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From:   Marc Zyngier <maz@kernel.org>
To:     linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu,
        kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Jason Cooper <jason@lakedaemon.net>,
        Robert Richter <rrichter@marvell.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Zenghui Yu <yuzenghui@huawei.com>,
        Eric Auger <eric.auger@redhat.com>,
        James Morse <james.morse@arm.com>,
        Julien Thierry <julien.thierry.kdev@gmail.com>,
        Suzuki K Poulose <suzuki.poulose@arm.com>
Subject: [PATCH v4 01/20] irqchip/gic-v4.1: Skip absent CPUs while iterating over redistributors
Date:   Fri, 14 Feb 2020 14:57:17 +0000
Message-Id: <20200214145736.18550-2-maz@kernel.org>
In-Reply-To: <20200214145736.18550-1-maz@kernel.org>
References: <20200214145736.18550-1-maz@kernel.org>
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In a system that is only sparsly populated with CPUs, we can end-up with
redistributors structures that are not initialized. Let's make sure we
don't try and access those when iterating over them (in this case when
checking we have a L2 VPE table).

Fixes: 4e6437f12d6e ("irqchip/gic-v4.1: Ensure L2 vPE table is allocated at RD level")
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 drivers/irqchip/irq-gic-v3-its.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 83b1186ffcad..da883a691028 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -2452,6 +2452,10 @@ static bool allocate_vpe_l2_table(int cpu, u32 id)
 	if (!gic_rdists->has_rvpeid)
 		return true;
 
+	/* Skip non-present CPUs */
+	if (!base)
+		return true;
+
 	val  = gicr_read_vpropbaser(base + SZ_128K + GICR_VPROPBASER);
 
 	esz  = FIELD_GET(GICR_VPROPBASER_4_1_ENTRY_SIZE, val) + 1;
-- 
2.20.1