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Date: Tue, 29 May 2018 14:04:38 -0400
From: Boris Ostrovsky <boris.ostrovsky@...cle.com>
To: Oleksandr Andrushchenko <andr2000@...il.com>,
xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org,
dri-devel@...ts.freedesktop.org, linux-media@...r.kernel.org,
jgross@...e.com, konrad.wilk@...cle.com
Cc: daniel.vetter@...el.com, dongwon.kim@...el.com,
matthew.d.roper@...el.com,
Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
Subject: Re: [PATCH 2/8] xen/balloon: Move common memory reservation routines
to a module
On 05/25/2018 11:33 AM, Oleksandr Andrushchenko wrote:
> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.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
IIUIC this is not really a module, it's a common file.
> for the shared code and export corresponding
> symbols for other kernel modules.
>
> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.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
>
> 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]);
Can you make a single call to xenmem_reservation_va_mapping_update(rc,
...)? You need to keep track of pages but presumable they can be put
into an array (or a list). In fact, perhaps we can have
balloon_retrieve() return a set of pages.
>
> /* 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);
and here too.
>
> - 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
Why is this "OR MIT"? The original file was licensed GPLv2 only.
> +
> +/******************************************************************************
> + * 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);
> +
> +void xenmem_reservation_va_mapping_update(unsigned long count,
> + struct page **pages,
> + xen_pfn_t *frames)
> +{
> +#ifdef CONFIG_XEN_HAVE_PVMMU
> + int i;
> +
> + for (i = 0; i < count; i++) {
> + struct page *page;
> +
> + page = pages[i];
> + 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);
> +
> + if (!xen_feature(XENFEAT_auto_translated_physmap)) {
> + unsigned long pfn = page_to_pfn(page);
> +
> + 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);
> + }
> + }
> + }
> +#endif
> +}
> +EXPORT_SYMBOL(xenmem_reservation_va_mapping_update);
> +
> +void xenmem_reservation_va_mapping_reset(unsigned long count,
> + struct page **pages)
> +{
> +#ifdef CONFIG_XEN_HAVE_PVMMU
> + int i;
> +
> + for (i = 0; i < count; i++) {
> + /*
> + * 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)) {
> + struct page *page = pages[i];
> + unsigned long pfn = page_to_pfn(page);
> +
> + 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);
> + }
> + }
> +#endif
> +}
> +EXPORT_SYMBOL(xenmem_reservation_va_mapping_reset);
> +
> +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(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(xenmem_reservation_decrease);
> diff --git a/include/xen/mem_reservation.h b/include/xen/mem_reservation.h
> new file mode 100644
> index 000000000000..9306d9b8743c
> --- /dev/null
> +++ b/include/xen/mem_reservation.h
> @@ -0,0 +1,29 @@
> +/* SPDX-License-Identifier: GPL-2.0 OR MIT */
and here too.
-boris
> +
> +/*
> + * 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
> +
> +void xenmem_reservation_scrub_page(struct page *page);
> +
> +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);
> +
> +int xenmem_reservation_increase(int count, xen_pfn_t *frames);
> +
> +int xenmem_reservation_decrease(int count, xen_pfn_t *frames);
> +
> +#endif
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