x86: add hugepagesz option on 64-bit

Add an hugepagesz=...  option similar to IA64, PPC etc.  to x86-64.

This finally allows to select GB pages for hugetlbfs in x86 now that all
the infrastructure is in place.
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Documentation/kernel-parameters.txt

@@ -774,8 +774,15 @@ and is between 256 and 4096 characters. It is defined in the file
 	hisax=		[HW,ISDN]
 			See Documentation/isdn/README.HiSax.
 
-	hugepages=	[HW,X86-32,IA-64] Maximal number of HugeTLB pages.
-	hugepagesz=	[HW,IA-64,PPC] The size of the HugeTLB pages.
+	hugepages=	[HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
+	hugepagesz=	[HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
+			On x86 this option can be specified multiple times
+			interleaved with hugepages= to reserve huge pages
+			of different sizes. Valid pages sizes on x86-64
+			are 2M (when the CPU supports "pse") and 1G (when the
+			CPU supports the "pdpe1gb" cpuinfo flag)
+			Note that 1GB pages can only be allocated at boot time
+			using hugepages= and not freed afterwards.
 
 	i8042.direct	[HW] Put keyboard port into non-translated mode
 	i8042.dumbkbd	[HW] Pretend that controller can only read data from

arch/x86/mm/hugetlbpage.c

@@ -425,3 +425,20 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 
 #endif /*HAVE_ARCH_HUGETLB_UNMAPPED_AREA*/
 
+#ifdef CONFIG_X86_64
+static __init int setup_hugepagesz(char *opt)
+{
+	unsigned long ps = memparse(opt, &opt);
+	if (ps == PMD_SIZE) {
+		hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT);
+	} else if (ps == PUD_SIZE && cpu_has_gbpages) {
+		hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
+	} else {
+		printk(KERN_ERR "hugepagesz: Unsupported page size %lu M\n",
+			ps >> 20);
+		return 0;
+	}
+	return 1;
+}
+__setup("hugepagesz=", setup_hugepagesz);
+#endif

include/asm-x86/page.h

@@ -32,6 +32,8 @@
 #define HPAGE_MASK		(~(HPAGE_SIZE - 1))
 #define HUGETLB_PAGE_ORDER	(HPAGE_SHIFT - PAGE_SHIFT)
 
+#define HUGE_MAX_HSTATE 2
+
 /* to align the pointer to the (next) page boundary */
 #define PAGE_ALIGN(addr)	(((addr)+PAGE_SIZE-1)&PAGE_MASK)