[RFC PATCH V2 6/10] x86/Hyper-V/Balloon: Enable mem hot-remove capability

[lantianyu1986@gmail.com]

From: Tianyu Lan <Tianyu.Lan@microsoft.com>

Enable mem hot-remove capability, handle request in the
common work and add mem hot-remove operation later.

Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
---
 drivers/hv/hv_balloon.c | 104 ++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 101 insertions(+), 3 deletions(-)

diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
index 729dc5551302..43e490f492d5 100644
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -49,6 +49,7 @@
  * Changes to 0.2 on 2009/05/14
  * Changes to 0.3 on 2009/12/03
  * Changed to 1.0 on 2011/04/05
+ * Changed to 2.0 on 2019/12/10
  */
 
 #define DYNMEM_MAKE_VERSION(Major, Minor) ((__u32)(((Major) << 16) | (Minor)))
@@ -94,7 +95,13 @@ enum dm_message_type {
 	 * Version 1.0.
 	 */
 	DM_INFO_MESSAGE			= 12,
-	DM_VERSION_1_MAX		= 12
+	DM_VERSION_1_MAX		= 12,
+
+	/*
+	 * Version 2.0
+	 */
+	DM_MEM_HOT_REMOVE_REQUEST        = 13,
+	DM_MEM_HOT_REMOVE_RESPONSE       = 14
 };
 
 
@@ -123,7 +130,8 @@ union dm_caps {
 		 * represents an alignment of 2^n in mega bytes.
 		 */
 		__u64 hot_add_alignment:4;
-		__u64 reservedz:58;
+		__u64 hot_remove:1;
+		__u64 reservedz:57;
 	} cap_bits;
 	__u64 caps;
 } __packed;
@@ -234,7 +242,9 @@ struct dm_capabilities {
 struct dm_capabilities_resp_msg {
 	struct dm_header hdr;
 	__u64 is_accepted:1;
-	__u64 reservedz:63;
+	__u64 hot_remove:1;
+	__u64 suppress_pressure_reports:1;
+	__u64 reservedz:61;
 } __packed;
 
 /*
@@ -377,6 +387,27 @@ struct dm_hot_add_response {
 	__u32 result;
 } __packed;
 
+struct dm_hot_remove {
+	struct dm_header hdr;
+	__u32 virtual_node;
+	__u32 page_count;
+	__u32 qos_flags;
+	__u32 reservedZ;
+} __packed;
+
+struct dm_hot_remove_response {
+	struct dm_header hdr;
+	__u32 result;
+	__u32 range_count;
+	__u64 more_pages:1;
+	__u64 reservedz:63;
+	union dm_mem_page_range range_array[];
+} __packed;
+
+#define DM_REMOVE_QOS_LARGE	 (1 << 0)
+#define DM_REMOVE_QOS_LOCAL	 (1 << 1)
+#define DM_REMOVE_QOS_MASK       (0x3)
+
 /*
  * Types of information sent from host to the guest.
  */
@@ -455,6 +486,11 @@ union dm_msg_info {
 		union dm_mem_page_range ha_page_range;
 		union dm_mem_page_range ha_region_range;
 	} hot_add;
+	struct {
+		__u32 virtual_node;
+		__u32 page_count;
+		__u32 qos_flags;
+	} hot_remove;
 };
 
 struct dm_msg_wrk {
@@ -496,6 +532,7 @@ enum hv_dm_state {
 	DM_BALLOON_UP,
 	DM_BALLOON_DOWN,
 	DM_HOT_ADD,
+	DM_HOT_REMOVE,
 	DM_INIT_ERROR
 };
 
@@ -571,6 +608,35 @@ static struct hv_dynmem_device dm_device;
 
 static void post_status(struct hv_dynmem_device *dm);
 
+static int hv_send_hot_remove_response(
+		struct dm_hot_remove_response *resp,
+		unsigned long request_count, bool more_pages)
+{
+	struct hv_dynmem_device *dm = &dm_device;
+	int ret;
+
+	resp->hdr.type = DM_MEM_HOT_REMOVE_RESPONSE;
+	resp->range_count = request_count;
+	resp->more_pages = more_pages;
+	resp->hdr.size = sizeof(struct dm_hot_remove_response)
+			+ sizeof(union dm_mem_page_range) * request_count;
+	resp->result = !!request_count;
+
+	do {
+		resp->hdr.trans_id = atomic_inc_return(&trans_id);
+		ret = vmbus_sendpacket(dm->dev->channel, resp,
+				       resp->hdr.size,
+				       (unsigned long)NULL,
+				       VM_PKT_DATA_INBAND, 0);
+
+		if (ret == -EAGAIN)
+			msleep(20);
+		post_status(&dm_device);
+	} while (ret == -EAGAIN);
+
+	return ret;
+}
+
 #ifdef CONFIG_MEMORY_HOTPLUG
 static inline bool has_pfn_is_backed(struct hv_hotadd_state *has,
 				     unsigned long pfn)
@@ -982,6 +1048,17 @@ static unsigned long process_hot_add(unsigned long pg_start,
 
 #endif
 
+static void hot_remove_req(union dm_msg_info *msg_info)
+{
+	struct hv_dynmem_device *dm = &dm_device;
+
+	/* Add hot remove operation later and send failure response. */
+	hv_send_hot_remove_response((struct dm_hot_remove_response *)
+				balloon_up_send_buffer, 0, false);
+
+	dm->state = DM_INITIALIZED;
+}
+
 static void hot_add_req(union dm_msg_info *msg_info)
 {
 	struct dm_hot_add_response resp;
@@ -1366,6 +1443,9 @@ static void dm_msg_work(struct work_struct *dummy)
 	case DM_MEM_HOT_ADD_REQUEST:
 		hot_add_req(msg_info);
 		break;
+	case DM_MEM_HOT_REMOVE_REQUEST:
+		hot_remove_req(msg_info);
+		break;
 	default:
 		return;
 	}
@@ -1506,6 +1586,7 @@ static void balloon_onchannelcallback(void *context)
 	struct hv_dynmem_device *dm = hv_get_drvdata(dev);
 	struct dm_balloon *bal_msg;
 	struct dm_hot_add *ha_msg;
+	struct dm_hot_remove *hr_msg;
 	struct dm_msg_wrk *dm_wrk = &dm_device.dm_wrk;
 	union dm_msg_info *msg_info = &dm_wrk->dm_msg;
 	union dm_mem_page_range *ha_pg_range;
@@ -1587,6 +1668,22 @@ static void balloon_onchannelcallback(void *context)
 			schedule_work(&dm_wrk->wrk);
 			break;
 
+		case DM_MEM_HOT_REMOVE_REQUEST:
+			if (dm->state == DM_HOT_REMOVE)
+				pr_warn("Currently hot-removing.\n");
+
+			dm->state = DM_HOT_REMOVE;
+			hr_msg = (struct dm_hot_remove *)recv_buffer;
+
+			msg_info->hot_remove.virtual_node
+					= hr_msg->virtual_node;
+			msg_info->hot_remove.page_count = hr_msg->page_count;
+			msg_info->hot_remove.qos_flags = hr_msg->qos_flags;
+
+			dm_wrk->msg_type = DM_MEM_HOT_REMOVE_REQUEST;
+			schedule_work(&dm_wrk->wrk);
+			break;
+
 		case DM_INFO_MESSAGE:
 			process_info(dm, (struct dm_info_msg *)dm_msg);
 			break;
@@ -1665,6 +1762,7 @@ static int balloon_connect_vsp(struct hv_device *dev)
 	 */
 	cap_msg.caps.cap_bits.balloon = 1;
 	cap_msg.caps.cap_bits.hot_add = 1;
+	cap_msg.caps.cap_bits.hot_remove = 1;
 
 	/*
 	 * Specify our alignment requirements as it relates
-- 
2.14.5