linux-kernel - [RFC PATCH 1/3] irqchip/gic-v3: Make use of ICC

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Date:   Mon, 29 Mar 2021 16:52:08 +0800
From:   Jingyi Wang <wangjingyi11@...wei.com>
To:     <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>
CC:     <maz@...nel.org>, <tglx@...utronix.de>,
        <wanghaibin.wang@...wei.com>, <wangjingyi11@...wei.com>,
        <yuzenghui@...wei.com>, <zhukeqian1@...wei.com>
Subject: [RFC PATCH 1/3] irqchip/gic-v3: Make use of ICC_SGI1R IRM bit

IRM, bit[40] in ICC_SGI1R, determines how the generated SGIs
are distributed to PEs. If the bit is set, interrupts are routed
to all PEs in the system excluding "self". We use cpumask to
determine if this bit should be set and make use of that.

This will reduce vm trap when broadcast IPIs are sent.

Signed-off-by: Jingyi Wang <wangjingyi11@...wei.com>
---
 drivers/irqchip/irq-gic-v3.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index eb0ee356a629..8ecc1b274ea8 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -1127,6 +1127,7 @@ static void gic_send_sgi(u64 cluster_id, u16 tlist, unsigned int irq)
 static void gic_ipi_send_mask(struct irq_data *d, const struct cpumask *mask)
 {
 	int cpu;
+	cpumask_t tmp;
 
 	if (WARN_ON(d->hwirq >= 16))
 		return;
@@ -1137,6 +1138,17 @@ static void gic_ipi_send_mask(struct irq_data *d, const struct cpumask *mask)
 	 */
 	wmb();
 
+	if (!cpumask_and(&tmp, mask, cpumask_of(smp_processor_id()))) {
+		/* Set Interrupt Routing Mode bit */
+		u64 val;
+		val = (d->hwirq) << ICC_SGI1R_SGI_ID_SHIFT;
+		val |= BIT_ULL(ICC_SGI1R_IRQ_ROUTING_MODE_BIT);
+		gic_write_sgi1r(val);
+
+		isb();
+		return;
+	}
+
 	for_each_cpu(cpu, mask) {
 		u64 cluster_id = MPIDR_TO_SGI_CLUSTER_ID(cpu_logical_map(cpu));
 		u16 tlist;
-- 
2.19.1