CVS commit: src/sys/arch/arm/cortex

["Jared D. McNeill" <jmcneill%netbsd.org@localhost>]

Module Name:    src
Committed By:   jmcneill
Date:           Sun May 24 22:00:52 UTC 2026

Modified Files:
        src/sys/arch/arm/cortex: gicv3_its.c gicv3_its.h

Log Message:
gicv3_its: Fix ITT sizing.

The ITT being allocated did not match the size specified on the MAPD
command. This could cause hardware to read past the end of the ITT.

The old code used a fixed offset mapping scheme to assign eventIDs (the
eventID was derived from the LPI INTID). This scheme is wasteful and
doesn't scale well as the ITT is essentially an array of ITEs starting
with eventID 0. This change introduces per-deviceID namespaces for
eventIDs and allocates them starting with 0. A fixed number of eventIDs is
made available for each deviceID (MAXCPUS * 2). On a platform with an ITE
size of 8 bytes, this allows the ITT to fit in a single page.

The ITT is sized larger than the initial request as multiple requestors
could potentially share the same deviceID (this is the case for legacy PCI
devices behind a PCIe-to-PCI bridge).

The size parameter of the MAPD command now matches the allocated ITT.

Tested on QEMU KVM Virtual Machine and Ampere eMAG (Lenovo HR330A).


To generate a diff of this commit:
cvs rdiff -u -r1.41 -r1.42 src/sys/arch/arm/cortex/gicv3_its.c
cvs rdiff -u -r1.10 -r1.11 src/sys/arch/arm/cortex/gicv3_its.h

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.