From fbcf3a7a7a61cc66aba87955aefefad97358900b Mon Sep 17 00:00:00 2001
From: Sebastien Boeuf <sebastien.boeuf@intel.com>
Date: Mon, 20 Apr 2020 16:30:36 +0200
Subject: [PATCH] vm-virtio: Implement userspace_mappings() for virtio-pmem

When hot-unplugging the virtio-pmem from the VM, we don't remove the
associated userspace mapping. This patch will let us fix this in a
following patch. For now, it simply adapts the code so that the Pmem
device knows about the mapping associated with it. By knowing about it,
it can expose it to the caller through the new userspace_mappings()
function.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
---
 vm-virtio/src/pmem.rs     | 11 +++++++++--
 vmm/src/device_manager.rs | 17 +++++++++++++----
 2 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/vm-virtio/src/pmem.rs b/vm-virtio/src/pmem.rs
index 87a97e47a..4ab05a4f8 100644
--- a/vm-virtio/src/pmem.rs
+++ b/vm-virtio/src/pmem.rs
@@ -8,8 +8,8 @@
 
 use super::Error as DeviceError;
 use super::{
-    ActivateError, ActivateResult, DescriptorChain, DeviceEventT, Queue, VirtioDevice,
-    VirtioDeviceType, VIRTIO_F_IOMMU_PLATFORM, VIRTIO_F_VERSION_1,
+    ActivateError, ActivateResult, DescriptorChain, DeviceEventT, Queue, UserspaceMapping,
+    VirtioDevice, VirtioDeviceType, VIRTIO_F_IOMMU_PLATFORM, VIRTIO_F_VERSION_1,
 };
 use crate::{VirtioInterrupt, VirtioInterruptType};
 use epoll;
@@ -322,6 +322,7 @@ pub struct Pmem {
     interrupt_cb: Option<Arc<dyn VirtioInterrupt>>,
     epoll_threads: Option<Vec<thread::JoinHandle<result::Result<(), DeviceError>>>>,
     paused: Arc<AtomicBool>,
+    mapping: UserspaceMapping,
 
     // Hold ownership of the memory that is allocated for the device
     // which will be automatically dropped when the device is dropped
@@ -332,6 +333,7 @@ impl Pmem {
     pub fn new(
         disk: File,
         addr: GuestAddress,
+        mapping: UserspaceMapping,
         _region: MmapRegion,
         iommu: bool,
     ) -> io::Result<Pmem> {
@@ -357,6 +359,7 @@ impl Pmem {
             interrupt_cb: None,
             epoll_threads: None,
             paused: Arc::new(AtomicBool::new(false)),
+            mapping,
             _region,
         })
     }
@@ -513,6 +516,10 @@ impl VirtioDevice for Pmem {
             self.queue_evts.take().unwrap(),
         ))
     }
+
+    fn userspace_mappings(&self) -> Vec<UserspaceMapping> {
+        vec![self.mapping.clone()]
+    }
 }
 
 virtio_pausable!(Pmem);
diff --git a/vmm/src/device_manager.rs b/vmm/src/device_manager.rs
index 96b93c8ed..0c5bd696b 100644
--- a/vmm/src/device_manager.rs
+++ b/vmm/src/device_manager.rs
@@ -1569,22 +1569,31 @@ impl DeviceManager {
                 },
         )
         .map_err(DeviceManagerError::NewMmapRegion)?;
-        let addr: u64 = mmap_region.as_ptr() as u64;
+        let host_addr: u64 = mmap_region.as_ptr() as u64;
 
-        self.memory_manager
+        let mem_slot = self
+            .memory_manager
             .lock()
             .unwrap()
             .create_userspace_mapping(
                 pmem_guest_addr.raw_value(),
                 size,
-                addr,
+                host_addr,
                 pmem_cfg.mergeable,
                 pmem_cfg.discard_writes,
             )
             .map_err(DeviceManagerError::MemoryManager)?;
 
+        let mapping = vm_virtio::UserspaceMapping {
+            host_addr,
+            mem_slot,
+            addr: pmem_guest_addr,
+            len: size,
+            mergeable: pmem_cfg.mergeable,
+        };
+
         let virtio_pmem_device = Arc::new(Mutex::new(
-            vm_virtio::Pmem::new(file, pmem_guest_addr, mmap_region, pmem_cfg.iommu)
+            vm_virtio::Pmem::new(file, pmem_guest_addr, mapping, mmap_region, pmem_cfg.iommu)
                 .map_err(DeviceManagerError::CreateVirtioPmem)?,
         ));