pci: Remove ioeventfds() from PciDevice trait

The PciDevice trait is supposed to describe only functions related to
PCI. The specific method ioeventfds() has nothing to do with PCI, but
instead would be more specific to virtio transport devices.

This commit removes the ioeventfds() method from the PciDevice trait,
adding some convenient helper as_any() to retrieve the Any trait from
the structure behing the PciDevice trait. This is the only way to keep
calling into ioeventfds() function from VirtioPciDevice, so that we can
still properly reprogram the PCI BAR.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

pci/src/bus.rs

@@ -9,6 +9,7 @@ use crate::device::{DeviceRelocation, Error as PciDeviceError, PciDevice};
 use byteorder::{ByteOrder, LittleEndian};
 use devices::BusDevice;
 use std;
+use std::any::Any;
 use std::ops::DerefMut;
 use std::sync::{Arc, Mutex, Weak};
 use vm_memory::{Address, GuestAddress, GuestUsize};
@@ -69,6 +70,10 @@ impl PciDevice for PciRoot {
     fn read_config_register(&self, reg_idx: usize) -> u32 {
         self.config.read_reg(reg_idx)
     }
+
+    fn as_any(&mut self) -> &mut dyn Any {
+        self
+    }
 }
 
 pub struct PciBus {

pci/src/device.rs

@@ -6,12 +6,12 @@ use crate::configuration::{self, PciBarRegionType};
 use crate::msix::MsixTableEntry;
 use crate::PciInterruptPin;
 use devices::BusDevice;
+use std::any::Any;
 use std::fmt::{self, Display};
 use std::sync::Arc;
 use std::{self, io, result};
 use vm_allocator::SystemAllocator;
 use vm_memory::{GuestAddress, GuestUsize};
-use vmm_sys_util::eventfd::EventFd;
 
 pub struct InterruptParameters<'a> {
     pub msix: Option<&'a MsixTableEntry>,
@@ -78,11 +78,6 @@ pub trait PciDevice: BusDevice {
         Ok(Vec::new())
     }
 
-    /// Gets a list of ioeventfds that should be registered with the running VM. The list is
-    /// returned as a Vec of (eventfd, addr, datamatch) tuples.
-    fn ioeventfds(&self) -> Vec<(&EventFd, u64, u64)> {
-        Vec::new()
-    }
     /// Sets a register in the configuration space.
     /// * `reg_idx` - The index of the config register to modify.
     /// * `offset` - Offset in to the register.
@@ -110,6 +105,9 @@ pub trait PciDevice: BusDevice {
     fn move_bar(&mut self, _old_base: u64, _new_base: u64) -> result::Result<(), io::Error> {
         Ok(())
     }
+    /// Provides a mutable reference to the Any trait. This is useful to let
+    /// the caller have access to the underlying type behind the trait.
+    fn as_any(&mut self) -> &mut dyn Any;
 }
 
 /// This trait defines a set of functions which can be triggered whenever a

vfio/src/vfio_pci.rs

@@ -20,6 +20,7 @@ use pci::{
     PciCapabilityID, PciClassCode, PciConfiguration, PciDevice, PciDeviceError, PciHeaderType,
     PciSubclass, MSIX_TABLE_ENTRY_SIZE,
 };
+use std::any::Any;
 use std::os::unix::io::AsRawFd;
 use std::ptr::null_mut;
 use std::sync::Arc;
@@ -1045,4 +1046,8 @@ impl PciDevice for VfioPciDevice {
 
         Ok(())
     }
+
+    fn as_any(&mut self) -> &mut dyn Any {
+        self
+    }
 }

vm-virtio/src/transport/pci_device.rs

@@ -14,6 +14,7 @@ extern crate vm_memory;
 extern crate vmm_sys_util;
 
 use libc::EFD_NONBLOCK;
+use std::any::Any;
 use std::sync::atomic::{AtomicU16, AtomicUsize, Ordering};
 use std::sync::{Arc, Mutex, RwLock};
 
@@ -361,6 +362,22 @@ impl VirtioPciDevice {
         }
     }
 
+    pub fn ioeventfds(&self) -> Vec<(&EventFd, u64, u64)> {
+        let bar0 = self.configuration.get_bar_addr(self.settings_bar as usize);
+        let notify_base = bar0 + NOTIFICATION_BAR_OFFSET;
+        self.queue_evts()
+            .iter()
+            .enumerate()
+            .map(|(i, event)| {
+                (
+                    event,
+                    notify_base + i as u64 * u64::from(NOTIFY_OFF_MULTIPLIER),
+                    i as u64,
+                )
+            })
+            .collect()
+    }
+
     fn add_pci_capabilities(
         &mut self,
         settings_bar: u8,
@@ -528,22 +545,6 @@ impl PciDevice for VirtioPciDevice {
         self.configuration.detect_bar_reprogramming(reg_idx, data)
     }
 
-    fn ioeventfds(&self) -> Vec<(&EventFd, u64, u64)> {
-        let bar0 = self.configuration.get_bar_addr(self.settings_bar as usize);
-        let notify_base = bar0 + NOTIFICATION_BAR_OFFSET;
-        self.queue_evts()
-            .iter()
-            .enumerate()
-            .map(|(i, event)| {
-                (
-                    event,
-                    notify_base + i as u64 * u64::from(NOTIFY_OFF_MULTIPLIER),
-                    i as u64,
-                )
-            })
-            .collect()
-    }
-
     fn allocate_bars(
         &mut self,
         allocator: &mut SystemAllocator,
@@ -733,6 +734,10 @@ impl PciDevice for VirtioPciDevice {
             }
         }
     }
+
+    fn as_any(&mut self) -> &mut dyn Any {
+        self
+    }
 }
 
 impl BusDevice for VirtioPciDevice {

vmm/src/device_manager.rs

@@ -356,10 +356,13 @@ impl DeviceRelocation for AddressManager {
             }
         }
 
-        for (event, addr, _) in pci_dev.ioeventfds() {
-            let io_addr = IoEventAddress::Mmio(addr);
-            self.vm_fd
-                .register_ioevent(event.as_raw_fd(), &io_addr, NoDatamatch)?;
+        let any_dev = pci_dev.as_any();
+        if let Some(virtio_pci_dev) = any_dev.downcast_ref::<VirtioPciDevice>() {
+            for (event, addr, _) in virtio_pci_dev.ioeventfds() {
+                let io_addr = IoEventAddress::Mmio(addr);
+                self.vm_fd
+                    .register_ioevent(event.as_raw_fd(), &io_addr, NoDatamatch)?;
+            }
         }
 
         pci_dev.move_bar(old_base, new_base)