linux-kernel - [tip: irq/core] irqchip/gic-v4.1: Ensure mutual exclusion betwen invalidations on the same RD

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Date:   Sun, 29 Mar 2020 20:26:15 -0000
From:   "tip-bot2 for Marc Zyngier" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Marc Zyngier <maz@...nel.org>, Zenghui Yu <yuzenghui@...wei.com>,
        Eric Auger <eric.auger@...hat.com>, x86 <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [tip: irq/core] irqchip/gic-v4.1: Ensure mutual exclusion betwen
 invalidations on the same RD

The following commit has been merged into the irq/core branch of tip:

Commit-ID:     9058a4e980648e7d068a7f7726a8ea4c67d0e88a
Gitweb:        https://git.kernel.org/tip/9058a4e980648e7d068a7f7726a8ea4c67d0e88a
Author:        Marc Zyngier <maz@...nel.org>
AuthorDate:    Wed, 04 Mar 2020 20:33:12 
Committer:     Marc Zyngier <maz@...nel.org>
CommitterDate: Fri, 20 Mar 2020 17:48:21 

irqchip/gic-v4.1: Ensure mutual exclusion betwen invalidations on the same RD

The GICv4.1 spec says that it is CONTRAINED UNPREDICTABLE to write to
any of the GICR_INV{LPI,ALL}R registers if GICR_SYNCR.Busy == 1.

To deal with it, we must ensure that only a single invalidation can
happen at a time for a given redistributor. Add a per-RD lock to that
effect and take it around the invalidation/syncr-read to deal with this.

Signed-off-by: Marc Zyngier <maz@...nel.org>
Reviewed-by: Zenghui Yu <yuzenghui@...wei.com>
Reviewed-by: Eric Auger <eric.auger@...hat.com>
Link: https://lore.kernel.org/r/20200304203330.4967-6-maz@kernel.org
---
 drivers/irqchip/irq-gic-v3-its.c   | 6 ++++++
 drivers/irqchip/irq-gic-v3.c       | 1 +
 include/linux/irqchip/arm-gic-v3.h | 1 +
 3 files changed, 8 insertions(+)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index c843702..fc57885 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -1373,10 +1373,12 @@ static void direct_lpi_inv(struct irq_data *d)
 
 	/* Target the redistributor this LPI is currently routed to */
 	cpu = irq_to_cpuid_lock(d, &flags);
+	raw_spin_lock(&gic_data_rdist_cpu(cpu)->rd_lock);
 	rdbase = per_cpu_ptr(gic_rdists->rdist, cpu)->rd_base;
 	gic_write_lpir(val, rdbase + GICR_INVLPIR);
 
 	wait_for_syncr(rdbase);
+	raw_spin_unlock(&gic_data_rdist_cpu(cpu)->rd_lock);
 	irq_to_cpuid_unlock(d, flags);
 }
 
@@ -3662,9 +3664,11 @@ static void its_vpe_send_inv(struct irq_data *d)
 		void __iomem *rdbase;
 
 		/* Target the redistributor this VPE is currently known on */
+		raw_spin_lock(&gic_data_rdist_cpu(vpe->col_idx)->rd_lock);
 		rdbase = per_cpu_ptr(gic_rdists->rdist, vpe->col_idx)->rd_base;
 		gic_write_lpir(d->parent_data->hwirq, rdbase + GICR_INVLPIR);
 		wait_for_syncr(rdbase);
+		raw_spin_unlock(&gic_data_rdist_cpu(vpe->col_idx)->rd_lock);
 	} else {
 		its_vpe_send_cmd(vpe, its_send_inv);
 	}
@@ -3825,10 +3829,12 @@ static void its_vpe_4_1_invall(struct its_vpe *vpe)
 	val |= FIELD_PREP(GICR_INVALLR_VPEID, vpe->vpe_id);
 
 	/* Target the redistributor this vPE is currently known on */
+	raw_spin_lock(&gic_data_rdist_cpu(vpe->col_idx)->rd_lock);
 	rdbase = per_cpu_ptr(gic_rdists->rdist, vpe->col_idx)->rd_base;
 	gic_write_lpir(val, rdbase + GICR_INVALLR);
 
 	wait_for_syncr(rdbase);
+	raw_spin_unlock(&gic_data_rdist_cpu(vpe->col_idx)->rd_lock);
 }
 
 static int its_vpe_4_1_set_vcpu_affinity(struct irq_data *d, void *vcpu_info)
diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index b6b0f86..0f716c2 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -834,6 +834,7 @@ static int __gic_populate_rdist(struct redist_region *region, void __iomem *ptr)
 	typer = gic_read_typer(ptr + GICR_TYPER);
 	if ((typer >> 32) == aff) {
 		u64 offset = ptr - region->redist_base;
+		raw_spin_lock_init(&gic_data_rdist()->rd_lock);
 		gic_data_rdist_rd_base() = ptr;
 		gic_data_rdist()->phys_base = region->phys_base + offset;
 
diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h
index c29a026..b28acfa 100644
--- a/include/linux/irqchip/arm-gic-v3.h
+++ b/include/linux/irqchip/arm-gic-v3.h
@@ -652,6 +652,7 @@
 
 struct rdists {
 	struct {
+		raw_spinlock_t	rd_lock;
 		void __iomem	*rd_base;
 		struct page	*pend_page;
 		phys_addr_t	phys_base;