU.
 - iommufd_vdevice for IOMMUFD_OBJ_VDEVICE.
+- iommufd_virq for IOMMUFD_OBJ_VIRQ.
 
 Several terminologies when looking at these datastructures:
 
-- 
2.43.0