Re: [PATCH v16 0/9] RISC-V IPI Improvements

[Anup Patel]

Hi Marc,

On Thu, Jan 12, 2023 at 5:47 PM Anup Patel <apatel@xxxxxxxxxxxxxxxx> wrote:
>
> Hi Marc,
>
> On Tue, Jan 3, 2023 at 7:42 PM Anup Patel <apatel@xxxxxxxxxxxxxxxx> wrote:
> >
> > This series aims to improve IPI support in Linux RISC-V in following ways:
> >  1) Treat IPIs as normal per-CPU interrupts instead of having custom RISC-V
> >     specific hooks. This also makes Linux RISC-V IPI support aligned with
> >     other architectures.
> >  2) Remote TLB flushes and icache flushes should prefer local IPIs instead
> >     of SBI calls whenever we have specialized hardware (such as RISC-V AIA
> >     IMSIC and RISC-V SWI) which allows S-mode software to directly inject
> >     IPIs without any assistance from M-mode runtime firmware.
> >
> > These patches were originally part of the "Linux RISC-V ACLINT Support"
> > series but this now a separate series so that it can be merged independently
> > of the "Linux RISC-V ACLINT Support" series.
> > (Refer, https://lore.kernel.org/lkml/20211007123632.697666-1-anup.patel@xxxxxxx/)
> >
> > These patches are also a preparatory patches for the up-coming:
> >  1) Linux RISC-V AIA support
> >  2) Linux RISC-V SWI support
> >
> > These patches can also be found in riscv_ipi_imp_v16 branch at:
> > https://github.com/avpatel/linux.git
> >
> > Changes since v15:
> >  - Rebased on Linux-6.2-rc2
> >  - Added Reviewed-by and Tested-by tags to some of the patches.
> >
> > Changes since v14:
> >  - Minor fixes in commit description of PATCH3 (as suggested by tglx)
> >  - Don't disable parent IPI when CPU goes offline for SBI IPI driver and
> >    CLINT driver in PATCH4.
> >  - Include Apple AIC driver changes from Marc Z as PATCH9
> >
> > Changes since v13:
> >  - Included changes suggested by Marc Z in PATCH3
> >  - Use chained handlers in PATCH4
> >  - Added new PATCH8 to have empty irq_eoi() in RISC-V INTC driver. This
> >    avoids the unnecessary mask/unmask dance at time of handling interrupts.
> >
> > Changes since v12:
> >  - Rebased on Linux-6.1-rc7
> >  - Bring-back the IPI optimization in ipi_mux_send_mask() for PATCH3
> >  - Call ipi_mux_send() for one target CPU at a time in PATCH3
> >
> > Changes since v11:
> >  - Removed ipi_mux_pre/post_handle() callbacks in PATCH3
> >  - Removed sturct ipi_mux_ops in PATCH3
> >  - Removed parent_virq and data pointer from everywhere in PATCH3
> >  - Removed struct ipi_mux_control in PATCH3
> >  - Improved function signature of ipi_mux_send() callback in PATCH3
> >  - Used unsigned type with atomic operation in PATCH3
> >
> > Changes since v10:
> >  - Rebased on Linux-6.1-rc5
> >  - Drop the "!(pending & ibit)" check in ipi_mux_send_mask() of PATCH3
> >  - Disable local interrupts in ipi_mux_send_mask() of PATCH3 because we
> >    can be preempted while using a per-CPU temporary variable.
> >
> > Changes since v9:
> >  - Rebased on Linux-6.1-rc3
> >  - Updated header comment block of ipi-mux.c in PATCH3
> >  - Use a struct for global data of ipi-mux.c in PATCH3
> >  - Add per-CPU temp cpumask for sending IPIs in PATCH3
> >  - Drop the use of fwspec in PATCH3
> >  - Use static key for ipi_mux_pre_handle() and ipi_mux_post_handle()
> >    in PATCH3
> >  - Remove redundant pr_warn_ratelimited() called by ipi_mux_process()
> >    in PATCH3
> >  - Remove CPUHP thingy from ipi_mux_create() in PATCH3
> >
> > Changes since v8:
> >  - Rebased on Linux-6.0-rc3
> >  - Use dummy percpu data as parameter for request_percpu_irq() in PATCH4.
> >
> > Changes since v7:
> >  - Rebased on Linux-6.0-rc1
> >  - Use atomic operations to track per-CPU pending and enabled IPIs in PATCH3.
> >    (Note: this is inspired from IPI muxing implemented in
> >     drivers/irqchip/irq-apple-aic.c)
> >  - Made "struct ipi_mux_ops" (added by PATCH3) flexible so that
> >    drivers/irqchip/irq-apple-aic.c can adopt it in future.
> >
> > Changes since v6:
> >  - Rebased on Linux-5.19-rc7
> >  - Added documentation for struct ipi_mux_ops in PATCH3
> >  - Dropped dummy irq_mask()/unmask() in PATCH3
> >  - Added const for "ipi_mux_chip" in PATCH3
> >  - Removed "type" initialization from ipi_mux_domain_alloc() in PATCH3
> >  - Dropped translate() from "ipi_mux_domain_ops" in PATCH3
> >  - Improved barrier documentation in ipi_mux_process() of PATCH3
> >  - Added percpu check in ipi_mux_create() for parent_virq of PATCH3
> >  - Added nr_ipi parameter in ipi_mux_create() of PATCH3
> >
> > Changes since v5:
> >  - Rebased on Linux-5.18-rc3
> >  - Used kernel doc style in PATCH3
> >  - Removed redundant loop in ipi_mux_process() of PATCH3
> >  - Removed "RISC-V" prefix form ipi_mux_chip.name of PATCH3
> >  - Removed use of "this patch" in PATCH3 commit description
> >  - Addressed few other nit comments in PATCH3
> >
> > Changes since v4:
> >  - Rebased on Linux-5.17
> >  - Includes new PATCH3 which adds mechanism to multiplex a single HW IPI
> >
> > Changes since v3:
> >  - Rebased on Linux-5.17-rc6
> >  - Updated PATCH2 to not export riscv_set_intc_hwnode_fn()
> >  - Simplified riscv_intc_hwnode() in PATCH2
> >
> > Changes since v2:
> >  - Rebased on Linux-5.17-rc4
> >  - Updated PATCH2 to not create synthetic INTC fwnode and instead provide
> >    a function which allows drivers to directly discover INTC fwnode
> >
> > Changes since v1:
> >  - Use synthetic fwnode for INTC instead of irq_set_default_host() in PATCH2
> >
> > Anup Patel (8):
> >   RISC-V: Clear SIP bit only when using SBI IPI operations
> >   irqchip/riscv-intc: Allow drivers to directly discover INTC hwnode
> >   genirq: Add mechanism to multiplex a single HW IPI
> >   RISC-V: Treat IPIs as normal Linux IRQs
> >   RISC-V: Allow marking IPIs as suitable for remote FENCEs
> >   RISC-V: Use IPIs for remote TLB flush when possible
> >   RISC-V: Use IPIs for remote icache flush when possible
> >   irqchip/riscv-intc: Add empty irq_eoi() for chained irq handlers
> >
> > Marc Zyngier (1):
> >   irqchip/apple-aic: Move over to core ipi-mux
> >
> >  arch/riscv/Kconfig                |   2 +
> >  arch/riscv/include/asm/irq.h      |   4 +
> >  arch/riscv/include/asm/sbi.h      |   9 +-
> >  arch/riscv/include/asm/smp.h      |  49 +++++--
> >  arch/riscv/kernel/Makefile        |   1 +
> >  arch/riscv/kernel/cpu-hotplug.c   |   3 +-
> >  arch/riscv/kernel/irq.c           |  21 ++-
> >  arch/riscv/kernel/sbi-ipi.c       |  77 +++++++++++
> >  arch/riscv/kernel/sbi.c           | 100 +++------------
> >  arch/riscv/kernel/smp.c           | 171 ++++++++++++------------
> >  arch/riscv/kernel/smpboot.c       |   5 +-
> >  arch/riscv/mm/cacheflush.c        |   5 +-
> >  arch/riscv/mm/tlbflush.c          |  93 +++++++++++---
> >  drivers/clocksource/timer-clint.c |  65 +++++++---
> >  drivers/irqchip/Kconfig           |   2 +
> >  drivers/irqchip/irq-apple-aic.c   | 161 ++---------------------
> >  drivers/irqchip/irq-riscv-intc.c  |  71 ++++++----
> >  include/linux/irq.h               |   3 +
> >  kernel/irq/Kconfig                |   5 +
> >  kernel/irq/Makefile               |   1 +
> >  kernel/irq/ipi-mux.c              | 207 ++++++++++++++++++++++++++++++
> >  21 files changed, 654 insertions(+), 401 deletions(-)
> >  create mode 100644 arch/riscv/kernel/sbi-ipi.c
> >  create mode 100644 kernel/irq/ipi-mux.c
> >
> > --
> > 2.34.1
> >
>
> Friendly ping ?

Any further comments on this series ?

Regards,
Anup