drivers/misc/vmw_balloon.c

8  * acts like a "balloon" that can be inflated to reclaim physical pages by
11  * other guests.  The balloon can also be deflated to allow the guest to
54 /* Magic number for the balloon mount-point */
140  * @VMW_BALLOON_CMD_GET_TARGET: Gets the balloon target size.
143  *			    to be deflated from the balloon.
150  *				  balloon (up to 512).
157  *				       that would be invoked when the balloon
271 	 * @size: balloon actual size in basic page size (frames).
279 	 * @target: balloon target size in basic page size (frames).
300 	 * @capabilities: hypervisor balloon capabilities.
348 	 * @b_dev_info: balloon device information descriptor.
386 static struct vmballoon balloon;
539  * @b: pointer to the balloon.
613  * vmballoon_send_get_target() - Retrieve desired balloon size from the host.
615  * @b: pointer to the balloon.
641  * @b: pointer to the balloon.
645  * Tries to allocate @req_n_pages. Add them to the list of balloon pages in
707 	/* On success do nothing. The page is already on the balloon list. */
725  * @b: pointer to the balloon.
758  * @b: pointer to the balloon.
764  * balloon) so that host can use it without fear that guest will need it (or
807  * @b: pointer to the balloon.
828  * @b: pointer to the balloon.
927  * balloon but were refused by the host for one reason or another.
940  * vmballoon_change - retrieve the required balloon change
942  * @b: pointer for the balloon.
944  * Return: the required change for the balloon size. A positive number
962 	/* consider a 2MB slack on deflate, unless the balloon is emptied */
977  * @b: pointer to balloon.
998 		 * for the balloon compaction mechanism.
1018  * @b: pointer to balloon.
1024  * Dequeues the number of requested pages from the balloon for deflation. The
1088  * vmballoon_inflate() - Inflate the balloon towards its target size.
1090  * @b: pointer to the balloon.
1130 		/* Update the balloon size */
1158 	 * balloon but were refused by the host for one reason or another,
1168  * vmballoon_deflate() - Decrease the size of the balloon.
1170  * @b: pointer to the balloon
1175  * Decrease the size of the balloon allowing guest to use more memory.
1208 		 * performed according to the target and balloon size.
1225 		/* First take the pages from the balloon pages. */
1326  * Receive notification and resize balloon
1354  * @b: pointer to the balloon.
1359  * Initialize vmci doorbell, to get notified as soon as balloon changes.
1389  * vmballoon_pop - Quickly release all pages allocate for the balloon.
1391  * @b: pointer to the balloon.
1393  * This function is called when host decides to "reset" balloon for one reason
1406  * Perform standard reset sequence by popping the balloon (in case it
1454  * vmballoon_work - periodic balloon worker for reset, inflation and deflation.
1458  * Resets the protocol if needed, gets the new size and adjusts balloon as
1495 	 * We are using a freezable workqueue so that balloon operations are
1504  * vmballoon_shrinker_scan() - deflate the balloon due to memory pressure.
1505  * @shrinker: pointer to the balloon shrinker.
1513 	struct vmballoon *b = &balloon;
1534 	 * which balloon continuously grows and shrinks. Use WRITE_ONCE() since
1546  * @shrinker: pointer to the balloon shrinker.
1549  * Returns: number of 4k pages that are allocated for the balloon and can
1555 	struct vmballoon *b = &balloon;
1572 	b->shrinker = shrinker_alloc(0, "vmw-balloon");
1630  * vmballoon_debug_show - shows statistics of balloon operations.
1654 	seq_printf(f, "%-22s: %#16x\n", "balloon capabilities",
1721  * vmballoon_migratepage() - migrates a balloon page.
1722  * @b_dev_info: balloon device information descriptor.
1746 	 * (i.e., balloon reset), so try again.
1799 		 * we will decrease the size of the balloon to reflect the
1813 	/* Update the balloon list under the @pages_lock */
1839  * vmballoon_compaction_init() - initialized compaction for the balloon.
1841  * @b: pointer to the balloon.
1871 	INIT_DELAYED_WORK(&balloon.dwork, vmballoon_work);
1873 	error = vmballoon_register_shrinker(&balloon);
1881 	balloon_devinfo_init(&balloon.b_dev_info);
1882 	vmballoon_compaction_init(&balloon);
1884 	INIT_LIST_HEAD(&balloon.huge_pages);
1885 	spin_lock_init(&balloon.comm_lock);
1886 	init_rwsem(&balloon.conf_sem);
1887 	balloon.vmci_doorbell = VMCI_INVALID_HANDLE;
1888 	balloon.batch_page = NULL;
1889 	balloon.page = NULL;
1890 	balloon.reset_required = true;
1892 	queue_delayed_work(system_freezable_wq, &balloon.dwork, 0);
1894 	vmballoon_debugfs_init(&balloon);
1900  * Using late_initcall() instead of module_init() allows the balloon to use the
1901  * VMCI doorbell even when the balloon is built into the kernel. Otherwise the
1902  * VMCI is probed only after the balloon is initialized. If the balloon is used
1909 	vmballoon_unregister_shrinker(&balloon);
1910 	vmballoon_vmci_cleanup(&balloon);
1911 	cancel_delayed_work_sync(&balloon.dwork);
1913 	vmballoon_debugfs_exit(&balloon);
1920 	vmballoon_send_start(&balloon, 0);
1921 	vmballoon_pop(&balloon);