Tags from firecracker

Firecracker v1.11.0

2025-03-18T14:29:45Z

Added

* [#4987](#4987): Reset
physical counter register (`CNTPCT_EL0`) on VM startup. This avoids VM reading
the host physical counter value. This is only possible on 6.4 and newer
kernels. For older kernels physical counter will still be passed to the guest
unmodified. See more info
[here](https://github.com/firecracker-microvm/firecracker/blob/main/docs/prod-host-setup.md#arm-only-vm-physical-counter-behaviour)
* [#5088](#5088): Added
AMD Genoa as a supported and tested platform for Firecracker.

Changed

* [#4913](#4913): Removed
unnecessary fields (`max_connections` and `max_pending_resets`) from the
snapshot format, bumping the snapshot version to 5.0.0. Users need to
regenerate snapshots.
* [#4926](#4926): Replace
underlying implementation for seccompiler from in house one in favor of
`libseccomp` which produces smaller and more optimized BPF code.

Deprecated

Removed

Fixed

* [#4921](#4921): Fixed
swagger `CpuConfig` definition to include missing aarch64-specific fields.
* [#4916](#4916): Fixed
`IovDeque` implementation to work with any host page size. This fixes
virtio-net device on non 4K host kernels.
* [#4991](#4991): Fixed
`mem_size_mib` and `track_dirty_pages` being mandatory for all
`PATCH /machine-config` requests. Now, they can be omitted which leaves these
parts of the machine configuration unchanged.
* [#5007](#5007): Fixed
watchdog softlockup warning on x86_64 guests when a vCPU is paused during GDB
debugging.
* [#5021](#5021) If a
balloon device is inflated post UFFD-backed snapshot restore, Firecracker now
causes `remove` UFFD messages to be sent to the UFFD handler. Previously, no
such message would be sent.
* [#5034](#5034): Fix an
integer underflow in the jailer when computing the value it passes to
Firecracker's `--parent-cpu-time-us` values, which caused development builds
of Firecracker to crash (but production builds were unaffected as underflows
do not panic in release mode).
* [#5045](#5045): Fixed
an issue where firecracker intermittently receives SIGHUP when using jailer
with `--new-pid-ns` but without `--daemonize`.
* [#4995](#4995):
Firecracker no longer overwrites CPUID leaf 0x80000000 when running AMD
hardware, meaning the guest can now discover a greater range of CPUID leaves
in the extended function range (this range is host kernel dependent).
* [#5046](#5046): Retry
KVM_CREATE_VM on EINTR that occasionally happen on heavily loaded hosts to
improve reliability of microVM creation.
* [#5052](#5052): Build
the empty seccomp policy as default for debug builds to avoid crashes on
syscalls introduced by debug assertions from Rust 1.80.0.

v1.12.0-dev

2025-03-04T14:13:18Z

Firecracker v1.10.1

2024-11-13T10:56:54Z

Changed

* [#4907](#4907): Bump
snapshot version to 4.0.0.

v1.11.0-dev

2024-11-07T12:09:32Z

Firecracker v1.10.0

2024-11-07T18:54:21Z

Added

* [#4834](#4834): Add
`VIRTIO_NET_F_RX_MRGBUF` support to the `virtio-net` device. When this feature
is negotiated, guest `virtio-net` driver can perform more efficient memory
management which in turn improves RX and TX performance.
* [#4460](#4460): Add a
call to
[`KVM_KVMCLOCK_CTRL`](https://docs.kernel.org/virt/kvm/api.html#kvm-kvmclock-ctrl)
after pausing vCPUs on x86_64 architectures. This ioctl sets a flag in the KVM
state of the vCPU indicating that it has been paused by the host userspace. In
guests that use kvmclock, the soft lockup watchdog checks this flag. If it is
set, it won't trigger the lockup condition. Calling the ioctl for guests that
don't use kvmclock will fail. These failures are not fatal. We log the failure
and increase the `vcpu.kvmclock_ctrl_fails` metric.
* [#4869](#4869): Added
support for Aarch64 systems which feature CPU caches with a number of sets
higher than `u16::MAX`.
* [#4797](#4797),
[#4854](#4854): Added
GDB debugging support for a microVM guest kernel. Please see our
[GDB debugging documentation](docs/gdb-debugging.md) for more information.

Changed

* [#4844](#4844): Upgrade
`virtio-net` device to use `readv` syscall to avoid unnecessary memory copies
on RX path, increasing the RX performance.

Deprecated

Removed

* [#4804](#4804): Drop
Support for guest kernel 4.14. Linux 4.14 reached end-of-life in
[January 2024](https://lore.kernel.org/lkml/2024011046-ecology-tiptoeing-ce50@gregkh/)
The minimum supported guest kernel now is 5.10.

Fixed

* [#4796](#4796): Fixed
Vsock not notifying guest about `TRANSPORT_RESET_EVENT` event after snapshot
restore. This resulted in guest waiting indefinitely on a connection which was
reset during snapshot creation.
* [#4790](#4790): v1.9.0
was missing most of the debugging information in the debuginfo file, due to a
change in the Cargo defaults. This has been corrected.
* [#4826](#4826): Add
missing configuration of tap offload features when restoring from a snapshot.
Setting the features was previously
[moved](49ed5ea)
from net device creation to device activation time, but it was not reflected
in the restore path. This was leading to inability to connect to the restored
VM if the offload features were used.

Firecracker v1.9.1

2024-11-26T17:15:23Z

Fixed

* [#4824](#4824): Add
missing configuration of tap offload features when restoring from a snapshot.
Setting the features was previously
[moved](49ed5ea)
from net device creation to device activation time, but it was not reflected
in the restore path. This was leading to inability to connect to the restored
VM if the offload features were used.
* [#4829](#4829): v1.9.0
was missing most of the debugging information in the debuginfo file, due to a
change in the Cargo defaults. This has been corrected.

Firecracker v1.9.0

2024-09-03T12:11:11Z

Added

* [#4687](#4687): Added
VMGenID support for microVMs running on ARM hosts with 6.1 guest kernels.
Support for VMGenID via DeviceTree bindings exists only on mainline 6.10 Linux
onwards. Users of Firecracker will need to backport the relevant patches on
top of their 6.1 kernels to make use of the feature.
* [#4732](#4732),
[#4733](#4733),
[#4741](#4741),
[#4746](#4746): Added
official support for 6.1 microVM guest kernels.

Changed

Deprecated

* Support for guest kernel 4.14 is now deprecated. We will completely remove
4.14 support with Firecracker version v1.10

Removed

* [#4689](#4689): Drop
support for host kernel 4.14. Linux 4.14 reached end-of-life in
[January 2024](https://lore.kernel.org/lkml/2024011046-ecology-tiptoeing-ce50@gregkh/).
The minimum supported kernel now is 5.10. Guest kernel 4.14 is still
supported.

Fixed

* [4680](#4680): Fixed an
issue
([#4659](#4659))
where the virtio-net device implementation would always assume the guest
accepts all VirtIO features the device offers. This is always true with the
Linux guest kernels we are testing but other kernels, like FreeBSD make
different assumptions. This PR fixes the emulation code to set the TAP
features based on the features accepted by the guest.

v1.10.0-dev

2024-08-30T12:42:48Z

Firecracker v1.8.0

2024-07-10T09:15:47Z

Added

* [#4428](#4428): Added
ACPI support to Firecracker for x86_64 microVMs. Currently, we pass ACPI
tables with information about the available vCPUs, interrupt controllers,
VirtIO and legacy x86 devices to the guest. This allows booting kernels
without MPTable support. Please see our
[kernel policy documentation](docs/kernel-policy.md) for more information
regarding relevant kernel configurations.
* [#4487](#4487): Added
support for the Virtual Machine Generation Identifier (VMGenID) device on
x86_64 platforms. VMGenID is a virtual device that allows VMMs to notify
guests when they are resumed from a snapshot. Linux includes VMGenID support
since version 5.18. It uses notifications from the device to reseed its
internal CSPRNG. Please refer to
[snapshot support](docs/snapshotting/snapshot-support.md) and
[random for clones](docs/snapshotting/random-for-clones.md) documention for
more info on VMGenID. VMGenID state is part of the snapshot format of
Firecracker. As a result, Firecracker snapshot version is now 2.0.0.

Changed

* [#4492](#4492): Changed
`--config` parameter of `cpu-template-helper` optional. Users no longer need
to prepare kernel, rootfs and Firecracker configuration files to use
`cpu-template-helper`.
* [#4537](#4537) Changed
T2CL template to pass through bit 27 and 28 of `MSR_IA32_ARCH_CAPABILITIES`
(`RFDS_NO` and `RFDS_CLEAR`) since KVM consider they are able to be passed
through and T2CL isn't designed for secure snapshot migration between
different processors.
* [#4537](#4537) Changed
T2S template to set bit 27 of `MSR_IA32_ARCH_CAPABILITIES` (`RFDS_NO`) to 1
since it assumes that the fleet only consists of processors that are not
affected by RFDS.
* [#4388](#4388): Avoid
setting `kvm_immediate_exit` to 1 if are already handling an exit, or if the
vCPU is stopped. This avoids a spurious KVM exit upon restoring snapshots.
* [#4567](#4567): Do not
initialize vCPUs in powered-off state upon snapshot restore. No functional
change, as vCPU initialization is only relevant for the booted case (where the
guest expects CPUs to be powered off).

Deprecated

* Firecracker's `--start-time-cpu-us` and `--start-time-us` parameters are
deprecated and will be removed in v2.0 or later. They are used by the jailer
to pass the value that should be subtracted from the (CPU) time, when emitting
the `start_time_us` and `start_time_cpu_us` metrics. These parameters were
never meant to be used by end customers, and we recommend doing any such time
adjustments outside Firecracker.
* Booting with microVM kernels that rely on MPTable on x86_64 is deprecated and
support will be removed in v2.0 or later. We suggest to users of Firecracker
to use guest kernels with ACPI support. For x86_64 microVMs, ACPI will be the
only way Firecracker passes hardware information to the guest once MPTable
support is removed.

Fixed

* [#4526](#4526): Added a
check in the network TX path that the size of the network frames the guest
passes to us is not bigger than the maximum frame the device expects to
handle. On the TX path, we copy frames destined to MMDS from guest memory to
Firecracker memory. Without the check, a mis-behaving virtio-net driver could
cause an increase in the memory footprint of the Firecracker process. Now, if
we receive such a frame, we ignore it and increase `Net::tx_malformed_frames`
metric.
* [#4536](#4536): Make
the first differential snapshot taken after a full snapshot contain only the
set of memory pages changed since the full snapshot. Previously, these
differential snapshots would contain all memory pages. This will result in
potentially much smaller differential snapshots after a full snapshot.
* [#4578](#4578): Fix
UFFD support not being forward-compatible with new ioctl options introduced in
Linux 6.6. See also
bytecodealliance/userfaultfd-rs#61.
* [#4630](#4630): On
x86_64, when taking a snapshot, if a vCPU has MSR_IA32_TSC_DEADLINE set to 0,
Firecracker will replace it with the MSR_IA32_TSC value from the same vCPU.
This is to guarantee that the vCPU will continue receiving TSC interrupts
after restoring from the snapshot even if an interrupt is lost when taking a
snapshot.
* [#4666](#4666): Fixed
Firecracker sometimes restoring `MSR_IA32_TSC_DEADLINE` before `MSR_IA32_TSC`.
Now it always restores `MSR_IA32_TSC_DEADLINE` MSR after `MSR_IA32_TSC`, as
KVM relies on the guest TSC for correct restoration of
`MSR_IA32_TSC_DEADLINE`. This fixed guests using the `TSC_DEADLINE` hardware
feature receiving incorrect timer interrupts after snapshot restoration, which
could lead to them seemingly getting stuck in sleep-related syscalls (see also
#4099).

v1.9.0-dev

2024-05-21T13:32:54Z