[PATCH v3 0/3] Add support for Supervisor Software Events extension

[Clément Léger]

The SBI Supervisor Software Events (SSE) extensions provides a mechanism
to inject software events from an SBI implementation to supervisor
software such that it preempts all other supervisor level traps and
interrupts [1]. This series implements the V3 version of the spec.

Various events are defined and can be send asynchronously to supervisor
software (RAS, PMU, DEBUG, Asynchronous page fault) from SBI as well
as platform specific events. Events can be either local (per-hart) or
global. Events can be nested on top of each other based on priority and
can interrupt the supervisor mode at any time.

This implementation can be tested using kvm-unit-tests [2] with the
following commands:

Build kvm-unit-tests:

$ git clone https://github.com/clementleger/kvm-unit-tests.git
$ cd kvm-unit-tests
$ git switch dev/cleger/sse
$ ./configure --arch=riscv64 --cross-prefix=$CROSS_COMPILE
$ make

Run using Qemu:

$ ./qemu-system-riscv64 \
        -smp 4 \
        -M virt \
        -cpu rv64 \
        -nographic \
        -serial mon:stdio \
        -bios <opensbi>/build/platform/generic/firmware/fw_jump.bin \
        -kernel <kvm-unit-tests>/riscv/sbi_sse.flat

An implementation of a SSE "client" in linux is available [3].
This series can be found on github [5].

Link: https://lists.riscv.org/g/tech-prs/message/798 [1]
Link: https://github.com/clementleger/kvm-unit-tests/tree/dev/cleger/sse [2]
Link: https://github.com/rivosinc/linux/tree/dev/cleger/sse [3]
Link: http://lists.infradead.org/pipermail/opensbi/2024-March/006670.html [4]
Link: https://github.com/rivosinc/opensbi/tree/dev/cleger/sse_v3 [5]

---

Changes from v3:
 - Changes to follow v3 SSE specification
 - Use masks instead of struct with bitfields for status
 - Rework locking
 - SSE pending event processing is now done upon returning to previous
   mode

v2: http://lists.infradead.org/pipermail/opensbi/2024-January/006223.html

Changes from v2:
 - Move local/global event count initialization out of sse_global_init()
 - Remove PMU_IRQ_CLEAR SBI call and clear IRQ on SSE event completion
 - Change SBI_ERR_X to SBI_EXX defines
 - Add guards for invalid __riscv_xlen values
 - Update parameters passing (a6, a7)

v1: http://lists.infradead.org/pipermail/opensbi/2023-November/006015.html

Changes from v1:
 - Implemented SSE Spec v2
 - Change event state checking (Xiang W)

Clément Léger (3):
  lib: sbi: Add support for Supervisor Software Events extension
  lib: sbi: Implement SBI SSE extension
  lib: sbi: Add SSE support for PMU events

 include/sbi/sbi_ecall_interface.h |   79 +-
 include/sbi/sbi_error.h           |    2 +
 include/sbi/sbi_pmu.h             |    3 +
 include/sbi/sbi_sse.h             |   94 +++
 lib/sbi/Kconfig                   |    4 +
 lib/sbi/objects.mk                |    4 +
 lib/sbi/sbi_ecall_sse.c           |   57 ++
 lib/sbi/sbi_init.c                |   13 +
 lib/sbi/sbi_pmu.c                 |   51 ++
 lib/sbi/sbi_sse.c                 | 1131 +++++++++++++++++++++++++++++
 lib/sbi/sbi_trap.c                |   11 +
 11 files changed, 1448 insertions(+), 1 deletion(-)
 create mode 100644 include/sbi/sbi_sse.h
 create mode 100644 lib/sbi/sbi_ecall_sse.c
 create mode 100644 lib/sbi/sbi_sse.c

-- 
2.43.0