x86: find nr_irqs_gsi with mp_ioapic_routing

Impact: find right nr_irqs_gsi on some systems.

One test-system has gap between gsi's:

[    0.000000] ACPI: IOAPIC (id[0x04] address[0xfec00000] gsi_base[0])
[    0.000000] IOAPIC[0]: apic_id 4, version 0, address 0xfec00000, GSI 0-23
[    0.000000] ACPI: IOAPIC (id[0x05] address[0xfeafd000] gsi_base[48])
[    0.000000] IOAPIC[1]: apic_id 5, version 0, address 0xfeafd000, GSI 48-54
[    0.000000] ACPI: IOAPIC (id[0x06] address[0xfeafc000] gsi_base[56])
[    0.000000] IOAPIC[2]: apic_id 6, version 0, address 0xfeafc000, GSI 56-62
...
[    0.000000] nr_irqs_gsi: 38

So nr_irqs_gsi is not right. some irq for MSI will overwrite with io_apic.

need to get that with acpi_probe_gsi when acpi io_apic is used

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 23 insertions, 0 deletions

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 3efa996b036c..c334fe75dcd6 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -961,6 +961,29 @@ void __init mp_register_ioapic(int id, u32 address, u32 gsi_base)
         nr_ioapics++;
 }
 
+int __init acpi_probe_gsi(void)
+{
+        int idx;
+        int gsi;
+        int max_gsi = 0;
+
+        if (acpi_disabled)
+                return 0;
+
+        if (!acpi_ioapic)
+                return 0;
+
+        max_gsi = 0;
+        for (idx = 0; idx < nr_ioapics; idx++) {
+                gsi = mp_ioapic_routing[idx].gsi_end;
+
+                if (gsi > max_gsi)
+                        max_gsi = gsi;
+        }
+
+        return max_gsi + 1;
+}
+
 static void assign_to_mp_irq(struct mpc_intsrc *m,
                                     struct mpc_intsrc *mp_irq)
 {