Re: [PATCH 2/8] xen/balloon: Move common memory reservation routines to a module
From: Oleksandr Andrushchenko
Date: Tue May 29 2018 - 14:22:38 EST
On 05/29/2018 09:04 PM, Boris Ostrovsky wrote:
On 05/25/2018 11:33 AM, Oleksandr Andrushchenko wrote:
From: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
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.
Sure, will put "file" here
for the shared code and export corresponding
symbols for other kernel modules.
Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
---
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.
This is actually how it is used later on for dma-buf, but I just didn't want
to alter original balloon code too much, but this can be done, in order
of simplicity:
1. Similar to frame_list, e.g. static array of struct page* of size
ARRAY_SIZE(frame_list):
more static memory is used, but no allocations
2. Allocated at run-time with kcalloc: allocation can fail
3. Make balloon_retrieve() return a set of pages: will require
list/array allocation
and handling, allocation may fail, balloon_retrieve prototype change
Could you please tell which of the above will fit better?
/* 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.
see above
- 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.
Will fix - I was not sure about the license to be used here, thanks
+
+/******************************************************************************
+ * 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.
will fix
-boris
Thank you,
Oleksandr
+
+/*
+ * 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