linux-kernel - [PATCH v9 7/7] RISC-V: Use IPIs for remote icache flush when possible

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Message-Id: <20220903161309.32848-8-apatel@ventanamicro.com>
Date:   Sat,  3 Sep 2022 21:43:09 +0530
From:   Anup Patel <apatel@...tanamicro.com>
To:     Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     Atish Patra <atishp@...shpatra.org>,
        Alistair Francis <Alistair.Francis@....com>,
        Anup Patel <anup@...infault.org>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Anup Patel <apatel@...tanamicro.com>
Subject: [PATCH v9 7/7] RISC-V: Use IPIs for remote icache flush when possible

If we have specialized interrupt controller (such as AIA IMSIC) which
allows supervisor mode to directly inject IPIs without any assistance
from M-mode or HS-mode then using such specialized interrupt controller,
we can do remote icache flushe directly from supervisor mode instead of
using the SBI RFENCE calls.

This patch extends remote icache flush functions to use supervisor mode
IPIs whenever direct supervisor mode IPIs.are supported by interrupt
controller.

Signed-off-by: Anup Patel <apatel@...tanamicro.com>
---
 arch/riscv/mm/cacheflush.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/mm/cacheflush.c b/arch/riscv/mm/cacheflush.c
index 336c5deea870..45bcf1f635c5 100644
--- a/arch/riscv/mm/cacheflush.c
+++ b/arch/riscv/mm/cacheflush.c
@@ -20,7 +20,7 @@ void flush_icache_all(void)
 {
 	local_flush_icache_all();
 
-	if (IS_ENABLED(CONFIG_RISCV_SBI))
+	if (IS_ENABLED(CONFIG_RISCV_SBI) && !riscv_use_ipi_for_rfence())
 		sbi_remote_fence_i(NULL);
 	else
 		on_each_cpu(ipi_remote_fence_i, NULL, 1);
@@ -68,7 +68,8 @@ void flush_icache_mm(struct mm_struct *mm, bool local)
 		 * with flush_icache_deferred().
 		 */
 		smp_mb();
-	} else if (IS_ENABLED(CONFIG_RISCV_SBI)) {
+	} else if (IS_ENABLED(CONFIG_RISCV_SBI) &&
+		   !riscv_use_ipi_for_rfence()) {
 		sbi_remote_fence_i(&others);
 	} else {
 		on_each_cpu_mask(&others, ipi_remote_fence_i, NULL, 1);
-- 
2.34.1