vmm: Make Transparent Huge Pages controllable (default on)

Add MemoryConfig::thp and `--memory thp=on|off` to allow control of
Transparent Huge Pages.

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

fuzz/fuzz_targets/mem.rs

@@ -137,6 +137,7 @@ fn create_dummy_virtio_mem(bytes: &[u8; VIRTIO_MEM_DATA_SIZE]) -> (Mem, Arc<Gues
         None,
         numa_id,
         None,
+        false,
     )
     .unwrap();
 

src/main.rs

@@ -166,7 +166,7 @@ fn create_app(default_vcpus: String, default_memory: String, default_rng: String
                      hotplug_method=acpi|virtio-mem,\
                      hotplug_size=<hotpluggable_memory_size>,\
                      hotplugged_size=<hotplugged_memory_size>,\
-                     prefault=on|off\"",
+                     prefault=on|off,thp=on|off\"",
                 )
                 .default_value(default_memory)
                 .group("vm-config"),
@@ -676,6 +676,7 @@ mod unit_tests {
                 hugepage_size: None,
                 prefault: false,
                 zones: None,
+                thp: true,
             },
             payload: Some(PayloadConfig {
                 kernel: Some(PathBuf::from("/path/to/kernel")),

vmm/src/config.rs

@@ -658,7 +658,8 @@ impl MemoryConfig {
             .add("shared")
             .add("hugepages")
             .add("hugepage_size")
-            .add("prefault");
+            .add("prefault")
+            .add("thp");
         parser.parse(memory).map_err(Error::ParseMemory)?;
 
         let size = parser
@@ -702,6 +703,11 @@ impl MemoryConfig {
             .map_err(Error::ParseMemory)?
             .unwrap_or(Toggle(false))
             .0;
+        let thp = parser
+            .convert::<Toggle>("thp")
+            .map_err(Error::ParseMemory)?
+            .unwrap_or(Toggle(true))
+            .0;
 
         let zones: Option<Vec<MemoryZoneConfig>> = if let Some(memory_zones) = &memory_zones {
             let mut zones = Vec::new();
@@ -788,6 +794,7 @@ impl MemoryConfig {
             hugepage_size,
             prefault,
             zones,
+            thp,
         })
     }
 
@@ -2727,6 +2734,7 @@ mod tests {
                 hugepage_size: None,
                 prefault: false,
                 zones: None,
+                thp: true,
             },
             payload: Some(PayloadConfig {
                 kernel: Some(PathBuf::from("/path/to/kernel")),

vmm/src/lib.rs

@@ -2062,6 +2062,7 @@ mod unit_tests {
                 hugepage_size: None,
                 prefault: false,
                 zones: None,
+                thp: true,
             },
             payload: Some(PayloadConfig {
                 kernel: Some(PathBuf::from("/path/to/kernel")),

vmm/src/memory_manager.rs

@@ -175,6 +175,7 @@ pub struct MemoryManager {
     hugepages: bool,
     hugepage_size: Option<u64>,
     prefault: bool,
+    thp: bool,
     #[cfg(target_arch = "x86_64")]
     sgx_epc_region: Option<SgxEpcRegion>,
     user_provided_zones: bool,
@@ -442,6 +443,7 @@ impl MemoryManager {
         ram_regions: &[(GuestAddress, usize)],
         zones: &[MemoryZoneConfig],
         prefault: Option<bool>,
+        thp: bool,
     ) -> Result<(Vec<Arc<GuestRegionMmap>>, MemoryZones), Error> {
         let mut zones = zones.to_owned();
         let mut mem_regions = Vec::new();
@@ -498,6 +500,7 @@ impl MemoryManager {
                     zone.hugepage_size,
                     zone.host_numa_node,
                     None,
+                    thp,
                 )?;
 
                 // Add region to the list of regions associated with the
@@ -550,6 +553,7 @@ impl MemoryManager {
         zones_config: &[MemoryZoneConfig],
         prefault: Option<bool>,
         mut existing_memory_files: HashMap<u32, File>,
+        thp: bool,
     ) -> Result<(Vec<Arc<GuestRegionMmap>>, MemoryZones), Error> {
         let mut memory_regions = Vec::new();
         let mut memory_zones = HashMap::new();
@@ -575,6 +579,7 @@ impl MemoryManager {
                         zone_config.hugepage_size,
                         zone_config.host_numa_node,
                         existing_memory_files.remove(&guest_ram_mapping.slot),
+                        thp,
                     )?;
                     memory_regions.push(Arc::clone(&region));
                     if let Some(memory_zone) = memory_zones.get_mut(&guest_ram_mapping.zone_id) {
@@ -911,6 +916,7 @@ impl MemoryManager {
                 &zones,
                 prefault,
                 existing_memory_files.unwrap_or_default(),
+                config.thp,
             )?;
             let guest_memory =
                 GuestMemoryMmap::from_arc_regions(regions).map_err(Error::GuestMemory)?;
@@ -948,7 +954,7 @@ impl MemoryManager {
                 .collect();
 
             let (mem_regions, mut memory_zones) =
-                Self::create_memory_regions_from_zones(&ram_regions, &zones, prefault)?;
+                Self::create_memory_regions_from_zones(&ram_regions, &zones, prefault, config.thp)?;
 
             let mut guest_memory =
                 GuestMemoryMmap::from_arc_regions(mem_regions).map_err(Error::GuestMemory)?;
@@ -997,6 +1003,7 @@ impl MemoryManager {
                                 zone.hugepage_size,
                                 zone.host_numa_node,
                                 None,
+                                config.thp,
                             )?;
 
                             guest_memory = guest_memory
@@ -1125,6 +1132,7 @@ impl MemoryManager {
             dynamic,
             #[cfg(target_arch = "aarch64")]
             uefi_flash: None,
+            thp: config.thp,
         };
 
         memory_manager.allocate_address_space()?;
@@ -1298,6 +1306,7 @@ impl MemoryManager {
         hugepage_size: Option<u64>,
         host_numa_node: Option<u32>,
         existing_memory_file: Option<File>,
+        thp: bool,
     ) -> Result<Arc<GuestRegionMmap>, Error> {
         let mut mmap_flags = libc::MAP_NORESERVE;
 
@@ -1336,7 +1345,7 @@ impl MemoryManager {
         )
         .map_err(Error::GuestMemory)?;
 
-        if region.file_offset().is_none() {
+        if region.file_offset().is_none() && thp {
             info!(
                 "Anonymous mapping at 0x{:x} (size = 0x{:x})",
                 region.as_ptr() as u64,
@@ -1438,6 +1447,7 @@ impl MemoryManager {
             self.hugepage_size,
             None,
             None,
+            self.thp,
         )?;
 
         // Map it into the guest

vmm/src/vm_config.rs

@@ -139,6 +139,10 @@ impl Default for HotplugMethod {
     }
 }
 
+fn default_memoryconfig_thp() -> bool {
+    true
+}
+
 #[derive(Clone, Debug, PartialEq, Eq, Deserialize, Serialize)]
 pub struct MemoryConfig {
     pub size: u64,
@@ -160,6 +164,8 @@ pub struct MemoryConfig {
     pub prefault: bool,
     #[serde(default)]
     pub zones: Option<Vec<MemoryZoneConfig>>,
+    #[serde(default = "default_memoryconfig_thp")]
+    pub thp: bool,
 }
 
 pub const DEFAULT_MEMORY_MB: u64 = 512;
@@ -177,6 +183,7 @@ impl Default for MemoryConfig {
             hugepage_size: None,
             prefault: false,
             zones: None,
+            thp: true,
         }
     }
 }