From 8b5202aa5a1cb26db61e65e87c331ba280f80443 Mon Sep 17 00:00:00 2001
From: Sebastien Boeuf <sebastien.boeuf@intel.com>
Date: Mon, 14 Sep 2020 17:48:13 +0200
Subject: [PATCH] vmm: Always add virtio-mem region upon VM creation

Now that e820 tables are created from the 'boot_guest_memory', we can
simplify the memory manager code by adding the virtio-mem regions when
they are created. There's no need to wait for the first hotplug to
insert these regions.

This also anticipates the need for starting a VM with some memory
already plugged into the virtio-mem region.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
---
 vmm/src/memory_manager.rs | 32 +++++++++++---------------------
 vmm/src/vm.rs             | 15 ++-------------
 2 files changed, 13 insertions(+), 34 deletions(-)

diff --git a/vmm/src/memory_manager.rs b/vmm/src/memory_manager.rs
index 9484e6ccd..3bdb1ba6c 100644
--- a/vmm/src/memory_manager.rs
+++ b/vmm/src/memory_manager.rs
@@ -619,8 +619,9 @@ impl MemoryManager {
             Ok(())
         })?;
 
-        for region in virtio_mem_regions.iter() {
-            memory_manager.lock().unwrap().create_userspace_mapping(
+        for region in virtio_mem_regions.drain(..) {
+            let mut mm = memory_manager.lock().unwrap();
+            mm.create_userspace_mapping(
                 region.start_addr().raw_value(),
                 region.len() as u64,
                 region.as_ptr() as u64,
@@ -632,6 +633,7 @@ impl MemoryManager {
                 .unwrap()
                 .allocate_mmio_addresses(Some(region.start_addr()), region.len(), None)
                 .ok_or(Error::MemoryRangeAllocation)?;
+            mm.add_region(region)?;
         }
 
         // Allocate RAM and Reserved address ranges.
@@ -1129,12 +1131,8 @@ impl MemoryManager {
         Ok(())
     }
 
-    pub fn virtio_mem_resize(
-        &mut self,
-        id: &str,
-        size: u64,
-    ) -> Result<Option<Arc<GuestRegionMmap>>, Error> {
-        let virtio_mem_region = if let Some(memory_zone) = self.memory_zones.get_mut(id) {
+    pub fn virtio_mem_resize(&mut self, id: &str, size: u64) -> Result<(), Error> {
+        if let Some(memory_zone) = self.memory_zones.get_mut(id) {
             if let Some(resize) = &memory_zone.virtio_mem_resize {
                 resize.work(size).map_err(Error::VirtioMemResizeFail)?;
             } else {
@@ -1142,18 +1140,11 @@ impl MemoryManager {
                 return Err(Error::MissingVirtioMemHandler);
             }
 
-            memory_zone.virtio_mem_region.take()
-        } else {
-            error!("Failed resizing virtio-mem region: Unknown memory zone");
-            return Err(Error::UnknownMemoryZone);
-        };
-
-        // Add the region if that's the first time we resize.
-        if let Some(region) = virtio_mem_region.clone() {
-            self.add_region(region)?;
+            return Ok(());
         }
 
-        Ok(virtio_mem_region)
+        error!("Failed resizing virtio-mem region: Unknown memory zone");
+        Err(Error::UnknownMemoryZone)
     }
 
     pub fn balloon_resize(&mut self, expected_ram: u64) -> Result<u64, Error> {
@@ -1189,8 +1180,7 @@ impl MemoryManager {
         match self.hotplug_method {
             HotplugMethod::VirtioMem => {
                 if desired_ram >= self.boot_ram {
-                    region =
-                        self.virtio_mem_resize(DEFAULT_MEMORY_ZONE, desired_ram - self.boot_ram)?;
+                    self.virtio_mem_resize(DEFAULT_MEMORY_ZONE, desired_ram - self.boot_ram)?;
                     self.current_ram = desired_ram;
                 }
             }
@@ -1210,7 +1200,7 @@ impl MemoryManager {
         id: &str,
         desired_ram: u64,
         config: &MemoryConfig,
-    ) -> Result<Option<Arc<GuestRegionMmap>>, Error> {
+    ) -> Result<(), Error> {
         if !self.user_provided_zones {
             error!(
                 "Not allowed to resize guest memory zone when no zone is \
diff --git a/vmm/src/vm.rs b/vmm/src/vm.rs
index 276447e8e..29217a196 100644
--- a/vmm/src/vm.rs
+++ b/vmm/src/vm.rs
@@ -925,22 +925,11 @@ impl Vm {
     }
 
     pub fn resize_zone(&mut self, id: String, desired_memory: u64) -> Result<()> {
-        let new_region = self
-            .memory_manager
+        self.memory_manager
             .lock()
             .unwrap()
             .resize_zone(&id, desired_memory, &self.config.lock().unwrap().memory)
-            .map_err(Error::MemoryManager)?;
-
-        if let Some(new_region) = &new_region {
-            self.device_manager
-                .lock()
-                .unwrap()
-                .update_memory(&new_region)
-                .map_err(Error::DeviceManager)?;
-        }
-
-        Ok(())
+            .map_err(Error::MemoryManager)
     }
 
     #[cfg(not(feature = "pci_support"))]