[PATCH 0/2] GIC v4.1: Disable VSGI support for GIC CPUIF < v4.1

[Lorenzo Pieralisi]

GIC v4.1 introduced changes to the GIC CPU interface; systems that
integrate CPUs that do not support GIC v4.1 features (as reported in the
ID_AA64PFR0_EL1.GIC bitfield) and a GIC v4.1 controller must disable in
software virtual SGIs support since the CPUIF and GIC controller version
mismatch results in CONSTRAINED UNPREDICTABLE behaviour at architectural
level.

For systems with CPUs reporting ID_AA64PFR0_EL1.GIC == b0001 integrated
in a system with a GIC v4.1 it _should_ still be safe to enable vLPIs
(other than vSGI) since the protocol between the GIC redistributor and
the GIC CPUIF was not changed from GIC v4.0 to GIC v4.1.

Cc: Will Deacon <will at kernel.org>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Marc Zyngier <maz at kernel.org>

Lorenzo Pieralisi (2):
  arm64: cpufeature: Add GIC CPUIF v4.1 detection
  irqchip/gic-v3-its: Disable vSGI upon (CPUIF < v4.1) detection

 arch/arm64/include/asm/cpucaps.h |  3 ++-
 arch/arm64/kernel/cpufeature.c   | 10 ++++++++++
 drivers/irqchip/irq-gic-v3-its.c | 20 +++++++++++++++++++-
 3 files changed, 31 insertions(+), 2 deletions(-)

-- 
2.29.1