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xen/virtio: fix balloon drivers to not mark pages as WIRED

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Prevent the Xen and VirtIO balloon drivers from marking pages as
wired. This prevents them from increasing the system wired page count,
which can lead to mlock failing because of hitting the limit in
vm.max_wired.

In the Xen case make sure pages are zeroed before giving them back to
the hypervisor, or else we might be leaking data. Also remove the
balloon_{append/retrieve} and link pages directly into the
ballooned_pages queue using the plinks.q field in the page struct.

Sponsored by: Citrix Systems R&D
Reviewed by: kib, bryanv
Approved by: gibbs

dev/virtio/balloon/virtio_balloon.c:
 - Don't allocate pages with VM_ALLOC_WIRED.

dev/xen/balloon/balloon.c:
 - Don't allocate pages with VM_ALLOC_WIRED.
 - Make sure pages are zeroed before giving them back to the
   hypervisor.
 - Remove the balloon_entry struct and the balloon_{append/retrieve}
   functions and use the page plinks.q entry to link the pages
   directly into the ballooned_pages queue.
This commit is contained in:
Roger Pau Monné 2014-06-25 09:51:08 +00:00
parent 50dd6996c0
commit 68e58ea7ed
2 changed files with 25 additions and 68 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

4
sys/dev/virtio/balloon/virtio_balloon.c
View file

@ -438,8 +438,7 @@ vtballoon_alloc_page(struct vtballoon_softc *sc)
{
vm_page_t m;
m = vm_page_alloc(NULL, 0, VM_ALLOC_NORMAL | VM_ALLOC_WIRED |
VM_ALLOC_NOOBJ);
m = vm_page_alloc(NULL, 0, VM_ALLOC_NORMAL | VM_ALLOC_NOOBJ);
if (m != NULL)
sc->vtballoon_current_npages++;
@ -450,7 +449,6 @@ static void
vtballoon_free_page(struct vtballoon_softc *sc, vm_page_t m)
{
vm_page_unwire(m, PQ_INACTIVE);
vm_page_free(m);
sc->vtballoon_current_npages--;
}

89
sys/dev/xen/balloon/balloon.c
View file

@ -94,13 +94,8 @@ SYSCTL_ULONG(_dev_xen_balloon, OID_AUTO, low_mem, CTLFLAG_RD,
SYSCTL_ULONG(_dev_xen_balloon, OID_AUTO, high_mem, CTLFLAG_RD,
&bs.balloon_high, 0, "High-mem balloon");
struct balloon_entry {
vm_page_t page;
STAILQ_ENTRY(balloon_entry) list;
};
/* List of ballooned pages, threaded through the mem_map array. */
static STAILQ_HEAD(,balloon_entry) ballooned_pages;
static TAILQ_HEAD(,vm_page) ballooned_pages;
/* Main work function, always executed in process context. */
static void balloon_process(void *unused);
@ -110,47 +105,6 @@ static void balloon_process(void *unused);
#define WPRINTK(fmt, args...) \
printk(KERN_WARNING "xen_mem: " fmt, ##args)
/* balloon_append: add the given page to the balloon. */
static int
balloon_append(vm_page_t page)
{
struct balloon_entry *entry;
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. */
static vm_page_t
balloon_retrieve(void)
{
vm_page_t page;
struct balloon_entry *entry;
mtx_assert(&balloon_mutex, MA_OWNED);
if (STAILQ_EMPTY(&ballooned_pages))
return (NULL);
entry = STAILQ_FIRST(&ballooned_pages);
STAILQ_REMOVE_HEAD(&ballooned_pages, list);
page = entry->page;
free(entry, M_BALLOON);
bs.balloon_low--;
return (page);
}
static unsigned long
current_target(void)
{
@ -203,7 +157,6 @@ static int
increase_reservation(unsigned long nr_pages)
{
unsigned long pfn, i;
struct balloon_entry *entry;
vm_page_t page;
long rc;
struct xen_memory_reservation reservation = {
@ -217,10 +170,9 @@ increase_reservation(unsigned long nr_pages)
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)) {
KASSERT(entry, ("ballooned_pages list corrupt"));
page = entry->page;
for (page = TAILQ_FIRST(&ballooned_pages), i = 0;
i < nr_pages; i++, page = TAILQ_NEXT(page, plinks.q)) {
KASSERT(page != NULL, ("ballooned_pages list corrupt"));
frame_list[i] = (VM_PAGE_TO_PHYS(page) >> PAGE_SHIFT);
}
@ -245,8 +197,10 @@ increase_reservation(unsigned long nr_pages)
}
for (i = 0; i < nr_pages; i++) {
page = balloon_retrieve();
KASSERT(page, ("balloon_retrieve failed"));
page = TAILQ_FIRST(&ballooned_pages);
KASSERT(page != NULL, ("Unable to get ballooned page"));
TAILQ_REMOVE(&ballooned_pages, page, plinks.q);
bs.balloon_low--;
pfn = (VM_PAGE_TO_PHYS(page) >> PAGE_SHIFT);
KASSERT((xen_feature(XENFEAT_auto_translated_physmap) ||
@ -255,7 +209,6 @@ increase_reservation(unsigned long nr_pages)
set_phys_to_machine(pfn, frame_list[i]);
vm_page_unwire(page, PQ_INACTIVE);
vm_page_free(page);
}
@ -286,24 +239,29 @@ decrease_reservation(unsigned long nr_pages)
for (i = 0; i < nr_pages; i++) {
if ((page = vm_page_alloc(NULL, 0,
VM_ALLOC_NORMAL | VM_ALLOC_NOOBJ |
VM_ALLOC_WIRED | VM_ALLOC_ZERO)) == NULL) {
VM_ALLOC_ZERO)) == NULL) {
nr_pages = i;
need_sleep = 1;
break;
}
if ((page->flags & PG_ZERO) == 0) {
/*
* Zero the page, or else we might be leaking
* important data to other domains on the same
* host. Xen doesn't scrub ballooned out memory
* pages, the guest is in charge of making
* sure that no information is leaked.
*/
pmap_zero_page(page);
}
pfn = (VM_PAGE_TO_PHYS(page) >> PAGE_SHIFT);
frame_list[i] = PFNTOMFN(pfn);
set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
if (balloon_append(page) != 0) {
vm_page_unwire(page, PQ_INACTIVE);
vm_page_free(page);
nr_pages = i;
need_sleep = 1;
break;
}
TAILQ_INSERT_HEAD(&ballooned_pages, page, plinks.q);
bs.balloon_low++;
}
set_xen_guest_handle(reservation.extent_start, frame_list);
@ -438,7 +396,8 @@ balloon_init(void *arg)
/* Initialise the balloon with excess memory space. */
for (pfn = xen_start_info->nr_pages; pfn < max_pfn; pfn++) {
page = PHYS_TO_VM_PAGE(pfn << PAGE_SHIFT);
balloon_append(page);
TAILQ_INSERT_HEAD(&ballooned_pages, page, plinks.q);
bs.balloon_low++;
}
#undef max_pfn
#endif