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-rw-r--r--arch/x86/virt/vmx/tdx/tdxcall.S96
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