x86/virt/tdx: Add SEAMCALL error printing for module initialization

The SEAMCALLs involved during the TDX module initialization are not
expected to fail.  In fact, they are not expected to return any non-zero
code (except the "running out of entropy error", which can be handled
internally already).

Add yet another set of SEAMCALL wrappers, which treats all non-zero
return code as error, to support printing SEAMCALL error upon failure
for module initialization.  Note the TDX module initialization doesn't
use the _saved_ret() variant thus no wrapper is added for it.

SEAMCALL assembly can also return kernel-defined error codes for three
special cases: 1) TDX isn't enabled by the BIOS; 2) TDX module isn't
loaded; 3) CPU isn't in VMX operation.  Whether they can legally happen
depends on the caller, so leave to the caller to print error message
when desired.

Also convert the SEAMCALL error codes to the kernel error codes in the
new wrappers so that each SEAMCALL caller doesn't have to repeat the
conversion.

[ dhansen: Align the register dump with show_regs().  Zero-pad the
	   contents, split on two lines and use consistent spacing. ]
Signed-off-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/all/20231208170740.53979-5-dave.hansen%40intel.com

arch/x86/include/asm/tdx.h

@@ -27,6 +27,7 @@
 /*
  * TDX module SEAMCALL leaf function error codes
  */
+#define TDX_SUCCESS		0ULL
 #define TDX_RND_NO_ENTROPY	0x8000020300000000ULL
 
 #ifndef __ASSEMBLY__

arch/x86/virt/vmx/tdx/tdx.c

@@ -21,6 +21,50 @@ static u32 tdx_global_keyid __ro_after_init;
 static u32 tdx_guest_keyid_start __ro_after_init;
 static u32 tdx_nr_guest_keyids __ro_after_init;
 
+typedef void (*sc_err_func_t)(u64 fn, u64 err, struct tdx_module_args *args);
+
+static inline void seamcall_err(u64 fn, u64 err, struct tdx_module_args *args)
+{
+	pr_err("SEAMCALL (0x%016llx) failed: 0x%016llx\n", fn, err);
+}
+
+static inline void seamcall_err_ret(u64 fn, u64 err,
+				    struct tdx_module_args *args)
+{
+	seamcall_err(fn, err, args);
+	pr_err("RCX 0x%016llx RDX 0x%016llx R08 0x%016llx\n",
+			args->rcx, args->rdx, args->r8);
+	pr_err("R09 0x%016llx R10 0x%016llx R11 0x%016llx\n",
+			args->r9, args->r10, args->r11);
+}
+
+static inline int sc_retry_prerr(sc_func_t func, sc_err_func_t err_func,
+				 u64 fn, struct tdx_module_args *args)
+{
+	u64 sret = sc_retry(func, fn, args);
+
+	if (sret == TDX_SUCCESS)
+		return 0;
+
+	if (sret == TDX_SEAMCALL_VMFAILINVALID)
+		return -ENODEV;
+
+	if (sret == TDX_SEAMCALL_GP)
+		return -EOPNOTSUPP;
+
+	if (sret == TDX_SEAMCALL_UD)
+		return -EACCES;
+
+	err_func(fn, sret, args);
+	return -EIO;
+}
+
+#define seamcall_prerr(__fn, __args)						\
+	sc_retry_prerr(__seamcall, seamcall_err, (__fn), (__args))
+
+#define seamcall_prerr_ret(__fn, __args)					\
+	sc_retry_prerr(__seamcall_ret, seamcall_err_ret, (__fn), (__args))
+
 static __init int record_keyid_partitioning(u32 *tdx_keyid_start,
 					    u32 *nr_tdx_keyids)
 {