diff --git a/phd-tests/framework/src/guest_os/mod.rs b/phd-tests/framework/src/guest_os/mod.rs
index 7359deebd..246369a0f 100644
--- a/phd-tests/framework/src/guest_os/mod.rs
+++ b/phd-tests/framework/src/guest_os/mod.rs
@@ -99,6 +99,30 @@ pub enum GuestOsKind {
     WindowsServer2022,
 }
 
+impl GuestOsKind {
+    pub fn is_linux(&self) -> bool {
+        match self {
+            GuestOsKind::Alpine
+            | GuestOsKind::Debian11NoCloud
+            | GuestOsKind::Ubuntu2204 => true,
+            GuestOsKind::WindowsServer2016
+            | GuestOsKind::WindowsServer2019
+            | GuestOsKind::WindowsServer2022 => false,
+        }
+    }
+
+    pub fn is_windows(&self) -> bool {
+        match self {
+            GuestOsKind::WindowsServer2016
+            | GuestOsKind::WindowsServer2019
+            | GuestOsKind::WindowsServer2022 => true,
+            GuestOsKind::Alpine
+            | GuestOsKind::Debian11NoCloud
+            | GuestOsKind::Ubuntu2204 => false,
+        }
+    }
+}
+
 impl FromStr for GuestOsKind {
     type Err = std::io::Error;
 
diff --git a/phd-tests/framework/src/guest_os/windows.rs b/phd-tests/framework/src/guest_os/windows.rs
index 2c8f4d226..8da922532 100644
--- a/phd-tests/framework/src/guest_os/windows.rs
+++ b/phd-tests/framework/src/guest_os/windows.rs
@@ -37,6 +37,22 @@ pub(super) fn get_login_sequence_for<'a>(
     ));
 
     let mut commands = vec![
+        // Look for `BdsDxe:` as a sign that we're actually seeing a fresh boot.
+        // This is not terribly important in the case of a first boot, but in a
+        // case such as logging out and waiting for reboot, exiting a cmd.exe
+        // session causes Windows to redraw its previous screen - everything
+        // past `Computer is booting, ...` below.
+        //
+        // A test that tries to boot and wait for a new login sequence would
+        // then incorrectly identify the already-booted VM as the freshly-booted
+        // OS it was waiting for, log in again, and at some point later finally
+        // actually reboot.
+        //
+        // At least on Windows Server 2022, there is an XML prelude that is
+        // printed to COM1 that we could look for here, but check for `BdsDxe: `
+        // instead as that comes from OVMF and will be consistent regardless of
+        // guest OS version.
+        CommandSequenceEntry::wait_for("BdsDxe: loading "),
         CommandSequenceEntry::wait_for(
             "Computer is booting, SAC started and initialized.",
         ),
diff --git a/phd-tests/tests/src/boot_order.rs b/phd-tests/tests/src/boot_order.rs
index 89f640390..0e5af8f2b 100644
--- a/phd-tests/tests/src/boot_order.rs
+++ b/phd-tests/tests/src/boot_order.rs
@@ -98,6 +98,9 @@ async fn configurable_boot_order(ctx: &Framework) {
     // We haven't specified a boot order. So, we'll expect that we boot to the
     // lower-numbered PCI device (4) and end up in Alpine 3.20.
     let mut vm = ctx.spawn_vm(&cfg, None).await?;
+    if !vm.guest_os_kind().is_linux() {
+        phd_skip!("boot order tests require efivarfs to manipulate UEFI vars");
+    }
     vm.launch().await?;
     vm.wait_to_boot().await?;
 
@@ -162,6 +165,9 @@ async fn unbootable_disk_skipped(ctx: &Framework) {
     cfg.boot_order(vec!["unbootable", "boot-disk"]);
 
     let mut vm = ctx.spawn_vm(&cfg, None).await?;
+    if !vm.guest_os_kind().is_linux() {
+        phd_skip!("boot order tests require efivarfs to manipulate UEFI vars");
+    }
     vm.launch().await?;
     vm.wait_to_boot().await?;
 
@@ -279,6 +285,9 @@ async fn guest_can_adjust_boot_order(ctx: &Framework) {
     cfg.boot_order(vec!["boot-disk", "unbootable"]);
 
     let mut vm = ctx.spawn_vm(&cfg, None).await?;
+    if !vm.guest_os_kind().is_linux() {
+        phd_skip!("boot order tests require efivarfs to manipulate UEFI vars");
+    }
     vm.launch().await?;
     vm.wait_to_boot().await?;
 
@@ -446,6 +455,9 @@ async fn boot_order_source_priority(ctx: &Framework) {
     cfg.clear_boot_order();
 
     let mut vm_no_bootorder = ctx.spawn_vm(&cfg, None).await?;
+    if !vm_no_bootorder.guest_os_kind().is_linux() {
+        phd_skip!("boot order tests require efivarfs to manipulate UEFI vars");
+    }
     vm_no_bootorder.launch().await?;
     vm_no_bootorder.wait_to_boot().await?;
 
diff --git a/phd-tests/tests/src/crucible/smoke.rs b/phd-tests/tests/src/crucible/smoke.rs
index 2955d8bdc..a27134579 100644
--- a/phd-tests/tests/src/crucible/smoke.rs
+++ b/phd-tests/tests/src/crucible/smoke.rs
@@ -37,10 +37,7 @@ async fn guest_reboot_test(ctx: &Framework) {
     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?;
+    vm.graceful_reboot().await?;
 }
 
 #[phd_testcase]
diff --git a/phd-tests/tests/src/disk.rs b/phd-tests/tests/src/disk.rs
index 1db141c90..aac22a3f3 100644
--- a/phd-tests/tests/src/disk.rs
+++ b/phd-tests/tests/src/disk.rs
@@ -25,6 +25,9 @@ async fn in_memory_backend_smoke_test(ctx: &Framework) {
     );
 
     let mut vm = ctx.spawn_vm(&cfg, None).await?;
+    if vm.guest_os_kind().is_windows() {
+        phd_skip!("this test uses mount options not supported by Cygwin");
+    }
     vm.launch().await?;
     vm.wait_to_boot().await?;
 
diff --git a/phd-tests/tests/src/smoke.rs b/phd-tests/tests/src/smoke.rs
index 5537e19eb..592145b60 100644
--- a/phd-tests/tests/src/smoke.rs
+++ b/phd-tests/tests/src/smoke.rs
@@ -30,10 +30,7 @@ async fn guest_reboot_test(ctx: &Framework) {
     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?;
+    vm.graceful_reboot().await?;
 }
 
 #[phd_testcase]