For ARM64 guests, Linux is able to support either 64K or 4K page
granularity. Although, the hypercall interface is always based on 4K
page granularity.
With 64K page granuliarty, a single page will be spread over multiple
Xen frame.
When a driver request/free a balloon page, the balloon driver will have
to split the Linux page in 4K chunk before asking Xen to add/remove the
frame from the guest.
Note that this can work on any page granularity assuming it's a multiple
of 4K.
Signed-off-by: Julien Grall <julien.gr...@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.w...@oracle.com>
Cc: Boris Ostrovsky <boris.ostrov...@oracle.com>
Cc: David Vrabel <david.vra...@citrix.com>
Cc: Wei Liu <wei.l...@citrix.com>
---
Changes in v2:
- Use xen_apply_to_page to split a page in 4K chunk
- It's not necessary to have a smaller frame list. Re-use
PAGE_SIZE
- Convert reserve_additional_memory to use XEN_... macro
---
drivers/xen/balloon.c | 147 +++++++++++++++++++++++++++++++++++---------------
1 file changed, 105 insertions(+), 42 deletions(-)
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index fd93369..19a72b1 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -230,6 +230,7 @@ static enum bp_state reserve_additional_memory(long credit)
nid = memory_add_physaddr_to_nid(hotplug_start_paddr);
#ifdef CONFIG_XEN_HAVE_PVMMU
+ /* TODO */
/*
* add_memory() will build page tables for the new memory so
* the p2m must contain invalid entries so the correct
@@ -242,8 +243,8 @@ static enum bp_state reserve_additional_memory(long credit)
if (!xen_feature(XENFEAT_auto_translated_physmap)) {
unsigned long pfn, i;
- pfn = PFN_DOWN(hotplug_start_paddr);
- for (i = 0; i < balloon_hotplug; i++) {
+ pfn = XEN_PFN_DOWN(hotplug_start_paddr);
+ for (i = 0; i < (balloon_hotplug * XEN_PFN_PER_PAGE); i++) {
if (!set_phys_to_machine(pfn + i, INVALID_P2M_ENTRY)) {
pr_warn("set_phys_to_machine() failed, no
memory added\n");
return BP_ECANCELED;
@@ -323,10 +324,72 @@ static enum bp_state reserve_additional_memory(long
credit)
}
#endif /* CONFIG_XEN_BALLOON_MEMORY_HOTPLUG */
+static int set_frame(struct page *page, unsigned long pfn, void *data)
+{
+ unsigned long *index = data;
+
+ frame_list[(*index)++] = pfn;
+
+ return 0;
+}
+
+#ifdef CONFIG_XEN_HAVE_PVMMU
+static int pvmmu_update_mapping(struct page *page, unsigned long pfn,
+ void *data)
+{
+ unsigned long *index = data;
+ xen_pfn_t frame = frame_list[*index];
+
+ set_phys_to_machine(pfn, frame);
+ /* Link back into the page tables if not highmem. */
+ if (!PageHighMem(page)) {
+ int ret;
+ ret = HYPERVISOR_update_va_mapping(
+ (unsigned long)__va(pfn << XEN_PAGE_SHIFT),
+ mfn_pte(frame, PAGE_KERNEL),
+ 0);
+ BUG_ON(ret);
+ }
+
+ (*index)++;
+
+ return 0;
+}
+#endif
+
+static int balloon_remove_mapping(struct page *page, unsigned long pfn,
+ void *data)
+{
+ unsigned long *index = data;
+
+ /* We expect the frame_list to contain the same pfn */
+ BUG_ON(pfn != frame_list[*index]);
+
+ frame_list[*index] = pfn_to_mfn(pfn);
+
+#ifdef CONFIG_XEN_HAVE_PVMMU
+ if (!xen_feature(XENFEAT_auto_translated_physmap)) {
+ if (!PageHighMem(page)) {
+ int ret;
+
+ ret = HYPERVISOR_update_va_mapping(
+ (unsigned long)__va(pfn <<
XEN_PAGE_SHIFT),
+ __pte_ma(0), 0);
+ BUG_ON(ret);
+ }
+ __set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
+ }
+#endif
+
+ (*index)++;
+
+ return 0;
+}
+
static enum bp_state increase_reservation(unsigned long nr_pages)
{
int rc;
- unsigned long pfn, i;
+ unsigned long i, frame_idx;
struct page *page;
struct xen_memory_reservation reservation = {
.address_bits = 0,
@@ -343,44 +406,43 @@ static enum bp_state increase_reservation(unsigned long
nr_pages)
}
#endif
- if (nr_pages > ARRAY_SIZE(frame_list))
- nr_pages = ARRAY_SIZE(frame_list);
+ if (nr_pages > (ARRAY_SIZE(frame_list) / XEN_PFN_PER_PAGE))
+ nr_pages = ARRAY_SIZE(frame_list) / XEN_PFN_PER_PAGE;
+ frame_idx = 0;
page = list_first_entry_or_null(&ballooned_pages, struct page, lru);
for (i = 0; i < nr_pages; i++) {
if (!page) {
nr_pages = i;
break;
}
- frame_list[i] = page_to_pfn(page);
+
+ rc = xen_apply_to_page(page, set_frame, &frame_idx);
+
page = balloon_next_page(page);
}
set_xen_guest_handle(reservation.extent_start, frame_list);
- reservation.nr_extents = nr_pages;
+ reservation.nr_extents = nr_pages * XEN_PFN_PER_PAGE;
rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
if (rc <= 0)
return BP_EAGAIN;
- for (i = 0; i < rc; i++) {
+ /* rc is equal to the number of Xen page populated */
+ nr_pages = rc / XEN_PFN_PER_PAGE;
+
+ for (i = 0; i < nr_pages; i++) {
page = balloon_retrieve(false);
BUG_ON(page == NULL);
- pfn = page_to_pfn(page);
-
#ifdef CONFIG_XEN_HAVE_PVMMU
+ frame_idx = 0;
if (!xen_feature(XENFEAT_auto_translated_physmap)) {
- 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);
- }
+ int ret;
+
+ ret = xen_apply_to_page(page, pvmmu_update_mapping,
+ &frame_idx);
+ BUG_ON(ret);
}
#endif
@@ -388,7 +450,7 @@ static enum bp_state increase_reservation(unsigned long
nr_pages)
__free_reserved_page(page);
}
- balloon_stats.current_pages += rc;
+ balloon_stats.current_pages += nr_pages;
return BP_DONE;
}
@@ -396,7 +458,7 @@ static enum bp_state increase_reservation(unsigned long
nr_pages)
static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
{
enum bp_state state = BP_DONE;
- unsigned long pfn, i;
+ unsigned long pfn, i, frame_idx, nr_frames;
struct page *page;
int ret;
struct xen_memory_reservation reservation = {
@@ -414,9 +476,10 @@ static enum bp_state decrease_reservation(unsigned long
nr_pages, gfp_t gfp)
}
#endif
- if (nr_pages > ARRAY_SIZE(frame_list))
- nr_pages = ARRAY_SIZE(frame_list);
+ if (nr_pages > (ARRAY_SIZE(frame_list) / XEN_PFN_PER_PAGE))
+ nr_pages = ARRAY_SIZE(frame_list) / XEN_PFN_PER_PAGE;
+ frame_idx = 0;
for (i = 0; i < nr_pages; i++) {
page = alloc_page(gfp);
if (page == NULL) {
@@ -426,9 +489,12 @@ static enum bp_state decrease_reservation(unsigned long
nr_pages, gfp_t gfp)
}
scrub_page(page);
- frame_list[i] = page_to_pfn(page);
+ ret = xen_apply_to_page(page, set_frame, &frame_idx);
+ BUG_ON(ret);
}
+ nr_frames = nr_pages * XEN_PFN_PER_PAGE;
+
/*
* Ensure that ballooned highmem pages don't have kmaps.
*
@@ -439,22 +505,19 @@ static enum bp_state decrease_reservation(unsigned long
nr_pages, gfp_t gfp)
kmap_flush_unused();
/* Update direct mapping, invalidate P2M, and add to balloon. */
+ frame_idx = 0;
for (i = 0; i < nr_pages; i++) {
- pfn = frame_list[i];
- frame_list[i] = pfn_to_mfn(pfn);
- page = pfn_to_page(pfn);
+ /*
+ * The Xen PFN for a given Linux Page are contiguous in
+ * frame_list
+ */
+ pfn = frame_list[frame_idx];
+ page = xen_pfn_to_page(pfn);
-#ifdef CONFIG_XEN_HAVE_PVMMU
- if (!xen_feature(XENFEAT_auto_translated_physmap)) {
- 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
+
+ ret = xen_apply_to_page(page, balloon_remove_mapping,
+ &frame_idx);
+ BUG_ON(ret);
balloon_append(page);
}
@@ -462,9 +525,9 @@ 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;
+ reservation.nr_extents = nr_frames;
ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation);
- BUG_ON(ret != nr_pages);
+ BUG_ON(ret != nr_frames);
balloon_stats.current_pages -= nr_pages;
--
2.1.4
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
