When a total ordering between multiple atomic variables is not required
then use Ordering::Acquire with atomic loads and Ordering::Release with
atomic stores.
This will improve performance as this does not require a memory fence
on x86_64 which Ordering::SeqCst will use.
Add a comment to the code in the vCPU handling code where it operates on
multiple atomics to explain why Ordering::SeqCst is required.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
The DeviceNode cannot be fully represented as it embeds a Rust style
enum (i.e. with data) which is instead represented by a simple
associative array.
Fixes: #1167
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
When the x86 instruction decoder tells us about some missing bytes from
the instruction stream, we call into the platform fetch method and
emulate one last instruction.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
In preparation for the instruction fetching step, we modify the decoding
loop so that we can check what the last decoding error is.
We also switch to explictly using decode_out() which removes a 32 bytes
copy compared to decode().
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
In order to validate emulated memory accesses, we need to be able to get
all the segments descriptor attributes.
This is done by abstracting the SegmentRegister attributes through a
trait that each hypervisor will have to implement.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
We need to be able to build the CPU mode from its state in order to
start implementing mode related checks in the x86 emulator.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
If we rely on timeouts at the top level we can get builds being aborted
simply because they took too long to be scheduled rather than because
the actual integration tests took too long.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
The MockVMM platform will be used by other instructions emulation
implementations, but also by the emulator framework.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
The observation here is PlatformEmulator can be seen as the context for
emulation to take place. It should be rather easy to construct a context
that satisfies the lifetime constraints for instruction emulation.
The thread doing the emulation will have full ownership over the
context, so this removes the need to wrap PlatformEmulator in Arc and
Mutex, as well as the need for the context to be either Clone or Copy.
Signed-off-by: Wei Liu <liuwe@microsoft.com>
The emulator gets a CPU state from a CpuStateManager instance, emulates
the passed instructions stream and returns the modified CPU state.
The emulator is a skeleton for now since it comes with an empty
instruction mnemonic map.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
And an InstructionMap helper structure to map x86 mnemonic codes
to instruction handlers.
Any instruction emulation implementation should then boil down with
implementing InstructionHandler for any supported mnemonic.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Minimal will be defined by the amount of emulated instructions.
Carrying all GPRs, all CRs, segment registers and table registers should
cover quite a few instructions.
Co-developed-by: Wei Liu <liuwe@microsoft.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
For efficiently emulating x86 instructions, we need to build and pass a
CPU state copy/reference to instruction emulation handlers. Those handlers
will typically modify the CPU state and let the caller commit those
changes back through the PlatformEmulator trait set_cpu_state method.
Hypervisors typically have internal CPU state structures, that maps back
to the correspinding kernel APIs. By implementing the CpuState trait,
instruction emulators will be able to directly work on CPU state
instances that are directly consumable by the underlying hypervisor and
its kernel APIs.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
In order to emulate instructions, we need a way to get access to some of
the guest resources. The PlatformEmulator interface provides guest
memory and CPU state access to emulator implementations.
Typically, an hypervisor will implement PlatformEmulator for architecture
specific instruction emulators to build their framework on top of.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
We will need the GDT API for the hypervisor's x86 instruction
emulator implementation, it's better if the arch crate depends on the
hypervisor one rather than the other way around.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
The configuration is stored separately to the Vm in the VMM. The failure
to store the config was preventing the VM from shutting down correctly
as Vmm::vm_delete() checks for the presence of the config.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Rather return the None to the caller to handle instead. This removes the
source of a potential panic.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
