x86/idt: Simplify alloc_intr_gate()

The only users of alloc_intr_gate() are hypervisors, which both check the
used_vectors bitmap whether they have allocated the gate already. Move that
check into alloc_intr_gate() and simplify the users.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170828064959.580830286@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 70e717f..9fc3265 100644 (file)
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -59,13 +59,8 @@ void hyperv_vector_handler(struct pt_regs *regs)
 void hv_setup_vmbus_irq(void (*handler)(void))
 {
        vmbus_handler = handler;
-       /*
-        * Setup the IDT for hypervisor callback. Prevent reallocation
-        * at module reload.
-        */
-       if (!test_bit(HYPERVISOR_CALLBACK_VECTOR, used_vectors))
-               alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR,
-                               hyperv_callback_vector);
+       /* Setup the IDT for hypervisor callback */
+       alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, hyperv_callback_vector);
 }
 
 void hv_remove_vmbus_irq(void)

diff --git a/arch/x86/kernel/idt.c b/arch/x86/kernel/idt.c
index 8e9318d..b609eac 100644 (file)
--- a/arch/x86/kernel/idt.c
+++ b/arch/x86/kernel/idt.c
@@ -354,7 +354,7 @@ void set_intr_gate(unsigned int n, const void *addr)
 
 void alloc_intr_gate(unsigned int n, const void *addr)
 {
-       BUG_ON(test_bit(n, used_vectors) || n < FIRST_SYSTEM_VECTOR);
-       set_bit(n, used_vectors);
-       set_intr_gate(n, addr);
+       BUG_ON(n < FIRST_SYSTEM_VECTOR);
+       if (!test_and_set_bit(n, used_vectors))
+               set_intr_gate(n, addr);
 }

diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index 2d43118..1ab4bd1 100644 (file)
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -1653,10 +1653,8 @@ void xen_callback_vector(void)
                        return;
                }
                pr_info("Xen HVM callback vector for event delivery is enabled\n");
-               /* in the restore case the vector has already been allocated */
-               if (!test_bit(HYPERVISOR_CALLBACK_VECTOR, used_vectors))
-                       alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR,
-                                       xen_hvm_callback_vector);
+               alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR,
+                               xen_hvm_callback_vector);
        }
 }
 #else