x86, ioapic: Fix non atomic allocation with interrupts disabled

Impact: fix possible race

save_mask_IO_APIC_setup() was using non atomic memory allocation while getting
called with interrupts disabled. Fix this by splitting this into two different
function. Allocation part save_IO_APIC_setup() now happens before
disabling interrupts.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

3 files changed, 31 insertions, 17 deletions

diff --git a/arch/x86/include/asm/io_apic.h b/arch/x86/include/asm/io_apic.h
index ffcd08f96e47..373cc2bbcad2 100644
--- a/arch/x86/include/asm/io_apic.h
+++ b/arch/x86/include/asm/io_apic.h
@@ -162,7 +162,8 @@ extern int (*ioapic_renumber_irq)(int ioapic, int irq);
 extern void ioapic_init_mappings(void);
 
 #ifdef CONFIG_X86_64
-extern int save_mask_IO_APIC_setup(void);
+extern int save_IO_APIC_setup(void);
+extern void mask_IO_APIC_setup(void);
 extern void restore_IO_APIC_setup(void);
 extern void reinit_intr_remapped_IO_APIC(int);
 #endif
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 699f8cf76bbb..85eb8e100818 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1334,15 +1334,16 @@ void __init enable_IR_x2apic(void)
                 return;
         }
 
-        local_irq_save(flags);
-        mask_8259A();
-
-        ret = save_mask_IO_APIC_setup();
+        ret = save_IO_APIC_setup();
         if (ret) {
                 pr_info("Saving IO-APIC state failed: %d\n", ret);
                 goto end;
         }
 
+        local_irq_save(flags);
+        mask_IO_APIC_setup();
+        mask_8259A();
+
         ret = enable_intr_remapping(1);
 
         if (ret && x2apic_preenabled) {
@@ -1367,10 +1368,10 @@ end_restore:
         else
                 reinit_intr_remapped_IO_APIC(x2apic_preenabled);
 
-end:
         unmask_8259A();
         local_irq_restore(flags);
 
+end:
         if (!ret) {
                 if (!x2apic_preenabled)
                         pr_info("Enabled x2apic and interrupt-remapping\n");
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index cf27795c641c..ff1759a1128e 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -853,9 +853,9 @@ __setup("pirq=", ioapic_pirq_setup);
 static struct IO_APIC_route_entry *early_ioapic_entries[MAX_IO_APICS];
 
 /*
- * Saves and masks all the unmasked IO-APIC RTE's
+ * Saves all the IO-APIC RTE's
  */
-int save_mask_IO_APIC_setup(void)
+int save_IO_APIC_setup(void)
 {
         union IO_APIC_reg_01 reg_01;
         unsigned long flags;
@@ -880,16 +880,9 @@ int save_mask_IO_APIC_setup(void)
         }
 
         for (apic = 0; apic < nr_ioapics; apic++)
-                for (pin = 0; pin < nr_ioapic_registers[apic]; pin++) {
-                        struct IO_APIC_route_entry entry;
-
-                        entry = early_ioapic_entries[apic][pin] =
+                for (pin = 0; pin < nr_ioapic_registers[apic]; pin++)
+                        early_ioapic_entries[apic][pin] =
                                 ioapic_read_entry(apic, pin);
-                        if (!entry.mask) {
-                                entry.mask = 1;
-                                ioapic_write_entry(apic, pin, entry);
-                        }
-                }
 
         return 0;
 
@@ -902,6 +895,25 @@ nomem:
         return -ENOMEM;
 }
 
+void mask_IO_APIC_setup(void)
+{
+        int apic, pin;
+
+        for (apic = 0; apic < nr_ioapics; apic++) {
+                if (!early_ioapic_entries[apic])
+                        break;
+                for (pin = 0; pin < nr_ioapic_registers[apic]; pin++) {
+                        struct IO_APIC_route_entry entry;
+
+                        entry = early_ioapic_entries[apic][pin];
+                        if (!entry.mask) {
+                                entry.mask = 1;
+                                ioapic_write_entry(apic, pin, entry);
+                        }
+                }
+        }
+}
+
 void restore_IO_APIC_setup(void)
 {
         int apic, pin;