Re: [PATCH V3] irqchip/gic-v3: Workaround Marvell erratum 38545 when reading IAR

[Catalin Marinas <catalin.marinas@arm.com>]

On Mon, Mar 07, 2022 at 02:39:25PM +0000, Marc Zyngier wrote:
> On Mon, 07 Mar 2022 14:30:14 +0000,
> Linu Cherian <lcherian@marvell.com> wrote:
> > 
> > When a IAR register read races with a GIC interrupt RELEASE event,
> > GIC-CPU interface could wrongly return a valid INTID to the CPU
> > for an interrupt that is already released(non activated) instead of 0x3ff.
> > 
> > As a side effect, an interrupt handler could run twice, once with
> > interrupt priority and then with idle priority.
> > 
> > As a workaround, gic_read_iar is updated so that it will return a
> > valid interrupt ID only if there is a change in the active priority list
> > after the IAR read on all the affected Silicons.
> > 
> > Since there are silicon variants where both 23154 and 38545 are applicable,
> > workaround for erratum 23154 has been extended to address both of them.
> > 
> > Signed-off-by: Linu Cherian <lcherian@marvell.com>
> > ---
> > Changes since V2:
> > - Changed masked part number to individual part numbers
> > - Added additional comment to clarify on priority groups
> > 
> > 
> > Changes since V1:
> > - IIDR based quirk management done for 23154 has been reverted
> > - Extended existing 23154 errata to address 38545 as well,
> >   so that existing static keys are reused. 
> > - Added MIDR based support macros to cover all the affected parts
> > - Changed the unlikely construct to likely construct in the workaround
> >   function.
> > 
> > 
> > 
> > 
> >  Documentation/arm64/silicon-errata.rst |  2 +-
> >  arch/arm64/Kconfig                     |  8 ++++++--
> >  arch/arm64/include/asm/arch_gicv3.h    | 23 +++++++++++++++++++++--
> >  arch/arm64/include/asm/cputype.h       | 13 +++++++++++++
> >  arch/arm64/kernel/cpu_errata.c         | 20 +++++++++++++++++---
> >  5 files changed, 58 insertions(+), 8 deletions(-)
> 
> Looks good to me this time.
> 
> Catalin, Will: happy to take this into the irqchip tree for 5.18 with
> your Ack, or you can take it into the arm64 tree with my
> 
> Reviewed-by: Marc Zyngier <maz@kernel.org>

Fine by me to take it into irqchip but do a quick check for conflicts
with other arm64 changes in for-next/core.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>