xen: remove tmem driver

The Xen tmem (transcendent memory) driver can be removed, as the
related Xen hypervisor feature never made it past the "experimental"
state and will be removed in future Xen versions (>= 4.13).

The xen-selfballoon driver depends on tmem, so it can be removed, too.
Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>

Documentation/admin-guide/kernel-parameters.txt

@@ -4674,27 +4674,6 @@
 			Force threading of all interrupt handlers except those
 			marked explicitly IRQF_NO_THREAD.
 
-	tmem		[KNL,XEN]
-			Enable the Transcendent memory driver if built-in.
-
-	tmem.cleancache=0|1 [KNL, XEN]
-			Default is on (1). Disable the usage of the cleancache
-			API to send anonymous pages to the hypervisor.
-
-	tmem.frontswap=0|1 [KNL, XEN]
-			Default is on (1). Disable the usage of the frontswap
-			API to send swap pages to the hypervisor. If disabled
-			the selfballooning and selfshrinking are force disabled.
-
-	tmem.selfballooning=0|1 [KNL, XEN]
-			Default is on (1). Disable the driving of swap pages
-			to the hypervisor.
-
-	tmem.selfshrinking=0|1 [KNL, XEN]
-			Default is on (1). Partial swapoff that immediately
-			transfers pages from Xen hypervisor back to the
-			kernel based on different criteria.
-
 	topology=	[S390]
 			Format: {off | on}
 			Specify if the kernel should make use of the cpu

drivers/xen/Kconfig

@@ -10,21 +10,6 @@ config XEN_BALLOON
 	  the system to expand the domain's memory allocation, or alternatively
 	  return unneeded memory to the system.
 
-config XEN_SELFBALLOONING
-	bool "Dynamically self-balloon kernel memory to target"
-	depends on XEN && XEN_BALLOON && CLEANCACHE && SWAP && XEN_TMEM
-	help
-	  Self-ballooning dynamically balloons available kernel memory driven
-	  by the current usage of anonymous memory ("committed AS") and
-	  controlled by various sysfs-settable parameters.  Configuring
-	  FRONTSWAP is highly recommended; if it is not configured, self-
-	  ballooning is disabled by default. If FRONTSWAP is configured,
-	  frontswap-selfshrinking is enabled by default but can be disabled
-	  with the 'tmem.selfshrink=0' kernel boot parameter; and self-ballooning
-	  is enabled by default but can be disabled with the 'tmem.selfballooning=0'
-	  kernel boot parameter.  Note that systems without a sufficiently
-	  large swap device should not enable self-ballooning.
-
 config XEN_BALLOON_MEMORY_HOTPLUG
 	bool "Memory hotplug support for Xen balloon driver"
 	depends on XEN_BALLOON && MEMORY_HOTPLUG
@@ -191,14 +176,6 @@ config SWIOTLB_XEN
 	def_bool y
 	select SWIOTLB
 
-config XEN_TMEM
-	tristate
-	depends on !ARM && !ARM64
-	default m if (CLEANCACHE || FRONTSWAP)
-	help
-	  Shim to interface in-kernel Transcendent Memory hooks
-	  (e.g. cleancache and frontswap) to Xen tmem hypercalls.
-
 config XEN_PCIDEV_BACKEND
 	tristate "Xen PCI-device backend driver"
 	depends on PCI && X86 && XEN

drivers/xen/Makefile

@@ -17,14 +17,12 @@ dom0-$(CONFIG_X86) += pcpu.o
 obj-$(CONFIG_XEN_DOM0)			+= $(dom0-y)
 obj-$(CONFIG_BLOCK)			+= biomerge.o
 obj-$(CONFIG_XEN_BALLOON)		+= xen-balloon.o
-obj-$(CONFIG_XEN_SELFBALLOONING)	+= xen-selfballoon.o
 obj-$(CONFIG_XEN_DEV_EVTCHN)		+= xen-evtchn.o
 obj-$(CONFIG_XEN_GNTDEV)		+= xen-gntdev.o
 obj-$(CONFIG_XEN_GRANT_DEV_ALLOC)	+= xen-gntalloc.o
 obj-$(CONFIG_XENFS)			+= xenfs/
 obj-$(CONFIG_XEN_SYS_HYPERVISOR)	+= sys-hypervisor.o
 obj-$(CONFIG_XEN_PVHVM)			+= platform-pci.o
-obj-$(CONFIG_XEN_TMEM)			+= tmem.o
 obj-$(CONFIG_SWIOTLB_XEN)		+= swiotlb-xen.o
 obj-$(CONFIG_XEN_MCE_LOG)		+= mcelog.o
 obj-$(CONFIG_XEN_PCIDEV_BACKEND)	+= xen-pciback/

drivers/xen/xen-balloon.c

@@ -129,8 +129,6 @@ void xen_balloon_init(void)
 {
 	register_balloon(&balloon_dev);
 
-	register_xen_selfballooning(&balloon_dev);
-
 	register_xenstore_notifier(&xenstore_notifier);
 }
 EXPORT_SYMBOL_GPL(xen_balloon_init);

include/xen/balloon.h

@@ -27,16 +27,6 @@ void balloon_set_new_target(unsigned long target);
 int alloc_xenballooned_pages(int nr_pages, struct page **pages);
 void free_xenballooned_pages(int nr_pages, struct page **pages);
 
-struct device;
-#ifdef CONFIG_XEN_SELFBALLOONING
-extern int register_xen_selfballooning(struct device *dev);
-#else
-static inline int register_xen_selfballooning(struct device *dev)
-{
-	return -ENOSYS;
-}
-#endif
-
 #ifdef CONFIG_XEN_BALLOON
 void xen_balloon_init(void);
 #else

include/xen/tmem.h

-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _XEN_TMEM_H
-#define _XEN_TMEM_H
-
-#include <linux/types.h>
-
-#ifdef CONFIG_XEN_TMEM_MODULE
-#define tmem_enabled true
-#else
-/* defined in drivers/xen/tmem.c */
-extern bool tmem_enabled;
-#endif
-
-#ifdef CONFIG_XEN_SELFBALLOONING
-extern int xen_selfballoon_init(bool, bool);
-#endif
-
-#endif /* _XEN_TMEM_H */