[PATCH v13 05/22] 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.  Add a macro to do the SEAMCALL
retry in the common code and define a wrapper for each __seamcall*()
variant.

Signed-off-by: Kai Huang <kai.huang@xxxxxxxxx>
---

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

---
 arch/x86/include/asm/tdx.h | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index a252328734c7..cfae8b31a2e9 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__
 
 /*
@@ -82,6 +87,28 @@ 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>
+
+#define SEAMCALL_NO_ENTROPY_RETRY(__seamcall_func, __fn, __args)	\
+({									\
+	int ___retry = RDRAND_RETRY_LOOPS;				\
+	u64 ___sret;							\
+									\
+	do {								\
+		___sret = __seamcall_func((__fn), (__args));		\
+	} while (___sret == TDX_RND_NO_ENTROPY && --___retry);		\
+	___sret;							\
+})
+
+#define seamcall(__fn, __args)						\
+	SEAMCALL_NO_ENTROPY_RETRY(__seamcall, (__fn), (__args))
+
+#define seamcall_ret(__fn, __args)					\
+	SEAMCALL_NO_ENTROPY_RETRY(__seamcall_ret, (__fn), (__args))
+
+#define seamcall_saved_ret(__fn, __args)				\
+	SEAMCALL_NO_ENTROPY_RETRY(__seamcall_saved_ret, (__fn), (__args))
+
 bool platform_tdx_enabled(void);
 #else
 static inline bool platform_tdx_enabled(void) { return false; }
-- 
2.41.0