Commit afec6e04 authored by Dan Magenheimer's avatar Dan Magenheimer
Browse files

xen: prepare tmem shim to handle frontswap 



Provide the shim code for frontswap for Xen tmem even if the
frontswap patchset is not present yet.  (The egg is before
the chicken.)

Signed-off-by: default avatarDan Magenheimer <dan.magenheimer@oracle.com>
Reviewed-by: default avatarKonrad Wilk <konrad.wilk@oracle.com>
parent 55922c9d

drivers/xen/Kconfig

+7 −0
Original line number Diff line number Diff line
@@ -105,4 +105,11 @@ config SWIOTLB_XEN 
	depends on PCI

	select SWIOTLB



config XEN_TMEM

	bool

	default y if (CLEANCACHE || FRONTSWAP)

	help

	  Shim to interface in-kernel Transcendent Memory hooks

	  (e.g. cleancache and frontswap) to Xen tmem hypercalls.



endmenu

drivers/xen/Makefile

+1 −1
Original line number Diff line number Diff line 
obj-y	+= grant-table.o features.o events.o manage.o balloon.o

obj-y	+= xenbus/

obj-y	+= tmem.o



nostackp := $(call cc-option, -fno-stack-protector)

CFLAGS_features.o			:= $(nostackp)
@@ -15,6 +14,7 @@ obj-$(CONFIG_XEN_GRANT_DEV_ALLOC) += xen-gntalloc.o 
obj-$(CONFIG_XENFS)			+= xenfs/

obj-$(CONFIG_XEN_SYS_HYPERVISOR)	+= sys-hypervisor.o

obj-$(CONFIG_XEN_PLATFORM_PCI)		+= xen-platform-pci.o

obj-$(CONFIG_XEN_TMEM)			+= tmem.o

obj-$(CONFIG_SWIOTLB_XEN)		+= swiotlb-xen.o

obj-$(CONFIG_XEN_DOM0)			+= pci.o

drivers/xen/tmem.c

+158 −12
Original line number Diff line number Diff line 
/*

 * Xen implementation for transcendent memory (tmem)

 *

 * Copyright (C) 2009-2010 Oracle Corp.  All rights reserved.

 * Copyright (C) 2009-2011 Oracle Corp.  All rights reserved.

 * Author: Dan Magenheimer

 */
@@ -9,8 +9,14 @@ 
#include <linux/types.h>

#include <linux/init.h>

#include <linux/pagemap.h>

#include <linux/module.h>

#include <linux/cleancache.h>



/* temporary ifdef until include/linux/frontswap.h is upstream */

#ifdef CONFIG_FRONTSWAP

#include <linux/frontswap.h>

#endif



#include <xen/xen.h>

#include <xen/interface/xen.h>

#include <asm/xen/hypercall.h>
@@ -122,14 +128,8 @@ static int xen_tmem_flush_object(u32 pool_id, struct tmem_oid oid) 
	return xen_tmem_op(TMEM_FLUSH_OBJECT, pool_id, oid, 0, 0, 0, 0, 0);

}



static int xen_tmem_destroy_pool(u32 pool_id)

{

	struct tmem_oid oid = { { 0 } };



	return xen_tmem_op(TMEM_DESTROY_POOL, pool_id, oid, 0, 0, 0, 0, 0);

}



int tmem_enabled;

int tmem_enabled __read_mostly;

EXPORT_SYMBOL(tmem_enabled);



static int __init enable_tmem(char *s)

{
@@ -139,6 +139,14 @@ static int __init enable_tmem(char *s) 


__setup("tmem", enable_tmem);



#ifdef CONFIG_CLEANCACHE

static int xen_tmem_destroy_pool(u32 pool_id)

{

	struct tmem_oid oid = { { 0 } };



	return xen_tmem_op(TMEM_DESTROY_POOL, pool_id, oid, 0, 0, 0, 0, 0);

}



/* cleancache ops */



static void tmem_cleancache_put_page(int pool, struct cleancache_filekey key,
@@ -240,18 +248,156 @@ static struct cleancache_ops tmem_cleancache_ops = { 
	.init_shared_fs = tmem_cleancache_init_shared_fs,

	.init_fs = tmem_cleancache_init_fs

};

#endif



static int __init xen_tmem_init(void)

#ifdef CONFIG_FRONTSWAP

/* frontswap tmem operations */



/* a single tmem poolid is used for all frontswap "types" (swapfiles) */

static int tmem_frontswap_poolid;



/*

 * Swizzling increases objects per swaptype, increasing tmem concurrency

 * for heavy swaploads.  Later, larger nr_cpus -> larger SWIZ_BITS

 */

#define SWIZ_BITS		4

#define SWIZ_MASK		((1 << SWIZ_BITS) - 1)

#define _oswiz(_type, _ind)	((_type << SWIZ_BITS) | (_ind & SWIZ_MASK))

#define iswiz(_ind)		(_ind >> SWIZ_BITS)



static inline struct tmem_oid oswiz(unsigned type, u32 ind)

{

	struct cleancache_ops old_ops;

	struct tmem_oid oid = { .oid = { 0 } };

	oid.oid[0] = _oswiz(type, ind);

	return oid;

}



/* returns 0 if the page was successfully put into frontswap, -1 if not */

static int tmem_frontswap_put_page(unsigned type, pgoff_t offset,

				   struct page *page)

{

	u64 ind64 = (u64)offset;

	u32 ind = (u32)offset;

	unsigned long pfn = page_to_pfn(page);

	int pool = tmem_frontswap_poolid;

	int ret;



	if (pool < 0)

		return -1;

	if (ind64 != ind)

		return -1;

	mb(); /* ensure page is quiescent; tmem may address it with an alias */

	ret = xen_tmem_put_page(pool, oswiz(type, ind), iswiz(ind), pfn);

	/* translate Xen tmem return values to linux semantics */

	if (ret == 1)

		return 0;

	else

		return -1;

}



/*

 * returns 0 if the page was successfully gotten from frontswap, -1 if

 * was not present (should never happen!)

 */

static int tmem_frontswap_get_page(unsigned type, pgoff_t offset,

				   struct page *page)

{

	u64 ind64 = (u64)offset;

	u32 ind = (u32)offset;

	unsigned long pfn = page_to_pfn(page);

	int pool = tmem_frontswap_poolid;

	int ret;



	if (pool < 0)

		return -1;

	if (ind64 != ind)

		return -1;

	ret = xen_tmem_get_page(pool, oswiz(type, ind), iswiz(ind), pfn);

	/* translate Xen tmem return values to linux semantics */

	if (ret == 1)

		return 0;

	else

		return -1;

}



/* flush a single page from frontswap */

static void tmem_frontswap_flush_page(unsigned type, pgoff_t offset)

{

	u64 ind64 = (u64)offset;

	u32 ind = (u32)offset;

	int pool = tmem_frontswap_poolid;



	if (pool < 0)

		return;

	if (ind64 != ind)

		return;

	(void) xen_tmem_flush_page(pool, oswiz(type, ind), iswiz(ind));

}



/* flush all pages from the passed swaptype */

static void tmem_frontswap_flush_area(unsigned type)

{

	int pool = tmem_frontswap_poolid;

	int ind;



	if (pool < 0)

		return;

	for (ind = SWIZ_MASK; ind >= 0; ind--)

		(void)xen_tmem_flush_object(pool, oswiz(type, ind));

}



static void tmem_frontswap_init(unsigned ignored)

{

	struct tmem_pool_uuid private = TMEM_POOL_PRIVATE_UUID;



	/* a single tmem poolid is used for all frontswap "types" (swapfiles) */

	if (tmem_frontswap_poolid < 0)

		tmem_frontswap_poolid =

		    xen_tmem_new_pool(private, TMEM_POOL_PERSIST, PAGE_SIZE);

}



static int __initdata use_frontswap = 1;



static int __init no_frontswap(char *s)

{

	use_frontswap = 0;

	return 1;

}



__setup("nofrontswap", no_frontswap);



static struct frontswap_ops tmem_frontswap_ops = {

	.put_page = tmem_frontswap_put_page,

	.get_page = tmem_frontswap_get_page,

	.flush_page = tmem_frontswap_flush_page,

	.flush_area = tmem_frontswap_flush_area,

	.init = tmem_frontswap_init

};

#endif



static int __init xen_tmem_init(void)

{

	if (!xen_domain())

		return 0;

#ifdef CONFIG_FRONTSWAP

	if (tmem_enabled && use_frontswap) {

		char *s = "";

		struct frontswap_ops old_ops =

			frontswap_register_ops(&tmem_frontswap_ops);



		tmem_frontswap_poolid = -1;

		if (old_ops.init != NULL)

			s = " (WARNING: frontswap_ops overridden)";

		printk(KERN_INFO "frontswap enabled, RAM provided by "

				 "Xen Transcendent Memory\n");

	}

#endif

#ifdef CONFIG_CLEANCACHE

	BUG_ON(sizeof(struct cleancache_filekey) != sizeof(struct tmem_oid));

	if (tmem_enabled && use_cleancache) {

		char *s = "";

		old_ops = cleancache_register_ops(&tmem_cleancache_ops);

		struct cleancache_ops old_ops =

			cleancache_register_ops(&tmem_cleancache_ops);

		if (old_ops.init_fs != NULL)

			s = " (WARNING: cleancache_ops overridden)";

		printk(KERN_INFO "cleancache enabled, RAM provided by "