arch, vmm: Implement GIC Pausable trait

This commit implements the GIC (including both GICv3 and GICv3ITS)
Pausable trait. The pause of device manager will trigger a "pause"
of GIC, where we flush GIC pending tables and ITS tables to the
guest RAM.

Signed-off-by: Henry Wang <Henry.Wang@arm.com>

arch/src/aarch64/gic/gicv3.rs

@@ -109,9 +109,6 @@ pub mod kvm {
 
         /// Save the state of GIC.
         fn state(&self, gicr_typers: &[u64]) -> Result<Gicv3State> {
-            // Flush redistributors pending tables to guest RAM.
-            save_pending_tables(self.device()).map_err(Error::SavePendingTables)?;
-
             let gicd_ctlr =
                 read_ctlr(self.device()).map_err(Error::SaveDistributorCtrlRegisters)?;
 
@@ -255,7 +252,16 @@ pub mod kvm {
         }
     }
 
-    impl Pausable for KvmGicV3 {}
+    impl Pausable for KvmGicV3 {
+        fn pause(&mut self) -> std::result::Result<(), MigratableError> {
+            // Flush redistributors pending tables to guest RAM.
+            save_pending_tables(self.device()).map_err(|e| {
+                MigratableError::Pause(anyhow!("Could not save GICv3 GIC pending tables {:?}", e))
+            })?;
+
+            Ok(())
+        }
+    }
     impl Transportable for KvmGicV3 {}
     impl Migratable for KvmGicV3 {}
 }

arch/src/aarch64/gic/gicv3_its.rs

@@ -191,9 +191,6 @@ pub mod kvm {
 
         /// Save the state of GICv3ITS.
         fn state(&self, gicr_typers: &[u64]) -> Result<Gicv3ItsState> {
-            // Flush redistributors pending tables to guest RAM.
-            save_pending_tables(self.device()).map_err(Error::SavePendingTables)?;
-
             let gicd_ctlr =
                 read_ctlr(self.device()).map_err(Error::SaveDistributorCtrlRegisters)?;
 
@@ -206,10 +203,6 @@ pub mod kvm {
             let icc_state =
                 get_icc_regs(self.device(), gicr_typers).map_err(Error::SaveIccRegisters)?;
 
-            // Save GICv3ITS registers
-            gicv3_its_tables_access(self.its_device().unwrap(), true)
-                .map_err(Error::SaveITSTables)?;
-
             let its_baser_state: [u64; 8] = [0; 8];
             for i in 0..8 {
                 gicv3_its_attr_access(
@@ -501,7 +494,23 @@ pub mod kvm {
         }
     }
 
-    impl Pausable for KvmGicV3Its {}
+    impl Pausable for KvmGicV3Its {
+        fn pause(&mut self) -> std::result::Result<(), MigratableError> {
+            // Flush redistributors pending tables to guest RAM.
+            save_pending_tables(self.device()).map_err(|e| {
+                MigratableError::Pause(anyhow!(
+                    "Could not save GICv3ITS GIC pending tables {:?}",
+                    e
+                ))
+            })?;
+            // Flush ITS tables to guest RAM.
+            gicv3_its_tables_access(self.its_device().unwrap(), true).map_err(|e| {
+                MigratableError::Pause(anyhow!("Could not save GICv3ITS ITS tables {:?}", e))
+            })?;
+
+            Ok(())
+        }
+    }
     impl Transportable for KvmGicV3Its {}
     impl Migratable for KvmGicV3Its {}
 }