[v3,3/9] xen/balloon: Share common memory reservation routines

Commit Message

Oleksandr Andrushchenko June 12, 2018, 1:41 p.m. UTC

From: Oleksandr Andrushchenko <[e-mail]>

Memory {increase|decrease}_reservation and VA mappings update/reset
code used in balloon driver can be made common, so other drivers can
also re-use the same functionality without open-coding.
Create a dedicated file for the shared code and export corresponding
symbols for other kernel modules.

Signed-off-by: Oleksandr Andrushchenko <[e-mail]>
---
 drivers/xen/Makefile          |   1 +
 drivers/xen/balloon.c         |  71 ++-------------------
 drivers/xen/mem-reservation.c | 112 ++++++++++++++++++++++++++++++++++
 include/xen/mem-reservation.h |  64 +++++++++++++++++++
 4 files changed, 183 insertions(+), 65 deletions(-)
 create mode 100644 drivers/xen/mem-reservation.c
 create mode 100644 include/xen/mem-reservation.h

Comments

Boris Ostrovsky June 13, 2018, 12:47 a.m. UTC | #1

On 06/12/2018 09:41 AM, Oleksandr Andrushchenko wrote:
> From: Oleksandr Andrushchenko <[e-mail]>

> diff --git a/include/xen/mem-reservation.h b/include/xen/mem-reservation.h
> new file mode 100644
> index 000000000000..e0939387278d
> --- /dev/null
> +++ b/include/xen/mem-reservation.h
> @@ -0,0 +1,64 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +/*
> + * Xen memory reservation utilities.
> + *
> + * Copyright (c) 2003, B Dragovic
> + * Copyright (c) 2003-2004, M Williamson, K Fraser
> + * Copyright (c) 2005 Dan M. Smith, IBM Corporation
> + * Copyright (c) 2010 Daniel Kiper
> + * Copyright (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
> + */
> +
> +#ifndef _XENMEM_RESERVATION_H
> +#define _XENMEM_RESERVATION_H
> +
> +#include <linux/kernel.h>
> +#include <linux/slab.h>
> +
> +#include <asm/xen/hypercall.h>
> +#include <asm/tlb.h>
> +
> +#include <xen/interface/memory.h>
> +#include <xen/page.h>


I should have noticed this in the previous post but I suspect most of 
these includes belong in the C file. For example, there is no reason for 
hypercall.h here.

-boris


> +
> +static inline void xenmem_reservation_scrub_page(struct page *page)
> +{
> +#ifdef CONFIG_XEN_SCRUB_PAGES
> +	clear_highpage(page);
> +#endif
> +}
> +
> +#ifdef CONFIG_XEN_HAVE_PVMMU
> +void __xenmem_reservation_va_mapping_update(unsigned long count,
> +					    struct page **pages,
> +					    xen_pfn_t *frames);
> +
> +void __xenmem_reservation_va_mapping_reset(unsigned long count,
> +					   struct page **pages);
> +#endif
> +
> +static inline void xenmem_reservation_va_mapping_update(unsigned long count,
> +							struct page **pages,
> +							xen_pfn_t *frames)
> +{
> +#ifdef CONFIG_XEN_HAVE_PVMMU
> +	if (!xen_feature(XENFEAT_auto_translated_physmap))
> +		__xenmem_reservation_va_mapping_update(count, pages, frames);
> +#endif
> +}
> +
> +static inline void xenmem_reservation_va_mapping_reset(unsigned long count,
> +						       struct page **pages)
> +{
> +#ifdef CONFIG_XEN_HAVE_PVMMU
> +	if (!xen_feature(XENFEAT_auto_translated_physmap))
> +		__xenmem_reservation_va_mapping_reset(count, pages);
> +#endif
> +}
> +
> +int xenmem_reservation_increase(int count, xen_pfn_t *frames);
> +
> +int xenmem_reservation_decrease(int count, xen_pfn_t *frames);
> +
> +#endif
>

Boris Ostrovsky June 13, 2018, 1:07 a.m. UTC | #2

On 06/12/2018 09:41 AM, Oleksandr Andrushchenko wrote:



One more thing: please add a comment here saying that frames array is 
array of PFNs (in Xen granularity), which is what 
XENMEM_populate_physmap requires. And remove (or update to name the 
actual call you are making) the corresponding comment in 
increase_reservation().


> +
> +int xenmem_reservation_increase(int count, xen_pfn_t *frames)
> +{
> +	struct xen_memory_reservation reservation = {
> +		.address_bits = 0,
> +		.extent_order = EXTENT_ORDER,
> +		.domid        = DOMID_SELF
> +	};
> +
> +	set_xen_guest_handle(reservation.extent_start, frames);
> +	reservation.nr_extents = count;
> +	return HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
> +}
> +EXPORT_SYMBOL_GPL(xenmem_reservation_increase);


And similarly, here we are requesting GFNs, and update 
decrease_reservation().


-boris

> +
> +int xenmem_reservation_decrease(int count, xen_pfn_t *frames)
> +{
> +	struct xen_memory_reservation reservation = {
> +		.address_bits = 0,
> +		.extent_order = EXTENT_ORDER,
> +		.domid        = DOMID_SELF
> +	};
> +
> +	set_xen_guest_handle(reservation.extent_start, frames);
> +	reservation.nr_extents = count;
> +	return HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation);

Oleksandr Andrushchenko June 13, 2018, 6:26 a.m. UTC | #3

On 06/13/2018 03:47 AM, Boris Ostrovsky wrote:
>
>
> On 06/12/2018 09:41 AM, Oleksandr Andrushchenko wrote:
>> From: Oleksandr Andrushchenko <[e-mail]>
>
>> diff --git a/include/xen/mem-reservation.h 
>> b/include/xen/mem-reservation.h
>> new file mode 100644
>> index 000000000000..e0939387278d
>> --- /dev/null
>> +++ b/include/xen/mem-reservation.h
>> @@ -0,0 +1,64 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +
>> +/*
>> + * Xen memory reservation utilities.
>> + *
>> + * Copyright (c) 2003, B Dragovic
>> + * Copyright (c) 2003-2004, M Williamson, K Fraser
>> + * Copyright (c) 2005 Dan M. Smith, IBM Corporation
>> + * Copyright (c) 2010 Daniel Kiper
>> + * Copyright (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
>> + */
>> +
>> +#ifndef _XENMEM_RESERVATION_H
>> +#define _XENMEM_RESERVATION_H
>> +
>> +#include <linux/kernel.h>
>> +#include <linux/slab.h>
>> +
>> +#include <asm/xen/hypercall.h>
>> +#include <asm/tlb.h>
>> +
>> +#include <xen/interface/memory.h>
>> +#include <xen/page.h>
>
>
> I should have noticed this in the previous post but I suspect most of 
> these includes belong in the C file. For example, there is no reason 
> for hypercall.h here.
>
Yes, it seems that the header can only have
#include <xen/page.h>
Will move the rest into the .c file
> -boris
>
>
>> +
>> +static inline void xenmem_reservation_scrub_page(struct page *page)
>> +{
>> +#ifdef CONFIG_XEN_SCRUB_PAGES
>> +    clear_highpage(page);
>> +#endif
>> +}
>> +
>> +#ifdef CONFIG_XEN_HAVE_PVMMU
>> +void __xenmem_reservation_va_mapping_update(unsigned long count,
>> +                        struct page **pages,
>> +                        xen_pfn_t *frames);
>> +
>> +void __xenmem_reservation_va_mapping_reset(unsigned long count,
>> +                       struct page **pages);
>> +#endif
>> +
>> +static inline void xenmem_reservation_va_mapping_update(unsigned 
>> long count,
>> +                            struct page **pages,
>> +                            xen_pfn_t *frames)
>> +{
>> +#ifdef CONFIG_XEN_HAVE_PVMMU
>> +    if (!xen_feature(XENFEAT_auto_translated_physmap))
>> +        __xenmem_reservation_va_mapping_update(count, pages, frames);
>> +#endif
>> +}
>> +
>> +static inline void xenmem_reservation_va_mapping_reset(unsigned long 
>> count,
>> +                               struct page **pages)
>> +{
>> +#ifdef CONFIG_XEN_HAVE_PVMMU
>> +    if (!xen_feature(XENFEAT_auto_translated_physmap))
>> +        __xenmem_reservation_va_mapping_reset(count, pages);
>> +#endif
>> +}
>> +
>> +int xenmem_reservation_increase(int count, xen_pfn_t *frames);
>> +
>> +int xenmem_reservation_decrease(int count, xen_pfn_t *frames);
>> +
>> +#endif
>>

Oleksandr Andrushchenko June 13, 2018, 6:50 a.m. UTC | #4

On 06/13/2018 04:07 AM, Boris Ostrovsky wrote:
>
>
> On 06/12/2018 09:41 AM, Oleksandr Andrushchenko wrote:
>
>
>
> One more thing: please add a comment here saying that frames array is 
> array of PFNs (in Xen granularity), which is what 
> XENMEM_populate_physmap requires. And remove (or update to name the 
> actual call you are making) the corresponding comment in 
> increase_reservation().
>
I will remove corresponding comments from the balloon's 
{increase|decrease}_reservation
and move those into xenmem_reservation{increase|decrease} where they 
belong now.
I will also put a comment close to xenmem_reservation{increase|decrease}:

/* @frames is an array of PFNs */
int xenmem_reservation_increase(int count, xen_pfn_t *frames)
{
     [...]
}

/* @frames is an array of GFNs */
int xenmem_reservation_decrease(int count, xen_pfn_t *frames)
{
     [...]
}
>
>> +
>> +int xenmem_reservation_increase(int count, xen_pfn_t *frames)
>> +{
>> +    struct xen_memory_reservation reservation = {
>> +        .address_bits = 0,
>> +        .extent_order = EXTENT_ORDER,
>> +        .domid        = DOMID_SELF
>> +    };
>> +
>> +    set_xen_guest_handle(reservation.extent_start, frames);
>> +    reservation.nr_extents = count;
>> +    return HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
>> +}
>> +EXPORT_SYMBOL_GPL(xenmem_reservation_increase);
>
>
> And similarly, here we are requesting GFNs, and update 
> decrease_reservation().
>
Please see above
>
> -boris
>
Thank you,
Oleksandr
>> +
>> +int xenmem_reservation_decrease(int count, xen_pfn_t *frames)
>> +{
>> +    struct xen_memory_reservation reservation = {
>> +        .address_bits = 0,
>> +        .extent_order = EXTENT_ORDER,
>> +        .domid        = DOMID_SELF
>> +    };
>> +
>> +    set_xen_guest_handle(reservation.extent_start, frames);
>> +    reservation.nr_extents = count;
>> +    return HYPERVISOR_memory_op(XENMEM_decrease_reservation, 
>> &reservation);

Boris Ostrovsky June 13, 2018, 12:02 p.m. UTC | #5

On 06/13/2018 02:26 AM, Oleksandr Andrushchenko wrote:
> On 06/13/2018 03:47 AM, Boris Ostrovsky wrote:
>>
>>
>> On 06/12/2018 09:41 AM, Oleksandr Andrushchenko wrote:
>>> From: Oleksandr Andrushchenko <[e-mail]>
>>
>>> diff --git a/include/xen/mem-reservation.h 
>>> b/include/xen/mem-reservation.h
>>> new file mode 100644
>>> index 000000000000..e0939387278d
>>> --- /dev/null
>>> +++ b/include/xen/mem-reservation.h
>>> @@ -0,0 +1,64 @@
>>> +/* SPDX-License-Identifier: GPL-2.0 */
>>> +
>>> +/*
>>> + * Xen memory reservation utilities.
>>> + *
>>> + * Copyright (c) 2003, B Dragovic
>>> + * Copyright (c) 2003-2004, M Williamson, K Fraser
>>> + * Copyright (c) 2005 Dan M. Smith, IBM Corporation
>>> + * Copyright (c) 2010 Daniel Kiper
>>> + * Copyright (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
>>> + */
>>> +
>>> +#ifndef _XENMEM_RESERVATION_H
>>> +#define _XENMEM_RESERVATION_H
>>> +
>>> +#include <linux/kernel.h>
>>> +#include <linux/slab.h>
>>> +
>>> +#include <asm/xen/hypercall.h>
>>> +#include <asm/tlb.h>
>>> +
>>> +#include <xen/interface/memory.h>
>>> +#include <xen/page.h>
>>
>>
>> I should have noticed this in the previous post but I suspect most of 
>> these includes belong in the C file. For example, there is no reason 
>> for hypercall.h here.
>>
> Yes, it seems that the header can only have
> #include <xen/page.h>
> Will move the rest into the .c file


You may need something for clear_highpage() and maybe for Xen feature 
flags. But you'll find out for sure when you try to build. ;-)

-boris



>> -boris
>>
>>
>>> +
>>> +static inline void xenmem_reservation_scrub_page(struct page *page)
>>> +{
>>> +#ifdef CONFIG_XEN_SCRUB_PAGES
>>> +    clear_highpage(page);
>>> +#endif
>>> +}
>>> +
>>> +#ifdef CONFIG_XEN_HAVE_PVMMU
>>> +void __xenmem_reservation_va_mapping_update(unsigned long count,
>>> +                        struct page **pages,
>>> +                        xen_pfn_t *frames);
>>> +
>>> +void __xenmem_reservation_va_mapping_reset(unsigned long count,
>>> +                       struct page **pages);
>>> +#endif
>>> +
>>> +static inline void xenmem_reservation_va_mapping_update(unsigned 
>>> long count,
>>> +                            struct page **pages,
>>> +                            xen_pfn_t *frames)
>>> +{
>>> +#ifdef CONFIG_XEN_HAVE_PVMMU
>>> +    if (!xen_feature(XENFEAT_auto_translated_physmap))
>>> +        __xenmem_reservation_va_mapping_update(count, pages, frames);
>>> +#endif
>>> +}
>>> +
>>> +static inline void xenmem_reservation_va_mapping_reset(unsigned long 
>>> count,
>>> +                               struct page **pages)
>>> +{
>>> +#ifdef CONFIG_XEN_HAVE_PVMMU
>>> +    if (!xen_feature(XENFEAT_auto_translated_physmap))
>>> +        __xenmem_reservation_va_mapping_reset(count, pages);
>>> +#endif
>>> +}
>>> +
>>> +int xenmem_reservation_increase(int count, xen_pfn_t *frames);
>>> +
>>> +int xenmem_reservation_decrease(int count, xen_pfn_t *frames);
>>> +
>>> +#endif
>>>
>

Oleksandr Andrushchenko June 13, 2018, 12:03 p.m. UTC | #6

On 06/13/2018 03:02 PM, Boris Ostrovsky wrote:
>
>
> On 06/13/2018 02:26 AM, Oleksandr Andrushchenko wrote:
>> On 06/13/2018 03:47 AM, Boris Ostrovsky wrote:
>>>
>>>
>>> On 06/12/2018 09:41 AM, Oleksandr Andrushchenko wrote:
>>>> From: Oleksandr Andrushchenko <[e-mail]>
>>>
>>>> diff --git a/include/xen/mem-reservation.h 
>>>> b/include/xen/mem-reservation.h
>>>> new file mode 100644
>>>> index 000000000000..e0939387278d
>>>> --- /dev/null
>>>> +++ b/include/xen/mem-reservation.h
>>>> @@ -0,0 +1,64 @@
>>>> +/* SPDX-License-Identifier: GPL-2.0 */
>>>> +
>>>> +/*
>>>> + * Xen memory reservation utilities.
>>>> + *
>>>> + * Copyright (c) 2003, B Dragovic
>>>> + * Copyright (c) 2003-2004, M Williamson, K Fraser
>>>> + * Copyright (c) 2005 Dan M. Smith, IBM Corporation
>>>> + * Copyright (c) 2010 Daniel Kiper
>>>> + * Copyright (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
>>>> + */
>>>> +
>>>> +#ifndef _XENMEM_RESERVATION_H
>>>> +#define _XENMEM_RESERVATION_H
>>>> +
>>>> +#include <linux/kernel.h>
>>>> +#include <linux/slab.h>
>>>> +
>>>> +#include <asm/xen/hypercall.h>
>>>> +#include <asm/tlb.h>
>>>> +
>>>> +#include <xen/interface/memory.h>
>>>> +#include <xen/page.h>
>>>
>>>
>>> I should have noticed this in the previous post but I suspect most 
>>> of these includes belong in the C file. For example, there is no 
>>> reason for hypercall.h here.
>>>
>> Yes, it seems that the header can only have
>> #include <xen/page.h>
>> Will move the rest into the .c file
>
>
> You may need something for clear_highpage() and maybe for Xen feature 
> flags. But you'll find out for sure when you try to build. ;-)
>
#include <asm/tlb.h>

;)
> -boris
>
>
>
>>> -boris
>>>
>>>
>>>> +
>>>> +static inline void xenmem_reservation_scrub_page(struct page *page)
>>>> +{
>>>> +#ifdef CONFIG_XEN_SCRUB_PAGES
>>>> +    clear_highpage(page);
>>>> +#endif
>>>> +}
>>>> +
>>>> +#ifdef CONFIG_XEN_HAVE_PVMMU
>>>> +void __xenmem_reservation_va_mapping_update(unsigned long count,
>>>> +                        struct page **pages,
>>>> +                        xen_pfn_t *frames);
>>>> +
>>>> +void __xenmem_reservation_va_mapping_reset(unsigned long count,
>>>> +                       struct page **pages);
>>>> +#endif
>>>> +
>>>> +static inline void xenmem_reservation_va_mapping_update(unsigned 
>>>> long count,
>>>> +                            struct page **pages,
>>>> +                            xen_pfn_t *frames)
>>>> +{
>>>> +#ifdef CONFIG_XEN_HAVE_PVMMU
>>>> +    if (!xen_feature(XENFEAT_auto_translated_physmap))
>>>> +        __xenmem_reservation_va_mapping_update(count, pages, frames);
>>>> +#endif
>>>> +}
>>>> +
>>>> +static inline void xenmem_reservation_va_mapping_reset(unsigned 
>>>> long count,
>>>> +                               struct page **pages)
>>>> +{
>>>> +#ifdef CONFIG_XEN_HAVE_PVMMU
>>>> +    if (!xen_feature(XENFEAT_auto_translated_physmap))
>>>> +        __xenmem_reservation_va_mapping_reset(count, pages);
>>>> +#endif
>>>> +}
>>>> +
>>>> +int xenmem_reservation_increase(int count, xen_pfn_t *frames);
>>>> +
>>>> +int xenmem_reservation_decrease(int count, xen_pfn_t *frames);
>>>> +
>>>> +#endif
>>>>
>>

Oleksandr Andrushchenko June 13, 2018, 12:27 p.m. UTC | #7

On 06/13/2018 03:03 PM, Oleksandr Andrushchenko wrote:
> On 06/13/2018 03:02 PM, Boris Ostrovsky wrote:
>>
>>
>> On 06/13/2018 02:26 AM, Oleksandr Andrushchenko wrote:
>>> On 06/13/2018 03:47 AM, Boris Ostrovsky wrote:
>>>>
>>>>
>>>> On 06/12/2018 09:41 AM, Oleksandr Andrushchenko wrote:
>>>>> From: Oleksandr Andrushchenko <[e-mail]>
>>>>
>>>>> diff --git a/include/xen/mem-reservation.h 
>>>>> b/include/xen/mem-reservation.h
>>>>> new file mode 100644
>>>>> index 000000000000..e0939387278d
>>>>> --- /dev/null
>>>>> +++ b/include/xen/mem-reservation.h
>>>>> @@ -0,0 +1,64 @@
>>>>> +/* SPDX-License-Identifier: GPL-2.0 */
>>>>> +
>>>>> +/*
>>>>> + * Xen memory reservation utilities.
>>>>> + *
>>>>> + * Copyright (c) 2003, B Dragovic
>>>>> + * Copyright (c) 2003-2004, M Williamson, K Fraser
>>>>> + * Copyright (c) 2005 Dan M. Smith, IBM Corporation
>>>>> + * Copyright (c) 2010 Daniel Kiper
>>>>> + * Copyright (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
>>>>> + */
>>>>> +
>>>>> +#ifndef _XENMEM_RESERVATION_H
>>>>> +#define _XENMEM_RESERVATION_H
>>>>> +
>>>>> +#include <linux/kernel.h>
>>>>> +#include <linux/slab.h>
>>>>> +
>>>>> +#include <asm/xen/hypercall.h>
>>>>> +#include <asm/tlb.h>
>>>>> +
>>>>> +#include <xen/interface/memory.h>
>>>>> +#include <xen/page.h>
>>>>
>>>>
>>>> I should have noticed this in the previous post but I suspect most 
>>>> of these includes belong in the C file. For example, there is no 
>>>> reason for hypercall.h here.
>>>>
>>> Yes, it seems that the header can only have
>>> #include <xen/page.h>
>>> Will move the rest into the .c file
>>
>>
>> You may need something for clear_highpage() and maybe for Xen feature 
>> flags. But you'll find out for sure when you try to build. ;-)
>>
> #include <asm/tlb.h>
>
Or even
#include <linux/highmem.h>
according to [1]
> ;)
>> -boris
>>
>>
>>
>>>> -boris
>>>>
>>>>
>>>>> +
>>>>> +static inline void xenmem_reservation_scrub_page(struct page *page)
>>>>> +{
>>>>> +#ifdef CONFIG_XEN_SCRUB_PAGES
>>>>> +    clear_highpage(page);
>>>>> +#endif
>>>>> +}
>>>>> +
>>>>> +#ifdef CONFIG_XEN_HAVE_PVMMU
>>>>> +void __xenmem_reservation_va_mapping_update(unsigned long count,
>>>>> +                        struct page **pages,
>>>>> +                        xen_pfn_t *frames);
>>>>> +
>>>>> +void __xenmem_reservation_va_mapping_reset(unsigned long count,
>>>>> +                       struct page **pages);
>>>>> +#endif
>>>>> +
>>>>> +static inline void xenmem_reservation_va_mapping_update(unsigned 
>>>>> long count,
>>>>> +                            struct page **pages,
>>>>> +                            xen_pfn_t *frames)
>>>>> +{
>>>>> +#ifdef CONFIG_XEN_HAVE_PVMMU
>>>>> +    if (!xen_feature(XENFEAT_auto_translated_physmap))
>>>>> +        __xenmem_reservation_va_mapping_update(count, pages, 
>>>>> frames);
>>>>> +#endif
>>>>> +}
>>>>> +
>>>>> +static inline void xenmem_reservation_va_mapping_reset(unsigned 
>>>>> long count,
>>>>> +                               struct page **pages)
>>>>> +{
>>>>> +#ifdef CONFIG_XEN_HAVE_PVMMU
>>>>> +    if (!xen_feature(XENFEAT_auto_translated_physmap))
>>>>> +        __xenmem_reservation_va_mapping_reset(count, pages);
>>>>> +#endif
>>>>> +}
>>>>> +
>>>>> +int xenmem_reservation_increase(int count, xen_pfn_t *frames);
>>>>> +
>>>>> +int xenmem_reservation_decrease(int count, xen_pfn_t *frames);
>>>>> +
>>>>> +#endif
>>>>>
>>>
>
[1] https://elixir.bootlin.com/linux/v4.17.1/ident/clear_highpage

Patch

diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index 451e833f5931..3c87b0c3aca6 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -2,6 +2,7 @@ 
 obj-$(CONFIG_HOTPLUG_CPU)		+= cpu_hotplug.o
 obj-$(CONFIG_X86)			+= fallback.o
 obj-y	+= grant-table.o features.o balloon.o manage.o preempt.o time.o
+obj-y	+= mem-reservation.o
 obj-y	+= events/
 obj-y	+= xenbus/
 
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 065f0b607373..bdbce4257b65 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -71,6 +71,7 @@ 
 #include <xen/balloon.h>
 #include <xen/features.h>
 #include <xen/page.h>
+#include <xen/mem-reservation.h>
 
 static int xen_hotplug_unpopulated;
 
@@ -157,13 +158,6 @@  static DECLARE_DELAYED_WORK(balloon_worker, balloon_process);
 #define GFP_BALLOON \
 	(GFP_HIGHUSER | __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC)
 
-static void scrub_page(struct page *page)
-{
-#ifdef CONFIG_XEN_SCRUB_PAGES
-	clear_highpage(page);
-#endif
-}
-
 /* balloon_append: add the given page to the balloon. */
 static void __balloon_append(struct page *page)
 {
@@ -463,11 +457,6 @@  static enum bp_state increase_reservation(unsigned long nr_pages)
 	int rc;
 	unsigned long i;
 	struct page   *page;
-	struct xen_memory_reservation reservation = {
-		.address_bits = 0,
-		.extent_order = EXTENT_ORDER,
-		.domid        = DOMID_SELF
-	};
 
 	if (nr_pages > ARRAY_SIZE(frame_list))
 		nr_pages = ARRAY_SIZE(frame_list);
@@ -486,9 +475,7 @@  static enum bp_state increase_reservation(unsigned long nr_pages)
 		page = balloon_next_page(page);
 	}
 
-	set_xen_guest_handle(reservation.extent_start, frame_list);
-	reservation.nr_extents = nr_pages;
-	rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
+	rc = xenmem_reservation_increase(nr_pages, frame_list);
 	if (rc <= 0)
 		return BP_EAGAIN;
 
@@ -496,29 +483,7 @@  static enum bp_state increase_reservation(unsigned long nr_pages)
 		page = balloon_retrieve(false);
 		BUG_ON(page == NULL);
 
-#ifdef CONFIG_XEN_HAVE_PVMMU
-		/*
-		 * We don't support PV MMU when Linux and Xen is using
-		 * different page granularity.
-		 */
-		BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
-
-		if (!xen_feature(XENFEAT_auto_translated_physmap)) {
-			unsigned long pfn = page_to_pfn(page);
-
-			set_phys_to_machine(pfn, frame_list[i]);
-
-			/* Link back into the page tables if not highmem. */
-			if (!PageHighMem(page)) {
-				int ret;
-				ret = HYPERVISOR_update_va_mapping(
-						(unsigned long)__va(pfn << PAGE_SHIFT),
-						mfn_pte(frame_list[i], PAGE_KERNEL),
-						0);
-				BUG_ON(ret);
-			}
-		}
-#endif
+		xenmem_reservation_va_mapping_update(1, &page, &frame_list[i]);
 
 		/* Relinquish the page back to the allocator. */
 		free_reserved_page(page);
@@ -535,11 +500,6 @@  static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
 	unsigned long i;
 	struct page *page, *tmp;
 	int ret;
-	struct xen_memory_reservation reservation = {
-		.address_bits = 0,
-		.extent_order = EXTENT_ORDER,
-		.domid        = DOMID_SELF
-	};
 	LIST_HEAD(pages);
 
 	if (nr_pages > ARRAY_SIZE(frame_list))
@@ -553,7 +513,7 @@  static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
 			break;
 		}
 		adjust_managed_page_count(page, -1);
-		scrub_page(page);
+		xenmem_reservation_scrub_page(page);
 		list_add(&page->lru, &pages);
 	}
 
@@ -575,25 +535,8 @@  static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
 		/* XENMEM_decrease_reservation requires a GFN */
 		frame_list[i++] = xen_page_to_gfn(page);
 
-#ifdef CONFIG_XEN_HAVE_PVMMU
-		/*
-		 * We don't support PV MMU when Linux and Xen is using
-		 * different page granularity.
-		 */
-		BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
-
-		if (!xen_feature(XENFEAT_auto_translated_physmap)) {
-			unsigned long pfn = page_to_pfn(page);
+		xenmem_reservation_va_mapping_reset(1, &page);
 
-			if (!PageHighMem(page)) {
-				ret = HYPERVISOR_update_va_mapping(
-						(unsigned long)__va(pfn << PAGE_SHIFT),
-						__pte_ma(0), 0);
-				BUG_ON(ret);
-			}
-			__set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
-		}
-#endif
 		list_del(&page->lru);
 
 		balloon_append(page);
@@ -601,9 +544,7 @@  static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
 
 	flush_tlb_all();
 
-	set_xen_guest_handle(reservation.extent_start, frame_list);
-	reservation.nr_extents   = nr_pages;
-	ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation);
+	ret = xenmem_reservation_decrease(nr_pages, frame_list);
 	BUG_ON(ret != nr_pages);
 
 	balloon_stats.current_pages -= nr_pages;
diff --git a/drivers/xen/mem-reservation.c b/drivers/xen/mem-reservation.c
new file mode 100644
index 000000000000..aa551d58001c
--- /dev/null
+++ b/drivers/xen/mem-reservation.c
@@ -0,0 +1,112 @@ 
+// SPDX-License-Identifier: GPL-2.0
+
+/******************************************************************************
+ * Xen memory reservation utilities.
+ *
+ * Copyright (c) 2003, B Dragovic
+ * Copyright (c) 2003-2004, M Williamson, K Fraser
+ * Copyright (c) 2005 Dan M. Smith, IBM Corporation
+ * Copyright (c) 2010 Daniel Kiper
+ * Copyright (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
+ */
+
+#include <xen/mem-reservation.h>
+
+/*
+ * Use one extent per PAGE_SIZE to avoid to break down the page into
+ * multiple frame.
+ */
+#define EXTENT_ORDER (fls(XEN_PFN_PER_PAGE) - 1)
+
+#ifdef CONFIG_XEN_HAVE_PVMMU
+void __xenmem_reservation_va_mapping_update(unsigned long count,
+					    struct page **pages,
+					    xen_pfn_t *frames)
+{
+	int i;
+
+	for (i = 0; i < count; i++) {
+		struct page *page = pages[i];
+		unsigned long pfn = page_to_pfn(page);
+
+		BUG_ON(page == NULL);
+
+		/*
+		 * We don't support PV MMU when Linux and Xen is using
+		 * different page granularity.
+		 */
+		BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
+
+
+		set_phys_to_machine(pfn, frames[i]);
+
+		/* Link back into the page tables if not highmem. */
+		if (!PageHighMem(page)) {
+			int ret;
+
+			ret = HYPERVISOR_update_va_mapping(
+					(unsigned long)__va(pfn << PAGE_SHIFT),
+					mfn_pte(frames[i], PAGE_KERNEL),
+					0);
+			BUG_ON(ret);
+		}
+	}
+}
+EXPORT_SYMBOL_GPL(__xenmem_reservation_va_mapping_update);
+
+void __xenmem_reservation_va_mapping_reset(unsigned long count,
+					   struct page **pages)
+{
+	int i;
+
+	for (i = 0; i < count; i++) {
+		struct page *page = pages[i];
+		unsigned long pfn = page_to_pfn(page);
+
+		/*
+		 * We don't support PV MMU when Linux and Xen is using
+		 * different page granularity.
+		 */
+		BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
+
+		if (!PageHighMem(page)) {
+			int ret;
+
+			ret = HYPERVISOR_update_va_mapping(
+					(unsigned long)__va(pfn << PAGE_SHIFT),
+					__pte_ma(0), 0);
+			BUG_ON(ret);
+		}
+		__set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
+	}
+}
+EXPORT_SYMBOL_GPL(__xenmem_reservation_va_mapping_reset);
+#endif /* CONFIG_XEN_HAVE_PVMMU */
+
+int xenmem_reservation_increase(int count, xen_pfn_t *frames)
+{
+	struct xen_memory_reservation reservation = {
+		.address_bits = 0,
+		.extent_order = EXTENT_ORDER,
+		.domid        = DOMID_SELF
+	};
+
+	set_xen_guest_handle(reservation.extent_start, frames);
+	reservation.nr_extents = count;
+	return HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
+}
+EXPORT_SYMBOL_GPL(xenmem_reservation_increase);
+
+int xenmem_reservation_decrease(int count, xen_pfn_t *frames)
+{
+	struct xen_memory_reservation reservation = {
+		.address_bits = 0,
+		.extent_order = EXTENT_ORDER,
+		.domid        = DOMID_SELF
+	};
+
+	set_xen_guest_handle(reservation.extent_start, frames);
+	reservation.nr_extents = count;
+	return HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation);
+}
+EXPORT_SYMBOL_GPL(xenmem_reservation_decrease);
diff --git a/include/xen/mem-reservation.h b/include/xen/mem-reservation.h
new file mode 100644
index 000000000000..e0939387278d
--- /dev/null
+++ b/include/xen/mem-reservation.h
@@ -0,0 +1,64 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * Xen memory reservation utilities.
+ *
+ * Copyright (c) 2003, B Dragovic
+ * Copyright (c) 2003-2004, M Williamson, K Fraser
+ * Copyright (c) 2005 Dan M. Smith, IBM Corporation
+ * Copyright (c) 2010 Daniel Kiper
+ * Copyright (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
+ */
+
+#ifndef _XENMEM_RESERVATION_H
+#define _XENMEM_RESERVATION_H
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+
+#include <asm/xen/hypercall.h>
+#include <asm/tlb.h>
+
+#include <xen/interface/memory.h>
+#include <xen/page.h>
+
+static inline void xenmem_reservation_scrub_page(struct page *page)
+{
+#ifdef CONFIG_XEN_SCRUB_PAGES
+	clear_highpage(page);
+#endif
+}
+
+#ifdef CONFIG_XEN_HAVE_PVMMU
+void __xenmem_reservation_va_mapping_update(unsigned long count,
+					    struct page **pages,
+					    xen_pfn_t *frames);
+
+void __xenmem_reservation_va_mapping_reset(unsigned long count,
+					   struct page **pages);
+#endif
+
+static inline void xenmem_reservation_va_mapping_update(unsigned long count,
+							struct page **pages,
+							xen_pfn_t *frames)
+{
+#ifdef CONFIG_XEN_HAVE_PVMMU
+	if (!xen_feature(XENFEAT_auto_translated_physmap))
+		__xenmem_reservation_va_mapping_update(count, pages, frames);
+#endif
+}
+
+static inline void xenmem_reservation_va_mapping_reset(unsigned long count,
+						       struct page **pages)
+{
+#ifdef CONFIG_XEN_HAVE_PVMMU
+	if (!xen_feature(XENFEAT_auto_translated_physmap))
+		__xenmem_reservation_va_mapping_reset(count, pages);
+#endif
+}
+
+int xenmem_reservation_increase(int count, xen_pfn_t *frames);
+
+int xenmem_reservation_decrease(int count, xen_pfn_t *frames);
+
+#endif