Merge tag 'hyperv-next-signed-20220322' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux

Pull hyperv updates from Wei Liu:
 "Minor patches from various people"

* tag 'hyperv-next-signed-20220322' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux:
  x86/hyperv: Output host build info as normal Windows version number
  hv_balloon: rate-limit "Unhandled message" warning
  drivers: hv: log when enabling crash_kexec_post_notifiers
  hv_utils: Add comment about max VMbus packet size in VSS driver
  Drivers: hv: Compare cpumasks and not their weights in init_vp_index()
  Drivers: hv: Rename 'alloced' to 'allocated'
  Drivers: hv: vmbus: Use struct_size() helper in kmalloc()

1 files changed, 11 insertions, 0 deletions

diff --git a/include/uapi/linux/hyperv.h b/include/uapi/linux/hyperv.h
index daf82a230c0e..aaa502a7bff4 100644
--- a/include/uapi/linux/hyperv.h
+++ b/include/uapi/linux/hyperv.h
@@ -90,6 +90,17 @@ struct hv_vss_check_dm_info {
 	__u32 flags;
 } __attribute__((packed));
 
+/*
+ * struct hv_vss_msg encodes the fields that the Linux VSS
+ * driver accesses. However, FREEZE messages from Hyper-V contain
+ * additional LUN information that Linux doesn't use and are not
+ * represented in struct hv_vss_msg. A received FREEZE message may
+ * be as large as 6,260 bytes, so the driver must allocate at least
+ * that much space, not sizeof(struct hv_vss_msg). Other messages
+ * such as AUTO_RECOVER may be as large as 12,500 bytes. However,
+ * because the Linux VSS driver responds that it doesn't support
+ * auto-recovery, it should not receive such messages.
+ */
 struct hv_vss_msg {
 	union {
 		struct hv_vss_hdr vss_hdr;