Re: [PATCH 00/10] irqchip/gic-v5: Fix misc IRS and ITS host driver issues

[Lorenzo Pieralisi <lpieralisi@kernel.org>]

On Mon, Nov 02, 2026 at 01:32:53PM +0000, Sascha Bischoff wrote:
> This series fixes issues in the GICv5 host IRS and ITS drivers.
> 
> The ITS invalidation serialisation fix addresses Sashiko's report of a
> race between event and device invalidation commands [1]. The other
> patches correct IRS allocation and routing behaviour, serialise IRS
> synchronisation, and fix ITS L1/L2 table selection, cache maintenance,
> ACPI coherency handling, and resource cleanup.
> 
> The IRS changes:
> * Reject allocation of an SPI without an IRS, preventing a null-pointer
>   dereference, and warn about low-quality firmware.
> * Only program IRS_PE_CR0.DPS when 1-of-N routing is supported as this field
>   is RES0, otherwise.
> * Serialise IRS synchronisation requests, as the IRS ignores a request while
>   an earlier one is still active.
> 
> The ITS changes:
> * Serialise event and device cache invalidations because both use the ITS's
>   shared DIDR register, so concurrent writes are a bad idea!
> * Select linear device and interrupt translation tables when one L2
>   table covers the full ID space. Currently, this selects the wrong
>   path, then the L1 table code rejects the attempt to create the
>   table.
> * Check the ACPI noncoherent flag with ACPI, rather than checking the
>   DT's property.
> * Correct cache-maintenance sizing after limiting the DeviceID width.
> * Invalidate the device cache before freeing an ITT.
> * Use firmware-node names in initialisation warnings.
> * Release the reserved MMIO region if DT-based ITS initialisation fails.
> 
> I've CC'd stable for the IRS/ITS locking fixes, the ITS table alloc
> issue, and the ACPI coherency fix, as these are the most important
> changes to backport.
> 
> The series is based on v7.4-rc1. Thanks for taking a look!

Thank you for fixing these bugs Sascha.

Lorenzo

> 
> Sascha
> 
> [1] https://sashiko.dev/#/patchset/20261016155741.979985-1-sascha.bischoff@arm.com?part=11
> 
> Signed-off-by: Sascha Bischoff <sascha.bischoff@arm.com>
> ---
> Sascha Bischoff (10):
>       irqchip/gic-v5: Reject SPIs not backed by an IRS
>       irqchip/gic-v5: Only set IRS DPS when 1ofN routing is supported
>       irqchip/gic-v5: Serialise IRS synchronisation requests
>       irqchip/gic-v5: Serialise ITS invalidation commands
>       irqchip/gic-v5: Use linear DT and ITT when L2 covers all IDs
>       irqchip/gic-v5: Honour ACPI ITS noncoherent flag
>       irqchip/gic-v5: Use firmware node name in ITS warning
>       irqchip/gic-v5: Invalidate ITS device cache before freeing ITT
>       irqchip/gic-v5: Clean the allocated linear device table size
>       irqchip/gic-v5: Release ITS MMIO region on DT probe failure
> 
>  drivers/irqchip/irq-gic-v5-irs.c   | 22 +++++++++++++++-------
>  drivers/irqchip/irq-gic-v5-its.c   | 29 ++++++++++++++++++++++++-----
>  drivers/irqchip/irq-gic-v5.c       |  9 +++++++++
>  include/linux/irqchip/arm-gic-v5.h |  1 +
>  4 files changed, 49 insertions(+), 12 deletions(-)
> ---
> base-commit: 6628e7d4c6b25c8d18f1345e3a20d21829aae7e4
> change-id: 20261102-host_gicv5_fixes-1eeea29d2ea4
> 
> Best regards,
> --  
> Sascha Bischoff <sascha.bischoff@arm.com>
>