Drivers: hv: balloon: Remove dependencies on guest page size

Hyper-V assumes page size to be 4K. This might not be the case for
ARM64 architecture. Hence use hyper-v specific page size and page
shift definitions to avoid conflicts between different host and guest
page sizes on ARM64.

Also, remove some old and incorrect comments and redefine ballooning
granularities to handle larger page sizes correctly.
Signed-off-by: Himadri Pandya <himadri18.07@gmail.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/hv/hv_balloon.c

@@ -23,6 +23,7 @@
 #include <linux/percpu_counter.h>
 
 #include <linux/hyperv.h>
+#include <asm/hyperv-tlfs.h>
 
 #define CREATE_TRACE_POINTS
 #include "hv_trace_balloon.h"
@@ -341,8 +342,6 @@ struct dm_unballoon_response {
  *
  * 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 {
@@ -477,7 +476,7 @@ 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);
+static int dm_ring_size = 20 * 1024;
 
 /*
  * Driver specific state.
@@ -493,10 +492,10 @@ enum hv_dm_state {
 };
 
 
-static __u8 recv_buffer[PAGE_SIZE];
-static __u8 balloon_up_send_buffer[PAGE_SIZE];
-#define PAGES_IN_2M	512
-#define HA_CHUNK (32 * 1024)
+static __u8 recv_buffer[HV_HYP_PAGE_SIZE];
+static __u8 balloon_up_send_buffer[HV_HYP_PAGE_SIZE];
+#define PAGES_IN_2M (2 * 1024 * 1024 / PAGE_SIZE)
+#define HA_CHUNK (128 * 1024 * 1024 / PAGE_SIZE)
 
 struct hv_dynmem_device {
 	struct hv_device *dev;
@@ -1076,7 +1075,7 @@ static void process_info(struct hv_dynmem_device *dm, struct dm_info_msg *msg)
 			__u64 *max_page_count = (__u64 *)&info_hdr[1];
 
 			pr_info("Max. dynamic memory size: %llu MB\n",
-				(*max_page_count) >> (20 - PAGE_SHIFT));
+				(*max_page_count) >> (20 - HV_HYP_PAGE_SHIFT));
 		}
 
 		break;
@@ -1218,7 +1217,7 @@ static unsigned int alloc_balloon_pages(struct hv_dynmem_device *dm,
 
 	for (i = 0; (i * alloc_unit) < num_pages; i++) {
 		if (bl_resp->hdr.size + sizeof(union dm_mem_page_range) >
-			PAGE_SIZE)
+			HV_HYP_PAGE_SIZE)
 			return i * alloc_unit;
 
 		/*
@@ -1274,9 +1273,9 @@ static void balloon_up(struct work_struct *dummy)
 
 	/*
 	 * We will attempt 2M allocations. However, if we fail to
-	 * allocate 2M chunks, we will go back to 4k allocations.
+	 * allocate 2M chunks, we will go back to PAGE_SIZE allocations.
 	 */
-	alloc_unit = 512;
+	alloc_unit = PAGES_IN_2M;
 
 	avail_pages = si_mem_available();
 	floor = compute_balloon_floor();
@@ -1292,7 +1291,7 @@ static void balloon_up(struct work_struct *dummy)
 	}
 
 	while (!done) {
-		memset(balloon_up_send_buffer, 0, PAGE_SIZE);
+		memset(balloon_up_send_buffer, 0, HV_HYP_PAGE_SIZE);
 		bl_resp = (struct dm_balloon_response *)balloon_up_send_buffer;
 		bl_resp->hdr.type = DM_BALLOON_RESPONSE;
 		bl_resp->hdr.size = sizeof(struct dm_balloon_response);
@@ -1491,7 +1490,7 @@ static void balloon_onchannelcallback(void *context)
 
 	memset(recv_buffer, 0, sizeof(recv_buffer));
 	vmbus_recvpacket(dev->channel, recv_buffer,
-			 PAGE_SIZE, &recvlen, &requestid);
+			 HV_HYP_PAGE_SIZE, &recvlen, &requestid);
 
 	if (recvlen > 0) {
 		dm_msg = (struct dm_message *)recv_buffer;