linux-kernel - [PATCH] irqchip/gic-v3: do runtime cpu cap check only when necessary

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Date:   Sat, 27 Aug 2022 13:19:27 +0800
From:   Puyou Lu <puyou.lu@...il.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>,
        Robert Richter <rrichter@...ium.com>,
        Catalin Marinas <catalin.marinas@....com>,
        linux-kernel@...r.kernel.org, Puyou Lu <puyou.lu@...il.com>
Subject: [PATCH] irqchip/gic-v3: do runtime cpu cap check only when necessary

Now cpu cap check is done every exception happens on every arm64 platform,
but this check is necessary on just few of then, so we can drop this
check at compile time on others. This can decrease exception handle time
on most cases.

Fixes: 6d4e11c5e2e8 ("irqchip/gicv3: Workaround for Cavium ThunderX erratum 23154")
Signed-off-by: Puyou Lu <puyou.lu@...il.com>
---
 drivers/irqchip/irq-gic-v3.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index 262658fd5f9e..3f08c2ef1251 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -237,9 +237,11 @@ static void gic_redist_wait_for_rwp(void)
 
 static u64 __maybe_unused gic_read_iar(void)
 {
+#ifdef CONFIG_CAVIUM_ERRATUM_23154
 	if (cpus_have_const_cap(ARM64_WORKAROUND_CAVIUM_23154))
 		return gic_read_iar_cavium_thunderx();
 	else
+#endif
 		return gic_read_iar_common();
 }
 #endif
-- 
2.17.1