irqchip/gic-v4.1: Ensure accessing the correct RD when writing INVALLR

The GICv4.1 spec tells us that it's CONSTRAINED UNPREDICTABLE to issue a
register-based invalidation operation for a vPEID not mapped to that RD,
or another RD within the same CommonLPIAff group.

To follow this rule, commit f3a0592 ("irqchip/gic-v4.1: Ensure mutual
exclusion between vPE affinity change and RD access") tried to address the
race between the RD accesses and the vPE affinity change, but somehow
forgot to take GICR_INVALLR into account. Let's take the vpe_lock before
evaluating vpe->col_idx to fix it.

Fixes: f3a0592 ("irqchip/gic-v4.1: Ensure mutual exclusion between vPE affinity change and RD access")
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200720092328.708-1-yuzenghui@huawei.com

drivers/irqchip/irq-gic-v3-its.c

@@ -4079,18 +4079,22 @@ static void its_vpe_4_1_deschedule(struct its_vpe *vpe,
 static void its_vpe_4_1_invall(struct its_vpe *vpe)
 {
 	void __iomem *rdbase;
+	unsigned long flags;
 	u64 val;
+	int cpu;
 
 	val  = GICR_INVALLR_V;
 	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;
+	cpu = vpe_to_cpuid_lock(vpe, &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_INVALLR);
 
 	wait_for_syncr(rdbase);
-	raw_spin_unlock(&gic_data_rdist_cpu(vpe->col_idx)->rd_lock);
+	raw_spin_unlock(&gic_data_rdist_cpu(cpu)->rd_lock);
+	vpe_to_cpuid_unlock(vpe, flags);
 }
 
 static int its_vpe_4_1_set_vcpu_affinity(struct irq_data *d, void *vcpu_info)