diff options
Diffstat (limited to 'arch/x86/coco/tdx/tdcall.S')
| -rw-r--r-- | arch/x86/coco/tdx/tdcall.S | 208 |
1 files changed, 33 insertions, 175 deletions
diff --git a/arch/x86/coco/tdx/tdcall.S b/arch/x86/coco/tdx/tdcall.S index f9eb1134f22d..52d9786da308 100644 --- a/arch/x86/coco/tdx/tdcall.S +++ b/arch/x86/coco/tdx/tdcall.S @@ -1,205 +1,63 @@ /* SPDX-License-Identifier: GPL-2.0 */ #include <asm/asm-offsets.h> #include <asm/asm.h> -#include <asm/frame.h> -#include <asm/unwind_hints.h> #include <linux/linkage.h> -#include <linux/bits.h> #include <linux/errno.h> #include "../../virt/vmx/tdx/tdxcall.S" -/* - * Bitmasks of exposed registers (with VMM). - */ -#define TDX_R10 BIT(10) -#define TDX_R11 BIT(11) -#define TDX_R12 BIT(12) -#define TDX_R13 BIT(13) -#define TDX_R14 BIT(14) -#define TDX_R15 BIT(15) - -/* - * These registers are clobbered to hold arguments for each - * TDVMCALL. They are safe to expose to the VMM. - * Each bit in this mask represents a register ID. Bit field - * details can be found in TDX GHCI specification, section - * titled "TDCALL [TDG.VP.VMCALL] leaf". - */ -#define TDVMCALL_EXPOSE_REGS_MASK ( TDX_R10 | TDX_R11 | \ - TDX_R12 | TDX_R13 | \ - TDX_R14 | TDX_R15 ) +.section .noinstr.text, "ax" /* - * __tdx_module_call() - Used by TDX guests to request services from - * the TDX module (does not include VMM services) using TDCALL instruction. - * - * Transforms function call register arguments into the TDCALL register ABI. - * After TDCALL operation, TDX module output is saved in @out (if it is - * provided by the user). - * - *------------------------------------------------------------------------- - * TDCALL ABI: - *------------------------------------------------------------------------- - * Input Registers: - * - * RAX - TDCALL Leaf number. - * RCX,RDX,R8-R9 - TDCALL Leaf specific input registers. + * __tdcall() - Used by TDX guests to request services from the TDX + * module (does not include VMM services) using TDCALL instruction. * - * Output Registers: + * __tdcall() function ABI: * - * RAX - TDCALL instruction error code. - * RCX,RDX,R8-R11 - TDCALL Leaf specific output registers. + * @fn (RDI) - TDCALL Leaf ID, moved to RAX + * @args (RSI) - struct tdx_module_args for input * - *------------------------------------------------------------------------- - * - * __tdx_module_call() function ABI: - * - * @fn (RDI) - TDCALL Leaf ID, moved to RAX - * @rcx (RSI) - Input parameter 1, moved to RCX - * @rdx (RDX) - Input parameter 2, moved to RDX - * @r8 (RCX) - Input parameter 3, moved to R8 - * @r9 (R8) - Input parameter 4, moved to R9 - * - * @out (R9) - struct tdx_module_output pointer - * stored temporarily in R12 (not - * shared with the TDX module). It - * can be NULL. + * Only RCX/RDX/R8-R11 are used as input registers. * * Return status of TDCALL via RAX. */ -SYM_FUNC_START(__tdx_module_call) - FRAME_BEGIN +SYM_FUNC_START(__tdcall) TDX_MODULE_CALL host=0 - FRAME_END - RET -SYM_FUNC_END(__tdx_module_call) +SYM_FUNC_END(__tdcall) /* - * __tdx_hypercall() - Make hypercalls to a TDX VMM using TDVMCALL leaf - * of TDCALL instruction - * - * Transforms values in function call argument struct tdx_hypercall_args @args - * into the TDCALL register ABI. After TDCALL operation, VMM output is saved - * back in @args. + * __tdcall_ret() - Used by TDX guests to request services from the TDX + * module (does not include VMM services) using TDCALL instruction, with + * saving output registers to the 'struct tdx_module_args' used as input. * - *------------------------------------------------------------------------- - * TD VMCALL ABI: - *------------------------------------------------------------------------- + * __tdcall_ret() function ABI: * - * Input Registers: + * @fn (RDI) - TDCALL Leaf ID, moved to RAX + * @args (RSI) - struct tdx_module_args for input and output * - * RAX - TDCALL instruction leaf number (0 - TDG.VP.VMCALL) - * RCX - BITMAP which controls which part of TD Guest GPR - * is passed as-is to the VMM and back. - * R10 - Set 0 to indicate TDCALL follows standard TDX ABI - * specification. Non zero value indicates vendor - * specific ABI. - * R11 - VMCALL sub function number - * RBX, RBP, RDI, RSI - Used to pass VMCALL sub function specific arguments. - * R8-R9, R12-R15 - Same as above. + * Only RCX/RDX/R8-R11 are used as input/output registers. * - * Output Registers: - * - * RAX - TDCALL instruction status (Not related to hypercall - * output). - * R10 - Hypercall output error code. - * R11-R15 - Hypercall sub function specific output values. + * Return status of TDCALL via RAX. + */ +SYM_FUNC_START(__tdcall_ret) + TDX_MODULE_CALL host=0 ret=1 +SYM_FUNC_END(__tdcall_ret) + +/* + * __tdcall_saved_ret() - Used by TDX guests to request services from the + * TDX module (including VMM services) using TDCALL instruction, with + * saving output registers to the 'struct tdx_module_args' used as input. * - *------------------------------------------------------------------------- + * __tdcall_saved_ret() function ABI: * - * __tdx_hypercall() function ABI: + * @fn (RDI) - TDCALL leaf ID, moved to RAX + * @args (RSI) - struct tdx_module_args for input/output * - * @args (RDI) - struct tdx_hypercall_args for input and output - * @flags (RSI) - TDX_HCALL_* flags + * All registers in @args are used as input/output registers. * * On successful completion, return the hypercall error code. */ -SYM_FUNC_START(__tdx_hypercall) - FRAME_BEGIN - - /* Save callee-saved GPRs as mandated by the x86_64 ABI */ - push %r15 - push %r14 - push %r13 - push %r12 - - /* Mangle function call ABI into TDCALL ABI: */ - /* Set TDCALL leaf ID (TDVMCALL (0)) in RAX */ - xor %eax, %eax - - /* Copy hypercall registers from arg struct: */ - movq TDX_HYPERCALL_r10(%rdi), %r10 - movq TDX_HYPERCALL_r11(%rdi), %r11 - movq TDX_HYPERCALL_r12(%rdi), %r12 - movq TDX_HYPERCALL_r13(%rdi), %r13 - movq TDX_HYPERCALL_r14(%rdi), %r14 - movq TDX_HYPERCALL_r15(%rdi), %r15 - - movl $TDVMCALL_EXPOSE_REGS_MASK, %ecx - - /* - * For the idle loop STI needs to be called directly before the TDCALL - * that enters idle (EXIT_REASON_HLT case). STI instruction enables - * interrupts only one instruction later. If there is a window between - * STI and the instruction that emulates the HALT state, there is a - * chance for interrupts to happen in this window, which can delay the - * HLT operation indefinitely. Since this is the not the desired - * result, conditionally call STI before TDCALL. - */ - testq $TDX_HCALL_ISSUE_STI, %rsi - jz .Lskip_sti - sti -.Lskip_sti: - tdcall - - /* - * RAX==0 indicates a failure of the TDVMCALL mechanism itself and that - * something has gone horribly wrong with the TDX module. - * - * The return status of the hypercall operation is in a separate - * register (in R10). Hypercall errors are a part of normal operation - * and are handled by callers. - */ - testq %rax, %rax - jne .Lpanic - - /* TDVMCALL leaf return code is in R10 */ - movq %r10, %rax - - /* Copy hypercall result registers to arg struct if needed */ - testq $TDX_HCALL_HAS_OUTPUT, %rsi - jz .Lout - - movq %r10, TDX_HYPERCALL_r10(%rdi) - movq %r11, TDX_HYPERCALL_r11(%rdi) - movq %r12, TDX_HYPERCALL_r12(%rdi) - movq %r13, TDX_HYPERCALL_r13(%rdi) - movq %r14, TDX_HYPERCALL_r14(%rdi) - movq %r15, TDX_HYPERCALL_r15(%rdi) -.Lout: - /* - * Zero out registers exposed to the VMM to avoid speculative execution - * with VMM-controlled values. This needs to include all registers - * present in TDVMCALL_EXPOSE_REGS_MASK (except R12-R15). R12-R15 - * context will be restored. - */ - xor %r10d, %r10d - xor %r11d, %r11d - - /* Restore callee-saved GPRs as mandated by the x86_64 ABI */ - pop %r12 - pop %r13 - pop %r14 - pop %r15 - - FRAME_END - - RET -.Lpanic: - call __tdx_hypercall_failed - /* __tdx_hypercall_failed never returns */ - REACHABLE - jmp .Lpanic -SYM_FUNC_END(__tdx_hypercall) +SYM_FUNC_START(__tdcall_saved_ret) + TDX_MODULE_CALL host=0 ret=1 saved=1 +SYM_FUNC_END(__tdcall_saved_ret) |