powerpc: Update page-in counter for CMM

A new field has been added to the VPA as a method for the client OS to
communicate to firmware the number of page-ins it is performing when
running collaborative memory overcommit.  The hypervisor will use this
information to better determine if a partition is experiencing memory
pressure and needs more memory allocated to it.
Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/include/asm/lppaca.h

@@ -133,7 +133,8 @@ struct lppaca {
 //=============================================================================
 // CACHE_LINE_4-5 0x0180 - 0x027F Contains PMC interrupt data
 //=============================================================================
-	u8	pmc_save_area[256];	// PMC interrupt Area           x00-xFF
+	u32	page_ins;			// CMO Hint - # page ins by OS  x00-x04
+	u8	pmc_save_area[252];	// PMC interrupt Area           x04-xFF
 } __attribute__((__aligned__(0x400)));
 
 extern struct lppaca lppaca[];

arch/powerpc/kernel/paca.c

@@ -37,6 +37,7 @@ struct lppaca lppaca[] = {
 		.end_of_quantum = 0xfffffffffffffffful,
 		.slb_count = 64,
 		.vmxregs_in_use = 0,
+		.page_ins = 0,
 	},
 };
 

arch/powerpc/mm/fault.c

@@ -30,6 +30,7 @@
 #include <linux/kprobes.h>
 #include <linux/kdebug.h>
 
+#include <asm/firmware.h>
 #include <asm/page.h>
 #include <asm/pgtable.h>
 #include <asm/mmu.h>
@@ -318,9 +319,16 @@ good_area:
 			goto do_sigbus;
 		BUG();
 	}
-	if (ret & VM_FAULT_MAJOR)
+	if (ret & VM_FAULT_MAJOR) {
 		current->maj_flt++;
-	else
+#ifdef CONFIG_PPC_SMLPAR
+		if (firmware_has_feature(FW_FEATURE_CMO)) {
+			preempt_disable();
+			get_lppaca()->page_ins++;
+			preempt_enable();
+		}
+#endif
+	} else
 		current->min_flt++;
 	up_read(&mm->mmap_sem);
 	return 0;