hyp: Refactor HypervisorCap to harden backends
The Hypervisor trait previously required backends to implement all of
its functions, even when they related to features that their underlying
hypervisor did not implement. To deal with this, capabilities were
introduced so that client code would conditionally call those functions
based on the availability of the feature (discovered through the
capabilities). This resulted in useless boiler-plate code in the
backends (either using unimplemented()! or returning placeholders to
please the caller) and a high risk of making use of unavailable features
in hypervisor-agnostic client code.
Instead, rework Hypervisor as an Inlineable Dyn Extension Trait [1],
making it programmatically impossible to call a function for a feature
that the running hypervisor doesn't provide. This also removes the need
for any boilerplate code in the backends.
Introduce the accessors get_mmio_guard() and get_mem_sharer().
No functional change intended.
[1]: https://github.com/daniel5151/inlinable-dyn-extension-traits/blob/master/writeup.md
Test: atest DebugPolicyHostTests#testNoAdbInDebugPolicy_withDebugLevelNone_boots
Test: atest rialto_test vmbase_example.integration_test
Change-Id: I6404fa141f53d074c9529403c4606ab90867cf6c
diff --git a/libs/hyp/src/lib.rs b/libs/hyp/src/lib.rs
index 3b3b30a..486a181 100644
--- a/libs/hyp/src/lib.rs
+++ b/libs/hyp/src/lib.rs
@@ -21,8 +21,6 @@
mod util;
pub use error::{Error, Result};
-pub use hypervisor::{
- get_hypervisor, Hypervisor, HypervisorCap, KvmError, MMIO_GUARD_GRANULE_SIZE,
-};
+pub use hypervisor::{get_mem_sharer, get_mmio_guard, KvmError, MMIO_GUARD_GRANULE_SIZE};
use hypervisor::GeniezoneError;