linux-kernel - [PATCH 13/35] irqchip/gic-v4.1: Implement the v4.1 flavour of VMOVP

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Message-Id: <20190923182606.32100-14-maz@kernel.org>
Date:   Mon, 23 Sep 2019 19:25:44 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     kvmarm@...ts.cs.columbia.edu, linux-kernel@...r.kernel.org
Cc:     Eric Auger <eric.auger@...hat.com>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Andrew Murray <Andrew.Murray@....com>
Subject: [PATCH 13/35] irqchip/gic-v4.1: Implement the v4.1 flavour of VMOVP

With GICv4.1, VMOVP is extended to allow a default doorbell to be
specified, as well as a validity bit for this doorbell. As an added
bonus, VMOPVP isn't required anymore of moving a VPE between
redistributors that share the same affinity.

Let's add this support to the VMOVP builder, and make sure we don't
issuer the command if we don't really need to.

Signed-off-by: Marc Zyngier <maz@...nel.org>
---
 drivers/irqchip/irq-gic-v3-its.c | 40 ++++++++++++++++++++++++++------
 1 file changed, 33 insertions(+), 7 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index a9976bc81d9a..c71aa0046bf0 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -443,6 +443,17 @@ static void its_encode_vmapp_default_db(struct its_cmd_block *cmd,
 	its_mask_encode(&cmd->raw_cmd[1], vpe_db_lpi, 31, 0);
 }
 
+static void its_encode_vmovp_default_db(struct its_cmd_block *cmd,
+					u32 vpe_db_lpi)
+{
+	its_mask_encode(&cmd->raw_cmd[3], vpe_db_lpi, 31, 0);
+}
+
+static void its_encode_db(struct its_cmd_block *cmd, bool db)
+{
+	its_mask_encode(&cmd->raw_cmd[2], db, 63, 63);
+}
+
 static inline void its_fixup_cmd(struct its_cmd_block *cmd)
 {
 	/* Let's fixup BE commands */
@@ -729,6 +740,11 @@ static struct its_vpe *its_build_vmovp_cmd(struct its_node *its,
 	its_encode_vpeid(cmd, desc->its_vmovp_cmd.vpe->vpe_id);
 	its_encode_target(cmd, target);
 
+	if (is_v4_1(its)) {
+		its_encode_db(cmd, true);
+		its_encode_vmovp_default_db(cmd, desc->its_vmovp_cmd.vpe->vpe_db_lpi);
+	}
+
 	its_fixup_cmd(cmd);
 
 	return valid_vpe(its, desc->its_vmovp_cmd.vpe);
@@ -3178,7 +3194,7 @@ static int its_vpe_set_affinity(struct irq_data *d,
 				bool force)
 {
 	struct its_vpe *vpe = irq_data_get_irq_chip_data(d);
-	int cpu = cpumask_first(mask_val);
+	int from, cpu = cpumask_first(mask_val);
 
 	/*
 	 * Changing affinity is mega expensive, so let's be as lazy as
@@ -3186,14 +3202,24 @@ static int its_vpe_set_affinity(struct irq_data *d,
 	 * into the proxy device, we need to move the doorbell
 	 * interrupt to its new location.
 	 */
-	if (vpe->col_idx != cpu) {
-		int from = vpe->col_idx;
+	if (vpe->col_idx == cpu)
+		goto out;
 
-		vpe->col_idx = cpu;
-		its_send_vmovp(vpe);
-		its_vpe_db_proxy_move(vpe, from, cpu);
-	}
+	from = vpe->col_idx;
+	vpe->col_idx = cpu;
+
+	/*
+	 * GICv4.1 allows us to skip VMOVP if moving to a cpu whose RD
+	 * is sharing its VPE table with the current one.
+	 */
+	if (gic_data_rdist_cpu(cpu)->vpe_table_mask &&
+	    cpumask_test_cpu(from, gic_data_rdist_cpu(cpu)->vpe_table_mask))
+		goto out;
 
+	its_send_vmovp(vpe);
+	its_vpe_db_proxy_move(vpe, from, cpu);
+
+out:
 	irq_data_update_effective_affinity(d, cpumask_of(cpu));
 
 	return IRQ_SET_MASK_OK_DONE;
-- 
2.20.1