RE: [Patch v3 1/5] Drivers: hv: Allocate interrupt and monitor pages aligned to system page boundary

From: longli@linuxonhyperv.com longli@linuxonhyperv.com Sent: Monday, May 5, 2025 5:57 PM

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: ca48739e59df ("Drivers: hv: vmbus: Move Hyper-V page allocator to arch neutral code") Signed-off-by: Long Li longli@microsoft.com

---

drivers/hv/connection.c | 23 +++++++++++++++++------ 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c index 8351360bba16..be490c598785 100644 --- a/drivers/hv/connection.c +++ b/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; }

}

2.34.1

Reviewed-by: Michael Kelley mhklinux@outlook.com