[virtio-mem] Dynamic slots and performance tests

.buildkite/pipeline_perf.py

@@ -65,6 +65,11 @@
         "tests": "integration_tests/performance/test_jailer.py",
         "devtool_opts": "-c 1-10 -m 0",
     },
+    "memory-hotplug": {
+        "label": ":🔌 Memory hotplug",
+        "tests": "integration_tests/performance/test_hotplug_memory.py",
+        "devtool_opts": "-c 1-10 -m 0",
+    },
 }
 
 REVISION_A = os.environ.get("REVISION_A")

resources/seccomp/aarch64-unknown-linux-musl.json

@@ -445,6 +445,18 @@
                     }
                 ]
             },
+            {
+                "syscall": "ioctl",
+                "args": [
+                    {
+                        "index": 1,
+                        "type": "dword",
+                        "op": "eq",
+                        "val": 1075883590,
+                        "comment": "KVM_SET_USER_MEMORY_REGION"
+                    }
+                ]
+            },
             {
                 "syscall": "sched_yield",
                 "comment": "Used by the rust standard library in std::sync::mpmc. Firecracker uses mpsc channels from this module for inter-thread communication"
@@ -460,6 +472,10 @@
             {
                 "syscall": "restart_syscall",
                 "comment": "automatically issued by the kernel when specific timing-related syscalls (e.g. nanosleep) get interrupted by SIGSTOP"
+            },
+            {
+                "syscall": "mprotect",
+                "comment": "Used by memory hotplug to protect access to underlying host memory"
             }
         ]
     },

resources/seccomp/x86_64-unknown-linux-musl.json

@@ -457,6 +457,18 @@
                     }
                 ]
             },
+            {
+                "syscall": "ioctl",
+                "args": [
+                    {
+                        "index": 1,
+                        "type": "dword",
+                        "op": "eq",
+                        "val": 1075883590,
+                        "comment": "KVM_SET_USER_MEMORY_REGION"
+                    }
+                ]
+            },
             {
                 "syscall": "sched_yield",
                 "comment": "Used by the rust standard library in std::sync::mpmc. Firecracker uses mpsc channels from this module for inter-thread communication"
@@ -472,6 +484,10 @@
             {
                 "syscall": "restart_syscall",
                 "comment": "automatically issued by the kernel when specific timing-related syscalls (e.g. nanosleep) get interrupted by SIGSTOP"
+            },
+            {
+                "syscall": "mprotect",
+                "comment": "Used by memory hotplug to protect access to underlying host memory"
             }
         ]
     },

src/vmm/src/builder.rs

@@ -183,7 +183,10 @@ pub fn build_microvm_for_boot(
         let hotplug_memory_region = vm_resources
             .allocate_memory_region(addr, mib_to_bytes(memory_hotplug.total_size_mib))
             .map_err(StartMicrovmError::GuestMemory)?;
-        vm.register_hotpluggable_memory_region(hotplug_memory_region)?;
+        vm.register_hotpluggable_memory_region(
+            hotplug_memory_region,
+            mib_to_bytes(memory_hotplug.slot_size_mib),
+        )?;
         Some(addr)
     } else {
         None

src/vmm/src/devices/virtio/mem/device.rs

@@ -33,7 +33,9 @@ use crate::devices::virtio::transport::{VirtioInterrupt, VirtioInterruptType};
 use crate::logger::{IncMetric, debug, error};
 use crate::utils::{bytes_to_mib, mib_to_bytes, u64_to_usize, usize_to_u64};
 use crate::vstate::interrupts::InterruptError;
-use crate::vstate::memory::{ByteValued, GuestMemoryExtension, GuestMemoryMmap, GuestRegionMmap};
+use crate::vstate::memory::{
+    ByteValued, GuestMemoryExtension, GuestMemoryMmap, GuestRegionMmap, GuestRegionType,
+};
 use crate::vstate::vm::VmError;
 use crate::{Vm, impl_device_type};
 
@@ -76,6 +78,8 @@ pub enum VirtioMemError {
     PlugRequestIsTooBig,
     /// The requested range cannot be unplugged because it's {0:?}.
     UnplugRequestBlockStateInvalid(BlockRangeState),
+    /// There was an error updating the KVM slot.
+    UpdateKvmSlot(VmError),
 }
 
 #[derive(Debug)]
@@ -501,6 +505,32 @@ impl VirtioMem {
         &self.activate_event
     }
 
+    fn update_kvm_slots(&self, updated_range: &RequestedRange) -> Result<(), VirtioMemError> {
+        let hp_region = self
+            .guest_memory()
+            .iter()
+            .find(|r| r.region_type == GuestRegionType::Hotpluggable)
+            .expect("there should be one and only one hotpluggable region");
+        hp_region
+            .slots_intersecting_range(
+                updated_range.addr,
+                self.nb_blocks_to_len(updated_range.nb_blocks),
+            )
+            .try_for_each(|slot| {
+                let slot_range = RequestedRange {
+                    addr: slot.guest_addr,
+                    nb_blocks: slot.slice.len() / u64_to_usize(self.config.block_size),
+                };
+                match self.range_state(&slot_range) {
+                    BlockRangeState::Mixed | BlockRangeState::Plugged => {
+                        hp_region.update_slot(&self.vm, slot.slot, true)
+                    }
+                    BlockRangeState::Unplugged => hp_region.update_slot(&self.vm, slot.slot, false),
+                }
+                .map_err(VirtioMemError::UpdateKvmSlot)
+            })
+    }
+
     /// Plugs/unplugs the given range
     ///
     /// Note: the range passed to this function must be within the device memory to avoid
@@ -527,9 +557,7 @@ impl VirtioMem {
                 });
         }
 
-        // TODO: update KVM slots to plug/unplug them
-
-        Ok(())
+        self.update_kvm_slots(range)
     }
 
     /// Updates the requested size of the virtio-mem device.
@@ -692,6 +720,7 @@ pub(crate) mod test_utils {
             .unwrap()
             .pop()
             .unwrap(),
+            mib_to_bytes(128),
         );
         let vm = Arc::new(vm);
         VirtioMem::new(vm, addr, 1024, 2, 128).unwrap()

src/vmm/src/devices/virtio/pmem/device.rs

@@ -26,12 +26,13 @@ use crate::logger::{IncMetric, error};
 use crate::utils::{align_up, u64_to_usize};
 use crate::vmm_config::pmem::PmemConfig;
 use crate::vstate::memory::{ByteValued, Bytes, GuestMemoryMmap, GuestMmapRegion};
+use crate::vstate::vm::VmError;
 use crate::{Vm, impl_device_type};
 
 #[derive(Debug, thiserror::Error, displaydoc::Display)]
 pub enum PmemError {
     /// Cannot set the memory regions: {0}
-    SetUserMemoryRegion(kvm_ioctls::Error),
+    SetUserMemoryRegion(VmError),
     /// Unablet to allocate a KVM slot for the device
     NoKvmSlotAvailable,
     /// Error accessing backing file: {0}
@@ -221,7 +222,7 @@ impl Pmem {
 
     /// Set user memory region in KVM
     pub fn set_mem_region(&mut self, vm: &Vm) -> Result<(), PmemError> {
-        let next_slot = vm.next_kvm_slot().ok_or(PmemError::NoKvmSlotAvailable)?;
+        let next_slot = vm.next_kvm_slot(1).ok_or(PmemError::NoKvmSlotAvailable)?;
         let memory_region = kvm_userspace_memory_region {
             slot: next_slot,
             guest_phys_addr: self.config_space.start,
@@ -233,14 +234,9 @@ impl Pmem {
                 0
             },
         };
-        // SAFETY: The fd is a valid VM file descriptor and all fields in the
-        // `memory_region` struct are valid.
-        unsafe {
-            vm.fd()
-                .set_user_memory_region(memory_region)
-                .map_err(PmemError::SetUserMemoryRegion)?;
-        }
-        Ok(())
+
+        vm.set_user_memory_region(memory_region)
+            .map_err(PmemError::SetUserMemoryRegion)
     }
 
     fn handle_queue(&mut self) -> Result<(), PmemError> {

src/vmm/src/persist.rs

@@ -571,6 +571,7 @@ fn send_uffd_handshake(
 mod tests {
     use std::os::unix::net::UnixListener;
 
+    use bitvec::vec::BitVec;
     use vmm_sys_util::tempfile::TempFile;
 
     use super::*;
@@ -694,6 +695,7 @@ mod tests {
                 base_address: 0,
                 size: 0x20000,
                 region_type: GuestRegionType::Dram,
+                plugged: BitVec::repeat(true, 1),
             }],
         };