[PATCH v2 13/21] x86/virt/seamldr: Abort updates if errors occurred midway

[Chao Gao <chao.gao@intel.com>]

The TDX Module update process has multiple stages, each of which may
encounter failures.

The current state machine of updates proceeds to the next stage
regardless of errors. But continuing updates when errors occur midway
is pointless.

Add support of transitioning directly to the final stage on errors,
effectively aborting the update and skipping all remaining stages.

Signed-off-by: Chao Gao <chao.gao@intel.com>
Tested-by: Farrah Chen <farrah.chen@intel.com>
---
 arch/x86/virt/vmx/tdx/seamldr.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/arch/x86/virt/vmx/tdx/seamldr.c b/arch/x86/virt/vmx/tdx/seamldr.c
index b074630d42e3..fca558b90f72 100644
--- a/arch/x86/virt/vmx/tdx/seamldr.c
+++ b/arch/x86/virt/vmx/tdx/seamldr.c
@@ -235,6 +235,7 @@ enum tdp_state {
 static struct {
 	enum tdp_state state;
 	atomic_t thread_ack;
+	atomic_t failed;
 } tdp_data;
 
 static void set_target_state(enum tdp_state state)
@@ -249,8 +250,16 @@ static void set_target_state(enum tdp_state state)
 /* Last one to ack a state moves to the next state. */
 static void ack_state(void)
 {
-	if (atomic_dec_and_test(&tdp_data.thread_ack))
-		set_target_state(tdp_data.state + 1);
+	if (atomic_dec_and_test(&tdp_data.thread_ack)) {
+		/*
+		 * If an error occurred, abort the update by skipping to
+		 * the final state
+		 */
+		if (atomic_read(&tdp_data.failed))
+			set_target_state(TDP_DONE);
+		else
+			set_target_state(tdp_data.state + 1);
+	}
 }
 
 /*
@@ -273,6 +282,9 @@ static int do_seamldr_install_module(void *params)
 			default:
 				break;
 			}
+
+			if (ret)
+				atomic_inc(&tdp_data.failed);
 			ack_state();
 		} else {
 			touch_nmi_watchdog();
@@ -308,6 +320,7 @@ int seamldr_install_module(const u8 *data, u32 size)
 		return -EBUSY;
 	}
 
+	atomic_set(&tdp_data.failed, 0);
 	set_target_state(TDP_START + 1);
 	ret = stop_machine_cpuslocked(do_seamldr_install_module, params, cpu_online_mask);
 	if (ret)
-- 
2.47.3