[PATCH v2 1/2] x86/tdx: Move port I/O definitions to a shared header

From: Vishal Verma <vishal.l.verma@intel.com>
Date: 2026-09-21 19:53:01
Also in: kvm, linux-doc, lkml
Reply to: Vishal Verma, 2026-09-21

In preparation for adding a 'tdx' option for early_printk which uses
direct TDVMCALLs for I/O, factor out the PORT_READ and PORT_WRITE
definitions from arch/x86/coco/tdx/tdx.c into
arch/x86/include/asm/shared/tdx.h, and namespace them with 'TDVMCALL_'.

The decompressor also used 0/1 literals in its tdx_io_{in,out} helpers -
switch those to use the new definitions.

Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
Reviewed-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
---
 arch/x86/include/asm/shared/tdx.h | 6 ++++++
 arch/x86/boot/compressed/tdx.c    | 4 ++--
 arch/x86/coco/tdx/tdx.c           | 8 ++------
 3 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/shared/tdx.h b/arch/x86/include/asm/shared/tdx.h
index f20e91d7ac35..ecaf965f059b 100644
--- a/arch/x86/include/asm/shared/tdx.h
+++ b/arch/x86/include/asm/shared/tdx.h

@@ -84,6 +84,12 @@
 #define TDVMCALL_STATUS_ALIGN_ERROR	0x8000000000000002ULL
 #define TDVMCALL_STATUS_SUBFUNC_UNSUPPORTED	0x8000000000000003ULL
 
+/*
+ * TDG.VP.VMCALL<Instruction.IO> direction (passed in R13)
+ */
+#define TDVMCALL_PORT_READ		0
+#define TDVMCALL_PORT_WRITE		1
+
 /*
  * Bitmasks of exposed registers (with VMM).
  */

diff --git a/arch/x86/boot/compressed/tdx.c b/arch/x86/boot/compressed/tdx.c
index 8451d6a1030c..ed278bac3c93 100644
--- a/arch/x86/boot/compressed/tdx.c
+++ b/arch/x86/boot/compressed/tdx.c

@@ -22,7 +22,7 @@ static inline unsigned int tdx_io_in(int size, u16 port)
 		.r10 = TDX_HYPERCALL_STANDARD,
 		.r11 = hcall_func(EXIT_REASON_IO_INSTRUCTION),
 		.r12 = size,
-		.r13 = 0,
+		.r13 = TDVMCALL_PORT_READ,
 		.r14 = port,
 	};

@@ -38,7 +38,7 @@ static inline void tdx_io_out(int size, u16 port, u32 value)
 		.r10 = TDX_HYPERCALL_STANDARD,
 		.r11 = hcall_func(EXIT_REASON_IO_INSTRUCTION),
 		.r12 = size,
-		.r13 = 1,
+		.r13 = TDVMCALL_PORT_WRITE,
 		.r14 = port,
 		.r15 = value,
 	};

diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c
index f904a636d449..7d1a93ee2534 100644
--- a/arch/x86/coco/tdx/tdx.c
+++ b/arch/x86/coco/tdx/tdx.c

@@ -24,10 +24,6 @@
 #define EPT_READ	0
 #define EPT_WRITE	1
 
-/* Port I/O direction */
-#define PORT_READ	0
-#define PORT_WRITE	1
-
 /* See Exit Qualification for I/O Instructions in VMX documentation */
 #define VE_IS_IO_IN(e)		((e) & BIT(3))
 #define VE_GET_IO_SIZE(e)	(((e) & GENMASK(2, 0)) + 1)

@@ -691,7 +687,7 @@ static bool handle_in(struct pt_regs *regs, int size, int port)
 		.r10 = TDX_HYPERCALL_STANDARD,
 		.r11 = hcall_func(EXIT_REASON_IO_INSTRUCTION),
 		.r12 = size,
-		.r13 = PORT_READ,
+		.r13 = TDVMCALL_PORT_READ,
 		.r14 = port,
 	};
 	bool success;

@@ -720,7 +716,7 @@ static bool handle_out(struct pt_regs *regs, int size, int port)
 	 * "TDG.VP.VMCALL<Instruction.IO>".
 	 */
 	return !_tdx_hypercall(hcall_func(EXIT_REASON_IO_INSTRUCTION), size,
-			       PORT_WRITE, port, regs->ax & mask);
+			       TDVMCALL_PORT_WRITE, port, regs->ax & mask);
 }
 
 /*

-- 
2.55.0

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