After shutting down the running TDX module, the next step is to install the
new TDX Module supplied by userspace.

P-SEAMLDR provides the SEAMLDR.INSTALL SEAMCALL for that. The SEAMCALL
accepts the seamldr_params struct and should be called serially on all
CPUs.

Invoke the SEAMLDR.INSTALL SEAMCALL serially on all CPUs and add a new
spinlock to enforce serialization.

Signed-off-by: Chao Gao <chao.gao@intel.com>
Tested-by: Farrah Chen <farrah.chen@intel.com>
---
 arch/x86/virt/vmx/tdx/seamldr.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/arch/x86/virt/vmx/tdx/seamldr.c b/arch/x86/virt/vmx/tdx/seamldr.c
index b497fa72ebb6..13c34e6378e0 100644
--- a/arch/x86/virt/vmx/tdx/seamldr.c
+++ b/arch/x86/virt/vmx/tdx/seamldr.c
@@ -13,6 +13,7 @@
 #include <linux/mm.h>
 #include <linux/nmi.h>
 #include <linux/slab.h>
+#include <linux/spinlock.h>
 #include <linux/stop_machine.h>
 #include <linux/types.h>
 
@@ -23,6 +24,7 @@
 
 /* P-SEAMLDR SEAMCALL leaf function */
 #define P_SEAMLDR_INFO			0x8000000000000000
+#define P_SEAMLDR_INSTALL		0x8000000000000001
 
 /* P-SEAMLDR can accept up to 496 4KB pages for TDX module binary */
 #define SEAMLDR_MAX_NR_MODULE_4KB_PAGES	496
@@ -45,6 +47,7 @@ struct seamldr_params {
 } __packed;
 
 static struct seamldr_info seamldr_info __aligned(256);
+static DEFINE_RAW_SPINLOCK(seamldr_lock);
 
 static inline int seamldr_call(u64 fn, struct tdx_module_args *args)
 {
@@ -235,6 +238,7 @@ static struct seamldr_params *init_seamldr_params(const u8 *data, u32 size)
 enum tdp_state {
 	TDP_START,
 	TDP_SHUTDOWN,
+	TDP_CPU_INSTALL,
 	TDP_DONE,
 };
 
@@ -272,9 +276,10 @@ static void print_update_failure_message(void)
  * See multi_cpu_stop() from where this multi-cpu state-machine was
  * adopted, and the rationale for touch_nmi_watchdog()
  */
-static int do_seamldr_install_module(void *params)
+static int do_seamldr_install_module(void *seamldr_params)
 {
 	enum tdp_state newstate, curstate = TDP_START;
+	struct tdx_module_args args = {};
 	int cpu = smp_processor_id();
 	bool primary;
 	int ret = 0;
@@ -293,6 +298,11 @@ static int do_seamldr_install_module(void *params)
 				if (primary)
 					ret = tdx_module_shutdown();
 				break;
+			case TDP_CPU_INSTALL:
+				args.rcx = __pa(seamldr_params);
+				scoped_guard(raw_spinlock, &seamldr_lock)
+					ret = seamldr_call(P_SEAMLDR_INSTALL, &args);
+				break;
 			default:
 				break;
 			}
-- 
2.47.3

On Fri, Jan 23, 2026 at 06:55:27AM -0800, Chao Gao wrote:
> After shutting down the running TDX module, the next step is to install the
> new TDX Module supplied by userspace.

Maybe clarify the next step part a bit with something like "the next step
in upgrading the TDX module"?

Otherwise the description can  be a bit hard to follow if not seen in the
patch email thread context.

Other than that:

Reviewed-by: Tony Lindgren <tony.lindgren@linux.intel.com>