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Diffstat (limited to '')
| -rw-r--r-- | arch/x86/virt/vmx/tdx/tdxcall.S | 96 |
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 |