We ran the Microsoft Windows installer in CHV (via network + VNC) and
the installation always failed when the installer wanted to write the
partition table. Since recently, for very good reason, sector 0 writes
are disabled if the image type is not set explicitly and only
implicitly auto-detected as raw [0].
To ease troubleshooting, I've added a descriptive log message. It is a
little spammy, but it is what is required to help users to troubleshoot.
[0] 6ecdf90e22
Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com
Signal the guest before processing queue submissions to enable
earlier guest side completion event handling, reducing end-to-end
latency for block device operations.
FIO benchmarks show up to 7.4% bandwidth improvement at 16
iodepth and 4k block size with NVMe devices.
Signed-off-by: wuxinyue <wuxinyue.wxy@antgroup.com>
Both process_input_queue and process_output_queue were only processing
the first descriptor of a chain, leading to data loss if the driver used
chained descriptors.
This change iterates through all descriptors in a chain. It also moves
the flush call out of the descriptor loops to improve performance.
Signed-off-by: Andrei Vagin <avagin@google.com>
For a transmit queue (guest to host), the host only reads from the
guest-provided buffers and does not write to them. According to the
virtio specification (e.g., Section 2.6.8 in Virtio 1.1), the 'len'
field in the used ring has to be set to the number of bytes written to
the buffers. Therefore, it should be 0 for the console transmit queue.
Signed-off-by: Andrei Vagin <avagin@google.com>
The update_console_size method was using fetch_and on the acked_features
atomic, which modified the atomic and cleared other feature bits.
Changed it to use a non-destructive load and bitwise AND.
Signed-off-by: Andrei Vagin <avagin@google.com>
Add a per-disk lock_granularity parameter that lets users choose
between byte-range OFD locks and whole-file OFD locks:
--disk path=/foo.img,lock_granularity=byte-range
--disk path=/bar.img,lock_granularity=full
Byte-range is the default and matches QEMU behavior, working
best with storage backends where whole-file OFD locks are treated
as mandatory. The full option restores the original whole-file
locking for environments that depend on it.
The LockGranularityChoice enum and its FromStr impl live in the
block crate alongside the existing LockGranularity type. The
Block device converts the user-facing choice to the internal
LockGranularity at lock time, keeping device_manager.rs simple.
Closes: #7553
Signed-off-by: Victor Vieux <vieux@repl.it>
Rename the transport feature bit constant from
VIRTIO_F_IOMMU_PLATFORM to VIRTIO_F_ACCESS_PLATFORM across
the entire virtio-devices crate.
The virtio specification as of v1.1 carries bit 33 as
VIRTIO_F_ACCESS_PLATFORM. The Linux kernel UAPI header
<linux/virtio_config.h> carries VIRTIO_F_IOMMU_PLATFORM
only as a backward-compatible alias.
This is a pure rename with no functional or behavioral
change.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Fix the _reserved field in VirtioIommuConfig from [u8; 7] to
[u8; 3], correcting the struct size from 44 bytes to the
spec-mandated 40 bytes.
The virtio specification v1.2, Section 5.13.4 defines struct
virtio_iommu_config as 40 bytes total.
The kernel UAPI header linux/virtio_iommu.h matches this
layout with __u8 reserved[3] since kernel 5.17. Prior to that,
the struct was 36 bytes with no bypass field at all.
The incorrect [u8; 7] made the packed struct 44 bytes. Since
the struct is exposed to the guest, the guest saw a 44 byte
device specific configuration region instead of 40 bytes.
While well behaved guest drivers only access fields at known
offsets and would not observe data corruption from the extra
4 zero bytes at the tail, the oversized config region is a
spec violation.
The write_config path is not affected because it validates
the exact offset of the bypass field before allowing writes,
and the bypass field sits at offset 36 regardless of the
trailing reserved size.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
This implements a generic vhost-user device. All information about this
device must be provided to Cloud Hypervisor via the command-line or API.
The main use-case is types of vhost-user devices Cloud Hypervisor
doesn't know about, but it can also be used for types it does know
about.
The generic device delegates all configuration space handling to the
backend. This means that the vhost-user backend must support
configuration space access. It also means that the backend has control
of configuration space. For instance, this means that setting the tag
of a virtio-fs device on the virtiofsd command line works as expected.
If the VM is snapshotted or migrated, the backend must write the
configuration space to a separate save file or migration stream.
Similarly, if the VM is restored or migrated, the backend must read the
configuration space from a separate save file or migration stream.
Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
As well as rejecting writes to sector 0 in the case of raw files where
the user hasn't specified the image_type also reject virtio requests of
type discard and write_zeroes.
Signed-off-by: Rob Bradford <rbradford@meta.com>
If the disk image was autodetected to raw (not specified with image_type
= 0) then in the virtio-block subsystem generate errors for writes to
block 0 (treat as if read-only). This gives an immediate error vs using
the image implementations in the block subsystem.
Signed-off-by: Rob Bradford <rbradford@meta.com>
Unlike most virtio feature bits, VIRTIO_BLK_F_RO is not optional.
It indicates that the host is refusing to permit write operations, and
the guest must not be allowed to override it.
However, the block device currently does not enforce this. If the guest
does not negotiate VIRTIO_BLK_F_RO, the block device will think the
device is writable and forward write requests to the backend.
This is not a security problem right now because the backing device of a
read-only device is always opened read-only. The kernel will thus
reject the write operations with EBADF. If support is added for
receiving the backing device file descriptor via SCM_RIGHTS (#7704),
it will be possible to have a read-only block device backed by a
writable file descriptor. This would make the bug a genuine security
vulnerability.
Fix the bug by explicitly checking if VIRTIO_BLK_F_RO was offered but
not negotiated. In this case, log a warning and proceed as if the guest
did acknowledge the feature. This always indicates a guest driver bug.
Fixes: #7697
Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
OVMF sends FLUSH requests to read-only virtio-block devices. Refusing
these requests prevents OVMF from accessing the EFI System Partition and
therefore makes VMs unable to boot. Accept these requests instead.
them.
Ignoring these requests is possible, but inconsistent with fsync(2)
which honors them.
Fixes: #7698
Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
Add supports_zero_flag() to DiskFile trait to indicate whether a disk
format can mark clusters/blocks as reading zeros without deallocating
storage.
QCOW2 supports this via the zero flag in L2 entries. VHDX also has
PAYLOAD_BLOCK_ZERO state for this, though it's not yet implemented in
cloud-hypervisor.
This enables DISCARD to be advertised even with sparse=false for formats
with zero-flag support, since they can mark regions as zeros (keeps
storage allocated) instead of requiring full deallocation.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Add sparse boolean configuration option to DiskConfig with a default
value of true to control disk space allocation behavior.
When sparse is true, the disk uses sparse allocation where deallocated
blocks are returned to the filesystem, and the DISCARD feature is
advertised to the guest.
When sparse is false, disk space is kept fully allocated and DISCARD
is not advertised.
WRITE_ZEROES is always advertised when the backend supports it,
regardless of the sparse setting.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Add capability query to DiskFile trait to check backend
support for sparse operations (punch hole, write zeroes,
discard). Only advertise VIRTIO_BLK_F_DISCARD and
VIRTIO_BLK_F_WRITE_ZEROES when the backend supports these
operations.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Instead of closing a file descriptor that belongs to the vhost-user
frontend, drop the vu_common_ctrl::VhostUserHandle and the
vhost::vhost_user::Frontend it contains. This causes the destructor to
drop the file descriptor.
This breaks the last DPDK test, so disable it. See #7689.
Fixes: #7163
Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
Since kernel commit 6693731487a8 ("vsock/virtio: Allocate nonlinear SKBs
for handling large transmit buffers"), a large vsock packet can be split
into multiple descriptors.
If we encounter such TX packets, pull the content into an owned buffer.
Fixes: #7672
Signed-off-by: Wei Liu <liuwe@microsoft.com>
This adds some missing features that are useful. In particular it adds
VIRTIO_F_RING_INDIRECT_DESC which gives a performance improvement.
Signed-off-by: Rob Bradford <rbradford@meta.com>
Reported-by: Daniel Farina <daniel@ubicloud.com>
VsockPacket::hdr holds a raw pointer to the address of the VSock packet
header, which is in guest memory. It opens the door to double-fetch
(or TOCTOU) race conditions. Therefore, VSockPacket::hdr content can't
be trusted since it can be arbitrarily changed by the guest, at any
time.
To mitigate this, we can copy the header content to an array in VMM's
memory that the guest can't modify.
Signed-off-by: Thomas Leroy <thomas.leroy.mp@gmail.com>
Based upon the discussion and in
https://github.com/rust-vmm/vhost/issues/29#issue-830820820 and the QEMU
behaviour the get_config offset should be zero. This was not caught by
our integration tests as the vhost-user-blk backend as implemented in
this repository does not use the offset.
Fixes: #7615
Signed-off-by: Rob Bradford <rbradford@meta.com>
It should always succeed and is apparently implicitly called by libc or
some dependency somewhere.
Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
This change is a prerequisite for live disk resizing. Before this
commit, the epoll-handler threads just got a copy of the sector
size which we cannot update during runtime.
On-behalf-of: SAP thomas.prescher@sap.com
Signed-off-by: Thomas Prescher <thomas.prescher@cyberus-technology.de>
Add fcntl to virtio_block_thread_rules to allow try_clone() on file
descriptors. The try_clone() method uses fcntl(fd, F_DUPFD_CLOEXEC)
to duplicate file descriptors, which is needed for efficient QCOW2
L1 table sync that avoids temporary allocations.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
https://github.com/cloud-hypervisor/cloud-hypervisor/pull/7294 adjusted
the checks for read-only requests made to virtio-blk devices and started
rejecting VIRTIO_BLK_T_GET_ID requests. These requests do not perform
any writes and are needed in order to access device serials from within
the guest.
Signed-off-by: Connor Brewster <cbrewster@hey.com>
This is a follow-up of [0].
# Advantages
- This saves dozens of unneeded clone()s across the whole code base
- Makes it much easier to reason about how parameters are used
(often we passed owned Arc/Rc versions without actually needing
ownership)
# Exceptions
For certain code paths, the alternatives would require awkward or overly
complex code, and in some cases the functions are the logical owners of
the values they take. In those cases, I've added
#[allow(clippy::needless_pass_by_value)].
This does not mean that one should not improve this in the future.
[0] 6a86c157af
Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com
This helps to uncover expensive and needless clones in the code base.
For example, I prevented extensive clones in the snapshot path where
(nested) BTreeMap's have been cloned over and over again. Further,
the lint helps devs to much better reason about the ownership of
parameters.
All of these changes have been done manually with the necessary
caution. A few structs that are cheap to clone are now `copy` so that
this lint won't trigger for them.
I didn't enable the lint so far as it is a massive rabbit hole and
needs much more fixes. Nevertheless, it is very useful.
Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com
The granularity has significant implications in typical cloud
deployments with network storage. The Linux kernel will sync advisory
locks to network file systems, but these backends may have different
policies and handle locks differently. For example, Netapp speaks a NFS
API but will treat advisory OFD locks for the whole file as mandatory
locks, whereas byte-range locks for the whole file will remain
advisory [0].
As it is a valid use case to prevent multiple CHV instances from
accessing the same disk but disk management software (e.g., Cinder in
OpenStack) should be able to snapshot disks while VMs are running, we
need special control over the lock granularity. Therefore, it is a valid
use case to lock the whole byte range of a disk image without
technically locking the whole file - to get the best of both worlds.
This also brings CHVs behavior in line with QEMU [1].
Whole-file locks remain a valid use case and could be supported later.
This patch only provides the necessary groundwork; making it
configurable is out of scope for now.
[0] https://kb.netapp.com/on-prem/ontap/da/NAS/NAS-KBs/How_is_Mandatory_Locking_supported_for_NFSv4_on_ONTAP_9
[1] <qemu>/util/osdep.c::qemu_lock_fcntl()
Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com
This should be guaranteed by GuestMemory and GuestMemoryRegion, but
those traits are currently safe, so add checks to guard against
incorrect implementations of them.
Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
Callers of get_host_address_range() rely on it returning a pointer to at
least size bytes of memory. mem.get_host_address() is an overrideable
method of a safe trait, so it is better for safe code to not rely on its
correctness for safety. Instead, use mem.get_slice(), which returns a
VolatileSlice whose invariants guarantee that it points to a sufficient
amount of memory. If mem.check_range() succeeds but mem.get_slice()
returns a slice that is too small, this means that there is either a
logic error or a situation the code cannot support yet, so panic.
Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
This API passes a u64 to a kernel API that treats the u64 as a userspace
address. Therefore, it should be marked unsafe, but it currently is not
[1]. Wrap the call in an unsafe block to document that invariants must
be upheld to avoid undefined behavior. This causes a compiler warning,
so suppress the warning with #[allow(unused_unsafe)].
[1]: https://github.com/rust-vmm/vfio/issues/100
Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
I believe that its only caller used it safely, but it is still better to
mark the code as unsafe. Also add additional validity checks.
Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
To ensure that struct sizes are the same on 32-bit and 64-bit, various
kernel APIs use __u64 (Rust u64) to represent userspace pointers.
Userspace is expected to cast pointers to __u64 before passing them to
the kernel, and cast kernel-provided __u64 to a pointer before using
them. However, various safe APIs in Cloud Hypervisor took
caller-provided u64 values and passed them to syscalls that interpret
them as userspace addresses. Therefore, passing bad u64 values would
cause memory disclosure or corruption.
Fix the bug by using usize and pointer types as appropriate. To make
soundness of the code easier to reason about, the PCI code gains a new
MmapRegion abstraction that ensures the validity of pointers. The rest
of the code already has an MmapRegion abstraction it can use. To avoid
having to reason about whether something is keeping the MmapRegion
alive, reference counting is added. MmapRegion cannot hold references
to other objects, so the reference counting cannot introduce cycles.
Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
This better aligns with the rest of the code and makes it clearer
that these tests can run "as is" in a normal hosted environments
without the special test environment.
Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com
A major improvement to the developer experience of clippy in
Cloud Hypervisor.
1. Make `cargo clippy` just work with the same lints we use in CI
2. Simplify adding new lints
Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com
This would be a good opportunity to optimize another pointless vector
away, but I don't have a good way to test this at the moment. But
maybe someone else gives it a shot.
On-behalf-of: SAP julian.stecklina@sap.com
Signed-off-by: Julian Stecklina <julian.stecklina@cyberus-technology.de>
as of rust 1.90, writes to unix socket streams use send_with_flags
instead of write, so it uses a sendto syscall instead of write.
Signed-off-by: Matt Moriarity <matt@mattmoriarity.com>
