[tip: x86/tdx] x86/virt/tdx: Enable TDX module runtime updates

[tip-bot2 for Chao Gao]

The following commit has been merged into the x86/tdx branch of tip:

Commit-ID:     d4516dcf9cd5d41238222a2a1b542a62ef7ed056
Gitweb:        https://git.kernel.org/tip/d4516dcf9cd5d41238222a2a1b542a62ef7ed056
Author:        Chao Gao <chao.gao@xxxxxxxxx>
AuthorDate:    Wed, 20 May 2026 15:29:13 -07:00
Committer:     Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
CommitterDate: Tue, 26 May 2026 08:29:15 -07:00

x86/virt/tdx: Enable TDX module runtime updates

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

Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx>
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Reviewed-by: Xu Yilun <yilun.xu@xxxxxxxxxxxxxxx>
Reviewed-by: Tony Lindgren <tony.lindgren@xxxxxxxxxxxxxxx>
Reviewed-by: Kiryl Shutsemau (Meta) <kas@xxxxxxxxxx>
Reviewed-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>
Link: https://patch.msgid.link/20260520133909.409394-24-chao.gao@xxxxxxxxx
Link: https://patch.msgid.link/20260520222913.97EF4217@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
---
 arch/x86/include/asm/tdx.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index 5d750fe..e5a9cf6 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -33,6 +33,7 @@
 #define TDX_RND_NO_ENTROPY	0x8000020300000000ULL
 
 /* Bit definitions of TDX_FEATURES0 metadata field */
+#define TDX_FEATURES0_TD_PRESERVING	BIT_ULL(1)
 #define TDX_FEATURES0_NO_RBP_MOD	BIT_ULL(18)
 
 #ifndef __ASSEMBLER__
@@ -113,8 +114,7 @@ const struct tdx_sys_info *tdx_get_sysinfo(void);
 
 static inline bool tdx_supports_runtime_update(const struct tdx_sys_info *sysinfo)
 {
-	/* To be enabled when kernel is ready. */
-	return false;
+	return sysinfo->features.tdx_features0 & TDX_FEATURES0_TD_PRESERVING;
 }
 
 int tdx_guest_keyid_alloc(void);