[PATCH v1 06/11] x86/tdx: Get TD execution environment information via TDINFO

[Kuppuswamy Sathyanarayanan]

From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>

Per Guest-Host-Communication Interface (GHCI) for Intel Trust
Domain Extensions (Intel TDX) specification, sec 2.4.2,
TDCALL[TDINFO] provides basic TD execution environment information, not
provided by CPUID.

Call TDINFO during early boot to be used for following system
initialization.

The call provides info on which bit in pfn is used to indicate that the
page is shared with the host and attributes of the TD, such as debug.

Information about the number of CPUs need not be saved because there are
no users so far for it.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Reviewed-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Reviewed-by: Tony Luck <tony.luck@xxxxxxxxx>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
---
 arch/x86/kernel/tdx.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/arch/x86/kernel/tdx.c b/arch/x86/kernel/tdx.c
index 97b54317f799..e4383b416ef3 100644
--- a/arch/x86/kernel/tdx.c
+++ b/arch/x86/kernel/tdx.c
@@ -4,6 +4,17 @@
 #define pr_fmt(fmt) "TDX: " fmt
 
 #include <asm/tdx.h>
+#include <asm/vmx.h>
+
+#include <linux/cpu.h>
+
+/* TDX Module call Leaf IDs */
+#define TDINFO				1
+
+static struct {
+	unsigned int gpa_width;
+	unsigned long attributes;
+} td_info __ro_after_init;
 
 /*
  * Wrapper for simple hypercalls that only return a success/error code.
@@ -63,6 +74,19 @@ bool is_tdx_guest(void)
 }
 EXPORT_SYMBOL_GPL(is_tdx_guest);
 
+static void tdg_get_info(void)
+{
+	u64 ret;
+	struct tdx_module_output out = {0};
+
+	ret = __tdx_module_call(TDINFO, 0, 0, 0, 0, &out);
+
+	BUG_ON(ret);
+
+	td_info.gpa_width = out.rcx & GENMASK(5, 0);
+	td_info.attributes = out.rdx;
+}
+
 void __init tdx_early_init(void)
 {
 	if (!cpuid_has_tdx_guest())
@@ -70,5 +94,7 @@ void __init tdx_early_init(void)
 
 	setup_force_cpu_cap(X86_FEATURE_TDX_GUEST);
 
+	tdg_get_info();
+
 	pr_info("TDX guest is initialized\n");
 }
-- 
2.25.1