Allow reading persistent component slot via mgs

task/control-plane-agent/src/main.rs

@@ -159,6 +159,9 @@ enum MgsMessage {
         slot: u16,
         persist: bool,
     },
+    ComponentGetPersistentSlot {
+        component: SpComponent,
+    },
     SerialConsoleBreak,
     SendHostNmi,
     SetIpccKeyValue {

task/control-plane-agent/src/mgs_common.rs

@@ -429,6 +429,31 @@ impl MgsCommon {
         }
     }
 
+    pub(crate) fn component_get_persistent_slot(
+        &mut self,
+        component: SpComponent,
+    ) -> Result<u16, GwSpError> {
+        match component {
+            SpComponent::SP_ITSELF => {
+                Ok(self.update_sp.get_pending_boot_slot().into())
+            }
+            SpComponent::ROT => {
+                let slot = match self
+                    .sprot
+                    .rot_boot_info()?
+                    .persistent_boot_preference
+                {
+                    SpSlotId::A => 0,
+                    SpSlotId::B => 1,
+                };
+                Ok(slot)
+            }
+            // We know that the LPC55S69 RoT bootloader does not have switchable banks.
+            SpComponent::STAGE0 => Ok(0),
+            _ => Err(GwSpError::RequestUnsupportedForComponent),
+        }
+    }
+
     pub(crate) fn read_sensor(
         &mut self,
         req: SensorRequest,

task/control-plane-agent/src/mgs_compute_sled.rs

@@ -991,6 +991,22 @@ impl SpHandler for MgsHandler {
         }
     }
 
+    fn component_get_persistent_slot(
+        &mut self,
+        component: SpComponent,
+    ) -> Result<u16, SpError> {
+        ringbuf_entry_root!(Log::MgsMessage(
+            MgsMessage::ComponentGetPersistentSlot { component }
+        ));
+
+        match component {
+            SpComponent::HOST_CPU_BOOT_FLASH => {
+                self.host_flash_update.persistent_slot()
+            }
+            _ => self.common.component_get_persistent_slot(component),
+        }
+    }
+
     fn component_clear_status(
         &mut self,
         component: SpComponent,

task/control-plane-agent/src/mgs_psc.rs

@@ -490,6 +490,17 @@ impl SpHandler for MgsHandler {
             .component_set_active_slot(component, slot, persist)
     }
 
+    fn component_get_persistent_slot(
+        &mut self,
+        component: SpComponent,
+    ) -> Result<u16, SpError> {
+        ringbuf_entry_root!(Log::MgsMessage(
+            MgsMessage::ComponentGetPersistentSlot { component }
+        ));
+
+        self.common.component_get_persistent_slot(component)
+    }
+
     fn component_clear_status(
         &mut self,
         component: SpComponent,

task/control-plane-agent/src/mgs_sidecar.rs

@@ -967,6 +967,17 @@ impl SpHandler for MgsHandler {
             .component_set_active_slot(component, slot, persist)
     }
 
+    fn component_get_persistent_slot(
+        &mut self,
+        component: SpComponent,
+    ) -> Result<u16, SpError> {
+        ringbuf_entry_root!(Log::MgsMessage(
+            MgsMessage::ComponentGetPersistentSlot { component }
+        ));
+
+        self.common.component_get_persistent_slot(component)
+    }
+
     fn component_clear_status(
         &mut self,
         component: SpComponent,

task/control-plane-agent/src/update/host_flash.rs

@@ -75,13 +75,23 @@ impl HostFlashUpdate {
     }
 
     pub(crate) fn active_slot(&self) -> Result<u16, SpError> {
-        match self
-            .task
+        self.task
             .get_dev()
-            .map_err(|err| SpError::ComponentOperationFailed(err as u32))?
-        {
-            HfDevSelect::Flash0 => Ok(0),
-            HfDevSelect::Flash1 => Ok(1),
+            .map(Self::dev_to_slot)
+            .map_err(|err| SpError::ComponentOperationFailed(err as u32))
+    }
+
+    pub(crate) fn persistent_slot(&self) -> Result<u16, SpError> {
+        self.task
+            .get_persistent_data()
+            .map(|data| Self::dev_to_slot(data.dev_select))
+            .map_err(hf_to_gwhf)
+    }
+
+    fn dev_to_slot(dev: HfDevSelect) -> u16 {
+        match dev {
+            HfDevSelect::Flash0 => 0,
+            HfDevSelect::Flash1 => 1,
         }
     }