x86/platform/uv: Insert per_cpu accessor function on uv_hub_nmi

UV: NMI: insert this_cpu_read accessor function on uv_hub_nmi.

On SGI UV systems a 'power nmi' command from the CMC causes
all processors to drop into uv_handle_nmi(). With the 4.0
kernel this results in

BUG: unable to handle kernel paging request

The bug is caused by the current code trying to use the PER_CPU
variable uv_cpu_nmi.hub without an appropriate accessor
function. That oversight occurred in

commit e16321709c82 ("uv: Replace __get_cpu_var")
Author: Christoph Lameter <[e-mail]>
Date: Sun Aug 17 12:30:41 2014 -0500

This patch inserts this_cpu_read() in the uv_hub_nmi macro
restoring the intended functionality.

Signed-off-by: George Beshers <[e-mail]>
Acked-by: Mike Travis <[e-mail]>
Cc: Alex Thorlton <[e-mail]>
Cc: Dimitri Sivanich <[e-mail]>
Cc: Hedi Berriche <[e-mail]>
Cc: Linus Torvalds <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Russ Anderson <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: [e-mail]
Signed-off-by: Ingo Molnar <[e-mail]>

arch/x86/include/asm/uv/uv_hub.h

···
 
 DECLARE_PER_CPU(struct uv_cpu_nmi_s, uv_cpu_nmi);
 
-#define uv_hub_nmi			(uv_cpu_nmi.hub)
+#define uv_hub_nmi			this_cpu_read(uv_cpu_nmi.hub)
 #define uv_cpu_nmi_per(cpu)		(per_cpu(uv_cpu_nmi, cpu))
 #define uv_hub_nmi_per(cpu)		(uv_cpu_nmi_per(cpu).hub)