* wiggle: adapt Wiggle guest slices for `unsafe` shared use
When multiple threads can concurrently modify a WebAssembly shared
memory, the underlying data for a Wiggle `GuestSlice` and
`GuestSliceMut` could change due to access from other threads. This
breaks Rust guarantees when `&[T]` and `&mut [T]` slices are handed out.
This change modifies `GuestPtr` to make `as_slice` and `as_slice_mut`
return an `Option` which is `None` when the underlying WebAssembly
memory is shared.
But WASI implementations still need access to the underlying WebAssembly
memory, both to read to it and write from it. This change adds new APIs:
- `GuestPtr::to_vec` copies the bytes from WebAssembly memory (from
which we can safely take a `&[T]`)
- `GuestPtr::as_unsafe_slice_mut` returns a wrapper `struct` from which
we can `unsafe`-ly return a mutable slice (users must accept the
unsafety of concurrently modifying a `&mut [T]`)
This approach allows us to maintain Wiggle's borrow-checking
infrastructure, which enforces the guarantee that Wiggle will not modify
overlapping regions, e.g. This is important because the underlying
system calls may expect this. Though other threads may modify the same
underlying region, this is impossible to prevent; at least Wiggle will
not be able to do so.
Finally, the changes to Wiggle's API are propagated to all WASI
implementations in Wasmtime. For now, code locations that attempt to get
a guest slice will panic if the underlying memory is shared. Note that
Wiggle is not enabled for shared memory (that will come later in
something like #5054), but when it is, these panics will be clear
indicators of locations that must be re-implemented in a thread-safe
way.
* review: remove double cast
* review: refactor to include more logic in 'UnsafeGuestSlice'
* review: add reference to #4203
* review: link all thread-safe WASI fixups to #5235
* fix: consume 'UnsafeGuestSlice' during conversion to safe versions
* review: remove 'as_slice' and 'as_slice_mut'
* review: use 'as_unsafe_slice_mut' in 'to_vec'
* review: add `UnsafeBorrowResult`
* ci: replace OpenVINO installer action
To test wasi-nn, we currently use an OpenVINO backend. The Wasmtime CI
must install OpenVINO using a custom GitHub action. This CI action has
not been updated in some time and in the meantime OpenVINO (and the
OpenVINO crates) have released several new versions.
https://github.com/abrown/install-openvino-action is an external action
that we plan to keep up to date with the latest releases. This change
replaces the current CI action with that one.
* wasi-nn: upgrade openvino dependency to v0.4.1
This eliminates a `lazy_static` dependency and changes a few parameters
to pass by reference. Importantly, it enables support for the latest
versions of OpenVINO (v2022.*) in wasi-nn.
* ci: update wasi-nn script to source correct env script
* ci: really use the correct path for the env script
Also, clarify which directory OpenVINO is installed in (the symlink may
not be present).
Updates the OpenVINO backend for wasi-nn to pre-configure all inputs as `NHWC`. This is not a long-term fix but no worse than the status quo, which configures all input tensors to the same layout. This change updates the CI script to use the latest version of OpenVINO. Closes#3948.
Co-authored-by: Andrew Brown <andrew.brown@intel.com>
