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From:   Kai Huang <kai.huang@intel.com>
To:     peterz@infradead.org, kirill.shutemov@linux.intel.com,
        linux-kernel@vger.kernel.org
Cc:     dave.hansen@intel.com, tglx@linutronix.de, bp@alien8.de,
        mingo@redhat.com, hpa@zytor.com, x86@kernel.org, seanjc@google.com,
        pbonzini@redhat.com, kvm@vger.kernel.org, isaku.yamahata@intel.com,
        sathyanarayanan.kuppuswamy@linux.intel.com, kai.huang@intel.com
Subject: [PATCH 03/10] x86/tdx: Move FRAME_BEGIN/END to TDX_MODULE_CALL asm macro
Date:   Wed, 12 Jul 2023 20:55:17 +1200
Message-ID: <c0206c457f366ab007ab67ca16970cc4fc562877.1689151537.git.kai.huang@intel.com>
In-Reply-To: <cover.1689151537.git.kai.huang@intel.com>
References: <cover.1689151537.git.kai.huang@intel.com>
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Currently, the TDX_MODULE_CALL asm macro and the __tdx_module_call()
take registers directly as input and a 'struct tdx_module_output' as
optional output.  This is different from the __tdx_hypercall(), which
simply uses a structure to carry all input/output.  There's no point to
leave __tdx_module_call() complicated as it is.

As a preparation to simplify the __tdx_module_call() to make it look
like __tdx_hypercall(), move FRAME_BEGIN/END and RET from the
__tdx_module_call() to the TDX_MODULE_CALL assembly macro.  This also
allows more implementation flexibility of the assembly inside the
TDX_MODULE_CALL macro, e.g., allowing putting an _ASM_EXTABLE() after
the main body of the assembly.

This is basically based on Peter's code.

Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Kai Huang <kai.huang@intel.com>
---
 arch/x86/coco/tdx/tdcall.S      | 3 ---
 arch/x86/virt/vmx/tdx/tdxcall.S | 5 +++++
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/x86/coco/tdx/tdcall.S b/arch/x86/coco/tdx/tdcall.S
index 2eca5f43734f..e5d4b7d8ecd4 100644
--- a/arch/x86/coco/tdx/tdcall.S
+++ b/arch/x86/coco/tdx/tdcall.S
@@ -78,10 +78,7 @@
  * Return status of TDCALL via RAX.
  */
 SYM_FUNC_START(__tdx_module_call)
-	FRAME_BEGIN
 	TDX_MODULE_CALL host=0
-	FRAME_END
-	RET
 SYM_FUNC_END(__tdx_module_call)
 
 /*
diff --git a/arch/x86/virt/vmx/tdx/tdxcall.S b/arch/x86/virt/vmx/tdx/tdxcall.S
index 3524915d8bd9..b5ab919c7fa8 100644
--- a/arch/x86/virt/vmx/tdx/tdxcall.S
+++ b/arch/x86/virt/vmx/tdx/tdxcall.S
@@ -1,5 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #include <asm/asm-offsets.h>
+#include <asm/frame.h>
 #include <asm/tdx.h>
 
 /*
@@ -18,6 +19,7 @@
  *            TDX module.
  */
 .macro TDX_MODULE_CALL host:req
+	FRAME_BEGIN
 	/*
 	 * R12 will be used as temporary storage for struct tdx_module_output
 	 * pointer. Since R12-R15 registers are not used by TDCALL/SEAMCALL
@@ -91,4 +93,7 @@
 .Lno_output_struct:
 	/* Restore the state of R12 register */
 	pop %r12
+
+	FRAME_END
+	RET
 .endm
-- 
2.41.0