Commit-ID: 25c51dad664d1e69f90541c2558a39fd86a506e6
Gitweb: https://git.kernel.org/tip/25c51dad664d1e69f90541c2558a39fd86a506e6
Author: Paul Burton <paul.burton@xxxxxxxx>
AuthorDate: Tue, 31 Oct 2017 09:41:48 -0700
Committer: Marc Zyngier <marc.zyngier@xxxxxxx>
CommitDate: Thu, 2 Nov 2017 15:55:47 +0000
irqchip: mips-gic: Use num_possible_cpus() to reserve IPIs
Reserving a number of IPIs based upon the number of VPs reported by the
GIC makes little sense for a few reasons:
- The kernel may have been configured with NR_CPUS less than the number
of VPs in the cluster, in which case using gic_vpes causes us to
reserve more interrupts for IPIs than we will possibly use.
- If a kernel is configured without support for multi-threading & runs
on a system with multi-threading & multiple VPs per core then we'll
similarly reserve more interrupts for IPIs than we will possibly use.
- In systems with multiple clusters the GIC can only provide us with
the number of VPs in its cluster, not across all clusters. In this
case we'll reserve fewer interrupts for IPIs than we need.
Fix these issues by using num_possible_cpus() instead, which in all
cases is actually indicative of how many IPIs we may need.
Signed-off-by: Paul Burton <paul.burton@xxxxxxxx>
Cc: Jason Cooper <jason@xxxxxxxxxxxxxx>
Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxx
Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
---
drivers/irqchip/irq-mips-gic.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/drivers/irqchip/irq-mips-gic.c b/drivers/irqchip/irq-mips-gic.c
index b1320cc..4304283 100644
--- a/drivers/irqchip/irq-mips-gic.c
+++ b/drivers/irqchip/irq-mips-gic.c
@@ -671,7 +671,7 @@ static int gic_cpu_startup(unsigned int cpu)
static int __init gic_of_init(struct device_node *node,
struct device_node *parent)
{
- unsigned int cpu_vec, i, gicconfig, v[2];
+ unsigned int cpu_vec, i, gicconfig, v[2], num_ipis;
unsigned long reserved;
phys_addr_t gic_base;
struct resource res;
@@ -781,10 +781,12 @@ static int __init gic_of_init(struct device_node *node,
!of_property_read_u32_array(node, "mti,reserved-ipi-vectors", v, 2)) {
bitmap_set(ipi_resrv, v[0], v[1]);
} else {
- /* Make the last 2 * gic_vpes available for IPIs */
- bitmap_set(ipi_resrv,
- gic_shared_intrs - 2 * gic_vpes,
- 2 * gic_vpes);
+ /*
+ * Reserve 2 interrupts per possible CPU/VP for use as IPIs,
+ * meeting the requirements of arch/mips SMP.
+ */
+ num_ipis = 2 * num_possible_cpus();
+ bitmap_set(ipi_resrv, gic_shared_intrs - num_ipis, num_ipis);
}
bitmap_copy(ipi_available, ipi_resrv, GIC_MAX_INTRS);
--
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