diff options
| -rw-r--r-- | drivers/misc/vmw_balloon.c | 829 |
1 files changed, 541 insertions, 288 deletions
diff --git a/drivers/misc/vmw_balloon.c b/drivers/misc/vmw_balloon.c index 0a2bdaf5773b..cb363db34b4a 100644 --- a/drivers/misc/vmw_balloon.c +++ b/drivers/misc/vmw_balloon.c @@ -27,6 +27,7 @@ #include <linux/seq_file.h> #include <linux/rwsem.h> #include <linux/slab.h> +#include <linux/spinlock.h> #include <linux/vmw_vmci_defs.h> #include <linux/vmw_vmci_api.h> #include <asm/hypervisor.h> @@ -89,6 +90,16 @@ enum vmballoon_page_size_type { #define VMW_BALLOON_NUM_PAGE_SIZES (VMW_BALLOON_LAST_SIZE + 1) +static const char * const vmballoon_page_size_names[] = { + [VMW_BALLOON_4K_PAGE] = "4k", + [VMW_BALLOON_2M_PAGE] = "2M" +}; + +enum vmballoon_op { + VMW_BALLOON_INFLATE, + VMW_BALLOON_DEFLATE +}; + enum vmballoon_op_stat_type { VMW_BALLOON_OP_STAT, VMW_BALLOON_OP_FAIL_STAT @@ -216,13 +227,18 @@ enum vmballoon_stat_general { static DEFINE_STATIC_KEY_TRUE(vmw_balloon_batching); static DEFINE_STATIC_KEY_FALSE(balloon_stat_enabled); -struct vmballoon_page_size { - /* list of reserved physical pages */ +struct vmballoon_ctl { struct list_head pages; - - /* transient list of non-balloonable pages */ struct list_head refused_pages; unsigned int n_refused_pages; + unsigned int n_pages; + enum vmballoon_page_size_type page_size; + enum vmballoon_op op; +}; + +struct vmballoon_page_size { + /* list of reserved physical pages */ + struct list_head pages; }; /** @@ -241,16 +257,47 @@ struct vmballoon_batch_entry { struct vmballoon { struct vmballoon_page_size page_sizes[VMW_BALLOON_NUM_PAGE_SIZES]; - /* supported page sizes. 1 == 4k pages only, 2 == 4k and 2m pages */ - unsigned supported_page_sizes; + /** + * @max_page_size: maximum supported page size for ballooning. + * + * Protected by @conf_sem + */ + enum vmballoon_page_size_type max_page_size; + + /** + * @size: balloon actual size in basic page size (frames). + * + * While we currently do not support size which is bigger than 32-bit, + * in preparation for future support, use 64-bits. + */ + atomic64_t size; - /* balloon size in pages */ - unsigned int size; - unsigned int target; + /** + * @target: balloon target size in basic page size (frames). + * + * We do not protect the target under the assumption that setting the + * value is always done through a single write. If this assumption ever + * breaks, we would have to use X_ONCE for accesses, and suffer the less + * optimized code. Although we may read stale target value if multiple + * accesses happen at once, the performance impact should be minor. + */ + unsigned long target; - /* reset flag */ + /** + * @reset_required: reset flag + * + * Setting this flag may introduce races, but the code is expected to + * handle them gracefully. In the worst case, another operation will + * fail as reset did not take place. Clearing the flag is done while + * holding @conf_sem for write. + */ bool reset_required; + /** + * @capabilities: hypervisor balloon capabilities. + * + * Protected by @conf_sem. + */ unsigned long capabilities; /** @@ -261,7 +308,25 @@ struct vmballoon { */ struct vmballoon_batch_entry *batch_page; + /** + * @batch_max_pages: maximum pages that can be locked/unlocked. + * + * Indicates the number of pages that the hypervisor can lock or unlock + * at once, according to whether batching is enabled. If batching is + * disabled, only a single page can be locked/unlock on each operation. + * + * Protected by @conf_sem. + */ unsigned int batch_max_pages; + + /** + * @page: page to be locked/unlocked by the hypervisor + * + * @page is only used when batching is disabled and a single page is + * reclaimed on each iteration. + * + * Protected by @comm_lock. + */ struct page *page; /* statistics */ @@ -274,12 +339,24 @@ struct vmballoon { struct delayed_work dwork; + /** + * @vmci_doorbell. + * + * Protected by @conf_sem. + */ struct vmci_handle vmci_doorbell; /** * @conf_sem: semaphore to protect the configuration and the statistics. */ struct rw_semaphore conf_sem; + + /** + * @comm_lock: lock to protect the communication with the host. + * + * Lock ordering: @conf_sem -> @comm_lock . + */ + spinlock_t comm_lock; }; static struct vmballoon balloon; @@ -326,10 +403,19 @@ static inline void vmballoon_stats_gen_add(struct vmballoon *b, static inline void vmballoon_stats_page_inc(struct vmballoon *b, enum vmballoon_stat_page stat, - bool is_2m_page) + enum vmballoon_page_size_type size) { if (is_vmballoon_stats_on()) - atomic64_inc(&b->stats->page_stat[stat][is_2m_page]); + atomic64_inc(&b->stats->page_stat[stat][size]); +} + +static inline void vmballoon_stats_page_add(struct vmballoon *b, + enum vmballoon_stat_page stat, + enum vmballoon_page_size_type size, + unsigned int val) +{ + if (is_vmballoon_stats_on()) + atomic64_add(val, &b->stats->page_stat[stat][size]); } static inline unsigned long @@ -361,7 +447,7 @@ __vmballoon_cmd(struct vmballoon *b, unsigned long cmd, unsigned long arg1, /* update target when applicable */ if (status == VMW_BALLOON_SUCCESS && ((1ul << cmd) & VMW_BALLOON_CMD_WITH_TARGET_MASK)) - b->target = local_result; + WRITE_ONCE(b->target, local_result); if (status != VMW_BALLOON_SUCCESS && status != VMW_BALLOON_SUCCESS_WITH_CAPABILITIES) { @@ -417,11 +503,11 @@ static bool vmballoon_send_start(struct vmballoon *b, unsigned long req_caps) * reason disabled, do not use 2MB pages, since otherwise the legacy * mechanism is used with 2MB pages, causing a failure. */ + b->max_page_size = VMW_BALLOON_4K_PAGE; if ((b->capabilities & VMW_BALLOON_BATCHED_2M_CMDS) && (b->capabilities & VMW_BALLOON_BATCHED_CMDS)) - b->supported_page_sizes = 2; - else - b->supported_page_sizes = 1; + b->max_page_size = VMW_BALLOON_2M_PAGE; + return success; } @@ -445,12 +531,28 @@ static bool vmballoon_send_guest_id(struct vmballoon *b) return false; } -static u16 vmballoon_page_size(bool is_2m_page) +/** + * vmballoon_page_order() - return the order of the page + * @page_size: the size of the page. + * + * Return: the allocation order. + */ +static inline +unsigned int vmballoon_page_order(enum vmballoon_page_size_type page_size) { - if (is_2m_page) - return 1 << VMW_BALLOON_2M_ORDER; + return page_size == VMW_BALLOON_2M_PAGE ? VMW_BALLOON_2M_ORDER : 0; +} - return 1; +/** + * vmballoon_page_in_frames() - returns the number of frames in a page. + * @page_size: the size of the page. + * + * Return: the number of 4k frames. + */ +static inline unsigned int +vmballoon_page_in_frames(enum vmballoon_page_size_type page_size) +{ + return 1 << vmballoon_page_order(page_size); } /** @@ -478,53 +580,78 @@ static int vmballoon_send_get_target(struct vmballoon *b) return status == VMW_BALLOON_SUCCESS ? 0 : -EIO; } -static struct page *vmballoon_alloc_page(bool is_2m_page) +/** + * vmballoon_alloc_page_list - allocates a list of pages. + * + * @b: pointer to the balloon. + * @ctl: pointer for the %struct vmballoon_ctl, which defines the operation. + * @req_n_pages: the number of requested pages. + * + * Tries to allocate @req_n_pages. Add them to the list of balloon pages in + * @ctl.pages and updates @ctl.n_pages to reflect the number of pages. + * + * Return: zero on success or error code otherwise. + */ +static int vmballoon_alloc_page_list(struct vmballoon *b, + struct vmballoon_ctl *ctl, + unsigned int req_n_pages) { - if (is_2m_page) - return alloc_pages(VMW_HUGE_PAGE_ALLOC_FLAGS, - VMW_BALLOON_2M_ORDER); + struct page *page; + unsigned int i; - return alloc_page(VMW_PAGE_ALLOC_FLAGS); -} + for (i = 0; i < req_n_pages; i++) { + if (ctl->page_size == VMW_BALLOON_2M_PAGE) + page = alloc_pages(VMW_HUGE_PAGE_ALLOC_FLAGS, + VMW_BALLOON_2M_ORDER); + else + page = alloc_page(VMW_PAGE_ALLOC_FLAGS); -static void vmballoon_free_page(struct page *page, bool is_2m_page) -{ - if (is_2m_page) - __free_pages(page, VMW_BALLOON_2M_ORDER); - else - __free_page(page); + /* Update statistics */ + vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_ALLOC, + ctl->page_size); + + if (page) { + /* Success. Add the page to the list and continue. */ + list_add(&page->lru, &ctl->pages); + continue; + } + + /* Allocation failed. Update statistics and stop. */ + vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_ALLOC_FAIL, + ctl->page_size); + break; + } + + ctl->n_pages = i; + + return req_n_pages == ctl->n_pages ? 0 : -ENOMEM; } -/* - * Quickly release all pages allocated for the balloon. This function is - * called when host decides to "reset" balloon for one reason or another. - * Unlike normal "deflate" we do not (shall not) notify host of the pages - * being released. +/** + * vmballoon_handle_one_result - Handle lock/unlock result for a single page. + * + * @b: pointer for %struct vmballoon. + * @page: pointer for the page whose result should be handled. + * @page_size: size of the page. + * @status: status of the operation as provided by the hypervisor. */ -static void vmballoon_pop(struct vmballoon *b) +static int vmballoon_handle_one_result(struct vmballoon *b, struct page *page, + enum vmballoon_page_size_type page_size, + unsigned long status) { - struct page *page, *next; - unsigned is_2m_pages; - - for (is_2m_pages = 0; is_2m_pages < VMW_BALLOON_NUM_PAGE_SIZES; - is_2m_pages++) { - struct vmballoon_page_size *page_size = - &b->page_sizes[is_2m_pages]; - u16 size_per_page = vmballoon_page_size(is_2m_pages); - - list_for_each_entry_safe(page, next, &page_size->pages, lru) { - list_del(&page->lru); - vmballoon_free_page(page, is_2m_pages); - vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_FREE, - is_2m_pages); - b->size -= size_per_page; - cond_resched(); - } - } + /* On success do nothing. The page is already on the balloon list. */ + if (likely(status == VMW_BALLOON_SUCCESS)) + return 0; - /* Clearing the batch_page unconditionally has no adverse effect */ - free_page((unsigned long)b->batch_page); - b->batch_page = NULL; + pr_debug("%s: failed comm pfn %lx status %lu page_size %s\n", __func__, + page_to_pfn(page), status, + vmballoon_page_size_names[page_size]); + + /* Error occurred */ + vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_REFUSED_ALLOC, + page_size); + + return -EIO; } /** @@ -565,8 +692,8 @@ static unsigned long vmballoon_status_page(struct vmballoon *b, int idx, * vmballoon_lock_op - notifies the host about inflated/deflated pages. * @b: pointer to the balloon. * @num_pages: number of inflated/deflated pages. - * @is_2m_pages: whether the page(s) are 2M (or 4k). - * @lock: whether the operation is lock (or unlock). + * @page_size: size of the page. + * @op: the type of operation (lock or unlock). * * Notify the host about page(s) that were ballooned (or removed from the * balloon) so that host can use it without fear that guest will need it (or @@ -578,21 +705,27 @@ static unsigned long vmballoon_status_page(struct vmballoon *b, int idx, */ static unsigned long vmballoon_lock_op(struct vmballoon *b, unsigned int num_pages, - bool is_2m_pages, bool lock) + enum vmballoon_page_size_type page_size, + enum vmballoon_op op) { unsigned long cmd, pfn; + lockdep_assert_held(&b->comm_lock); + if (static_branch_likely(&vmw_balloon_batching)) { - if (lock) - cmd = is_2m_pages ? VMW_BALLOON_CMD_BATCHED_2M_LOCK : - VMW_BALLOON_CMD_BATCHED_LOCK; + if (op == VMW_BALLOON_INFLATE) + cmd = page_size == VMW_BALLOON_2M_PAGE ? + VMW_BALLOON_CMD_BATCHED_2M_LOCK : + VMW_BALLOON_CMD_BATCHED_LOCK; else - cmd = is_2m_pages ? VMW_BALLOON_CMD_BATCHED_2M_UNLOCK : - VMW_BALLOON_CMD_BATCHED_UNLOCK; + cmd = page_size == VMW_BALLOON_2M_PAGE ? + VMW_BALLOON_CMD_BATCHED_2M_UNLOCK : + VMW_BALLOON_CMD_BATCHED_UNLOCK; pfn = PHYS_PFN(virt_to_phys(b->batch_page)); } else { - cmd = lock ? VMW_BALLOON_CMD_LOCK : VMW_BALLOON_CMD_UNLOCK; + cmd = op == VMW_BALLOON_INFLATE ? VMW_BALLOON_CMD_LOCK : + VMW_BALLOON_CMD_UNLOCK; pfn = page_to_pfn(b->page); /* In non-batching mode, PFNs must fit in 32-bit */ @@ -603,22 +736,75 @@ static unsigned long vmballoon_lock_op(struct vmballoon *b, return vmballoon_cmd(b, cmd, pfn, num_pages); } -static int vmballoon_lock(struct vmballoon *b, unsigned int num_pages, - bool is_2m_pages) +/** + * vmballoon_add_page - adds a page towards lock/unlock operation. + * + * @b: pointer to the balloon. + * @idx: index of the page to be ballooned in this batch. + * @p: pointer to the page that is about to be ballooned. + * + * Adds the page to be ballooned. Must be called while holding @comm_lock. + */ +static void vmballoon_add_page(struct vmballoon *b, unsigned int idx, + struct page *p) +{ + lockdep_assert_held(&b->comm_lock); + + if (static_branch_likely(&vmw_balloon_batching)) + b->batch_page[idx] = (struct vmballoon_batch_entry) + { .pfn = page_to_pfn(p) }; + else + b->page = p; +} + +/** + * vmballoon_lock - lock or unlock a batch of pages. + * + * @b: pointer to the balloon. + * @ctl: pointer for the %struct vmballoon_ctl, which defines the operation. + * + * Notifies the host of about ballooned pages (after inflation or deflation, + * according to @ctl). If the host rejects the page put it on the + * @ctl refuse list. These refused page are then released when moving to the + * next size of pages. + * + * Note that we neither free any @page here nor put them back on the ballooned + * pages list. Instead we queue it for later processing. We do that for several + * reasons. First, we do not want to free the page under the lock. Second, it + * allows us to unify the handling of lock and unlock. In the inflate case, the + * caller will check if there are too many refused pages and release them. + * Although it is not identical to the past behavior, it should not affect + * performance. + */ +static int vmballoon_lock(struct vmballoon *b, struct vmballoon_ctl *ctl) { unsigned long batch_status; - int i; - u16 size_per_page = vmballoon_page_size(is_2m_pages); + struct page *page; + unsigned int i, num_pages; + + num_pages = ctl->n_pages; + if (num_pages == 0) + return 0; - batch_status = vmballoon_lock_op(b, num_pages, is_2m_pages, true); + /* communication with the host is done under the communication lock */ + spin_lock(&b->comm_lock); + i = 0; + list_for_each_entry(page, &ctl->pages, lru) + vmballoon_add_page(b, i++, page); + + batch_status = vmballoon_lock_op(b, ctl->n_pages, ctl->page_size, + ctl->op); + + /* + * Iterate over the pages in the provided list. Since we are changing + * @ctl->n_pages we are saving the original value in @num_pages and + * use this value to bound the loop. + */ for (i = 0; i < num_pages; i++) { unsigned long status; - struct page *p; - struct vmballoon_page_size *page_size = - &b->page_sizes[is_2m_pages]; - status = vmballoon_status_page(b, i, &p); + status = vmballoon_status_page(b, i, &page); /* * Failure of the whole batch overrides a single operation @@ -627,109 +813,61 @@ static int vmballoon_lock(struct vmballoon *b, unsigned int num_pages, if (batch_status != VMW_BALLOON_SUCCESS) status = batch_status; - if (status == VMW_BALLOON_SUCCESS) { - /* track allocated page */ - list_add(&p->lru, &page_size->pages); - - /* update balloon size */ - b->size += size_per_page; + /* Continue if no error happened */ + if (!vmballoon_handle_one_result(b, page, ctl->page_size, + status)) continue; - } - - /* Error occurred */ - vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_REFUSED_ALLOC, - is_2m_pages); /* - * Place page on the list of non-balloonable pages - * and retry allocation, unless we already accumulated - * too many of them, in which case take a breather. + * Error happened. Move the pages to the refused list and update + * the pages number. */ - list_add(&p->lru, &page_size->refused_pages); - page_size->n_refused_pages++; + list_move(&page->lru, &ctl->refused_pages); + ctl->n_pages--; + ctl->n_refused_pages++; } + spin_unlock(&b->comm_lock); + return batch_status == VMW_BALLOON_SUCCESS ? 0 : -EIO; } -/* - * Release the page allocated for the balloon. Note that we first notify - * the host so it can make sure the page will be available for the guest - * to use, if needed. +/** + * vmballoon_release_page_list() - Releases a page list + * + * @page_list: list of pages to release. + * @n_pages: pointer to the number of pages. + * @page_size: whether the pages in the list are 2MB (or else 4KB). + * + * Releases the list of pages and zeros the number of pages. */ -static int vmballoon_unlock(struct vmballoon *b, unsigned int num_pages, - bool is_2m_pages) +static void vmballoon_release_page_list(struct list_head *page_list, + int *n_pages, + enum vmballoon_page_size_type page_size) { - int i; - unsigned long batch_status; - u16 size_per_page = vmballoon_page_size(is_2m_pages); - - batch_status = vmballoon_lock_op(b, num_pages, is_2m_pages, false); - - for (i = 0; i < num_pages; i++) { - struct vmballoon_page_size *page_size; - unsigned long status; - struct page *p; + struct page *page, *tmp; - status = vmballoon_status_page(b, i, &p); - page_size = &b->page_sizes[is_2m_pages]; - - /* - * Failure of the whole batch overrides a single operation - * results. - */ - if (batch_status != VMW_BALLOON_SUCCESS) - status = batch_status; - - if (status != VMW_BALLOON_SUCCESS) { - /* - * That page wasn't successfully unlocked by the - * hypervisor, re-add it to the list of pages owned by - * the balloon driver. - */ - list_add(&p->lru, &page_size->pages); - } else { - /* deallocate page */ - vmballoon_free_page(p, is_2m_pages); - vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_FREE, - is_2m_pages); - - /* update balloon size */ - b->size -= size_per_page; - } + list_for_each_entry_safe(page, tmp, page_list, lru) { + list_del(&page->lru); + __free_pages(page, vmballoon_page_order(page_size)); } - return batch_status == VMW_BALLOON_SUCCESS ? 0 : -EIO; + *n_pages = 0; } + /* * Release pages that were allocated while attempting to inflate the * balloon but were refused by the host for one reason or another. */ static void vmballoon_release_refused_pages(struct vmballoon *b, - bool is_2m_pages) + struct vmballoon_ctl *ctl) { - struct page *page, *next; - struct vmballoon_page_size *page_size = - &b->page_sizes[is_2m_pages]; + vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_REFUSED_FREE, + ctl->page_size); - list_for_each_entry_safe(page, next, &page_size->refused_pages, lru) { - list_del(&page->lru); - vmballoon_free_page(page, is_2m_pages); - vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_REFUSED_FREE, - is_2m_pages); - } - - page_size->n_refused_pages = 0; -} - -static void vmballoon_add_page(struct vmballoon *b, int idx, struct page *p) -{ - if (static_branch_likely(&vmw_balloon_batching)) - b->batch_page[idx] = (struct vmballoon_batch_entry) - { .pfn = page_to_pfn(p) }; - else - b->page = p; + vmballoon_release_page_list(&ctl->refused_pages, &ctl->n_refused_pages, + ctl->page_size); } /** @@ -744,8 +882,8 @@ static int64_t vmballoon_change(struct vmballoon *b) { int64_t size, target; - size = b->size; - target = b->target; + size = atomic64_read(&b->size); + target = READ_ONCE(b->target); /* * We must cast first because of int sizes @@ -756,154 +894,257 @@ static int64_t vmballoon_change(struct vmballoon *b) return 0; /* consider a 2MB slack on deflate, unless the balloon is emptied */ - if (target < size && size - target < vmballoon_page_size(true) && - target != 0) + if (target < size && target != 0 && + size - target < vmballoon_page_in_frames(VMW_BALLOON_2M_PAGE)) return 0; return target - size; } -/* - * Inflate the balloon towards its target size. Note that we try to limit - * the rate of allocation to make sure we are not choking the rest of the - * system. +/** + * vmballoon_enqueue_page_list() - Enqueues list of pages after inflation. + * + * @b: pointer to balloon. + * @pages: list of pages to enqueue. + * @n_pages: pointer to number of pages in list. The value is zeroed. + * @page_size: whether the pages are 2MB or 4KB pages. + * + * Enqueues the provides list of pages in the ballooned page list, clears the + * list and zeroes the number of pages that was provided. + */ +static void vmballoon_enqueue_page_list(struct vmballoon *b, + struct list_head *pages, + unsigned int *n_pages, + enum vmballoon_page_size_type page_size) +{ + struct vmballoon_page_size *page_size_info = &b->page_sizes[page_size]; + + list_splice_init(pages, &page_size_info->pages); + *n_pages = 0; +} + +/** + * vmballoon_dequeue_page_list() - Dequeues page lists for deflation. + * + * @b: pointer to balloon. + * @pages: list of pages to enqueue. + * @n_pages: pointer to number of pages in list. The value is zeroed. + * @page_size: whether the pages are 2MB or 4KB pages. + * @n_req_pages: the number of requested pages. + * + * Dequeues the number of requested pages from the balloon for deflation. The + * number of dequeued pages may be lower, if not enough pages in the requested + * size are available. + */ +static void vmballoon_dequeue_page_list(struct vmballoon *b, + struct list_head *pages, + unsigned int *n_pages, + enum vmballoon_page_size_type page_size, + unsigned int n_req_pages) +{ + struct vmballoon_page_size *page_size_info = &b->page_sizes[page_size]; + struct page *page, *tmp; + unsigned int i = 0; + + list_for_each_entry_safe(page, tmp, &page_size_info->pages, lru) { + list_move(&page->lru, pages); + if (++i == n_req_pages) + break; + } + *n_pages = i; +} + +/** + * vmballoon_inflate() - Inflate the balloon towards its target size. + * + * @b: pointer to the balloon. */ static void vmballoon_inflate(struct vmballoon *b) { - unsigned int num_pages = 0; - int error = 0; - bool is_2m_pages; + int64_t to_inflate_frames; + struct vmballoon_ctl ctl = { + .pages = LIST_HEAD_INIT(ctl.pages), + .refused_pages = LIST_HEAD_INIT(ctl.refused_pages), + .page_size = b->max_page_size, + .op = VMW_BALLOON_INFLATE + }; - /* - * First try NOSLEEP page allocations to inflate balloon. - * - * If we do not throttle nosleep allocations, we can drain all - * free pages in the guest quickly (if the balloon target is high). - * As a side-effect, draining free pages helps to inform (force) - * the guest to start swapping if balloon target is not met yet, - * which is a desired behavior. However, balloon driver can consume - * all available CPU cycles if too many pages are allocated in a - * second. Therefore, we throttle nosleep allocations even when - * the guest is not under memory pressure. OTOH, if we have already - * predicted that the guest is under memory pressure, then we - * slowdown page allocations considerably. - */ + while ((to_inflate_frames = vmballoon_change(b)) > 0) { + unsigned int to_inflate_pages, page_in_frames; + int alloc_error, lock_error = 0; - /* - * Start with no sleep allocation rate which may be higher - * than sleeping allocation rate. - */ - is_2m_pages = b->supported_page_sizes == VMW_BALLOON_NUM_PAGE_SIZES; + VM_BUG_ON(!list_empty(&ctl.pages)); + VM_BUG_ON(ctl.n_pages != 0); - while ((int64_t)(num_pages * vmballoon_page_size(is_2m_pages)) < - vmballoon_change(b)) { - struct page *page; + page_in_frames = vmballoon_page_in_frames(ctl.page_size); - vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_ALLOC, - is_2m_pages); - - page = vmballoon_alloc_page(is_2m_pages); - if (!page) { - vmballoon_stats_page_inc(b, - VMW_BALLOON_PAGE_STAT_ALLOC_FAIL, is_2m_pages); - - if (is_2m_pages) { - vmballoon_lock(b, num_pages, true); - - /* - * ignore errors from locking as we now switch - * to 4k pages and we might get different - * errors. - */ - - num_pages = 0; - is_2m_pages = false; - continue; - } + to_inflate_pages = min_t(unsigned long, b->batch_max_pages, + DIV_ROUND_UP_ULL(to_inflate_frames, + page_in_frames)); + + /* Start by allocating */ + alloc_error = vmballoon_alloc_page_list(b, &ctl, + to_inflate_pages); + + /* Actually lock the pages by telling the hypervisor */ + lock_error = vmballoon_lock(b, &ctl); + + /* + * If an error indicates that something serious went wrong, + * stop the inflation. + */ + if (lock_error) break; - } - vmballoon_add_page(b, num_pages++, page); - if (num_pages == b->batch_max_pages) { - struct vmballoon_page_size *page_size = - &b->page_sizes[is_2m_pages]; + /* Update the balloon size */ + atomic64_add(ctl.n_pages * page_in_frames, &b->size); - error = vmballoon_lock(b, num_pages, is_2m_pages); + vmballoon_enqueue_page_list(b, &ctl.pages, &ctl.n_pages, + ctl.page_size); - num_pages = 0; + /* + * If allocation failed or the number of refused pages exceeds + * the maximum allowed, move to the next page size. + */ + if (alloc_error || + ctl.n_refused_pages >= VMW_BALLOON_MAX_REFUSED) { + if (ctl.page_size == VMW_BALLOON_4K_PAGE) + break; /* - * Stop allocating this page size if we already - * accumulated too many pages that the hypervisor - * refused. + * Ignore errors from locking as we now switch to 4k + * pages and we might get different errors. */ - if (page_size->n_refused_pages >= - VMW_BALLOON_MAX_REFUSED) { - if (!is_2m_pages) - break; - - /* - * Release the refused pages as we move to 4k - * pages. - */ - vmballoon_release_refused_pages(b, true); - is_2m_pages = true; - } - - if (error) - break; + vmballoon_release_refused_pages(b, &ctl); + ctl.page_size--; } cond_resched(); } - if (num_pages > 0) - vmballoon_lock(b, num_pages, is_2m_pages); - - vmballoon_release_refused_pages(b, true); - vmballoon_release_refused_pages(b, false); + /* + * Release pages that were allocated while attempting to inflate the + * balloon but were refused by the host for one reason or another, + * and update the statistics. + */ + if (ctl.n_refused_pages != 0) + vmballoon_release_refused_pages(b, &ctl); } -/* +/** + * vmballoon_deflate() - Decrease the size of the balloon. + * + * @b: pointer to the balloon + * @n_frames: the number of frames to deflate. If zero, automatically + * calculated according to the target size. + * @coordinated: whether to coordinate with the host + * * Decrease the size of the balloon allowing guest to use more memory. + * + * Return: The number of deflated frames (i.e., basic page size units) */ -static void vmballoon_deflate(struct vmballoon *b) +static unsigned long vmballoon_deflate(struct vmballoon *b, uint64_t n_frames, + bool coordinated) { - unsigned is_2m_pages; + unsigned long deflated_frames = 0; + unsigned long tried_frames = 0; + struct vmballoon_ctl ctl = { + .pages = LIST_HEAD_INIT(ctl.pages), + .refused_pages = LIST_HEAD_INIT(ctl.refused_pages), + .page_size = VMW_BALLOON_4K_PAGE, + .op = VMW_BALLOON_DEFLATE + }; /* free pages to reach target */ - for (is_2m_pages = 0; is_2m_pages < b->supported_page_sizes; - is_2m_pages++) { - struct page *page, *next; - unsigned int num_pages = 0; - struct vmballoon_page_size *page_size = - &b->page_sizes[is_2m_pages]; - - list_for_each_entry_safe(page, next, &page_size->pages, lru) { - if ((int64_t)(num_pages * - vmballoon_page_size(is_2m_pages)) >= - -vmballoon_change(b)) - break; + while (true) { + unsigned int to_deflate_pages, n_unlocked_frames; + unsigned int page_in_frames; + int64_t to_deflate_frames; + bool deflated_all; + + page_in_frames = vmballoon_page_in_frames(ctl.page_size); + + VM_BUG_ON(!list_empty(&ctl.pages)); + VM_BUG_ON(ctl.n_pages); + VM_BUG_ON(!list_empty(&ctl.refused_pages)); + VM_BUG_ON(ctl.n_refused_pages); + + /* + * If we were requested a specific number of frames, we try to + * deflate this number of frames. Otherwise, deflation is + * performed according to the target and balloon size. + */ + to_deflate_frames = n_frames ? n_frames - tried_frames : + -vmballoon_change(b); + + /* break if no work to do */ + if (to_deflate_frames <= 0) + break; + + /* + * Calculate the number of frames based on current page size, + * but limit the deflated frames to a single chunk + */ + to_deflate_pages = min_t(unsigned long, b->batch_max_pages, + DIV_ROUND_UP_ULL(to_deflate_frames, + page_in_frames)); + + /* First take the pages from the balloon pages. */ + vmballoon_dequeue_page_list(b, &ctl.pages, &ctl.n_pages, + ctl.page_size, to_deflate_pages); - list_del(&page->lru); - vmballoon_add_page(b, num_pages++, page); + /* + * Before pages are moving to the refused list, count their + * frames as frames that we tried to deflate. + */ + tried_frames += ctl.n_pages * page_in_frames; + + /* + * Unlock the pages by communicating with the hypervisor if the + * communication is coordinated (i.e., not pop). We ignore the + * return code. Instead we check if all the pages we manage to + * unlock all the pages. If we failed, we will move to the next + * page size, and would eventually try again later. + */ + if (coordinated) + vmballoon_lock(b, &ctl); + + /* + * Check if we deflated enough. We will move to the next page + * size if we did not manage to do so. This calculation takes + * place now, as once the pages are released, the number of + * pages is zeroed. + */ + deflated_all = (ctl.n_pages == to_deflate_pages); - if (num_pages == b->batch_max_pages) { - int error; + /* Update local and global counters */ + n_unlocked_frames = ctl.n_pages * page_in_frames; + atomic64_sub(n_unlocked_frames, &b->size); + deflated_frames += n_unlocked_frames; - error = vmballoon_unlock(b, num_pages, - is_2m_pages); - num_pages = 0; - if (error) - return; - } + vmballoon_stats_page_add(b, VMW_BALLOON_PAGE_STAT_FREE, + ctl.page_size, ctl.n_pages); - cond_resched(); + /* free the ballooned pages */ + vmballoon_release_page_list(&ctl.pages, &ctl.n_pages, + ctl.page_size); + + /* Return the refused pages to the ballooned list. */ + vmballoon_enqueue_page_list(b, &ctl.refused_pages, + &ctl.n_refused_pages, + ctl.page_size); + + /* If we failed to unlock all the pages, move to next size. */ + if (!deflated_all) { + if (ctl.page_size == b->max_page_size) + break; + ctl.page_size++; } - if (num_pages > 0) - vmballoon_unlock(b, num_pages, is_2m_pages); + cond_resched(); } + + return deflated_frames; } /** @@ -1004,6 +1245,23 @@ fail: return -EIO; } +/** + * vmballoon_pop - Quickly release all pages allocate for the balloon. + * + * @b: pointer to the balloon. + * + * This function is called when host decides to "reset" balloon for one reason + * or another. Unlike normal "deflate" we do not (shall not) notify host of the + * pages being released. + */ +static void vmballoon_pop(struct vmballoon *b) +{ + unsigned long size; + + while ((size = atomic64_read(&b->size))) + vmballoon_deflate(b, size, false); +} + /* * Perform standard reset sequence by popping the balloon (in case it * is not empty) and then restarting protocol. This operation normally @@ -1080,13 +1338,13 @@ static void vmballoon_work(struct work_struct *work) change = vmballoon_change(b); if (change != 0) { - pr_debug("%s - size: %u, target %u", __func__, - b->size, b->target); + pr_debug("%s - size: %llu, target %lu\n", __func__, + atomic64_read(&b->size), READ_ONCE(b->target)); if (change > 0) vmballoon_inflate(b); else /* (change < 0) */ - vmballoon_deflate(b); + vmballoon_deflate(b, 0, true); } up_read(&b->conf_sem); @@ -1118,11 +1376,6 @@ static const char * const vmballoon_stat_names[] = { [VMW_BALLOON_STAT_DOORBELL] = "doorbell" }; -static const char * const vmballoon_page_size_names[] = { - [VMW_BALLOON_4K_PAGE] = "4k", - [VMW_BALLOON_2M_PAGE] = "2M" -}; - static int vmballoon_enable_stats(struct vmballoon *b) { int r = 0; @@ -1171,16 +1424,15 @@ static int vmballoon_debug_show(struct seq_file *f, void *offset) } /* format capabilities info */ - seq_printf(f, "%-22s: %#4x\n", "balloon capabilities", + seq_printf(f, "%-22s: %#16x\n", "balloon capabilities", VMW_BALLOON_CAPABILITIES); - seq_printf(f, "%-22s: %#4lx\n", "used capabilities", - b->capabilities); + seq_printf(f, "%-22s: %#16lx\n", "used capabilities", b->capabilities); seq_printf(f, "%-22s: %16s\n", "is resetting", b->reset_required ? "y" : "n"); /* format size info */ - seq_printf(f, "%-22s: %16u\n", "target", b->target); - seq_printf(f, "%-22s: %16u\n", "current", b->size); + seq_printf(f, "%-22s: %16lu\n", "target", READ_ONCE(b->target)); + seq_printf(f, "%-22s: %16llu\n", "current", atomic64_read(&b->size)); for (i = 0; i < VMW_BALLOON_CMD_NUM; i++) { if (vmballoon_cmd_names[i] == NULL) @@ -1259,8 +1511,9 @@ static inline void vmballoon_debugfs_exit(struct vmballoon *b) static int __init vmballoon_init(void) { + enum vmballoon_page_size_type page_size; int error; - unsigned is_2m_pages; + /* * Check if we are running on VMware's hypervisor and bail out * if we are not. @@ -1268,11 +1521,10 @@ static int __init vmballoon_init(void) if (x86_hyper_type != X86_HYPER_VMWARE) return -ENODEV; - for (is_2m_pages = 0; is_2m_pages < VMW_BALLOON_NUM_PAGE_SIZES; - is_2m_pages++) { - INIT_LIST_HEAD(&balloon.page_sizes[is_2m_pages].pages); - INIT_LIST_HEAD(&balloon.page_sizes[is_2m_pages].refused_pages); - } + for (page_size = VMW_BALLOON_4K_PAGE; + page_size <= VMW_BALLOON_LAST_SIZE; page_size++) + INIT_LIST_HEAD(&balloon.page_sizes[page_size].pages); + INIT_DELAYED_WORK(&balloon.dwork, vmballoon_work); @@ -1280,6 +1532,7 @@ static int __init vmballoon_init(void) if (error) return error; + spin_lock_init(&balloon.comm_lock); init_rwsem(&balloon.conf_sem); balloon.vmci_doorbell = VMCI_INVALID_HANDLE; balloon.batch_page = NULL; |
