[PATCH 2/2] Documentation: x86: Clarify Intel IOMMU documenation

From: Alex Deucher
Date: Wed Mar 09 2022 - 12:59:00 EST


Based on feedback from Robin on the initial AMD IOMMU
documentation, fix up the Intel documentation to
clarify IOMMU vs device and modern DMA API.

Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
---
Documentation/x86/intel-iommu.rst | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/Documentation/x86/intel-iommu.rst b/Documentation/x86/intel-iommu.rst
index 4d3391c7bd3f..22e1934a1335 100644
--- a/Documentation/x86/intel-iommu.rst
+++ b/Documentation/x86/intel-iommu.rst
@@ -19,8 +19,8 @@ Some Keywords
Basic stuff
-----------

-ACPI enumerates and lists the different DMA engines in the platform, and
-device scope relationships between PCI devices and which DMA engine controls
+ACPI enumerates and lists the different IOMMUs in the platform, and
+device scope relationships between PCI devices and which IOMMU controls
them.

What is RMRR?
@@ -36,9 +36,9 @@ unity mappings for these regions for these devices to access these regions.
How is IOVA generated?
----------------------

-Well behaved drivers call pci_map_*() calls before sending command to device
+Well behaved drivers call dma_map_*() calls before sending command to device
that needs to perform DMA. Once DMA is completed and mapping is no longer
-required, device performs a pci_unmap_*() calls to unmap the region.
+required, device performs a dma_unmap_*() calls to unmap the region.

The Intel IOMMU driver allocates a virtual address per domain. Each PCIE
device has its own domain (hence protection). Devices under p2p bridges
@@ -68,7 +68,7 @@ address from PCI MMIO ranges so they are not allocated for IOVA addresses.

Fault reporting
---------------
-When errors are reported, the DMA engine signals via an interrupt. The fault
+When errors are reported, the IOMMU signals via an interrupt. The fault
reason and device that caused it with fault reason is printed on console.

See below for sample.
--
2.35.1