linux-kernel - [PATCH v5 1/6] irqchip/gic-v3-its: Add a cache invalidation right after vPE unmapping

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Date:   Mon, 22 Mar 2021 14:01:53 +0800
From:   Shenming Lu <lushenming@...wei.com>
To:     Marc Zyngier <maz@...nel.org>, Eric Auger <eric.auger@...hat.com>,
        "Will Deacon" <will@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <kvmarm@...ts.cs.columbia.edu>, <kvm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
CC:     Alex Williamson <alex.williamson@...hat.com>,
        Cornelia Huck <cohuck@...hat.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        <wanghaibin.wang@...wei.com>, <yuzenghui@...wei.com>,
        <lushenming@...wei.com>
Subject: [PATCH v5 1/6] irqchip/gic-v3-its: Add a cache invalidation right after vPE unmapping

From: Marc Zyngier <maz@...nel.org>

Since there may be a direct read from the CPU side to the VPT after
unmapping the vPE, we add a cache coherency maintenance at the end
of its_vpe_irq_domain_deactivate() to ensure the validity of the VPT
read later.

Signed-off-by: Marc Zyngier <maz@...nel.org>
Signed-off-by: Shenming Lu <lushenming@...wei.com>
---
 drivers/irqchip/irq-gic-v3-its.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index ed46e6057e33..4eb907f65bd0 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -4554,6 +4554,15 @@ static void its_vpe_irq_domain_deactivate(struct irq_domain *domain,
 
 		its_send_vmapp(its, vpe, false);
 	}
+
+	/*
+	 * There may be a direct read to the VPT after unmapping the
+	 * vPE, to guarantee the validity of this, we make the VPT
+	 * memory coherent with the CPU caches here.
+	 */
+	if (find_4_1_its() && !atomic_read(&vpe->vmapp_count))
+		gic_flush_dcache_to_poc(page_address(vpe->vpt_page),
+					LPI_PENDBASE_SZ);
 }
 
 static const struct irq_domain_ops its_vpe_domain_ops = {
-- 
2.19.1