Samuel Holland dc892fb443 riscv: Use IPIs for remote cache/TLB flushes by default ... An IPI backend is always required in an SMP configuration, but an SBI implementation is not. For example, SBI will be unavailable when the kernel runs in M mode. For this reason, consider IPI delivery of cache and TLB flushes to be the base case, and any other implementation (such as the SBI remote fence extension) to be an optimization. Generally, if IPIs can be delivered without firmware assistance, they are assumed to be faster than SBI calls due to the SBI context switch overhead. However, when SBI is used as the IPI backend, then the context switch cost must be paid anyway, and performing the cache/TLB flush directly in the SBI implementation is more efficient than injecting an interrupt to S-mode. This is the only existing scenario where riscv_ipi_set_virq_range() is called with use_for_rfence set to false. sbi_ipi_init() already checks riscv_ipi_have_virq_range(), so it only calls riscv_ipi_set_virq_range() when no other IPI device is available. This allows moving the static key and dropping the use_for_rfence parameter. This decouples the static key from the irqchip driver probe order. Furthermore, the static branch only makes sense when CONFIG_RISCV_SBI is enabled. Optherwise, IPIs must be used. Add a fallback definition of riscv_use_sbi_for_rfence() which handles this case and removes the need to check CONFIG_RISCV_SBI elsewhere, such as in cacheflush.c. Reviewed-by: Anup Patel <anup@brainfault.org> Signed-off-by: Samuel Holland <samuel.holland@sifive.com> Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com> Link: https://lore.kernel.org/r/20240327045035.368512-4-samuel.holland@sifive.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>		2024-04-29 10:49:26 -07:00
..
boot	RISC-V Patches for the 6.9 Merge Window	2024-03-22 10:41:13 -07:00
configs	RISC-V Patches for the 6.9 Merge Window	2024-03-22 10:41:13 -07:00
crypto	crypto: riscv - add vector crypto accelerated AES-CBC-CTS	2024-03-20 08:56:11 -07:00
errata	riscv: errata: Rename defines for Andes	2024-03-12 07:13:12 -07:00
include	riscv: Use IPIs for remote cache/TLB flushes by default	2024-04-29 10:49:26 -07:00
kernel	riscv: Use IPIs for remote cache/TLB flushes by default	2024-04-29 10:49:26 -07:00
kvm	KVM/riscv changes for 6.9	2024-03-11 10:10:48 -04:00
lib	RISC-V Patches for the 6.9 Merge Window	2024-03-22 10:41:13 -07:00
mm	riscv: Use IPIs for remote cache/TLB flushes by default	2024-04-29 10:49:26 -07:00
net	bpf, riscv64/cfi: Support kCFI + BPF on riscv64	2024-03-06 15:18:16 -08:00
purgatory	riscv: Use SYM_*() assembly macros instead of deprecated ones	2023-11-06 09:42:47 -08:00
tools	riscv: Check relocations at compile time	2023-04-19 07:46:32 -07:00
Kbuild	RISC-V: hook new crypto subdir into build-system	2024-01-22 17:55:17 -08:00
Kconfig	RISC-V Patches for the 6.9 Merge Window	2024-03-22 10:41:13 -07:00
Kconfig.debug	riscv: Add tests for riscv module loading	2023-11-07 14:59:32 -08:00
Kconfig.errata	RISC-V Patches for the 6.8 Merge Window, Part 4	2024-01-20 11:06:04 -08:00
Kconfig.socs	riscv: dts: Move BUILTIN_DTB_SOURCE to common Kconfig	2024-03-06 00:08:32 +00:00
Makefile	RISC-V: build: Allow LTO to be selected	2024-01-22 10:06:29 -08:00
Makefile.postlink	kbuild: remove ARCH_POSTLINK from module builds	2023-10-28 21:10:08 +09:00