linux-kernel - [PATCH v3 1/2] irqchip/gicv3: Spell out when pseudo-NMIs are enabled

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Date:   Sat, 12 Sep 2020 16:37:06 +0100
From:   Alexandru Elisei <alexandru.elisei@....com>
To:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kvmarm@...ts.cs.columbia.edu
Cc:     jason@...edaemon.net, maz@...nel.org, catalin.marinas@....com,
        tglx@...utronix.de, will@...nel.org
Subject: [PATCH v3 1/2] irqchip/gicv3: Spell out when pseudo-NMIs are enabled

When NMIs cannot be enabled, the driver prints a message stating that
unambiguously. When they are enabled, the only feedback we get is a message
regarding the use of synchronization for ICC_PMR_EL1 writes, which is not
as useful for a user who is not intimately familiar with how NMIs are
implemented.

Let's make it obvious that pseudo-NMIs are enabled. Keep the message about
using a barrier for ICC_PMR_EL1 writes, because it has a non-negligible
impact on performance.

Signed-off-by: Alexandru Elisei <alexandru.elisei@....com>
---
 drivers/irqchip/irq-gic-v3.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index 850842f27bee..aa9b43d412b2 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -1564,8 +1564,8 @@ static void gic_enable_nmi_support(void)
 	if (gic_read_ctlr() & ICC_CTLR_EL1_PMHE_MASK)
 		static_branch_enable(&gic_pmr_sync);
 
-	pr_info("%s ICC_PMR_EL1 synchronisation\n",
-		static_branch_unlikely(&gic_pmr_sync) ? "Forcing" : "Relaxing");
+	pr_info("Pseudo-NMIs enabled using %s ICC_PMR_EL1 synchronisation\n",
+		static_branch_unlikely(&gic_pmr_sync) ? "forced" : "relaxed");
 
 	static_branch_enable(&supports_pseudo_nmis);
 
-- 
2.28.0