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

Kai Huang
2023-11-09T11:56:47Z

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@intel.com>
Reviewed-by: Kirill A. Shutemov <kirll.shutemov@linux.intel.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
---

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