| /* 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 ) |
| |
| /* |
| * __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. |
| * |
| * Output Registers: |
| * |
| * RAX - TDCALL instruction error code. |
| * RCX,RDX,R8-R11 - TDCALL Leaf specific output registers. |
| * |
| *------------------------------------------------------------------------- |
| * |
| * __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. |
| * |
| * Return status of TDCALL via RAX. |
| */ |
| SYM_FUNC_START(__tdx_module_call) |
| FRAME_BEGIN |
| TDX_MODULE_CALL host=0 |
| FRAME_END |
| RET |
| SYM_FUNC_END(__tdx_module_call) |
| |
| /* |
| * __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. |
| * |
| *------------------------------------------------------------------------- |
| * TD VMCALL ABI: |
| *------------------------------------------------------------------------- |
| * |
| * Input Registers: |
| * |
| * 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. |
| * |
| * Output Registers: |
| * |
| * RAX - TDCALL instruction status (Not related to hypercall |
| * output). |
| * R10 - Hypercall output error code. |
| * R11-R15 - Hypercall sub function specific output values. |
| * |
| *------------------------------------------------------------------------- |
| * |
| * __tdx_hypercall() function ABI: |
| * |
| * @args (RDI) - struct tdx_hypercall_args for input and output |
| * @flags (RSI) - TDX_HCALL_* flags |
| * |
| * 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) |
