diff --git a/lib/propolis/src/block/attachment.rs b/lib/propolis/src/block/attachment.rs
index 790ad14cd..2e521049f 100644
--- a/lib/propolis/src/block/attachment.rs
+++ b/lib/propolis/src/block/attachment.rs
@@ -66,13 +66,14 @@ impl BlockData {
                 }
                 Err(err) => match err {
                     ReqError::NonePending | ReqError::Paused => {
-                        let guard = self.lock.lock().unwrap();
                         // Double-check for attachment-related "error"
                         // conditions under protection of the lock before
                         // finally blocking.
-                        if check_state(att_state).is_err() {
+                        let guard = self.lock.lock().unwrap();
+                        if !att_state.is_attached() || att_state.is_stopped() {
                             return None;
                         }
+
                         let _guard = self.cv.wait(guard).unwrap();
                         continue;
                     }
diff --git a/phd-tests/framework/src/serial/raw_buffer.rs b/phd-tests/framework/src/serial/raw_buffer.rs
index d432dfebe..01fcda562 100644
--- a/phd-tests/framework/src/serial/raw_buffer.rs
+++ b/phd-tests/framework/src/serial/raw_buffer.rs
@@ -95,7 +95,8 @@ impl RawBuffer {
             "checking wait on raw serial buffer"
         );
         if let Some(idx) = self.wait_buffer.rfind(&waiter.wanted) {
-            let out = self.wait_buffer[..idx].to_owned();
+            let out = self.wait_buffer.drain(..idx).collect();
+            self.wait_buffer = self.wait_buffer.split_off(waiter.wanted.len());
 
             // Because incoming bytes from Propolis may be processed on a
             // separate task than the task that registered the wait, this
@@ -152,3 +153,66 @@ impl Drop for RawBuffer {
         }
     }
 }
+
+#[cfg(test)]
+mod test {
+    use tokio::sync::oneshot;
+
+    use super::*;
+
+    fn make_buffer() -> RawBuffer {
+        let file =
+            std::fs::OpenOptions::new().write(true).open("/dev/null").unwrap();
+
+        RawBuffer {
+            log: std::io::BufWriter::new(file),
+            line_buffer: String::new(),
+            wait_buffer: String::new(),
+            waiter: None,
+            parser: Parser::new(),
+        }
+    }
+
+    #[tokio::test]
+    async fn successful_wait_consumes_buffer_contents() {
+        let mut buf = make_buffer();
+        let (tx, mut rx) = oneshot::channel();
+        buf.push_str("the quick brown fox jumped over the lazy propolis");
+        buf.satisfy_or_set_wait(OutputWaiter {
+            wanted: "jumped over".to_string(),
+            preceding_tx: tx,
+        });
+        assert_eq!(rx.try_recv().unwrap(), "the quick brown fox ");
+        assert_eq!(buf.wait_buffer, " the lazy propolis");
+
+        // Repeat the test, but register the wait before the characters are
+        // pushed.
+        buf.clear();
+        let (tx, mut rx) = oneshot::channel();
+        buf.satisfy_or_set_wait(OutputWaiter {
+            wanted: "jumped over".to_string(),
+            preceding_tx: tx,
+        });
+        buf.push_str("the quick brown fox jumped over the lazy propolis");
+        assert_eq!(rx.try_recv().unwrap(), "the quick brown fox ");
+        assert_eq!(buf.wait_buffer, " the lazy propolis");
+    }
+
+    #[tokio::test]
+    async fn successful_wait_consumes_last_match() {
+        let mut buf = make_buffer();
+        let (tx, mut rx) = oneshot::channel();
+        buf.push_str(
+            "I put some Oxide in your Oxide so you can Oxide while you Oxide",
+        );
+        buf.satisfy_or_set_wait(OutputWaiter {
+            wanted: "you".to_string(),
+            preceding_tx: tx,
+        });
+        assert_eq!(
+            rx.try_recv().unwrap(),
+            "I put some Oxide in your Oxide so you can Oxide while "
+        );
+        assert_eq!(buf.wait_buffer, " Oxide");
+    }
+}
diff --git a/phd-tests/framework/src/test_vm/mod.rs b/phd-tests/framework/src/test_vm/mod.rs
index 03b8f24f9..a4b16f4b3 100644
--- a/phd-tests/framework/src/test_vm/mod.rs
+++ b/phd-tests/framework/src/test_vm/mod.rs
@@ -849,7 +849,7 @@ impl TestVm {
 
     /// Sends `string` to the guest's serial console worker, then waits for the
     /// entire string to be sent to the guest before returning.
-    pub(crate) async fn send_serial_str(&self, string: &str) -> Result<()> {
+    pub async fn send_serial_str(&self, string: &str) -> Result<()> {
         if !string.is_empty() {
             self.send_serial_bytes(Vec::from(string.as_bytes()))?.await?;
         }
diff --git a/phd-tests/tests/src/crucible/smoke.rs b/phd-tests/tests/src/crucible/smoke.rs
index 44eafc052..2955d8bdc 100644
--- a/phd-tests/tests/src/crucible/smoke.rs
+++ b/phd-tests/tests/src/crucible/smoke.rs
@@ -16,6 +16,33 @@ async fn boot_test(ctx: &Framework) {
     vm.wait_to_boot().await?;
 }
 
+#[phd_testcase]
+async fn api_reboot_test(ctx: &Framework) {
+    let mut config = ctx.vm_config_builder("crucible_guest_reboot_test");
+    super::add_default_boot_disk(ctx, &mut config)?;
+
+    let mut vm = ctx.spawn_vm(&config, None).await?;
+    vm.launch().await?;
+    vm.wait_to_boot().await?;
+    vm.reset().await?;
+    vm.wait_to_boot().await?;
+}
+
+#[phd_testcase]
+async fn guest_reboot_test(ctx: &Framework) {
+    let mut config = ctx.vm_config_builder("crucible_guest_reboot_test");
+    super::add_default_boot_disk(ctx, &mut config)?;
+
+    let mut vm = ctx.spawn_vm(&config, None).await?;
+    vm.launch().await?;
+    vm.wait_to_boot().await?;
+
+    // Don't use `run_shell_command` because the guest won't echo another prompt
+    // after this.
+    vm.send_serial_str("reboot\n").await?;
+    vm.wait_to_boot().await?;
+}
+
 #[phd_testcase]
 async fn shutdown_persistence_test(ctx: &Framework) {
     let mut config =
diff --git a/phd-tests/tests/src/smoke.rs b/phd-tests/tests/src/smoke.rs
index 8a797afae..9095e0c6d 100644
--- a/phd-tests/tests/src/smoke.rs
+++ b/phd-tests/tests/src/smoke.rs
@@ -15,6 +15,27 @@ async fn nproc_test(ctx: &Framework) {
     assert_eq!(nproc.parse::<u8>().unwrap(), 6);
 }
 
+#[phd_testcase]
+async fn api_reboot_test(ctx: &Framework) {
+    let mut vm = ctx.spawn_default_vm("api_reboot_test").await?;
+    vm.launch().await?;
+    vm.wait_to_boot().await?;
+    vm.reset().await?;
+    vm.wait_to_boot().await?;
+}
+
+#[phd_testcase]
+async fn guest_reboot_test(ctx: &Framework) {
+    let mut vm = ctx.spawn_default_vm("guest_reboot_test").await?;
+    vm.launch().await?;
+    vm.wait_to_boot().await?;
+
+    // Don't use `run_shell_command` because the guest won't echo another prompt
+    // after this.
+    vm.send_serial_str("reboot\n").await?;
+    vm.wait_to_boot().await?;
+}
+
 #[phd_testcase]
 async fn instance_spec_get_test(ctx: &Framework) {
     let mut vm = ctx