Author: gibbs
Date: Fri Nov 15 16:35:28 2013
New Revision: 258178
URL: http://svnweb.freebsd.org/changeset/base/258178
Log:
Improve robustness of the Xen balloon driver.
sys/dev/xen/balloon/balloon.c:
Remove unused and commented out code.
Fix deadlock caused by performing a sleepable malloc
while holding the balloon mutex.
Perform proper accounting of the memory used by the domain.
Submitted by: Roger Pau Monné
Sponsored by: Citrix Systems R&D
Reviewed by: gibbs
MFC after: 2 days
Modified:
head/sys/dev/xen/balloon/balloon.c
Modified: head/sys/dev/xen/balloon/balloon.c
==============================================================================
--- head/sys/dev/xen/balloon/balloon.c Fri Nov 15 16:16:55 2013
(r258177)
+++ head/sys/dev/xen/balloon/balloon.c Fri Nov 15 16:35:28 2013
(r258178)
@@ -52,18 +52,13 @@ __FBSDID("$FreeBSD$");
static MALLOC_DEFINE(M_BALLOON, "Balloon", "Xen Balloon Driver");
-struct mtx balloon_mutex;
+/* Convert from KB (as fetched from xenstore) to number of PAGES */
+#define KB_TO_PAGE_SHIFT (PAGE_SHIFT - 10)
-/*
- * Protects atomic reservation decrease/increase against concurrent increases.
- * Also protects non-atomic updates of current_pages and driver_pages, and
- * balloon lists.
- */
-struct mtx balloon_lock;
+struct mtx balloon_mutex;
/* We increase/decrease in batches which fit in a page */
static unsigned long frame_list[PAGE_SIZE / sizeof(unsigned long)];
-#define ARRAY_SIZE(A) (sizeof(A) / sizeof(A[0]))
struct balloon_stats {
/* We aim for 'current allocation' == 'target allocation'. */
@@ -116,15 +111,21 @@ static void balloon_process(void *unused
printk(KERN_WARNING "xen_mem: " fmt, ##args)
/* balloon_append: add the given page to the balloon. */
-static void
+static int
balloon_append(vm_page_t page)
{
struct balloon_entry *entry;
- entry = malloc(sizeof(struct balloon_entry), M_BALLOON, M_WAITOK);
+ mtx_assert(&balloon_mutex, MA_OWNED);
+
+ entry = malloc(sizeof(struct balloon_entry), M_BALLOON, M_NOWAIT);
+ if (!entry)
+ return (ENOMEM);
entry->page = page;
STAILQ_INSERT_HEAD(&ballooned_pages, entry, list);
bs.balloon_low++;
+
+ return (0);
}
/* balloon_retrieve: rescue a page from the balloon, if it is not empty. */
@@ -134,8 +135,10 @@ balloon_retrieve(void)
vm_page_t page;
struct balloon_entry *entry;
+ mtx_assert(&balloon_mutex, MA_OWNED);
+
if (STAILQ_EMPTY(&ballooned_pages))
- return NULL;
+ return (NULL);
entry = STAILQ_FIRST(&ballooned_pages);
STAILQ_REMOVE_HEAD(&ballooned_pages, list);
@@ -145,7 +148,7 @@ balloon_retrieve(void)
bs.balloon_low--;
- return page;
+ return (page);
}
static unsigned long
@@ -154,21 +157,22 @@ current_target(void)
unsigned long target = min(bs.target_pages, bs.hard_limit);
if (target > (bs.current_pages + bs.balloon_low + bs.balloon_high))
target = bs.current_pages + bs.balloon_low + bs.balloon_high;
- return target;
+ return (target);
}
static unsigned long
minimum_target(void)
{
#ifdef XENHVM
-#define max_pfn physmem
+#define max_pfn realmem
#else
#define max_pfn HYPERVISOR_shared_info->arch.max_pfn
#endif
unsigned long min_pages, curr_pages = current_target();
#define MB2PAGES(mb) ((mb) << (20 - PAGE_SHIFT))
- /* Simple continuous piecewiese linear function:
+ /*
+ * Simple continuous piecewiese linear function:
* max MiB -> min MiB gradient
* 0 0
* 16 16
@@ -189,12 +193,10 @@ minimum_target(void)
else
min_pages = MB2PAGES(296) + (max_pfn >> 5);
#undef MB2PAGES
+#undef max_pfn
/* Don't enforce growth */
- return min(min_pages, curr_pages);
-#ifndef CONFIG_XEN
-#undef max_pfn
-#endif
+ return (min(min_pages, curr_pages));
}
static int
@@ -210,10 +212,10 @@ increase_reservation(unsigned long nr_pa
.domid = DOMID_SELF
};
- if (nr_pages > ARRAY_SIZE(frame_list))
- nr_pages = ARRAY_SIZE(frame_list);
+ mtx_assert(&balloon_mutex, MA_OWNED);
- mtx_lock(&balloon_lock);
+ if (nr_pages > nitems(frame_list))
+ nr_pages = nitems(frame_list);
for (entry = STAILQ_FIRST(&ballooned_pages), i = 0;
i < nr_pages; i++, entry = STAILQ_NEXT(entry, list)) {
@@ -253,33 +255,14 @@ increase_reservation(unsigned long nr_pa
set_phys_to_machine(pfn, frame_list[i]);
-#if 0
-#ifndef XENHVM
- /* Link back into the page tables if not highmem. */
- if (pfn < max_low_pfn) {
- int ret;
- ret = HYPERVISOR_update_va_mapping(
- (unsigned long)__va(pfn << PAGE_SHIFT),
- pfn_pte_ma(frame_list[i], PAGE_KERNEL),
- 0);
- PASSING(ret == 0,
- ("HYPERVISOR_update_va_mapping failed"));
- }
-#endif
-#endif
-
- /* Relinquish the page back to the allocator. */
vm_page_unwire(page, 0);
vm_page_free(page);
}
bs.current_pages += nr_pages;
- //totalram_pages = bs.current_pages;
out:
- mtx_unlock(&balloon_lock);
-
- return 0;
+ return (0);
}
static int
@@ -295,8 +278,10 @@ decrease_reservation(unsigned long nr_pa
.domid = DOMID_SELF
};
- if (nr_pages > ARRAY_SIZE(frame_list))
- nr_pages = ARRAY_SIZE(frame_list);
+ mtx_assert(&balloon_mutex, MA_OWNED);
+
+ if (nr_pages > nitems(frame_list))
+ nr_pages = nitems(frame_list);
for (i = 0; i < nr_pages; i++) {
if ((page = vm_page_alloc(NULL, 0,
@@ -310,39 +295,15 @@ decrease_reservation(unsigned long nr_pa
pfn = (VM_PAGE_TO_PHYS(page) >> PAGE_SHIFT);
frame_list[i] = PFNTOMFN(pfn);
-#if 0
- if (!PageHighMem(page)) {
- v = phys_to_virt(pfn << PAGE_SHIFT);
- scrub_pages(v, 1);
-#ifdef CONFIG_XEN
- ret = HYPERVISOR_update_va_mapping(
- (unsigned long)v, __pte_ma(0), 0);
- BUG_ON(ret);
-#endif
- }
-#endif
-#ifdef CONFIG_XEN_SCRUB_PAGES
- else {
- v = kmap(page);
- scrub_pages(v, 1);
- kunmap(page);
- }
-#endif
- }
-
-#ifdef CONFIG_XEN
- /* Ensure that ballooned highmem pages don't have kmaps. */
- kmap_flush_unused();
- flush_tlb_all();
-#endif
-
- mtx_lock(&balloon_lock);
-
- /* No more mappings: invalidate P2M and add to balloon. */
- for (i = 0; i < nr_pages; i++) {
- pfn = MFNTOPFN(frame_list[i]);
set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
- balloon_append(PHYS_TO_VM_PAGE(pfn << PAGE_SHIFT));
+ if (balloon_append(page) != 0) {
+ vm_page_unwire(page, 0);
+ vm_page_free(page);
+
+ nr_pages = i;
+ need_sleep = 1;
+ break;
+ }
}
set_xen_guest_handle(reservation.extent_start, frame_list);
@@ -351,9 +312,6 @@ decrease_reservation(unsigned long nr_pa
KASSERT(ret == nr_pages, ("HYPERVISOR_memory_op failed"));
bs.current_pages -= nr_pages;
- //totalram_pages = bs.current_pages;
-
- mtx_unlock(&balloon_lock);
return (need_sleep);
}
@@ -425,11 +383,11 @@ watch_target(struct xs_watch *watch,
return;
}
- /* The given memory/target value is in KiB, so it needs converting to
- pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10.
- */
- set_new_target(new_target >> (PAGE_SHIFT - 10));
-
+ /*
+ * The given memory/target value is in KiB, so it needs converting to
+ * pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10.
+ */
+ set_new_target(new_target >> KB_TO_PAGE_SHIFT);
}
static void
@@ -461,13 +419,12 @@ balloon_init(void *arg)
if (!is_running_on_xen())
return;
- mtx_init(&balloon_lock, "balloon_lock", NULL, MTX_DEF);
mtx_init(&balloon_mutex, "balloon_mutex", NULL, MTX_DEF);
#ifndef XENHVM
bs.current_pages = min(xen_start_info->nr_pages, max_pfn);
#else
- bs.current_pages = physmem;
+ bs.current_pages = realmem;
#endif
bs.target_pages = bs.current_pages;
bs.balloon_low = 0;
@@ -497,76 +454,7 @@ void balloon_update_driver_allowance(lon
void
balloon_update_driver_allowance(long delta)
{
- mtx_lock(&balloon_lock);
+ mtx_lock(&balloon_mutex);
bs.driver_pages += delta;
- mtx_unlock(&balloon_lock);
-}
-
-#if 0
-static int dealloc_pte_fn(
- pte_t *pte, struct page *pte_page, unsigned long addr, void *data)
-{
- unsigned long mfn = pte_mfn(*pte);
- int ret;
- struct xen_memory_reservation reservation = {
- .extent_start = &mfn,
- .nr_extents = 1,
- .extent_order = 0,
- .domid = DOMID_SELF
- };
- set_pte_at(&init_mm, addr, pte, __pte_ma(0));
- set_phys_to_machine(__pa(addr) >> PAGE_SHIFT, INVALID_P2M_ENTRY);
- ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation);
- KASSERT(ret == 1, ("HYPERVISOR_memory_op failed"));
- return 0;
-}
-
-#endif
-
-#if 0
-vm_page_t
-balloon_alloc_empty_page_range(unsigned long nr_pages)
-{
- vm_page_t pages;
- int i, rc;
- unsigned long *mfn_list;
- struct xen_memory_reservation reservation = {
- .address_bits = 0,
- .extent_order = 0,
- .domid = DOMID_SELF
- };
-
- pages = vm_page_alloc_contig(nr_pages, 0, -1, 4, 4)
- if (pages == NULL)
- return NULL;
-
- mfn_list = malloc(nr_pages*sizeof(unsigned long), M_DEVBUF, M_WAITOK);
-
- for (i = 0; i < nr_pages; i++) {
- mfn_list[i] = PFNTOMFN(VM_PAGE_TO_PHYS(pages[i]) >> PAGE_SHIFT);
- PFNTOMFN(i) = INVALID_P2M_ENTRY;
- reservation.extent_start = mfn_list;
- reservation.nr_extents = nr_pages;
- rc = HYPERVISOR_memory_op(XENMEM_decrease_reservation,
- &reservation);
- KASSERT(rc == nr_pages, ("HYPERVISOR_memory_op failed"));
- }
-
- current_pages -= nr_pages;
-
- wakeup(balloon_process);
-
- return pages;
-}
-
-void
-balloon_dealloc_empty_page_range(vm_page_t page, unsigned long nr_pages)
-{
- unsigned long i;
-
- for (i = 0; i < nr_pages; i++)
- balloon_append(page + i);
-
- wakeup(balloon_process);
+ mtx_unlock(&balloon_mutex);
}
-#endif
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