remove automatic snapshot stack

Signed-off-by: Jorge Prendes <jorge.prendes@gmail.com>

Author: jprendes

src/hyperlight_host/src/mem/mgr.rs

@@ -15,7 +15,6 @@ limitations under the License.
 */
 
 use std::cmp::Ordering;
-use std::sync::{Arc, Mutex};
 
 use hyperlight_common::flatbuffer_wrappers::function_call::{
     FunctionCall, validate_guest_function_call_buffer,
@@ -34,7 +33,6 @@ use super::ptr::{GuestPtr, RawPtr};
 use super::ptr_offset::Offset;
 use super::shared_mem::{ExclusiveSharedMemory, GuestSharedMemory, HostSharedMemory, SharedMemory};
 use super::shared_mem_snapshot::SharedMemorySnapshot;
-use crate::HyperlightError::NoMemorySnapshot;
 use crate::sandbox::SandboxConfiguration;
 use crate::sandbox::uninitialized::GuestBlob;
 use crate::{Result, log_then_return, new_error};
@@ -75,9 +73,6 @@ pub(crate) struct SandboxMemoryManager<S> {
     pub(crate) entrypoint_offset: Offset,
     /// How many memory regions were mapped after sandbox creation
     pub(crate) mapped_rgns: u64,
-    /// A vector of memory snapshots that can be used to save and  restore the state of the memory
-    /// This is used by the Rust Sandbox implementation (rather than the mem_snapshot field above which only exists to support current C API)
-    snapshots: Arc<Mutex<Vec<SharedMemorySnapshot>>>,
 }
 
 impl<S> SandboxMemoryManager<S>
@@ -98,7 +93,6 @@ where
             load_addr,
             entrypoint_offset,
             mapped_rgns: 0,
-            snapshots: Arc::new(Mutex::new(Vec::new())),
         }
     }
 
@@ -288,39 +282,6 @@ where
         Ok(old_rgns - self.mapped_rgns)
     }
 
-    /// this function will create a memory snapshot and push it onto the stack of snapshots
-    /// It should be used when you want to save the state of the memory, for example, when evolving a sandbox to a new state
-    pub(crate) fn push_state(&mut self) -> Result<()> {
-        let snapshot = self.snapshot()?;
-        self.snapshots
-            .try_lock()
-            .map_err(|e| new_error!("Error locking at {}:{}: {}", file!(), line!(), e))?
-            .push(snapshot);
-        Ok(())
-    }
-
-    /// this function restores a memory snapshot from the last snapshot in the list but does not pop the snapshot
-    /// off the stack
-    /// It should be used when you want to restore the state of the memory to a previous state but still want to
-    /// retain that state, for example after calling a function in the guest
-    ///
-    /// Returns the number of memory regions mapped into the sandbox
-    /// that need to be unmapped in order for the restore to be
-    /// completed.
-    pub(crate) fn restore_state_from_last_snapshot(&mut self) -> Result<u64> {
-        let snapshots = self
-            .snapshots
-            .try_lock()
-            .map_err(|e| new_error!("Error locking at {}:{}: {}", file!(), line!(), e))?;
-        let last = snapshots.last();
-        let Some(snapshot) = last else {
-            log_then_return!(NoMemorySnapshot);
-        };
-        let old_rgns = self.mapped_rgns;
-        self.mapped_rgns = snapshot.restore_from_snapshot(&mut self.shared_mem)?;
-        Ok(old_rgns - self.mapped_rgns)
-    }
-
     /// Sets `addr` to the correct offset in the memory referenced by
     /// `shared_mem` to indicate the address of the outb pointer and context
     /// for calling outb function
@@ -446,15 +407,13 @@ impl SandboxMemoryManager<ExclusiveSharedMemory> {
                 load_addr: self.load_addr.clone(),
                 entrypoint_offset: self.entrypoint_offset,
                 mapped_rgns: 0,
-                snapshots: Arc::new(Mutex::new(Vec::new())),
             },
             SandboxMemoryManager {
                 shared_mem: gshm,
                 layout: self.layout,
                 load_addr: self.load_addr.clone(),
                 entrypoint_offset: self.entrypoint_offset,
                 mapped_rgns: 0,
-                snapshots: Arc::new(Mutex::new(Vec::new())),
             },
         )
     }

src/hyperlight_host/src/sandbox/initialized_multi_use.rs

@@ -124,9 +124,7 @@ impl MultiUseSandbox {
                 Output::TYPE,
                 args.into_value(),
             );
-            let ret = Output::from_value(ret?);
-            self.mem_mgr.unwrap_mgr_mut().push_state().unwrap();
-            ret
+            Output::from_value(ret?)
         })
     }
 
@@ -209,13 +207,11 @@ impl MultiUseSandbox {
         args: Vec<ParameterValue>,
     ) -> Result<ReturnValue> {
         maybe_time_and_emit_guest_call(func_name, || {
-            let ret = self.call_guest_function_by_name_no_reset(func_name, ret_type, args);
-            self.mem_mgr.unwrap_mgr_mut().push_state()?;
-            ret
+            self.call_guest_function_by_name_no_reset(func_name, ret_type, args)
         })
     }
 
-    pub(crate) fn call_guest_function_by_name_no_reset(
+    fn call_guest_function_by_name_no_reset(
         &mut self,
         function_name: &str,
         return_type: ReturnType,

src/hyperlight_host/src/sandbox/uninitialized_evolve.rs

@@ -129,19 +129,18 @@ where
 pub(super) fn evolve_impl_multi_use(u_sbox: UninitializedSandbox) -> Result<MultiUseSandbox> {
     evolve_impl(
         u_sbox,
-        |hf, mut hshm, vm, out_hdl, mem_hdl, dispatch_ptr| {
-            {
-                hshm.as_mut().push_state()?;
-            }
+        |hf, hshm, vm, out_hdl, mem_hdl, dispatch_ptr| {
+            #[cfg(gdb)]
+            let dbg_mem_wrapper = dbg_mem_access_handler_wrapper(hshm.clone());
             Ok(MultiUseSandbox::from_uninit(
                 hf,
-                hshm.clone(),
+                hshm,
                 vm,
                 out_hdl,
                 mem_hdl,
                 dispatch_ptr,
                 #[cfg(gdb)]
-                dbg_mem_access_handler_wrapper(hshm),
+                dbg_mem_wrapper,
             ))
         },
     )