vmm, pci: Fix potential deadlock in PCI BAR allocation

The allocator is locked by both the BAR allocation code and the
interrupt allocation code. Resulting in a potential lock inversion
error.

WARNING: ThreadSanitizer: lock-order-inversion (potential deadlock) (pid=26318)
  Cycle in lock order graph: M87 (0x7b0c00001e30) => M28 (0x7b0c00001830) => M87

  Mutex M28 acquired here while holding mutex M87 in thread T1:
    #0 pthread_mutex_lock /rustc/llvm/src/llvm-project/compiler-rt/lib/tsan/../sanitizer_common/sanitizer_common_interceptors.inc:4249:3 (cloud-hypervisor+0x9c368)
    #1 std::sys::unix::mutex::Mutex:🔒:hcd1b9aa06ff775d3 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/sys/unix/mutex.rs:63:17 (cloud-hypervisor+0x663954)
    #2 std::sys_common::mutex::MovableMutex::raw_lock::hff98d0b036469bca /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/sys_common/mutex.rs:76:18 (cloud-hypervisor+0x491bae)
    #3 std::sync::mutex::Mutex$LT$T$GT$:🔒:hc61622e5536f5b72 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/sync/mutex.rs:267:13 (cloud-hypervisor+0x36d07b)
    #4 _$LT$vmm..interrupt..MsiInterruptManager$LT$kvm_bindings..x86..bindings..kvm_irq_routing_entry$GT$$u20$as$u20$vm_device..interrupt..InterruptManager$GT$::create_group::hd412b5e1e8eeacc2 /home/rob/src/cloud-hypervisor/vmm/src/interrupt.rs:310:29 (cloud-hypervisor+0x6d1403)
    #5 virtio_devices::transport::pci_device::VirtioPciDevice:🆕:h3af603c3f00f4b3d /home/rob/src/cloud-hypervisor/virtio-devices/src/transport/pci_device.rs:376:38 (cloud-hypervisor+0x8e6137)
    #6 vmm::device_manager::DeviceManager::add_virtio_pci_device::h23608151d7668a1c /home/rob/src/cloud-hypervisor/vmm/src/device_manager.rs:3333:37 (cloud-hypervisor+0x3b6339)
    #7 vmm::device_manager::DeviceManager::add_pci_devices::h136cc20cbeb6b977 /home/rob/src/cloud-hypervisor/vmm/src/device_manager.rs:1236:30 (cloud-hypervisor+0x390aad)
    #8 vmm::device_manager::DeviceManager::create_devices::h29fc5b8a20e1aea5 /home/rob/src/cloud-hypervisor/vmm/src/device_manager.rs:1155:9 (cloud-hypervisor+0x38f48c)
    #9 vmm::vm::Vm:🆕:h43efe7c6cd97ede5 /home/rob/src/cloud-hypervisor/vmm/src/vm.rs:799:9 (cloud-hypervisor+0x334641)
    #10 vmm::Vmm::vm_boot::h06bdf54b95d5e14f /home/rob/src/cloud-hypervisor/vmm/src/lib.rs:379:26 (cloud-hypervisor+0x2e5ba8)
    #11 vmm::Vmm::control_loop::h40c9b48c7b800bed /home/rob/src/cloud-hypervisor/vmm/src/lib.rs:1299:48 (cloud-hypervisor+0x2f44e0)
    #12 vmm::start_vmm_thread::_$u7b$$u7b$closure$u7d$$u7d$::h016d2f7cff698175 /home/rob/src/cloud-hypervisor/vmm/src/lib.rs:263:17 (cloud-hypervisor+0x1dda20)
    #13 std::sys_common::backtrace::__rust_begin_short_backtrace::h7fd2df3e7cfba503 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/sys_common/backtrace.rs:123:18 (cloud-hypervisor+0x659bca)
    #14 std:🧵:Builder::spawn_unchecked::_$u7b$$u7b$closure$u7d$$u7d$::_$u7b$$u7b$closure$u7d$$u7d$::h89880b05fe892d7e /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/thread/mod.rs:477:17 (cloud-hypervisor+0x44100e)
    #15 _$LT$core..panic..unwind_safe..AssertUnwindSafe$LT$F$GT$$u20$as$u20$core..ops..function..FnOnce$LT$$LP$$RP$$GT$$GT$::call_once::h487382524d80571f /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/core/src/panic/unwind_safe.rs:271:9 (cloud-hypervisor+0x6dda5e)
    #16 std::panicking::try::do_call::h1d9c2ccdc39f3322 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/panicking.rs:406:40 (cloud-hypervisor+0x6d36d1)
    #17 __rust_try 3hkmq3dzyyv5ejsx (cloud-hypervisor+0x6d4718)
    #18 std::panicking::try::h251306df23d21913 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/panicking.rs:370:19 (cloud-hypervisor+0x6d2459)
    #19 std::panic::catch_unwind::h2a9ac2fb12c3c64e /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/panic.rs:133:14 (cloud-hypervisor+0x57bdce)
    #20 std:🧵:Builder::spawn_unchecked::_$u7b$$u7b$closure$u7d$$u7d$::h10f4c340611b55e4 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/thread/mod.rs:476:30 (cloud-hypervisor+0x43f913)
    #21 core::ops::function::FnOnce::call_once$u7b$$u7b$vtable.shim$u7d$$u7d$::hdd9b37241caf97b3 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/core/src/ops/function.rs:227:5 (cloud-hypervisor+0x3cf3f5)
    #22 _$LT$alloc..boxed..Box$LT$F$C$A$GT$$u20$as$u20$core..ops..function..FnOnce$LT$Args$GT$$GT$::call_once::ha5022a6bb7833f62 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/alloc/src/boxed.rs:1854:9 (cloud-hypervisor+0x119d492)
    #23 _$LT$alloc..boxed..Box$LT$F$C$A$GT$$u20$as$u20$core..ops..function..FnOnce$LT$Args$GT$$GT$::call_once::h481697829cbc6746 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/alloc/src/boxed.rs:1854:9 (cloud-hypervisor+0x119d492)
    #24 std::sys::unix:🧵:Thread:🆕:thread_start::h6fad62c4c393bbe7 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/sys/unix/thread.rs:108:17 (cloud-hypervisor+0x119d492)

  Mutex M87 previously acquired by the same thread here:
    #0 pthread_mutex_lock /rustc/llvm/src/llvm-project/compiler-rt/lib/tsan/../sanitizer_common/sanitizer_common_interceptors.inc:4249:3 (cloud-hypervisor+0x9c368)
    #1 std::sys::unix::mutex::Mutex:🔒:h9a2d3e97e05c6430 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/sys/unix/mutex.rs:63:17 (cloud-hypervisor+0x9ea344)
    #2 std::sys_common::mutex::MovableMutex::raw_lock::h8abb3b5cf55c0264 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/sys_common/mutex.rs:76:18 (cloud-hypervisor+0x96face)
    #3 std::sync::mutex::Mutex$LT$T$GT$:🔒:hecec128d40c6dd44 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/sync/mutex.rs:267:13 (cloud-hypervisor+0x97120a)
    #4 virtio_devices::transport::pci_device::VirtioPciDevice:🆕:h3af603c3f00f4b3d /home/rob/src/cloud-hypervisor/virtio-devices/src/transport/pci_device.rs:356:29 (cloud-hypervisor+0x8e5c0e)
    #5 vmm::device_manager::DeviceManager::add_virtio_pci_device::h23608151d7668a1c /home/rob/src/cloud-hypervisor/vmm/src/device_manager.rs:3333:37 (cloud-hypervisor+0x3b6339)
    #6 vmm::device_manager::DeviceManager::add_pci_devices::h136cc20cbeb6b977 /home/rob/src/cloud-hypervisor/vmm/src/device_manager.rs:1236:30 (cloud-hypervisor+0x390aad)
    #7 vmm::device_manager::DeviceManager::create_devices::h29fc5b8a20e1aea5 /home/rob/src/cloud-hypervisor/vmm/src/device_manager.rs:1155:9 (cloud-hypervisor+0x38f48c)
    #8 vmm::vm::Vm:🆕:h43efe7c6cd97ede5 /home/rob/src/cloud-hypervisor/vmm/src/vm.rs:799:9 (cloud-hypervisor+0x334641)
    #9 vmm::Vmm::vm_boot::h06bdf54b95d5e14f /home/rob/src/cloud-hypervisor/vmm/src/lib.rs:379:26 (cloud-hypervisor+0x2e5ba8)
    #10 vmm::Vmm::control_loop::h40c9b48c7b800bed /home/rob/src/cloud-hypervisor/vmm/src/lib.rs:1299:48 (cloud-hypervisor+0x2f44e0)
    #11 vmm::start_vmm_thread::_$u7b$$u7b$closure$u7d$$u7d$::h016d2f7cff698175 /home/rob/src/cloud-hypervisor/vmm/src/lib.rs:263:17 (cloud-hypervisor+0x1dda20)
    #12 std::sys_common::backtrace::__rust_begin_short_backtrace::h7fd2df3e7cfba503 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/sys_common/backtrace.rs:123:18 (cloud-hypervisor+0x659bca)
    #13 std:🧵:Builder::spawn_unchecked::_$u7b$$u7b$closure$u7d$$u7d$::_$u7b$$u7b$closure$u7d$$u7d$::h89880b05fe892d7e /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/thread/mod.rs:477:17 (cloud-hypervisor+0x44100e)
    #14 _$LT$core..panic..unwind_safe..AssertUnwindSafe$LT$F$GT$$u20$as$u20$core..ops..function..FnOnce$LT$$LP$$RP$$GT$$GT$::call_once::h487382524d80571f /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/core/src/panic/unwind_safe.rs:271:9 (cloud-hypervisor+0x6dda5e)
    #15 std::panicking::try::do_call::h1d9c2ccdc39f3322 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/panicking.rs:406:40 (cloud-hypervisor+0x6d36d1)
    #16 __rust_try 3hkmq3dzyyv5ejsx (cloud-hypervisor+0x6d4718)
    #17 std::panicking::try::h251306df23d21913 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/panicking.rs:370:19 (cloud-hypervisor+0x6d2459)
    #18 std::panic::catch_unwind::h2a9ac2fb12c3c64e /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/panic.rs:133:14 (cloud-hypervisor+0x57bdce)
    #19 std:🧵:Builder::spawn_unchecked::_$u7b$$u7b$closure$u7d$$u7d$::h10f4c340611b55e4 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/thread/mod.rs:476:30 (cloud-hypervisor+0x43f913)
    #20 core::ops::function::FnOnce::call_once$u7b$$u7b$vtable.shim$u7d$$u7d$::hdd9b37241caf97b3 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/core/src/ops/function.rs:227:5 (cloud-hypervisor+0x3cf3f5)
    #21 _$LT$alloc..boxed..Box$LT$F$C$A$GT$$u20$as$u20$core..ops..function..FnOnce$LT$Args$GT$$GT$::call_once::ha5022a6bb7833f62 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/alloc/src/boxed.rs:1854:9 (cloud-hypervisor+0x119d492)
    #22 _$LT$alloc..boxed..Box$LT$F$C$A$GT$$u20$as$u20$core..ops..function..FnOnce$LT$Args$GT$$GT$::call_once::h481697829cbc6746 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/alloc/src/boxed.rs:1854:9 (cloud-hypervisor+0x119d492)
    #23 std::sys::unix:🧵:Thread:🆕:thread_start::h6fad62c4c393bbe7 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/sys/unix/thread.rs:108:17 (cloud-hypervisor+0x119d492)

  Mutex M87 acquired here while holding mutex M28 in thread T1:
    #0 pthread_mutex_lock /rustc/llvm/src/llvm-project/compiler-rt/lib/tsan/../sanitizer_common/sanitizer_common_interceptors.inc:4249:3 (cloud-hypervisor+0x9c368)
    #1 std::sys::unix::mutex::Mutex:🔒:h9a2d3e97e05c6430 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/sys/unix/mutex.rs:63:17 (cloud-hypervisor+0x9ea344)
    #2 std::sys_common::mutex::MovableMutex::raw_lock::h8abb3b5cf55c0264 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/sys_common/mutex.rs:76:18 (cloud-hypervisor+0x96face)
    #3 std::sync::mutex::Mutex$LT$T$GT$:🔒:hecec128d40c6dd44 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/sync/mutex.rs:267:13 (cloud-hypervisor+0x97120a)
    #4 _$LT$virtio_devices..transport..pci_device..VirtioPciDevice$u20$as$u20$pci..device..PciDevice$GT$::allocate_bars::h39dc42b48fc8264c /home/rob/src/cloud-hypervisor/virtio-devices/src/transport/pci_device.rs:850:22 (cloud-hypervisor+0x8eb1a4)
    #5 vmm::device_manager::DeviceManager::add_pci_device::h561f6c8ed61db117 /home/rob/src/cloud-hypervisor/vmm/src/device_manager.rs:3087:20 (cloud-hypervisor+0x3b0c62)
    #6 vmm::device_manager::DeviceManager::add_virtio_pci_device::h23608151d7668a1c /home/rob/src/cloud-hypervisor/vmm/src/device_manager.rs:3359:20 (cloud-hypervisor+0x3b6707)
    #7 vmm::device_manager::DeviceManager::add_pci_devices::h136cc20cbeb6b977 /home/rob/src/cloud-hypervisor/vmm/src/device_manager.rs:1236:30 (cloud-hypervisor+0x390aad)
    #8 vmm::device_manager::DeviceManager::create_devices::h29fc5b8a20e1aea5 /home/rob/src/cloud-hypervisor/vmm/src/device_manager.rs:1155:9 (cloud-hypervisor+0x38f48c)
    #9 vmm::vm::Vm:🆕:h43efe7c6cd97ede5 /home/rob/src/cloud-hypervisor/vmm/src/vm.rs:799:9 (cloud-hypervisor+0x334641)
    #10 vmm::Vmm::vm_boot::h06bdf54b95d5e14f /home/rob/src/cloud-hypervisor/vmm/src/lib.rs:379:26 (cloud-hypervisor+0x2e5ba8)
    #11 vmm::Vmm::control_loop::h40c9b48c7b800bed /home/rob/src/cloud-hypervisor/vmm/src/lib.rs:1299:48 (cloud-hypervisor+0x2f44e0)
    #12 vmm::start_vmm_thread::_$u7b$$u7b$closure$u7d$$u7d$::h016d2f7cff698175 /home/rob/src/cloud-hypervisor/vmm/src/lib.rs:263:17 (cloud-hypervisor+0x1dda20)
    #13 std::sys_common::backtrace::__rust_begin_short_backtrace::h7fd2df3e7cfba503 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/sys_common/backtrace.rs:123:18 (cloud-hypervisor+0x659bca)
    #14 std:🧵:Builder::spawn_unchecked::_$u7b$$u7b$closure$u7d$$u7d$::_$u7b$$u7b$closure$u7d$$u7d$::h89880b05fe892d7e /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/thread/mod.rs:477:17 (cloud-hypervisor+0x44100e)
    #15 _$LT$core..panic..unwind_safe..AssertUnwindSafe$LT$F$GT$$u20$as$u20$core..ops..function..FnOnce$LT$$LP$$RP$$GT$$GT$::call_once::h487382524d80571f /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/core/src/panic/unwind_safe.rs:271:9 (cloud-hypervisor+0x6dda5e)
    #16 std::panicking::try::do_call::h1d9c2ccdc39f3322 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/panicking.rs:406:40 (cloud-hypervisor+0x6d36d1)
    #17 __rust_try 3hkmq3dzyyv5ejsx (cloud-hypervisor+0x6d4718)
    #18 std::panicking::try::h251306df23d21913 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/panicking.rs:370:19 (cloud-hypervisor+0x6d2459)
    #19 std::panic::catch_unwind::h2a9ac2fb12c3c64e /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/panic.rs:133:14 (cloud-hypervisor+0x57bdce)
    #20 std:🧵:Builder::spawn_unchecked::_$u7b$$u7b$closure$u7d$$u7d$::h10f4c340611b55e4 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/thread/mod.rs:476:30 (cloud-hypervisor+0x43f913)
    #21 core::ops::function::FnOnce::call_once$u7b$$u7b$vtable.shim$u7d$$u7d$::hdd9b37241caf97b3 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/core/src/ops/function.rs:227:5 (cloud-hypervisor+0x3cf3f5)
    #22 _$LT$alloc..boxed..Box$LT$F$C$A$GT$$u20$as$u20$core..ops..function..FnOnce$LT$Args$GT$$GT$::call_once::ha5022a6bb7833f62 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/alloc/src/boxed.rs:1854:9 (cloud-hypervisor+0x119d492)
    #23 _$LT$alloc..boxed..Box$LT$F$C$A$GT$$u20$as$u20$core..ops..function..FnOnce$LT$Args$GT$$GT$::call_once::h481697829cbc6746 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/alloc/src/boxed.rs:1854:9 (cloud-hypervisor+0x119d492)
    #24 std::sys::unix:🧵:Thread:🆕:thread_start::h6fad62c4c393bbe7 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/sys/unix/thread.rs:108:17 (cloud-hypervisor+0x119d492)

  Mutex M28 previously acquired by the same thread here:
    #0 pthread_mutex_lock /rustc/llvm/src/llvm-project/compiler-rt/lib/tsan/../sanitizer_common/sanitizer_common_interceptors.inc:4249:3 (cloud-hypervisor+0x9c368)
    #1 std::sys::unix::mutex::Mutex:🔒:hcd1b9aa06ff775d3 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/sys/unix/mutex.rs:63:17 (cloud-hypervisor+0x663954)
    #2 std::sys_common::mutex::MovableMutex::raw_lock::hff98d0b036469bca /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/sys_common/mutex.rs:76:18 (cloud-hypervisor+0x491bae)
    #3 std::sync::mutex::Mutex$LT$T$GT$:🔒:hc61622e5536f5b72 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/sync/mutex.rs:267:13 (cloud-hypervisor+0x36d07b)
    #4 vmm::device_manager::DeviceManager::add_pci_device::h561f6c8ed61db117 /home/rob/src/cloud-hypervisor/vmm/src/device_manager.rs:3091:22 (cloud-hypervisor+0x3b0a95)
    #5 vmm::device_manager::DeviceManager::add_virtio_pci_device::h23608151d7668a1c /home/rob/src/cloud-hypervisor/vmm/src/device_manager.rs:3359:20 (cloud-hypervisor+0x3b6707)
    #6 vmm::device_manager::DeviceManager::add_pci_devices::h136cc20cbeb6b977 /home/rob/src/cloud-hypervisor/vmm/src/device_manager.rs:1236:30 (cloud-hypervisor+0x390aad)
    #7 vmm::device_manager::DeviceManager::create_devices::h29fc5b8a20e1aea5 /home/rob/src/cloud-hypervisor/vmm/src/device_manager.rs:1155:9 (cloud-hypervisor+0x38f48c)
    #8 vmm::vm::Vm:🆕:h43efe7c6cd97ede5 /home/rob/src/cloud-hypervisor/vmm/src/vm.rs:799:9 (cloud-hypervisor+0x334641)
    #9 vmm::Vmm::vm_boot::h06bdf54b95d5e14f /home/rob/src/cloud-hypervisor/vmm/src/lib.rs:379:26 (cloud-hypervisor+0x2e5ba8)
    #10 vmm::Vmm::control_loop::h40c9b48c7b800bed /home/rob/src/cloud-hypervisor/vmm/src/lib.rs:1299:48 (cloud-hypervisor+0x2f44e0)
    #11 vmm::start_vmm_thread::_$u7b$$u7b$closure$u7d$$u7d$::h016d2f7cff698175 /home/rob/src/cloud-hypervisor/vmm/src/lib.rs:263:17 (cloud-hypervisor+0x1dda20)
    #12 std::sys_common::backtrace::__rust_begin_short_backtrace::h7fd2df3e7cfba503 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/sys_common/backtrace.rs:123:18 (cloud-hypervisor+0x659bca)
    #13 std:🧵:Builder::spawn_unchecked::_$u7b$$u7b$closure$u7d$$u7d$::_$u7b$$u7b$closure$u7d$$u7d$::h89880b05fe892d7e /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/thread/mod.rs:477:17 (cloud-hypervisor+0x44100e)
    #14 _$LT$core..panic..unwind_safe..AssertUnwindSafe$LT$F$GT$$u20$as$u20$core..ops..function..FnOnce$LT$$LP$$RP$$GT$$GT$::call_once::h487382524d80571f /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/core/src/panic/unwind_safe.rs:271:9 (cloud-hypervisor+0x6dda5e)
    #15 std::panicking::try::do_call::h1d9c2ccdc39f3322 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/panicking.rs:406:40 (cloud-hypervisor+0x6d36d1)
    #16 __rust_try 3hkmq3dzyyv5ejsx (cloud-hypervisor+0x6d4718)
    #17 std::panicking::try::h251306df23d21913 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/panicking.rs:370:19 (cloud-hypervisor+0x6d2459)
    #18 std::panic::catch_unwind::h2a9ac2fb12c3c64e /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/panic.rs:133:14 (cloud-hypervisor+0x57bdce)
    #19 std:🧵:Builder::spawn_unchecked::_$u7b$$u7b$closure$u7d$$u7d$::h10f4c340611b55e4 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/thread/mod.rs:476:30 (cloud-hypervisor+0x43f913)
    #20 core::ops::function::FnOnce::call_once$u7b$$u7b$vtable.shim$u7d$$u7d$::hdd9b37241caf97b3 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/core/src/ops/function.rs:227:5 (cloud-hypervisor+0x3cf3f5)
    #21 _$LT$alloc..boxed..Box$LT$F$C$A$GT$$u20$as$u20$core..ops..function..FnOnce$LT$Args$GT$$GT$::call_once::ha5022a6bb7833f62 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/alloc/src/boxed.rs:1854:9 (cloud-hypervisor+0x119d492)
    #22 _$LT$alloc..boxed..Box$LT$F$C$A$GT$$u20$as$u20$core..ops..function..FnOnce$LT$Args$GT$$GT$::call_once::h481697829cbc6746 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/alloc/src/boxed.rs:1854:9 (cloud-hypervisor+0x119d492)
    #23 std::sys::unix:🧵:Thread:🆕:thread_start::h6fad62c4c393bbe7 /rustc/7d6f948173ccb18822bab13d548c65632db5f0aa/library/std/src/sys/unix/thread.rs:108:17 (cloud-hypervisor+0x119d492)

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

pci/src/device.rs

@@ -5,7 +5,7 @@
 use crate::configuration::{self, PciBarRegionType};
 use std::any::Any;
 use std::fmt::{self, Display};
-use std::sync::{Arc, Barrier};
+use std::sync::{Arc, Barrier, Mutex};
 use std::{self, io, result};
 use vm_allocator::{AddressAllocator, SystemAllocator};
 use vm_device::BusDevice;
@@ -51,7 +51,7 @@ pub trait PciDevice: BusDevice {
     /// returns an address. Returns a Vec of (GuestAddress, GuestUsize) tuples.
     fn allocate_bars(
         &mut self,
-        _allocator: &mut SystemAllocator,
+        _allocator: &Arc<Mutex<SystemAllocator>>,
         _mmio_allocator: &mut AddressAllocator,
     ) -> Result<Vec<(GuestAddress, GuestUsize, PciBarRegionType)>> {
         Ok(Vec::new())

pci/src/vfio.rs

@@ -15,7 +15,7 @@ use std::collections::BTreeMap;
 use std::io;
 use std::os::unix::io::AsRawFd;
 use std::ptr::null_mut;
-use std::sync::{Arc, Barrier};
+use std::sync::{Arc, Barrier, Mutex};
 use thiserror::Error;
 use vfio_bindings::bindings::vfio::*;
 use vfio_ioctls::{VfioContainer, VfioDevice, VfioIrq, VfioRegionInfoCap};
@@ -360,7 +360,7 @@ pub(crate) struct VfioCommon {
 impl VfioCommon {
     pub(crate) fn allocate_bars(
         &mut self,
-        allocator: &mut SystemAllocator,
+        allocator: &Arc<Mutex<SystemAllocator>>,
         mmio_allocator: &mut AddressAllocator,
         vfio_wrapper: &dyn Vfio,
     ) -> Result<Vec<(GuestAddress, GuestUsize, PciBarRegionType)>, PciDeviceError> {
@@ -430,6 +430,8 @@ impl VfioCommon {
 
                     // The address needs to be 4 bytes aligned.
                     bar_addr = allocator
+                        .lock()
+                        .unwrap()
                         .allocate_io_addresses(None, region_size, Some(0x4))
                         .ok_or(PciDeviceError::IoAllocationFailed(region_size))?;
                 }
@@ -476,6 +478,8 @@ impl VfioCommon {
 
                 // BAR allocation must be naturally aligned
                 bar_addr = allocator
+                    .lock()
+                    .unwrap()
                     .allocate_mmio_hole_addresses(None, region_size, Some(region_size))
                     .ok_or(PciDeviceError::IoAllocationFailed(region_size))?;
             }
@@ -1308,7 +1312,7 @@ const PCI_ROM_EXP_BAR_INDEX: usize = 12;
 impl PciDevice for VfioPciDevice {
     fn allocate_bars(
         &mut self,
-        allocator: &mut SystemAllocator,
+        allocator: &Arc<Mutex<SystemAllocator>>,
         mmio_allocator: &mut AddressAllocator,
     ) -> Result<Vec<(GuestAddress, GuestUsize, PciBarRegionType)>, PciDeviceError> {
         self.common

pci/src/vfio_user.rs

@@ -389,7 +389,7 @@ impl Vfio for VfioUserClientWrapper {
 impl PciDevice for VfioUserPciDevice {
     fn allocate_bars(
         &mut self,
-        allocator: &mut SystemAllocator,
+        allocator: &Arc<Mutex<SystemAllocator>>,
         mmio_allocator: &mut AddressAllocator,
     ) -> Result<Vec<(GuestAddress, GuestUsize, PciBarRegionType)>, PciDeviceError> {
         self.common

virtio-devices/src/transport/pci_device.rs

@@ -841,7 +841,7 @@ impl PciDevice for VirtioPciDevice {
 
     fn allocate_bars(
         &mut self,
-        allocator: &mut SystemAllocator,
+        allocator: &Arc<Mutex<SystemAllocator>>,
         mmio_allocator: &mut AddressAllocator,
     ) -> std::result::Result<Vec<(GuestAddress, GuestUsize, PciBarRegionType)>, PciDeviceError>
     {
@@ -865,6 +865,8 @@ impl PciDevice for VirtioPciDevice {
         } else {
             let region_type = PciBarRegionType::Memory32BitRegion;
             let addr = allocator
+                .lock()
+                .unwrap()
                 .allocate_mmio_hole_addresses(
                     self.settings_bar_addr,
                     CAPABILITY_BAR_SIZE,

vmm/src/device_manager.rs

@@ -3088,7 +3088,7 @@ impl DeviceManager {
             .lock()
             .unwrap()
             .allocate_bars(
-                &mut self.address_manager.allocator.lock().unwrap(),
+                &self.address_manager.allocator,
                 &mut self.pci_segments[segment_id as usize]
                     .allocator
                     .lock()