vmm: Deprecate MemoryZoneConfig::file

Remove from the documentation and API definition but continue support
using the field (with a deprecation warning.)

See: #4837

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

docs/memory.md

@@ -207,7 +207,6 @@ describing how every memory region is backed and exposed to the guest.
 struct MemoryZoneConfig {
     id: String,
     size: u64,
-    file: Option<PathBuf>,
     shared: bool,
     hugepages: bool,
     hugepage_size: Option<u64>,
@@ -219,7 +218,7 @@ struct MemoryZoneConfig {
 ```
 
 ```
---memory-zone <memory-zone>	User defined memory zone parameters "size=<guest_memory_region_size>,file=<backing_file>,shared=on|off,hugepages=on|off,hugepage_size=<hugepage_size>,host_numa_node=<node_id>,id=<zone_identifier>,hotplug_size=<hotpluggable_memory_size>,hotplugged_size=<hotplugged_memory_size>,prefault=on|off"
+--memory-zone <memory-zone>	User defined memory zone parameters "size=<guest_memory_region_size>,shared=on|off,hugepages=on|off,hugepage_size=<hugepage_size>,host_numa_node=<node_id>,id=<zone_identifier>,hotplug_size=<hotpluggable_memory_size>,hotplugged_size=<hotplugged_memory_size>,prefault=on|off"
 ```
 
 This parameter expects one or more occurences, allowing for a list of memory
@@ -264,30 +263,6 @@ _Example_
 --memory-zone id=mem0,size=1G
 ```
 
-### `file`
-
-Path to the file backing the memory zone. This can be either a file or a
-directory. In case of a file, it will be opened and used as the backing file
-for the `mmap(2)` operation. In case of a directory, a temporary file with no
-hard link on the filesystem will be created. This file will be used as the
-backing file for the `mmap(2)` operation.
-
-This option can be particularly useful when trying to back a part of the guest
-RAM with a well known file. In the context of the snapshot/restore feature, and
-if the provided path is a file, the snapshot operation will not perform any
-copy of the guest RAM content for this specific memory zone since the user has
-access to it and it would duplicate data already stored on the current
-filesystem.
-
-Value is a string.
-
-_Example_
-
-```
---memory size=0
---memory-zone id=mem0,size=1G,file=/foo/bar
-```
-
 ### `shared`
 
 Specifies if the memory zone must be `mmap(2)` with `MAP_SHARED` flag.

src/main.rs

@@ -177,7 +177,7 @@ fn create_app(default_vcpus: String, default_memory: String, default_rng: String
                 .long("memory-zone")
                 .help(
                     "User defined memory zone parameters \
-                     \"size=<guest_memory_region_size>,file=<backing_file>,\
+                     \"size=<guest_memory_region_size>,\
                      shared=on|off,\
                      hugepages=on|off,hugepage_size=<hugepage_size>,\
                      host_numa_node=<node_id>,\

vmm/src/api/openapi/cloud-hypervisor.yaml

@@ -668,8 +668,6 @@ components:
           type: integer
           format: int64
           default: 512 MB
-        file:
-          type: string
         mergeable:
           type: boolean
           default: false

vmm/src/config.rs

@@ -2015,6 +2015,10 @@ impl VmConfig {
 
         if let Some(zones) = &self.memory.zones {
             for zone in zones.iter() {
+                if zone.file.is_some() {
+                    warn!("MemoryZoneConfig::file is deprecated and will be removed in future release (#4837)");
+                }
+
                 let id = zone.id.clone();
                 Self::validate_identifier(&mut id_list, &Some(id))?;
             }