x86, irq, ACPI: Implement interface to support ACPI based IOAPIC hot-addition

Implement acpi_register_ioapic() and enhance mp_register_ioapic()
to support ACPI based IOAPIC hot-addition.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Len Brown <len.brown@intel.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Link: http://lkml.kernel.org/r/1414387308-27148-16-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 21 insertions, 1 deletions

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 4333a75..826f44f 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -3861,7 +3861,13 @@ static int bad_ioapic_register(int idx)
 
 static int find_free_ioapic_entry(void)
 {
-	return nr_ioapics;
+	int idx;
+
+	for (idx = 0; idx < MAX_IO_APICS; idx++)
+		if (ioapics[idx].nr_registers == 0)
+			return idx;
+
+	return MAX_IO_APICS;
 }
 
 /**
@@ -3874,6 +3880,7 @@ static int find_free_ioapic_entry(void)
 int mp_register_ioapic(int id, u32 address, u32 gsi_base,
 		       struct ioapic_domain_cfg *cfg)
 {
+	bool hotplug = !!ioapic_initialized;
 	struct mp_ioapic_gsi *gsi_cfg;
 	int idx, ioapic, entries;
 	u32 gsi_end;
@@ -3935,6 +3942,19 @@ int mp_register_ioapic(int id, u32 address, u32 gsi_base,
 	ioapics[idx].irqdomain = NULL;
 	ioapics[idx].irqdomain_cfg = *cfg;
 
+	/*
+	 * If mp_register_ioapic() is called during early boot stage when
+	 * walking ACPI/SFI/DT tables, it's too early to create irqdomain,
+	 * we are still using bootmem allocator. So delay it to setup_IO_APIC().
+	 */
+	if (hotplug) {
+		if (mp_irqdomain_create(idx)) {
+			clear_fixmap(FIX_IO_APIC_BASE_0 + idx);
+			return -ENOMEM;
+		}
+		alloc_ioapic_saved_registers(idx);
+	}
+
 	if (gsi_cfg->gsi_end >= gsi_top)
 		gsi_top = gsi_cfg->gsi_end + 1;
 	if (nr_ioapics <= idx)