x86, irq, ACPI: Implement interfaces to support ACPI based IOAPIC hot-removal

Implement acpi_unregister_ioapic() to support ACPI based IOAPIC hot-removal.
An IOAPIC could only be removed when all its pins are unused.

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/1414387308-27148-17-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

2 files changed, 64 insertions, 4 deletions

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 0b993511e0c5..5427d9b70f75 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -810,15 +810,20 @@ int acpi_register_ioapic(acpi_handle handle, u64 phys_addr, u32 gsi_base)
 
         return ret;
 }
-
 EXPORT_SYMBOL(acpi_register_ioapic);
 
 int acpi_unregister_ioapic(acpi_handle handle, u32 gsi_base)
 {
-        /* TBD */
-        return -EINVAL;
-}
+        int ret = -ENOSYS;
+
+#ifdef CONFIG_ACPI_HOTPLUG_IOAPIC
+        mutex_lock(&acpi_ioapic_lock);
+        ret  = mp_unregister_ioapic(gsi_base);
+        mutex_unlock(&acpi_ioapic_lock);
+#endif
 
+        return ret;
+}
 EXPORT_SYMBOL(acpi_unregister_ioapic);
 
 static int __init acpi_parse_sbf(struct acpi_table_header *table)
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 826f44f0a2bf..06a0a6ce6750 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -112,6 +112,7 @@ static struct ioapic {
         struct ioapic_domain_cfg irqdomain_cfg;
         struct irq_domain *irqdomain;
         struct mp_pin_info *pin_info;
+        struct resource *iomem_res;
 } ioapics[MAX_IO_APICS];
 
 #define mpc_ioapic_ver(ioapic_idx)      ioapics[ioapic_idx].mp_config.apicver
@@ -250,6 +251,12 @@ static void alloc_ioapic_saved_registers(int idx)
                 pr_err("IOAPIC %d: suspend/resume impossible!\n", idx);
 }
 
+static void free_ioapic_saved_registers(int idx)
+{
+        kfree(ioapics[idx].saved_registers);
+        ioapics[idx].saved_registers = NULL;
+}
+
 int __init arch_early_irq_init(void)
 {
         struct irq_cfg *cfg;
@@ -2973,6 +2980,16 @@ static int mp_irqdomain_create(int ioapic)
         return 0;
 }
 
+static void ioapic_destroy_irqdomain(int idx)
+{
+        if (ioapics[idx].irqdomain) {
+                irq_domain_remove(ioapics[idx].irqdomain);
+                ioapics[idx].irqdomain = NULL;
+        }
+        kfree(ioapics[idx].pin_info);
+        ioapics[idx].pin_info = NULL;
+}
+
 void __init setup_IO_APIC(void)
 {
         int ioapic;
@@ -3743,6 +3760,7 @@ static struct resource * __init ioapic_setup_resources(void)
                 snprintf(mem, IOAPIC_RESOURCE_NAME_SIZE, "IOAPIC %u", i);
                 mem += IOAPIC_RESOURCE_NAME_SIZE;
                 num++;
+                ioapics[i].iomem_res = res;
         }
 
         ioapic_resources = res;
@@ -3971,6 +3989,43 @@ int mp_register_ioapic(int id, u32 address, u32 gsi_base,
         return 0;
 }
 
+int mp_unregister_ioapic(u32 gsi_base)
+{
+        int ioapic, pin;
+        int found = 0;
+        struct mp_pin_info *pin_info;
+
+        for_each_ioapic(ioapic)
+                if (ioapics[ioapic].gsi_config.gsi_base == gsi_base) {
+                        found = 1;
+                        break;
+                }
+        if (!found) {
+                pr_warn("can't find IOAPIC for GSI %d\n", gsi_base);
+                return -ENODEV;
+        }
+
+        for_each_pin(ioapic, pin) {
+                pin_info = mp_pin_info(ioapic, pin);
+                if (pin_info->count) {
+                        pr_warn("pin%d on IOAPIC%d is still in use.\n",
+                                pin, ioapic);
+                        return -EBUSY;
+                }
+        }
+
+        /* Mark entry not present */
+        ioapics[ioapic].nr_registers  = 0;
+        ioapic_destroy_irqdomain(ioapic);
+        free_ioapic_saved_registers(ioapic);
+        if (ioapics[ioapic].iomem_res)
+                release_resource(ioapics[ioapic].iomem_res);
+        clear_fixmap(FIX_IO_APIC_BASE_0 + ioapic);
+        memset(&ioapics[ioapic], 0, sizeof(ioapics[ioapic]));
+
+        return 0;
+}
+
 int mp_irqdomain_map(struct irq_domain *domain, unsigned int virq,
                      irq_hw_number_t hwirq)
 {