[PATCH] RISC-V: Do not issue remote fences until smp is available

[Atish Patra]

It is useless to issue remote fences if there is a single core
available. It becomes a bottleneck for sbi based rfences where
we will be making those ECALLs for no reason. Early code patching
because of static calls end up in this path.

Signed-off-by: Atish Patra <atishp at rivosinc.com>
---
 arch/riscv/mm/cacheflush.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/riscv/mm/cacheflush.c b/arch/riscv/mm/cacheflush.c
index f10cb47eac3a..7fafc8c26505 100644
--- a/arch/riscv/mm/cacheflush.c
+++ b/arch/riscv/mm/cacheflush.c
@@ -19,6 +19,10 @@ void flush_icache_all(void)
 {
 	local_flush_icache_all();
 
+	/* No need to issue remote fence if only 1 cpu is online */
+	if (num_online_cpus() == 1)
+		return;
+
 	if (IS_ENABLED(CONFIG_RISCV_SBI) && !riscv_use_ipi_for_rfence())
 		sbi_remote_fence_i(NULL);
 	else
-- 
2.34.1