[PATCH 01/15] x86/virt/tdx: Read global metadata for TDX Module Extensions

[Xu Yilun]

Add reading of the global metadata for TDX Module Extensions.

TDX Module Extensions is an add-on feature enumerated by TDX_FEATURES0.
But for the Module's integrity, Linux requires that all features that a
Module advertises must have a complete, valid set of metadata, and the
validation must succeed at core TDX initialization time.

Check TDX_FEATURES0 before reading these metadata. If a feature is
advertised, a failure in reading associated metadata causes the entire
TDX initialization to fail, otherwise skip.

Signed-off-by: Xu Yilun <yilun.xu@xxxxxxxxxxxxxxx>
---
 arch/x86/include/asm/tdx_global_metadata.h  |  6 ++++++
 arch/x86/virt/vmx/tdx/tdx.h                 |  1 +
 arch/x86/virt/vmx/tdx/tdx_global_metadata.c | 16 ++++++++++++++++
 3 files changed, 23 insertions(+)

diff --git a/arch/x86/include/asm/tdx_global_metadata.h b/arch/x86/include/asm/tdx_global_metadata.h
index 40689c8dc67e..533afe50a3f1 100644
--- a/arch/x86/include/asm/tdx_global_metadata.h
+++ b/arch/x86/include/asm/tdx_global_metadata.h
@@ -40,12 +40,18 @@ struct tdx_sys_info_td_conf {
 	u64 cpuid_config_values[128][2];
 };
 
+struct tdx_sys_info_ext {
+	u16 memory_pool_required_pages;
+	u8 ext_required;
+};
+
 struct tdx_sys_info {
 	struct tdx_sys_info_version version;
 	struct tdx_sys_info_features features;
 	struct tdx_sys_info_tdmr tdmr;
 	struct tdx_sys_info_td_ctrl td_ctrl;
 	struct tdx_sys_info_td_conf td_conf;
+	struct tdx_sys_info_ext ext;
 };
 
 #endif
diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h
index e2cf2dd48755..a5eec8e3cc71 100644
--- a/arch/x86/virt/vmx/tdx/tdx.h
+++ b/arch/x86/virt/vmx/tdx/tdx.h
@@ -87,6 +87,7 @@ struct tdmr_info {
 
 /* Bit definitions of TDX_FEATURES0 metadata field */
 #define TDX_FEATURES0_NO_RBP_MOD	BIT(18)
+#define TDX_FEATURES0_EXT		BIT_ULL(39)
 
 /*
  * Do not put any hardware-defined TDX structure representations below
diff --git a/arch/x86/virt/vmx/tdx/tdx_global_metadata.c b/arch/x86/virt/vmx/tdx/tdx_global_metadata.c
index c7db393a9cfb..3d3b56ef3d2f 100644
--- a/arch/x86/virt/vmx/tdx/tdx_global_metadata.c
+++ b/arch/x86/virt/vmx/tdx/tdx_global_metadata.c
@@ -100,6 +100,19 @@ static __init int get_tdx_sys_info_td_conf(struct tdx_sys_info_td_conf *sysinfo_
 	return ret;
 }
 
+static __init int get_tdx_sys_info_ext(struct tdx_sys_info_ext *sysinfo_ext)
+{
+	int ret = 0;
+	u64 val;
+
+	if (!ret && !(ret = read_sys_metadata_field(0x3100000100000000, &val)))
+		sysinfo_ext->memory_pool_required_pages = val;
+	if (!ret && !(ret = read_sys_metadata_field(0x3100000000000001, &val)))
+		sysinfo_ext->ext_required = val;
+
+	return ret;
+}
+
 static __init int get_tdx_sys_info(struct tdx_sys_info *sysinfo)
 {
 	int ret = 0;
@@ -116,5 +129,8 @@ static __init int get_tdx_sys_info(struct tdx_sys_info *sysinfo)
 	ret = ret ?: get_tdx_sys_info_td_ctrl(&sysinfo->td_ctrl);
 	ret = ret ?: get_tdx_sys_info_td_conf(&sysinfo->td_conf);
 
+	if (sysinfo->features.tdx_features0 & TDX_FEATURES0_EXT)
+		ret = ret ?: get_tdx_sys_info_ext(&sysinfo->ext);
+
 	return ret;
 }
-- 
2.25.1