All pieces of TDX Module runtime updates are in place. Enable it if it
is supported.

Signed-off-by: Chao Gao <chao.gao@intel.com>
---
 arch/x86/include/asm/tdx.h  | 5 ++++-
 arch/x86/virt/vmx/tdx/tdx.h | 3 ---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index ffadbf64d0c1..0cd408f902f4 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -32,6 +32,9 @@
 #define TDX_SUCCESS		0ULL
 #define TDX_RND_NO_ENTROPY	0x8000020300000000ULL
 
+/* Bit definitions of TDX_FEATURES0 metadata field */
+#define TDX_FEATURES0_TD_PRESERVING	BIT(1)
+#define TDX_FEATURES0_NO_RBP_MOD	BIT(18)
 #ifndef __ASSEMBLER__
 
 #include <uapi/asm/mce.h>
@@ -105,7 +108,7 @@ const struct tdx_sys_info *tdx_get_sysinfo(void);
 
 static inline bool tdx_supports_runtime_update(const struct tdx_sys_info *sysinfo)
 {
-	return false; /* To be enabled when kernel is ready */
+	return sysinfo->features.tdx_features0 & TDX_FEATURES0_TD_PRESERVING;
 }
 
 int tdx_guest_keyid_alloc(void);
diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h
index d1807a476d3b..749f4d74cb2c 100644
--- a/arch/x86/virt/vmx/tdx/tdx.h
+++ b/arch/x86/virt/vmx/tdx/tdx.h
@@ -88,9 +88,6 @@ struct tdmr_info {
 	DECLARE_FLEX_ARRAY(struct tdmr_reserved_area, reserved_areas);
 } __packed __aligned(TDMR_INFO_ALIGNMENT);
 
-/* Bit definitions of TDX_FEATURES0 metadata field */
-#define TDX_FEATURES0_NO_RBP_MOD	BIT(18)
-
 /*
  * Do not put any hardware-defined TDX structure representations below
  * this comment!
-- 
2.47.3

>  static inline bool tdx_supports_runtime_update(const struct tdx_sys_info *sysinfo)
>  {
> -	return false; /* To be enabled when kernel is ready */
> +	return sysinfo->features.tdx_features0 & TDX_FEATURES0_TD_PRESERVING;

Frankly speak, I don't know why we need endless one-line wrappers like
this, we've already exposed all details of the tdx_sys_info to its
users.

But I'm still OK with them.

Reviewed-by: Xu Yilun <yilun.xu@linux.intel.com>

On Fri, Jan 23, 2026 at 06:55:31AM -0800, Chao Gao wrote:
> --- a/arch/x86/include/asm/tdx.h
> +++ b/arch/x86/include/asm/tdx.h
> @@ -32,6 +32,9 @@
>  #define TDX_SUCCESS		0ULL
>  #define TDX_RND_NO_ENTROPY	0x8000020300000000ULL
>  
> +/* Bit definitions of TDX_FEATURES0 metadata field */
> +#define TDX_FEATURES0_TD_PRESERVING	BIT(1)
> +#define TDX_FEATURES0_NO_RBP_MOD	BIT(18)
>  #ifndef __ASSEMBLER__
>  
>  #include <uapi/asm/mce.h>

How about let's put these defines into arch/x86/include/asm/shared/tdx.h
instead? And use BIT_ULL?

This would allow cleaning up arch/x86/kvm/vmx/tdx.c in a follow-up patch
for MD_FIELD_ID_FEATURES0_TOPOLOGY_ENUM to use TDX_FEATURES0_TOPOLOGY_ENUM
BIT_ULL(20).

Of course it can be done later on too, so:

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

On Mon, Jan 26, 2026 at 01:14:07PM +0200, Tony Lindgren wrote:
> On Fri, Jan 23, 2026 at 06:55:31AM -0800, Chao Gao wrote:
> > --- a/arch/x86/include/asm/tdx.h
> > +++ b/arch/x86/include/asm/tdx.h
> > @@ -32,6 +32,9 @@
> >  #define TDX_SUCCESS		0ULL
> >  #define TDX_RND_NO_ENTROPY	0x8000020300000000ULL
> >  
> > +/* Bit definitions of TDX_FEATURES0 metadata field */
> > +#define TDX_FEATURES0_TD_PRESERVING	BIT(1)
> > +#define TDX_FEATURES0_NO_RBP_MOD	BIT(18)
> >  #ifndef __ASSEMBLER__
> >  
> >  #include <uapi/asm/mce.h>
> 
> How about let's put these defines into arch/x86/include/asm/shared/tdx.h
> instead? And use BIT_ULL?

Sorry I was confused. No need to move these defines to
arch/x86/include/asm/shared/tdx.h as far as I can tell.

The BIT_ULL comment still remains though.

Regards,

Tony