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SubjectRe: [PATCH 2/8] xen/balloon: Move common memory reservation routines to a module
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On 05/30/2018 07:32 AM, Juergen Gross wrote:
> On 25/05/18 17:33, Oleksandr Andrushchenko wrote:
>> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>>
>> 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 module for the shared code and export corresponding
>> symbols for other kernel modules.
>>
>> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>> ---
>> drivers/xen/Makefile | 1 +
>> drivers/xen/balloon.c | 71 ++----------------
>> drivers/xen/mem-reservation.c | 134 ++++++++++++++++++++++++++++++++++
>> include/xen/mem_reservation.h | 29 ++++++++
>> 4 files changed, 170 insertions(+), 65 deletions(-)
>> create mode 100644 drivers/xen/mem-reservation.c
>> create mode 100644 include/xen/mem_reservation.h
> Can you please name this include/xen/mem-reservation.h ?
>
Will rename
>> 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..57b482d67a3a 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..29882e4324f5
>> --- /dev/null
>> +++ b/drivers/xen/mem-reservation.c
>> @@ -0,0 +1,134 @@
>> +// SPDX-License-Identifier: GPL-2.0 OR MIT
>> +
>> +/******************************************************************************
>> + * 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 <linux/kernel.h>
>> +#include <linux/slab.h>
>> +
>> +#include <asm/tlb.h>
>> +#include <asm/xen/hypercall.h>
>> +
>> +#include <xen/interface/memory.h>
>> +#include <xen/page.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)
>> +
>> +void xenmem_reservation_scrub_page(struct page *page)
>> +{
>> +#ifdef CONFIG_XEN_SCRUB_PAGES
>> + clear_highpage(page);
>> +#endif
>> +}
>> +EXPORT_SYMBOL(xenmem_reservation_scrub_page);
> EXPORT_SYMBOL_GPL()
>
> Multiple times below, too.
Ok, will change to _GPL
> As a general rule of thumb: new exports should all be
> EXPORT_SYMBOL_GPL() if you can't give a reason why they shouldn't be.
>
>
> Juergen
Thank you,
Oleksandr

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