refactor: drop track_dirty_pages parameter from memory_init

We already know about dirty page tracking inside that function, based on
whether the memory regions have a bitmap associated with them or not. So
drop passing this information in again via a parameter, which saves us
quite a bit of plumbing.

Suggested-by: Nikita Kalyazin <[email protected]>
Signed-off-by: Patrick Roy <[email protected]>

Author: roypat

src/vmm/src/builder.rs

@@ -155,7 +155,6 @@ fn create_vmm_and_vcpus(
     event_manager: &mut EventManager,
     guest_memory: GuestMemoryMmap,
     uffd: Option<Uffd>,
-    track_dirty_pages: bool,
     vcpu_count: u8,
     kvm_capabilities: Vec<KvmCapability>,
 ) -> Result<(Vmm, Vec<Vcpu>), StartMicrovmError> {
@@ -172,7 +171,7 @@ fn create_vmm_and_vcpus(
     kvm.check_memory(&guest_memory)
         .map_err(VmmError::Kvm)
         .map_err(StartMicrovmError::Internal)?;
-    vm.memory_init(&guest_memory, track_dirty_pages)
+    vm.memory_init(&guest_memory)
         .map_err(VmmError::Vm)
         .map_err(StartMicrovmError::Internal)?;
 
@@ -292,7 +291,6 @@ pub fn build_microvm_for_boot(
         event_manager,
         guest_memory,
         None,
-        vm_resources.machine_config.track_dirty_pages,
         vm_resources.machine_config.vcpu_count,
         cpu_template.kvm_capabilities.clone(),
     )?;
@@ -482,7 +480,6 @@ pub fn build_microvm_from_snapshot(
         event_manager,
         guest_memory,
         uffd,
-        vm_resources.machine_config.track_dirty_pages,
         vm_resources.machine_config.vcpu_count,
         microvm_state.kvm_state.kvm_cap_modifiers.clone(),
     )?;
@@ -1140,7 +1137,7 @@ pub(crate) mod tests {
 
         let kvm = Kvm::new(vec![]).unwrap();
         let mut vm = Vm::new(&kvm).unwrap();
-        vm.memory_init(&guest_memory, false).unwrap();
+        vm.memory_init(&guest_memory).unwrap();
         let mmio_device_manager = MMIODeviceManager::new();
         let acpi_device_manager = ACPIDeviceManager::new();
         #[cfg(target_arch = "x86_64")]
@@ -1394,7 +1391,7 @@ pub(crate) mod tests {
         let kvm = Kvm::new(vec![]).expect("Cannot create Kvm");
         #[allow(unused_mut)]
         let mut vm = Vm::new(&kvm).unwrap();
-        vm.memory_init(&guest_memory, false).unwrap();
+        vm.memory_init(&guest_memory).unwrap();
         let evfd = EventFd::new(libc::EFD_NONBLOCK).unwrap();
 
         #[cfg(target_arch = "x86_64")]

src/vmm/src/device_manager/mmio.rs

@@ -666,7 +666,7 @@ mod tests {
         let guest_mem = multi_region_mem(&[(start_addr1, 0x1000), (start_addr2, 0x1000)]);
         let kvm = Kvm::new(vec![]).expect("Cannot create Kvm");
         let mut vm = Vm::new(&kvm).unwrap();
-        vm.memory_init(&guest_mem, false).unwrap();
+        vm.memory_init(&guest_mem).unwrap();
         let mut device_manager = MMIODeviceManager::new();
         let mut resource_allocator = ResourceAllocator::new().unwrap();
 
@@ -696,7 +696,7 @@ mod tests {
         let guest_mem = multi_region_mem(&[(start_addr1, 0x1000), (start_addr2, 0x1000)]);
         let kvm = Kvm::new(vec![]).expect("Cannot create Kvm");
         let mut vm = Vm::new(&kvm).unwrap();
-        vm.memory_init(&guest_mem, false).unwrap();
+        vm.memory_init(&guest_mem).unwrap();
         let mut device_manager = MMIODeviceManager::new();
         let mut resource_allocator = ResourceAllocator::new().unwrap();
 
@@ -751,7 +751,7 @@ mod tests {
         let guest_mem = multi_region_mem(&[(start_addr1, 0x1000), (start_addr2, 0x1000)]);
         let kvm = Kvm::new(vec![]).expect("Cannot create Kvm");
         let mut vm = Vm::new(&kvm).unwrap();
-        vm.memory_init(&guest_mem, false).unwrap();
+        vm.memory_init(&guest_mem).unwrap();
 
         let mem_clone = guest_mem.clone();
 

src/vmm/src/vstate/vm.rs

@@ -129,12 +129,8 @@ impl Vm {
     }
 
     /// Initializes the guest memory.
-    pub fn memory_init(
-        &self,
-        guest_mem: &GuestMemoryMmap,
-        track_dirty_pages: bool,
-    ) -> Result<(), VmError> {
-        self.set_kvm_memory_regions(guest_mem, track_dirty_pages)?;
+    pub fn memory_init(&self, guest_mem: &GuestMemoryMmap) -> Result<(), VmError> {
+        self.set_kvm_memory_regions(guest_mem)?;
         #[cfg(target_arch = "x86_64")]
         self.fd
             .set_tss_address(u64_to_usize(crate::arch::x86_64::layout::KVM_TSS_ADDRESS))
@@ -146,16 +142,17 @@ impl Vm {
     pub(crate) fn set_kvm_memory_regions(
         &self,
         guest_mem: &GuestMemoryMmap,
-        track_dirty_pages: bool,
     ) -> Result<(), VmError> {
-        let mut flags = 0u32;
-        if track_dirty_pages {
-            flags |= KVM_MEM_LOG_DIRTY_PAGES;
-        }
         guest_mem
             .iter()
             .zip(0u32..)
             .try_for_each(|(region, slot)| {
+                let flags = if region.bitmap().is_some() {
+                    KVM_MEM_LOG_DIRTY_PAGES
+                } else {
+                    0
+                };
+
                 let memory_region = kvm_userspace_memory_region {
                     slot,
                     guest_phys_addr: region.start_addr().raw_value(),
@@ -359,7 +356,7 @@ pub(crate) mod tests {
     pub(crate) fn setup_vm_with_memory(mem_size: usize) -> (Kvm, Vm, GuestMemoryMmap) {
         let (kvm, vm) = setup_vm();
         let gm = single_region_mem(mem_size);
-        vm.memory_init(&gm, false).unwrap();
+        vm.memory_init(&gm).unwrap();
         (kvm, vm, gm)
     }
 
@@ -375,7 +372,7 @@ pub(crate) mod tests {
         let (_, vm) = setup_vm();
         // Create valid memory region and test that the initialization is successful.
         let gm = single_region_mem(0x1000);
-        vm.memory_init(&gm, true).unwrap();
+        vm.memory_init(&gm).unwrap();
     }
 
     #[cfg(target_arch = "x86_64")]
@@ -452,13 +449,13 @@ pub(crate) mod tests {
         let (_, vm) = setup_vm();
 
         let gm = single_region_mem(0x1000);
-        let res = vm.set_kvm_memory_regions(&gm, false);
+        let res = vm.set_kvm_memory_regions(&gm);
         res.unwrap();
 
         // Trying to set a memory region with a size that is not a multiple of GUEST_PAGE_SIZE
         // will result in error.
         let gm = single_region_mem(0x10);
-        let res = vm.set_kvm_memory_regions(&gm, false);
+        let res = vm.set_kvm_memory_regions(&gm);
         assert_eq!(
             res.unwrap_err().to_string(),
             "Cannot set the memory regions: Invalid argument (os error 22)"