[PATCH v7 12/22] x86/virt/tdx: Reset software states during TDX module shutdown

Chao Gao
2026-03-31T12:43:33Z

The TDX module requires a one-time global initialization (TDH.SYS.INIT) and
per-CPU initialization (TDH.SYS.LP.INIT) before use. These initializations
are guarded by software flags to prevent repetition.

After TDX module updates, the new TDX module requires the same global and
per-CPU initializations, but the existing software flags prevent
re-initialization.

Reset all software flags guarding the initialization flows to allow the
global and per-CPU initializations to be triggered again after updates.

Set tdx_module_status to ERROR to indicate the module is unavailable. This
is to prevent re-initialization/tdx_sysinfo reporting on a failed update.
Using ERROR instead of UNINITIALIZED as the latter implicitly depends on
get_tdx_sys_info() failing early to prevent re-init after successful
shutdown followed by failed update.

Signed-off-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Tony Lindgren <tony.lindgren@linux.intel.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
---
v7:
- Use ERROR instead of UNINITIALIZED for tdx_module_status. Both work,
but UNINITIALIZED implicitly depends on get_tdx_sys_info() failing
early to prevent re-initialization after successful shutdown followed
by failed update

- add a comment to explain why no lock is held and re-initialization
isn't a problem.
v6:
- reset tdx_lp_initialized for offlined CPUs and update the comment
accordingly [Kai]
v5:
- add a comment to clarify why state access doesn't require holding a
lock. [Kai]
---
arch/x86/virt/vmx/tdx/tdx.c | 31 ++++++++++++++++++++++++++++---
1 file changed, 28 insertions(+), 3 deletions(-)

diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index f87fad429f4e..4c9565d507fe 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -55,6 +55,8 @@ static struct tdmr_info_list tdx_tdmr_list;

static enum tdx_module_status_t tdx_module_status;
static DEFINE_MUTEX(tdx_module_lock);
+static bool sysinit_done;
+static int sysinit_ret;

/* All TDX-usable memory regions. Protected by mem_hotplug_lock. */
static LIST_HEAD(tdx_memlist);
@@ -70,8 +72,6 @@ static int try_init_module_global(void)
{
struct tdx_module_args args = {};
static DEFINE_RAW_SPINLOCK(sysinit_lock);
- static bool sysinit_done;
- static int sysinit_ret;

lockdep_assert_irqs_disabled();

@@ -1179,6 +1179,7 @@ EXPORT_SYMBOL_FOR_KVM(tdx_enable);
int tdx_module_shutdown(void)
{
struct tdx_module_args args = {};
+ int ret, cpu;

/*
* Shut down the TDX module and prepare handoff data for the next
@@ -1188,7 +1189,31 @@ int tdx_module_shutdown(void)
* modules as new modules likely have higher handoff version.
*/
args.rcx = tdx_sysinfo.handoff.module_hv;
- return seamcall_prerr(TDH_SYS_SHUTDOWN, &args);
+ ret = seamcall_prerr(TDH_SYS_SHUTDOWN, &args);
+ if (ret)
+ return ret;
+
+ /*
+ * Mark the module is unavailable (in ERROR status) to prevent
+ * re-initialization and tdx_sysinfo reporting. Note the status
+ * will be restored after a successful update.
+ *
+ * No need to acquire tdx_module_lock here since this runs in
+ * stop_machine() where no concurrent initialization can occur.
+ */
+ tdx_module_status = TDX_MODULE_ERROR;
+ sysinit_done = false;
+ sysinit_ret = 0;
+
+ /*
+ * Since the TDX module is shut down and gone, mark all CPUs
+ * (including offlined ones) as uninitialized. This is called in
+ * stop_machine() (where CPU hotplug is disabled), preventing
+ * races with other tdx_lp_initialized accesses.
+ */
+ for_each_possible_cpu(cpu)
+ per_cpu(tdx_lp_initialized, cpu) = false;
+ return 0;
}

static bool is_pamt_page(unsigned long phys)
--
2.47.3