From 211786ab42eee9942d9ad660a0efbf26a7008d5a Mon Sep 17 00:00:00 2001
From: Rob Bradford <robert.bradford@intel.com>
Date: Fri, 17 Jan 2020 16:48:46 +0000
Subject: [PATCH] vmm: Only generate GED interrupt when the number of vCPUs has
 changed

Avoid activity in the the guest OS if the number of vCPUs has not
changed.

Signed-off-by: Rob Bradford <robert.bradford@intel.com>
---
 vmm/src/cpu.rs |  8 ++++----
 vmm/src/vm.rs  | 13 ++++++++-----
 2 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/vmm/src/cpu.rs b/vmm/src/cpu.rs
index 7eae968dc..a1e67f47d 100644
--- a/vmm/src/cpu.rs
+++ b/vmm/src/cpu.rs
@@ -661,11 +661,11 @@ impl CpuManager {
         self.activate_vcpus(self.boot_vcpus(), Some(entry_addr))
     }
 
-    pub fn resize(&mut self, desired_vcpus: u8) -> Result<()> {
+    pub fn resize(&mut self, desired_vcpus: u8) -> Result<bool> {
         match desired_vcpus.cmp(&self.present_vcpus()) {
-            cmp::Ordering::Greater => self.activate_vcpus(desired_vcpus, None),
-            cmp::Ordering::Less => self.mark_vcpus_for_removal(desired_vcpus),
-            _ => Ok(()),
+            cmp::Ordering::Greater => self.activate_vcpus(desired_vcpus, None).and(Ok(true)),
+            cmp::Ordering::Less => self.mark_vcpus_for_removal(desired_vcpus).and(Ok(true)),
+            _ => Ok(false),
         }
     }
 
diff --git a/vmm/src/vm.rs b/vmm/src/vm.rs
index 28f8f9323..e6e37c40b 100755
--- a/vmm/src/vm.rs
+++ b/vmm/src/vm.rs
@@ -485,14 +485,17 @@ impl Vm {
 
     pub fn resize(&mut self, desired_vcpus: Option<u8>, desired_memory: Option<u64>) -> Result<()> {
         if let Some(desired_vcpus) = desired_vcpus {
-            self.cpu_manager
+            if self
+                .cpu_manager
                 .lock()
                 .unwrap()
                 .resize(desired_vcpus)
-                .map_err(Error::CpuManager)?;
-            self.devices
-                .notify_hotplug(HotPlugNotificationFlags::CPU_DEVICES_CHANGED)
-                .map_err(Error::DeviceManager)?;
+                .map_err(Error::CpuManager)?
+            {
+                self.devices
+                    .notify_hotplug(HotPlugNotificationFlags::CPU_DEVICES_CHANGED)
+                    .map_err(Error::DeviceManager)?;
+            }
             self.config.lock().unwrap().cpus.boot_vcpus = desired_vcpus;
         }