Enabling TDX consumes additional memory (used by TDX as metadata) and
additional initialization time. Introduce a kernel command line to
allow to opt-in TDX host kernel support when user truly wants to use
TDX.
Signed-off-by: Kai Huang <kai.huang@xxxxxxxxx>
---
Documentation/admin-guide/kernel-parameters.txt | 6 ++++++
arch/x86/virt/vmx/tdx.c | 14 ++++++++++++++
2 files changed, 20 insertions(+)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index f5a27f067db9..9f85cafd0c2d 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5707,6 +5707,12 @@
tdfx= [HW,DRM]
+ tdx_host= [X86-64, TDX]
+ Format: {on|off}
+ on: Enable TDX host kernel support
+ off: Disable TDX host kernel support
+ Default is off.
+
test_suspend= [SUSPEND][,N]
Specify "mem" (for Suspend-to-RAM) or "standby" (for
standby suspend) or "freeze" (for suspend type freeze)
diff --git a/arch/x86/virt/vmx/tdx.c b/arch/x86/virt/vmx/tdx.c
index d9ad8dc7111e..2022f9c019b8 100644
--- a/arch/x86/virt/vmx/tdx.c
+++ b/arch/x86/virt/vmx/tdx.c
@@ -116,6 +116,16 @@ static struct tdsysinfo_struct tdx_sysinfo;
/* TDX global KeyID to protect TDX metadata */
static u32 tdx_global_keyid;
+static bool enable_tdx_host;
+
+static int __init tdx_host_setup(char *s)
+{
+ if (!strcmp(s, "on"))
+ enable_tdx_host = true;
+ return 1;
+}
+__setup("tdx_host=", tdx_host_setup);
+
static bool __seamrr_enabled(void)
{
return (seamrr_mask & SEAMRR_ENABLED_BITS) == SEAMRR_ENABLED_BITS;
@@ -501,6 +511,10 @@ static int detect_p_seamldr(void)
static int __tdx_detect(void)
{
+ /* Disabled by kernel command line */
+ if (!enable_tdx_host)
+ goto no_tdx_module;
+
/* The TDX module is not loaded if SEAMRR is disabled */
if (!seamrr_enabled()) {
pr_info("SEAMRR not enabled.\n");
--
2.35.1
