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>
---
TODO/LIMITATIONS:
- When CONFIG_XEN_HAVE_PMMU only 4K page granularity is supported
- It may be possible to extend the concept for ballooning 2M/1G
page.
---
drivers/xen/balloon.c | 93 +++++++++++++++++++++++++++++++++------------------
1 file changed, 60 insertions(+), 33 deletions(-)
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index fd93369..f0d8666 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -91,7 +91,7 @@ struct balloon_stats balloon_stats;
EXPORT_SYMBOL_GPL(balloon_stats);
/* We increase/decrease in batches which fit in a page */
-static xen_pfn_t frame_list[PAGE_SIZE / sizeof(unsigned long)];
+static xen_pfn_t frame_list[XEN_PAGE_SIZE / sizeof(unsigned long)];
/* List of ballooned pages, threaded through the mem_map array. */
@@ -326,7 +326,7 @@ static enum bp_state reserve_additional_memory(long credit)
static enum bp_state increase_reservation(unsigned long nr_pages)
{
int rc;
- unsigned long pfn, i;
+ unsigned long pfn, i, nr_frames;
struct page *page;
struct xen_memory_reservation reservation = {
.address_bits = 0,
@@ -343,30 +343,43 @@ 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;
+
+ nr_frames = nr_pages * XEN_PFN_PER_PAGE;
+
+ pfn = 0; /* make gcc happy */
page = list_first_entry_or_null(&ballooned_pages, struct page, lru);
- for (i = 0; i < nr_pages; i++) {
- if (!page) {
- nr_pages = i;
- break;
+ for (i = 0; i < nr_frames; i++) {
+ if (!(i % XEN_PFN_PER_PAGE)) {
+ if (!page) {
+ nr_frames = i;
+ break;
+ }
+ pfn = xen_page_to_pfn(page);
+ page = balloon_next_page(page);
}
- frame_list[i] = page_to_pfn(page);
- page = balloon_next_page(page);
+ frame_list[i] = pfn++;
}
set_xen_guest_handle(reservation.extent_start, frame_list);
- reservation.nr_extents = nr_pages;
+ reservation.nr_extents = nr_frames;
rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
if (rc <= 0)
return BP_EAGAIN;
for (i = 0; i < rc; i++) {
- page = balloon_retrieve(false);
- BUG_ON(page == NULL);
- pfn = page_to_pfn(page);
+ /* TODO: Make this code cleaner to make CONFIG_XEN_HAVE_PVMMU
+ * with 64K Pages
+ */
+ if (!(i % XEN_PFN_PER_PAGE)) {
+ page = balloon_retrieve(false);
+ BUG_ON(page == NULL);
+
+ pfn = page_to_pfn(page);
+ }
#ifdef CONFIG_XEN_HAVE_PVMMU
if (!xen_feature(XENFEAT_auto_translated_physmap)) {
@@ -385,7 +398,8 @@ static enum bp_state increase_reservation(unsigned long
nr_pages)
#endif
/* Relinquish the page back to the allocator. */
- __free_reserved_page(page);
+ if (!(i % XEN_PFN_PER_PAGE))
+ __free_reserved_page(page);
}
balloon_stats.current_pages += rc;
@@ -396,7 +410,7 @@ 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, nr_frames;
struct page *page;
int ret;
struct xen_memory_reservation reservation = {
@@ -414,19 +428,27 @@ 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;
- for (i = 0; i < nr_pages; i++) {
- page = alloc_page(gfp);
- if (page == NULL) {
- nr_pages = i;
- state = BP_EAGAIN;
- break;
+ nr_frames = nr_pages * XEN_PFN_PER_PAGE;
+
+ pfn = 0; /* Make GCC happy */
+
+ for (i = 0; i < nr_frames; i++) {
+
+ if (!(i % XEN_PFN_PER_PAGE)) {
+ page = alloc_page(gfp);
+ if (page == NULL) {
+ nr_frames = i;
+ state = BP_EAGAIN;
+ break;
+ }
+ scrub_page(page);
+ pfn = xen_page_to_pfn(page);
}
- scrub_page(page);
- frame_list[i] = page_to_pfn(page);
+ frame_list[i] = pfn++;
}
/*
@@ -439,16 +461,20 @@ 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. */
- for (i = 0; i < nr_pages; i++) {
+ for (i = 0; i < nr_frames; i++) {
pfn = frame_list[i];
frame_list[i] = pfn_to_mfn(pfn);
- page = pfn_to_page(pfn);
+ page = xen_pfn_to_page(pfn);
+
+ /* TODO: Make this code cleaner to make CONFIG_XEN_HAVE_PVMMU
+ * work with 64K pages
+ */
#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),
+ (unsigned long)__va(pfn <<
XEN_PAGE_SHIFT),
__pte_ma(0), 0);
BUG_ON(ret);
}
@@ -456,17 +482,18 @@ static enum bp_state decrease_reservation(unsigned long
nr_pages, gfp_t gfp)
}
#endif
- balloon_append(page);
+ if (!(i % XEN_PFN_PER_PAGE))
+ balloon_append(page);
}
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;
+ balloon_stats.current_pages -= nr_frames * XEN_PFN_PER_PAGE;
return state;
}
--
2.1.4
--
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