irqchip/riscv-intc: Fix SMP=n boot with ACPI

When CONFIG_SMP is disabled, the static array rintc_acpi_data with size
NR_CPUS is not sufficient to hold all RINTC structures passed from the
firmware.

All RINTC structures are required to configure IMSIC/APLIC/PLIC properly
irrespective of SMP in the OS. So, allocate dynamic memory based on the
number of RINTC structures in MADT to fix this issue.

Fixes: f8619b6 ("irqchip/riscv-intc: Add ACPI support for AIA")
Reported-by: Björn Töpel <bjorn@kernel.org>
Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/all/20241014065739.656959-1-sunilvl@ventanamicro.com
Closes: https://github.com/linux-riscv/linux-riscv/actions/runs/11280997511/job/31375229012

Author: vlsunil

drivers/irqchip/irq-riscv-intc.c

@@ -265,7 +265,7 @@ struct rintc_data {
 };
 
 static u32 nr_rintc;
-static struct rintc_data *rintc_acpi_data[NR_CPUS];
+static struct rintc_data **rintc_acpi_data;
 
 #define for_each_matching_plic(_plic_id)				\
 	unsigned int _plic;						\
@@ -329,13 +329,30 @@ int acpi_rintc_get_imsic_mmio_info(u32 index, struct resource *res)
 	return 0;
 }
 
+static int __init riscv_intc_acpi_match(union acpi_subtable_headers *header,
+					const unsigned long end)
+{
+	return 0;
+}
+
 static int __init riscv_intc_acpi_init(union acpi_subtable_headers *header,
 				       const unsigned long end)
 {
 	struct acpi_madt_rintc *rintc;
 	struct fwnode_handle *fn;
+	int count;
 	int rc;
 
+	if (!rintc_acpi_data) {
+		count = acpi_table_parse_madt(ACPI_MADT_TYPE_RINTC, riscv_intc_acpi_match, 0);
+		if (count <= 0)
+			return -EINVAL;
+
+		rintc_acpi_data = kcalloc(count, sizeof(*rintc_acpi_data), GFP_KERNEL);
+		if (!rintc_acpi_data)
+			return -ENOMEM;
+	}
+
 	rintc = (struct acpi_madt_rintc *)header;
 	rintc_acpi_data[nr_rintc] = kzalloc(sizeof(*rintc_acpi_data[0]), GFP_KERNEL);
 	if (!rintc_acpi_data[nr_rintc])