[PATCH v15 05/23] x86/virt/tdx: Handle SEAMCALL no entropy error in common code

[Kai Huang]

Some SEAMCALLs use the RDRAND hardware and can fail for the same reasons
as RDRAND.  Use the kernel RDRAND retry logic for them.

There are three __seamcall*() variants.  Do the SEAMCALL retry in common
code and add a wrapper for each of them.

Signed-off-by: Kai Huang <kai.huang@xxxxxxxxx>
Reviewed-by: Kirill A. Shutemov <kirll.shutemov@xxxxxxxxxxxxxxx>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
---

v14 -> v15:
 - Added Sathy's tag.

v13 -> v14:
 - Use real function sc_retry() instead of using macros. (Dave)
 - Added Kirill's tag.

v12 -> v13:
 - New implementation due to TDCALL assembly series.

---
 arch/x86/include/asm/tdx.h | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index ea9a0320b1f8..f1c0c15469f8 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -24,6 +24,11 @@
 #define TDX_SEAMCALL_GP			(TDX_SW_ERROR | X86_TRAP_GP)
 #define TDX_SEAMCALL_UD			(TDX_SW_ERROR | X86_TRAP_UD)
 
+/*
+ * TDX module SEAMCALL leaf function error codes
+ */
+#define TDX_RND_NO_ENTROPY	0x8000020300000000ULL
+
 #ifndef __ASSEMBLY__
 
 /*
@@ -84,6 +89,27 @@ u64 __seamcall(u64 fn, struct tdx_module_args *args);
 u64 __seamcall_ret(u64 fn, struct tdx_module_args *args);
 u64 __seamcall_saved_ret(u64 fn, struct tdx_module_args *args);
 
+#include <asm/archrandom.h>
+
+typedef u64 (*sc_func_t)(u64 fn, struct tdx_module_args *args);
+
+static inline u64 sc_retry(sc_func_t func, u64 fn,
+			   struct tdx_module_args *args)
+{
+	int retry = RDRAND_RETRY_LOOPS;
+	u64 ret;
+
+	do {
+		ret = func(fn, args);
+	} while (ret == TDX_RND_NO_ENTROPY && --retry);
+
+	return ret;
+}
+
+#define seamcall(_fn, _args)		sc_retry(__seamcall, (_fn), (_args))
+#define seamcall_ret(_fn, _args)	sc_retry(__seamcall_ret, (_fn), (_args))
+#define seamcall_saved_ret(_fn, _args)	sc_retry(__seamcall_saved_ret, (_fn), (_args))
+
 bool platform_tdx_enabled(void);
 #else
 static inline bool platform_tdx_enabled(void) { return false; }
-- 
2.41.0