Drivers: hv: Allocate interrupt and monitor pages aligned to system page boundary

There are use cases that interrupt and monitor pages are mapped to
user-mode through UIO, so they need to be system page aligned. Some
Hyper-V allocation APIs introduced earlier broke those requirements.

Fix this by using page allocation functions directly for interrupt
and monitor pages.

Cc: stable@vger.kernel.org
Fixes: ca48739 ("Drivers: hv: vmbus: Move Hyper-V page allocator to arch neutral code")
Signed-off-by: Long Li <longli@microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Link: https://lore.kernel.org/r/1746492997-4599-2-git-send-email-longli@linuxonhyperv.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <1746492997-4599-2-git-send-email-longli@linuxonhyperv.com>

Author: longlimsft

drivers/hv/connection.c

@@ -206,11 +206,20 @@ int vmbus_connect(void)
 	INIT_LIST_HEAD(&vmbus_connection.chn_list);
 	mutex_init(&vmbus_connection.channel_mutex);
 
+	/*
+	 * The following Hyper-V interrupt and monitor pages can be used by
+	 * UIO for mapping to user-space, so they should always be allocated on
+	 * system page boundaries. The system page size must be >= the Hyper-V
+	 * page size.
+	 */
+	BUILD_BUG_ON(PAGE_SIZE < HV_HYP_PAGE_SIZE);
+
 	/*
 	 * Setup the vmbus event connection for channel interrupt
 	 * abstraction stuff
 	 */
-	vmbus_connection.int_page = hv_alloc_hyperv_zeroed_page();
+	vmbus_connection.int_page =
+		(void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
 	if (vmbus_connection.int_page == NULL) {
 		ret = -ENOMEM;
 		goto cleanup;
@@ -225,8 +234,8 @@ int vmbus_connect(void)
 	 * Setup the monitor notification facility. The 1st page for
 	 * parent->child and the 2nd page for child->parent
 	 */
-	vmbus_connection.monitor_pages[0] = hv_alloc_hyperv_page();
-	vmbus_connection.monitor_pages[1] = hv_alloc_hyperv_page();
+	vmbus_connection.monitor_pages[0] = (void *)__get_free_page(GFP_KERNEL);
+	vmbus_connection.monitor_pages[1] = (void *)__get_free_page(GFP_KERNEL);
 	if ((vmbus_connection.monitor_pages[0] == NULL) ||
 	    (vmbus_connection.monitor_pages[1] == NULL)) {
 		ret = -ENOMEM;
@@ -342,21 +351,23 @@ void vmbus_disconnect(void)
 		destroy_workqueue(vmbus_connection.work_queue);
 
 	if (vmbus_connection.int_page) {
-		hv_free_hyperv_page(vmbus_connection.int_page);
+		free_page((unsigned long)vmbus_connection.int_page);
 		vmbus_connection.int_page = NULL;
 	}
 
 	if (vmbus_connection.monitor_pages[0]) {
 		if (!set_memory_encrypted(
 			(unsigned long)vmbus_connection.monitor_pages[0], 1))
-			hv_free_hyperv_page(vmbus_connection.monitor_pages[0]);
+			free_page((unsigned long)
+				vmbus_connection.monitor_pages[0]);
 		vmbus_connection.monitor_pages[0] = NULL;
 	}
 
 	if (vmbus_connection.monitor_pages[1]) {
 		if (!set_memory_encrypted(
 			(unsigned long)vmbus_connection.monitor_pages[1], 1))
-			hv_free_hyperv_page(vmbus_connection.monitor_pages[1]);
+			free_page((unsigned long)
+				vmbus_connection.monitor_pages[1]);
 		vmbus_connection.monitor_pages[1] = NULL;
 	}
 }