[PATCH v5 05/23] irqchip/gic-v4.1: Ensure mutual exclusion betwen invalidations on the same RD

Marc Zyngier
2020-03-04T20:34:46Z

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@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 c84370245bea..fc5788584df7 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 73e87e176d76..ba405becab53 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -835,6 +835,7 @@ 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 c29a02678a6f..b28acfa71f82 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;
--
2.20.1