1 files changed, 96 insertions, 0 deletions
diff --git a/arch/x86/virt/vmx/tdx/tdxcall.S b/arch/x86/virt/vmx/tdx/tdxcall.S
new file mode 100644
index 000000000..49a54356a
--- /dev/null
+++ b/arch/x86/virt/vmx/tdx/tdxcall.S
@@ -0,0 +1,96 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <asm/asm-offsets.h>
+#include <asm/tdx.h>
+
+/*
+ * TDCALL and SEAMCALL are supported in Binutils >= 2.36.
+ */
+#define tdcall		.byte 0x66,0x0f,0x01,0xcc
+#define seamcall	.byte 0x66,0x0f,0x01,0xcf
+
+/*
+ * TDX_MODULE_CALL - common helper macro for both
+ *                 TDCALL and SEAMCALL instructions.
+ *
+ * TDCALL   - used by TDX guests to make requests to the
+ *            TDX module and hypercalls to the VMM.
+ * SEAMCALL - used by TDX hosts to make requests to the
+ *            TDX module.
+ */
+.macro TDX_MODULE_CALL host:req
+	/*
+	 * R12 will be used as temporary storage for struct tdx_module_output
+	 * pointer. Since R12-R15 registers are not used by TDCALL/SEAMCALL
+	 * services supported by this function, it can be reused.
+	 */
+
+	/* Callee saved, so preserve it */
+	push %r12
+
+	/*
+	 * Push output pointer to stack.
+	 * After the operation, it will be fetched into R12 register.
+	 */
+	push %r9
+
+	/* Mangle function call ABI into TDCALL/SEAMCALL ABI: */
+	/* Move Leaf ID to RAX */
+	mov %rdi, %rax
+	/* Move input 4 to R9 */
+	mov %r8,  %r9
+	/* Move input 3 to R8 */
+	mov %rcx, %r8
+	/* Move input 1 to RCX */
+	mov %rsi, %rcx
+	/* Leave input param 2 in RDX */
+
+	.if \host
+	seamcall
+	/*
+	 * SEAMCALL instruction is essentially a VMExit from VMX root
+	 * mode to SEAM VMX root mode.  VMfailInvalid (CF=1) indicates
+	 * that the targeted SEAM firmware is not loaded or disabled,
+	 * or P-SEAMLDR is busy with another SEAMCALL.  %rax is not
+	 * changed in this case.
+	 *
+	 * Set %rax to TDX_SEAMCALL_VMFAILINVALID for VMfailInvalid.
+	 * This value will never be used as actual SEAMCALL error code as
+	 * it is from the Reserved status code class.
+	 */
+	jnc .Lno_vmfailinvalid
+	mov $TDX_SEAMCALL_VMFAILINVALID, %rax
+.Lno_vmfailinvalid:
+
+	.else
+	tdcall
+	.endif
+
+	/*
+	 * Fetch output pointer from stack to R12 (It is used
+	 * as temporary storage)
+	 */
+	pop %r12
+
+	/*
+	 * Since this macro can be invoked with NULL as an output pointer,
+	 * check if caller provided an output struct before storing output
+	 * registers.
+	 *
+	 * Update output registers, even if the call failed (RAX != 0).
+	 * Other registers may contain details of the failure.
+	 */
+	test %r12, %r12
+	jz .Lno_output_struct
+
+	/* Copy result registers to output struct: */
+	movq %rcx, TDX_MODULE_rcx(%r12)
+	movq %rdx, TDX_MODULE_rdx(%r12)
+	movq %r8,  TDX_MODULE_r8(%r12)
+	movq %r9,  TDX_MODULE_r9(%r12)
+	movq %r10, TDX_MODULE_r10(%r12)
+	movq %r11, TDX_MODULE_r11(%r12)
+
+.Lno_output_struct:
+	/* Restore the state of R12 register */
+	pop %r12
+.endm