/* * Copyright (c) 2012, Microsoft Corporation. * * Author: * K. Y. Srinivasan * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 as published * by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or * NON INFRINGEMENT. See the GNU General Public License for more * details. * */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include #include #include #include #include #include #include #include #include #include #include #include #include /* * We begin with definitions supporting the Dynamic Memory protocol * with the host. * * Begin protocol definitions. */ /* * Protocol versions. The low word is the minor version, the high word the major * version. * * History: * Initial version 1.0 * Changed to 0.1 on 2009/03/25 * Changes to 0.2 on 2009/05/14 * Changes to 0.3 on 2009/12/03 * Changed to 1.0 on 2011/04/05 */ #define DYNMEM_MAKE_VERSION(Major, Minor) ((__u32)(((Major) << 16) | (Minor))) #define DYNMEM_MAJOR_VERSION(Version) ((__u32)(Version) >> 16) #define DYNMEM_MINOR_VERSION(Version) ((__u32)(Version) & 0xff) enum { DYNMEM_PROTOCOL_VERSION_1 = DYNMEM_MAKE_VERSION(0, 3), DYNMEM_PROTOCOL_VERSION_2 = DYNMEM_MAKE_VERSION(1, 0), DYNMEM_PROTOCOL_VERSION_WIN7 = DYNMEM_PROTOCOL_VERSION_1, DYNMEM_PROTOCOL_VERSION_WIN8 = DYNMEM_PROTOCOL_VERSION_2, DYNMEM_PROTOCOL_VERSION_CURRENT = DYNMEM_PROTOCOL_VERSION_WIN8 }; /* * Message Types */ enum dm_message_type { /* * Version 0.3 */ DM_ERROR = 0, DM_VERSION_REQUEST = 1, DM_VERSION_RESPONSE = 2, DM_CAPABILITIES_REPORT = 3, DM_CAPABILITIES_RESPONSE = 4, DM_STATUS_REPORT = 5, DM_BALLOON_REQUEST = 6, DM_BALLOON_RESPONSE = 7, DM_UNBALLOON_REQUEST = 8, DM_UNBALLOON_RESPONSE = 9, DM_MEM_HOT_ADD_REQUEST = 10, DM_MEM_HOT_ADD_RESPONSE = 11, DM_VERSION_03_MAX = 11, /* * Version 1.0. */ DM_INFO_MESSAGE = 12, DM_VERSION_1_MAX = 12 }; /* * Structures defining the dynamic memory management * protocol. */ union dm_version { struct { __u16 minor_version; __u16 major_version; }; __u32 version; } __packed; union dm_caps { struct { __u64 balloon:1; __u64 hot_add:1; __u64 reservedz:62; } cap_bits; __u64 caps; } __packed; union dm_mem_page_range { struct { /* * The PFN number of the first page in the range. * 40 bits is the architectural limit of a PFN * number for AMD64. */ __u64 start_page:40; /* * The number of pages in the range. */ __u64 page_cnt:24; } finfo; __u64 page_range; } __packed; /* * The header for all dynamic memory messages: * * type: Type of the message. * size: Size of the message in bytes; including the header. * trans_id: The guest is responsible for manufacturing this ID. */ struct dm_header { __u16 type; __u16 size; __u32 trans_id; } __packed; /* * A generic message format for dynamic memory. * Specific message formats are defined later in the file. */ struct dm_message { struct dm_header hdr; __u8 data[]; /* enclosed message */ } __packed; /* * Specific message types supporting the dynamic memory protocol. */ /* * Version negotiation message. Sent from the guest to the host. * The guest is free to try different versions until the host * accepts the version. * * dm_version: The protocol version requested. * is_last_attempt: If TRUE, this is the last version guest will request. * reservedz: Reserved field, set to zero. */ struct dm_version_request { struct dm_header hdr; union dm_version version; __u32 is_last_attempt:1; __u32 reservedz:31; } __packed; /* * Version response message; Host to Guest and indicates * if the host has accepted the version sent by the guest. * * is_accepted: If TRUE, host has accepted the version and the guest * should proceed to the next stage of the protocol. FALSE indicates that * guest should re-try with a different version. * * reservedz: Reserved field, set to zero. */ struct dm_version_response { struct dm_header hdr; __u64 is_accepted:1; __u64 reservedz:63; } __packed; /* * Message reporting capabilities. This is sent from the guest to the * host. */ struct dm_capabilities { struct dm_header hdr; union dm_caps caps; __u64 min_page_cnt; __u64 max_page_number; } __packed; /* * Response to the capabilities message. This is sent from the host to the * guest. This message notifies if the host has accepted the guest's * capabilities. If the host has not accepted, the guest must shutdown * the service. * * is_accepted: Indicates if the host has accepted guest's capabilities. * reservedz: Must be 0. */ struct dm_capabilities_resp_msg { struct dm_header hdr; __u64 is_accepted:1; __u64 reservedz:63; } __packed; /* * This message is used to report memory pressure from the guest. * This message is not part of any transaction and there is no * response to this message. * * num_avail: Available memory in pages. * num_committed: Committed memory in pages. * page_file_size: The accumulated size of all page files * in the system in pages. * zero_free: The nunber of zero and free pages. * page_file_writes: The writes to the page file in pages. * io_diff: An indicator of file cache efficiency or page file activity, * calculated as File Cache Page Fault Count - Page Read Count. * This value is in pages. * * Some of these metrics are Windows specific and fortunately * the algorithm on the host side that computes the guest memory * pressure only uses num_committed value. */ struct dm_status { struct dm_header hdr; __u64 num_avail; __u64 num_committed; __u64 page_file_size; __u64 zero_free; __u32 page_file_writes; __u32 io_diff; } __packed; /* * Message to ask the guest to allocate memory - balloon up message. * This message is sent from the host to the guest. The guest may not be * able to allocate as much memory as requested. * * num_pages: number of pages to allocate. */ struct dm_balloon { struct dm_header hdr; __u32 num_pages; __u32 reservedz; } __packed; /* * Balloon response message; this message is sent from the guest * to the host in response to the balloon message. * * reservedz: Reserved; must be set to zero. * more_pages: If FALSE, this is the last message of the transaction. * if TRUE there will atleast one more message from the guest. * * range_count: The number of ranges in the range array. * * range_array: An array of page ranges returned to the host. * */ struct dm_balloon_response { struct dm_header hdr; __u32 reservedz; __u32 more_pages:1; __u32 range_count:31; union dm_mem_page_range range_array[]; } __packed; /* * Un-balloon message; this message is sent from the host * to the guest to give guest more memory. * * more_pages: If FALSE, this is the last message of the transaction. * if TRUE there will atleast one more message from the guest. * * reservedz: Reserved; must be set to zero. * * range_count: The number of ranges in the range array. * * range_array: An array of page ranges returned to the host. * */ struct dm_unballoon_request { struct dm_header hdr; __u32 more_pages:1; __u32 reservedz:31; __u32 range_count; union dm_mem_page_range range_array[]; } __packed; /* * Un-balloon response message; this message is sent from the guest * to the host in response to an unballoon request. * */ struct dm_unballoon_response { struct dm_header hdr; } __packed; /* * Hot add request message. Message sent from the host to the guest. * * mem_range: Memory range to hot add. * * On Linux we currently don't support this since we cannot hot add * arbitrary granularity of memory. */ struct dm_hot_add { struct dm_header hdr; union dm_mem_page_range range; } __packed; /* * Hot add response message. * This message is sent by the guest to report the status of a hot add request. * If page_count is less than the requested page count, then the host should * assume all further hot add requests will fail, since this indicates that * the guest has hit an upper physical memory barrier. * * Hot adds may also fail due to low resources; in this case, the guest must * not complete this message until the hot add can succeed, and the host must * not send a new hot add request until the response is sent. * If VSC fails to hot add memory DYNMEM_NUMBER_OF_UNSUCCESSFUL_HOTADD_ATTEMPTS * times it fails the request. * * * page_count: number of pages that were successfully hot added. * * result: result of the operation 1: success, 0: failure. * */ struct dm_hot_add_response { struct dm_header hdr; __u32 page_count; __u32 result; } __packed; /* * Types of information sent from host to the guest. */ enum dm_info_type { INFO_TYPE_MAX_PAGE_CNT = 0, MAX_INFO_TYPE }; /* * Header for the information message. */ struct dm_info_header { enum dm_info_type type; __u32 data_size; } __packed; /* * This message is sent from the host to the guest to pass * some relevant information (win8 addition). * * reserved: no used. * info_size: size of the information blob. * info: information blob. */ struct dm_info_msg { struct dm_header hdr; __u32 reserved; __u32 info_size; __u8 info[]; }; /* * End protocol definitions. */ static bool hot_add; static bool do_hot_add; /* * Delay reporting memory pressure by * the specified number of seconds. */ static uint pressure_report_delay = 30; module_param(hot_add, bool, (S_IRUGO | S_IWUSR)); MODULE_PARM_DESC(hot_add, "If set attempt memory hot_add"); module_param(pressure_report_delay, uint, (S_IRUGO | S_IWUSR)); MODULE_PARM_DESC(pressure_report_delay, "Delay in secs in reporting pressure"); static atomic_t trans_id = ATOMIC_INIT(0); static int dm_ring_size = (5 * PAGE_SIZE); /* * Driver specific state. */ enum hv_dm_state { DM_INITIALIZING = 0, DM_INITIALIZED, DM_BALLOON_UP, DM_BALLOON_DOWN, DM_HOT_ADD, DM_INIT_ERROR }; static __u8 recv_buffer[PAGE_SIZE]; static __u8 *send_buffer; #define PAGES_IN_2M 512 struct hv_dynmem_device { struct hv_device *dev; enum hv_dm_state state; struct completion host_event; struct completion config_event; /* * Number of pages we have currently ballooned out. */ unsigned int num_pages_ballooned; /* * This thread handles both balloon/hot-add * requests from the host as well as notifying * the host with regards to memory pressure in * the guest. */ struct task_struct *thread; /* * We start with the highest version we can support * and downgrade based on the host; we save here the * next version to try. */ __u32 next_version; }; static struct hv_dynmem_device dm_device; static void hot_add_req(struct hv_dynmem_device *dm, struct dm_hot_add *msg) { struct dm_hot_add_response resp; if (do_hot_add) { pr_info("Memory hot add not supported\n"); /* * Currently we do not support hot add. * Just fail the request. */ } memset(&resp, 0, sizeof(struct dm_hot_add_response)); resp.hdr.type = DM_MEM_HOT_ADD_RESPONSE; resp.hdr.size = sizeof(struct dm_hot_add_response); resp.hdr.trans_id = atomic_inc_return(&trans_id); resp.page_count = 0; resp.result = 0; dm->state = DM_INITIALIZED; vmbus_sendpacket(dm->dev->channel, &resp, sizeof(struct dm_hot_add_response), (unsigned long)NULL, VM_PKT_DATA_INBAND, 0); } static void process_info(struct hv_dynmem_device *dm, struct dm_info_msg *msg) { struct dm_info_header *info_hdr; info_hdr = (struct dm_info_header *)msg->info; switch (info_hdr->type) { case INFO_TYPE_MAX_PAGE_CNT: pr_info("Received INFO_TYPE_MAX_PAGE_CNT\n"); pr_info("Data Size is %d\n", info_hdr->data_size); break; default: pr_info("Received Unknown type: %d\n", info_hdr->type); } } /* * Post our status as it relates memory pressure to the * host. Host expects the guests to post this status * periodically at 1 second intervals. * * The metrics specified in this protocol are very Windows * specific and so we cook up numbers here to convey our memory * pressure. */ static void post_status(struct hv_dynmem_device *dm) { struct dm_status status; struct sysinfo val; if (pressure_report_delay > 0) { --pressure_report_delay; return; } si_meminfo(&val); memset(&status, 0, sizeof(struct dm_status)); status.hdr.type = DM_STATUS_REPORT; status.hdr.size = sizeof(struct dm_status); status.hdr.trans_id = atomic_inc_return(&trans_id); /* * The host expects the guest to report free memory. * Further, the host expects the pressure information to * include the ballooned out pages. */ status.num_avail = val.freeram; status.num_committed = vm_memory_committed() + dm->num_pages_ballooned; vmbus_sendpacket(dm->dev->channel, &status, sizeof(struct dm_status), (unsigned long)NULL, VM_PKT_DATA_INBAND, 0); } static void free_balloon_pages(struct hv_dynmem_device *dm, union dm_mem_page_range *range_array) { int num_pages = range_array->finfo.page_cnt; __u64 start_frame = range_array->finfo.start_page; struct page *pg; int i; for (i = 0; i < num_pages; i++) { pg = pfn_to_page(i + start_frame); __free_page(pg); dm->num_pages_ballooned--; } } static int alloc_balloon_pages(struct hv_dynmem_device *dm, int num_pages, struct dm_balloon_response *bl_resp, int alloc_unit, bool *alloc_error) { int i = 0; struct page *pg; if (num_pages < alloc_unit) return 0; for (i = 0; (i * alloc_unit) < num_pages; i++) { if (bl_resp->hdr.size + sizeof(union dm_mem_page_range) > PAGE_SIZE) return i * alloc_unit; /* * We execute this code in a thread context. Furthermore, * we don't want the kernel to try too hard. */ pg = alloc_pages(GFP_HIGHUSER | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN, get_order(alloc_unit << PAGE_SHIFT)); if (!pg) { *alloc_error = true; return i * alloc_unit; } dm->num_pages_ballooned += alloc_unit; bl_resp->range_count++; bl_resp->range_array[i].finfo.start_page = page_to_pfn(pg); bl_resp->range_array[i].finfo.page_cnt = alloc_unit; bl_resp->hdr.size += sizeof(union dm_mem_page_range); } return num_pages; } static void balloon_up(struct hv_dynmem_device *dm, struct dm_balloon *req) { int num_pages = req->num_pages; int num_ballooned = 0; struct dm_balloon_response *bl_resp; int alloc_unit; int ret; bool alloc_error = false; bool done = false; int i; /* * Currently, we only support 4k allocations. */ alloc_unit = 1; while (!done) { bl_resp = (struct dm_balloon_response *)send_buffer; memset(send_buffer, 0, PAGE_SIZE); bl_resp->hdr.type = DM_BALLOON_RESPONSE; bl_resp->hdr.trans_id = atomic_inc_return(&trans_id); bl_resp->hdr.size = sizeof(struct dm_balloon_response); bl_resp->more_pages = 1; num_pages -= num_ballooned; num_ballooned = alloc_balloon_pages(dm, num_pages, bl_resp, alloc_unit, &alloc_error); if ((alloc_error) || (num_ballooned == num_pages)) { bl_resp->more_pages = 0; done = true; dm->state = DM_INITIALIZED; } /* * We are pushing a lot of data through the channel; * deal with transient failures caused because of the * lack of space in the ring buffer. */ do { ret = vmbus_sendpacket(dm_device.dev->channel, bl_resp, bl_resp->hdr.size, (unsigned long)NULL, VM_PKT_DATA_INBAND, 0); if (ret == -EAGAIN) msleep(20); } while (ret == -EAGAIN); if (ret) { /* * Free up the memory we allocatted. */ pr_info("Balloon response failed\n"); for (i = 0; i < bl_resp->range_count; i++) free_balloon_pages(dm, &bl_resp->range_array[i]); done = true; } } } static void balloon_down(struct hv_dynmem_device *dm, struct dm_unballoon_request *req) { union dm_mem_page_range *range_array = req->range_array; int range_count = req->range_count; struct dm_unballoon_response resp; int i; for (i = 0; i < range_count; i++) free_balloon_pages(dm, &range_array[i]); if (req->more_pages == 1) return; memset(&resp, 0, sizeof(struct dm_unballoon_response)); resp.hdr.type = DM_UNBALLOON_RESPONSE; resp.hdr.trans_id = atomic_inc_return(&trans_id); resp.hdr.size = sizeof(struct dm_unballoon_response); vmbus_sendpacket(dm_device.dev->channel, &resp, sizeof(struct dm_unballoon_response), (unsigned long)NULL, VM_PKT_DATA_INBAND, 0); dm->state = DM_INITIALIZED; } static void balloon_onchannelcallback(void *context); static int dm_thread_func(void *dm_dev) { struct hv_dynmem_device *dm = dm_dev; int t; unsigned long scan_start; while (!kthread_should_stop()) { t = wait_for_completion_timeout(&dm_device.config_event, 1*HZ); /* * The host expects us to post information on the memory * pressure every second. */ if (t == 0) post_status(dm); scan_start = jiffies; switch (dm->state) { case DM_BALLOON_UP: balloon_up(dm, (struct dm_balloon *)recv_buffer); break; case DM_HOT_ADD: hot_add_req(dm, (struct dm_hot_add *)recv_buffer); break; default: break; } if (!time_in_range(jiffies, scan_start, scan_start + HZ)) post_status(dm); } return 0; } static void version_resp(struct hv_dynmem_device *dm, struct dm_version_response *vresp) { struct dm_version_request version_req; int ret; if (vresp->is_accepted) { /* * We are done; wakeup the * context waiting for version * negotiation. */ complete(&dm->host_event); return; } /* * If there are more versions to try, continue * with negotiations; if not * shutdown the service since we are not able * to negotiate a suitable version number * with the host. */ if (dm->next_version == 0) goto version_error; dm->next_version = 0; memset(&version_req, 0, sizeof(struct dm_version_request)); version_req.hdr.type = DM_VERSION_REQUEST; version_req.hdr.size = sizeof(struct dm_version_request); version_req.hdr.trans_id = atomic_inc_return(&trans_id); version_req.version.version = DYNMEM_PROTOCOL_VERSION_WIN7; version_req.is_last_attempt = 1; ret = vmbus_sendpacket(dm->dev->channel, &version_req, sizeof(struct dm_version_request), (unsigned long)NULL, VM_PKT_DATA_INBAND, 0); if (ret) goto version_error; return; version_error: dm->state = DM_INIT_ERROR; complete(&dm->host_event); } static void cap_resp(struct hv_dynmem_device *dm, struct dm_capabilities_resp_msg *cap_resp) { if (!cap_resp->is_accepted) { pr_info("Capabilities not accepted by host\n"); dm->state = DM_INIT_ERROR; } complete(&dm->host_event); } static void balloon_onchannelcallback(void *context) { struct hv_device *dev = context; u32 recvlen; u64 requestid; struct dm_message *dm_msg; struct dm_header *dm_hdr; struct hv_dynmem_device *dm = hv_get_drvdata(dev); memset(recv_buffer, 0, sizeof(recv_buffer)); vmbus_recvpacket(dev->channel, recv_buffer, PAGE_SIZE, &recvlen, &requestid); if (recvlen > 0) { dm_msg = (struct dm_message *)recv_buffer; dm_hdr = &dm_msg->hdr; switch (dm_hdr->type) { case DM_VERSION_RESPONSE: version_resp(dm, (struct dm_version_response *)dm_msg); break; case DM_CAPABILITIES_RESPONSE: cap_resp(dm, (struct dm_capabilities_resp_msg *)dm_msg); break; case DM_BALLOON_REQUEST: dm->state = DM_BALLOON_UP; complete(&dm->config_event); break; case DM_UNBALLOON_REQUEST: dm->state = DM_BALLOON_DOWN; balloon_down(dm, (struct dm_unballoon_request *)recv_buffer); break; case DM_MEM_HOT_ADD_REQUEST: dm->state = DM_HOT_ADD; complete(&dm->config_event); break; case DM_INFO_MESSAGE: process_info(dm, (struct dm_info_msg *)dm_msg); break; default: pr_err("Unhandled message: type: %d\n", dm_hdr->type); } } } static int balloon_probe(struct hv_device *dev, const struct hv_vmbus_device_id *dev_id) { int ret, t; struct dm_version_request version_req; struct dm_capabilities cap_msg; do_hot_add = hot_add; /* * First allocate a send buffer. */ send_buffer = kmalloc(PAGE_SIZE, GFP_KERNEL); if (!send_buffer) return -ENOMEM; ret = vmbus_open(dev->channel, dm_ring_size, dm_ring_size, NULL, 0, balloon_onchannelcallback, dev); if (ret) goto probe_error0; dm_device.dev = dev; dm_device.state = DM_INITIALIZING; dm_device.next_version = DYNMEM_PROTOCOL_VERSION_WIN7; init_completion(&dm_device.host_event); init_completion(&dm_device.config_event); dm_device.thread = kthread_run(dm_thread_func, &dm_device, "hv_balloon"); if (IS_ERR(dm_device.thread)) { ret = PTR_ERR(dm_device.thread); goto probe_error1; } hv_set_drvdata(dev, &dm_device); /* * Initiate the hand shake with the host and negotiate * a version that the host can support. We start with the * highest version number and go down if the host cannot * support it. */ memset(&version_req, 0, sizeof(struct dm_version_request)); version_req.hdr.type = DM_VERSION_REQUEST; version_req.hdr.size = sizeof(struct dm_version_request); version_req.hdr.trans_id = atomic_inc_return(&trans_id); version_req.version.version = DYNMEM_PROTOCOL_VERSION_WIN8; version_req.is_last_attempt = 0; ret = vmbus_sendpacket(dev->channel, &version_req, sizeof(struct dm_version_request), (unsigned long)NULL, VM_PKT_DATA_INBAND, VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED); if (ret) goto probe_error2; t = wait_for_completion_timeout(&dm_device.host_event, 5*HZ); if (t == 0) { ret = -ETIMEDOUT; goto probe_error2; } /* * If we could not negotiate a compatible version with the host * fail the probe function. */ if (dm_device.state == DM_INIT_ERROR) { ret = -ETIMEDOUT; goto probe_error2; } /* * Now submit our capabilities to the host. */ memset(&cap_msg, 0, sizeof(struct dm_capabilities)); cap_msg.hdr.type = DM_CAPABILITIES_REPORT; cap_msg.hdr.size = sizeof(struct dm_capabilities); cap_msg.hdr.trans_id = atomic_inc_return(&trans_id); cap_msg.caps.cap_bits.balloon = 1; /* * While we currently don't support hot-add, * we still advertise this capability since the * host requires that guests partcipating in the * dynamic memory protocol support hot add. */ cap_msg.caps.cap_bits.hot_add = 1; /* * Currently the host does not use these * values and we set them to what is done in the * Windows driver. */ cap_msg.min_page_cnt = 0; cap_msg.max_page_number = -1; ret = vmbus_sendpacket(dev->channel, &cap_msg, sizeof(struct dm_capabilities), (unsigned long)NULL, VM_PKT_DATA_INBAND, VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED); if (ret) goto probe_error2; t = wait_for_completion_timeout(&dm_device.host_event, 5*HZ); if (t == 0) { ret = -ETIMEDOUT; goto probe_error2; } /* * If the host does not like our capabilities, * fail the probe function. */ if (dm_device.state == DM_INIT_ERROR) { ret = -ETIMEDOUT; goto probe_error2; } dm_device.state = DM_INITIALIZED; return 0; probe_error2: kthread_stop(dm_device.thread); probe_error1: vmbus_close(dev->channel); probe_error0: kfree(send_buffer); return ret; } static int balloon_remove(struct hv_device *dev) { struct hv_dynmem_device *dm = hv_get_drvdata(dev); if (dm->num_pages_ballooned != 0) pr_warn("Ballooned pages: %d\n", dm->num_pages_ballooned); vmbus_close(dev->channel); kthread_stop(dm->thread); kfree(send_buffer); return 0; } static const struct hv_vmbus_device_id id_table[] = { /* Dynamic Memory Class ID */ /* 525074DC-8985-46e2-8057-A307DC18A502 */ { HV_DM_GUID, }, { }, }; MODULE_DEVICE_TABLE(vmbus, id_table); static struct hv_driver balloon_drv = { .name = "hv_balloon", .id_table = id_table, .probe = balloon_probe, .remove = balloon_remove, }; static int __init init_balloon_drv(void) { return vmbus_driver_register(&balloon_drv); } static void exit_balloon_drv(void) { vmbus_driver_unregister(&balloon_drv); } module_init(init_balloon_drv); module_exit(exit_balloon_drv); MODULE_DESCRIPTION("Hyper-V Balloon"); MODULE_VERSION(HV_DRV_VERSION); MODULE_LICENSE("GPL");