x86/idt: Hide set_intr_gate()

set_intr_gate() is an internal function of the IDT code. The only user left
is the KVM code which replaces the pagefault handler eventually.

Provide an explicit update_intr_gate() function and make set_intr_gate()
static. While at it replace the magic number 14 in the KVM code with the
proper trap define.

Signed-off-by: Thomas Gleixner <[email protected]>
Acked-by: Paolo Bonzini <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Steven Rostedt <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

Author: KAGA-KOKO

arch/x86/include/asm/desc.h

@@ -390,7 +390,7 @@ static inline void set_desc_limit(struct desc_struct *desc, unsigned long limit)
 	desc->limit1 = (limit >> 16) & 0xf;
 }
 
-void set_intr_gate(unsigned int n, const void *addr);
+void update_intr_gate(unsigned int n, const void *addr);
 void alloc_intr_gate(unsigned int n, const void *addr);
 
 extern unsigned long used_vectors[];

arch/x86/kernel/idt.c

@@ -225,6 +225,22 @@ idt_setup_from_table(gate_desc *idt, const struct idt_data *t, int size, bool sy
 	}
 }
 
+static void set_intr_gate(unsigned int n, const void *addr)
+{
+	struct idt_data data;
+
+	BUG_ON(n > 0xFF);
+
+	memset(&data, 0, sizeof(data));
+	data.vector	= n;
+	data.addr	= addr;
+	data.segment	= __KERNEL_CS;
+	data.bits.type	= GATE_INTERRUPT;
+	data.bits.p	= 1;
+
+	idt_setup_from_table(idt_table, &data, 1, false);
+}
+
 /**
  * idt_setup_early_traps - Initialize the idt table with early traps
  *
@@ -336,20 +352,11 @@ void idt_invalidate(void *addr)
 	load_idt(&idt);
 }
 
-void set_intr_gate(unsigned int n, const void *addr)
+void __init update_intr_gate(unsigned int n, const void *addr)
 {
-	struct idt_data data;
-
-	BUG_ON(n > 0xFF);
-
-	memset(&data, 0, sizeof(data));
-	data.vector	= n;
-	data.addr	= addr;
-	data.segment	= __KERNEL_CS;
-	data.bits.type	= GATE_INTERRUPT;
-	data.bits.p	= 1;
-
-	idt_setup_from_table(idt_table, &data, 1, false);
+	if (WARN_ON_ONCE(!test_bit(n, used_vectors)))
+		return;
+	set_intr_gate(n, addr);
 }
 
 void alloc_intr_gate(unsigned int n, const void *addr)

arch/x86/kernel/kvm.c

@@ -455,7 +455,7 @@ static int kvm_cpu_down_prepare(unsigned int cpu)
 
 static void __init kvm_apf_trap_init(void)
 {
-	set_intr_gate(14, async_page_fault);
+	update_intr_gate(X86_TRAP_PF, async_page_fault);
 }
 
 void __init kvm_guest_init(void)