linux-kernel - [PATCH v14 05/23] x86/virt/tdx: Handle SEAMCALL no entropy error in common code

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Date:   Tue, 17 Oct 2023 23:14:29 +1300
From:   Kai Huang <kai.huang@...el.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     x86@...nel.org, dave.hansen@...el.com,
        kirill.shutemov@...ux.intel.com, peterz@...radead.org,
        tony.luck@...el.com, tglx@...utronix.de, bp@...en8.de,
        mingo@...hat.com, hpa@...or.com, seanjc@...gle.com,
        pbonzini@...hat.com, rafael@...nel.org, david@...hat.com,
        dan.j.williams@...el.com, len.brown@...el.com, ak@...ux.intel.com,
        isaku.yamahata@...el.com, ying.huang@...el.com, chao.gao@...el.com,
        sathyanarayanan.kuppuswamy@...ux.intel.com, nik.borisov@...e.com,
        bagasdotme@...il.com, sagis@...gle.com, imammedo@...hat.com,
        kai.huang@...el.com
Subject: [PATCH v14 05/23] x86/virt/tdx: Handle SEAMCALL no entropy error in common code

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@...el.com>
Reviewed-by: Kirill A. Shutemov <kirll.shutemov@...ux.intel.com>
---

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 a252328734c7..d624aa25aab0 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 +87,27 @@ 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