1eb94f1b6SKuppuswamy Sathyanarayanan/* SPDX-License-Identifier: GPL-2.0 */ 2eb94f1b6SKuppuswamy Sathyanarayanan#include <asm/asm-offsets.h> 3eb94f1b6SKuppuswamy Sathyanarayanan#include <asm/asm.h> 4eb94f1b6SKuppuswamy Sathyanarayanan#include <asm/frame.h> 5eb94f1b6SKuppuswamy Sathyanarayanan#include <asm/unwind_hints.h> 6eb94f1b6SKuppuswamy Sathyanarayanan 7eb94f1b6SKuppuswamy Sathyanarayanan#include <linux/linkage.h> 8eb94f1b6SKuppuswamy Sathyanarayanan#include <linux/bits.h> 9eb94f1b6SKuppuswamy Sathyanarayanan#include <linux/errno.h> 10eb94f1b6SKuppuswamy Sathyanarayanan 11eb94f1b6SKuppuswamy Sathyanarayanan#include "../../virt/vmx/tdx/tdxcall.S" 12eb94f1b6SKuppuswamy Sathyanarayanan 13eb94f1b6SKuppuswamy Sathyanarayanan/* 14eb94f1b6SKuppuswamy Sathyanarayanan * Bitmasks of exposed registers (with VMM). 15eb94f1b6SKuppuswamy Sathyanarayanan */ 16eb94f1b6SKuppuswamy Sathyanarayanan#define TDX_R10 BIT(10) 17eb94f1b6SKuppuswamy Sathyanarayanan#define TDX_R11 BIT(11) 18eb94f1b6SKuppuswamy Sathyanarayanan#define TDX_R12 BIT(12) 19eb94f1b6SKuppuswamy Sathyanarayanan#define TDX_R13 BIT(13) 20eb94f1b6SKuppuswamy Sathyanarayanan#define TDX_R14 BIT(14) 21eb94f1b6SKuppuswamy Sathyanarayanan#define TDX_R15 BIT(15) 22eb94f1b6SKuppuswamy Sathyanarayanan 23eb94f1b6SKuppuswamy Sathyanarayanan/* 24eb94f1b6SKuppuswamy Sathyanarayanan * These registers are clobbered to hold arguments for each 25eb94f1b6SKuppuswamy Sathyanarayanan * TDVMCALL. They are safe to expose to the VMM. 26eb94f1b6SKuppuswamy Sathyanarayanan * Each bit in this mask represents a register ID. Bit field 27eb94f1b6SKuppuswamy Sathyanarayanan * details can be found in TDX GHCI specification, section 28eb94f1b6SKuppuswamy Sathyanarayanan * titled "TDCALL [TDG.VP.VMCALL] leaf". 29eb94f1b6SKuppuswamy Sathyanarayanan */ 30eb94f1b6SKuppuswamy Sathyanarayanan#define TDVMCALL_EXPOSE_REGS_MASK ( TDX_R10 | TDX_R11 | \ 31eb94f1b6SKuppuswamy Sathyanarayanan TDX_R12 | TDX_R13 | \ 32eb94f1b6SKuppuswamy Sathyanarayanan TDX_R14 | TDX_R15 ) 33eb94f1b6SKuppuswamy Sathyanarayanan 34eb94f1b6SKuppuswamy Sathyanarayanan/* 35eb94f1b6SKuppuswamy Sathyanarayanan * __tdx_module_call() - Used by TDX guests to request services from 36eb94f1b6SKuppuswamy Sathyanarayanan * the TDX module (does not include VMM services) using TDCALL instruction. 37eb94f1b6SKuppuswamy Sathyanarayanan * 38eb94f1b6SKuppuswamy Sathyanarayanan * Transforms function call register arguments into the TDCALL register ABI. 39eb94f1b6SKuppuswamy Sathyanarayanan * After TDCALL operation, TDX module output is saved in @out (if it is 40eb94f1b6SKuppuswamy Sathyanarayanan * provided by the user). 41eb94f1b6SKuppuswamy Sathyanarayanan * 42eb94f1b6SKuppuswamy Sathyanarayanan *------------------------------------------------------------------------- 43eb94f1b6SKuppuswamy Sathyanarayanan * TDCALL ABI: 44eb94f1b6SKuppuswamy Sathyanarayanan *------------------------------------------------------------------------- 45eb94f1b6SKuppuswamy Sathyanarayanan * Input Registers: 46eb94f1b6SKuppuswamy Sathyanarayanan * 47eb94f1b6SKuppuswamy Sathyanarayanan * RAX - TDCALL Leaf number. 48eb94f1b6SKuppuswamy Sathyanarayanan * RCX,RDX,R8-R9 - TDCALL Leaf specific input registers. 49eb94f1b6SKuppuswamy Sathyanarayanan * 50eb94f1b6SKuppuswamy Sathyanarayanan * Output Registers: 51eb94f1b6SKuppuswamy Sathyanarayanan * 52eb94f1b6SKuppuswamy Sathyanarayanan * RAX - TDCALL instruction error code. 53eb94f1b6SKuppuswamy Sathyanarayanan * RCX,RDX,R8-R11 - TDCALL Leaf specific output registers. 54eb94f1b6SKuppuswamy Sathyanarayanan * 55eb94f1b6SKuppuswamy Sathyanarayanan *------------------------------------------------------------------------- 56eb94f1b6SKuppuswamy Sathyanarayanan * 57eb94f1b6SKuppuswamy Sathyanarayanan * __tdx_module_call() function ABI: 58eb94f1b6SKuppuswamy Sathyanarayanan * 59eb94f1b6SKuppuswamy Sathyanarayanan * @fn (RDI) - TDCALL Leaf ID, moved to RAX 60eb94f1b6SKuppuswamy Sathyanarayanan * @rcx (RSI) - Input parameter 1, moved to RCX 61eb94f1b6SKuppuswamy Sathyanarayanan * @rdx (RDX) - Input parameter 2, moved to RDX 62eb94f1b6SKuppuswamy Sathyanarayanan * @r8 (RCX) - Input parameter 3, moved to R8 63eb94f1b6SKuppuswamy Sathyanarayanan * @r9 (R8) - Input parameter 4, moved to R9 64eb94f1b6SKuppuswamy Sathyanarayanan * 65eb94f1b6SKuppuswamy Sathyanarayanan * @out (R9) - struct tdx_module_output pointer 66eb94f1b6SKuppuswamy Sathyanarayanan * stored temporarily in R12 (not 67eb94f1b6SKuppuswamy Sathyanarayanan * shared with the TDX module). It 68eb94f1b6SKuppuswamy Sathyanarayanan * can be NULL. 69eb94f1b6SKuppuswamy Sathyanarayanan * 70eb94f1b6SKuppuswamy Sathyanarayanan * Return status of TDCALL via RAX. 71eb94f1b6SKuppuswamy Sathyanarayanan */ 72eb94f1b6SKuppuswamy SathyanarayananSYM_FUNC_START(__tdx_module_call) 73eb94f1b6SKuppuswamy Sathyanarayanan FRAME_BEGIN 74eb94f1b6SKuppuswamy Sathyanarayanan TDX_MODULE_CALL host=0 75eb94f1b6SKuppuswamy Sathyanarayanan FRAME_END 76eb94f1b6SKuppuswamy Sathyanarayanan ret 77eb94f1b6SKuppuswamy SathyanarayananSYM_FUNC_END(__tdx_module_call) 78eb94f1b6SKuppuswamy Sathyanarayanan 79eb94f1b6SKuppuswamy Sathyanarayanan/* 80eb94f1b6SKuppuswamy Sathyanarayanan * __tdx_hypercall() - Make hypercalls to a TDX VMM using TDVMCALL leaf 81eb94f1b6SKuppuswamy Sathyanarayanan * of TDCALL instruction 82eb94f1b6SKuppuswamy Sathyanarayanan * 83eb94f1b6SKuppuswamy Sathyanarayanan * Transforms values in function call argument struct tdx_hypercall_args @args 84eb94f1b6SKuppuswamy Sathyanarayanan * into the TDCALL register ABI. After TDCALL operation, VMM output is saved 85eb94f1b6SKuppuswamy Sathyanarayanan * back in @args. 86eb94f1b6SKuppuswamy Sathyanarayanan * 87eb94f1b6SKuppuswamy Sathyanarayanan *------------------------------------------------------------------------- 88eb94f1b6SKuppuswamy Sathyanarayanan * TD VMCALL ABI: 89eb94f1b6SKuppuswamy Sathyanarayanan *------------------------------------------------------------------------- 90eb94f1b6SKuppuswamy Sathyanarayanan * 91eb94f1b6SKuppuswamy Sathyanarayanan * Input Registers: 92eb94f1b6SKuppuswamy Sathyanarayanan * 93eb94f1b6SKuppuswamy Sathyanarayanan * RAX - TDCALL instruction leaf number (0 - TDG.VP.VMCALL) 94eb94f1b6SKuppuswamy Sathyanarayanan * RCX - BITMAP which controls which part of TD Guest GPR 95eb94f1b6SKuppuswamy Sathyanarayanan * is passed as-is to the VMM and back. 96eb94f1b6SKuppuswamy Sathyanarayanan * R10 - Set 0 to indicate TDCALL follows standard TDX ABI 97eb94f1b6SKuppuswamy Sathyanarayanan * specification. Non zero value indicates vendor 98eb94f1b6SKuppuswamy Sathyanarayanan * specific ABI. 99eb94f1b6SKuppuswamy Sathyanarayanan * R11 - VMCALL sub function number 100eb94f1b6SKuppuswamy Sathyanarayanan * RBX, RBP, RDI, RSI - Used to pass VMCALL sub function specific arguments. 101eb94f1b6SKuppuswamy Sathyanarayanan * R8-R9, R12-R15 - Same as above. 102eb94f1b6SKuppuswamy Sathyanarayanan * 103eb94f1b6SKuppuswamy Sathyanarayanan * Output Registers: 104eb94f1b6SKuppuswamy Sathyanarayanan * 105eb94f1b6SKuppuswamy Sathyanarayanan * RAX - TDCALL instruction status (Not related to hypercall 106eb94f1b6SKuppuswamy Sathyanarayanan * output). 107eb94f1b6SKuppuswamy Sathyanarayanan * R10 - Hypercall output error code. 108eb94f1b6SKuppuswamy Sathyanarayanan * R11-R15 - Hypercall sub function specific output values. 109eb94f1b6SKuppuswamy Sathyanarayanan * 110eb94f1b6SKuppuswamy Sathyanarayanan *------------------------------------------------------------------------- 111eb94f1b6SKuppuswamy Sathyanarayanan * 112eb94f1b6SKuppuswamy Sathyanarayanan * __tdx_hypercall() function ABI: 113eb94f1b6SKuppuswamy Sathyanarayanan * 114eb94f1b6SKuppuswamy Sathyanarayanan * @args (RDI) - struct tdx_hypercall_args for input and output 115eb94f1b6SKuppuswamy Sathyanarayanan * @flags (RSI) - TDX_HCALL_* flags 116eb94f1b6SKuppuswamy Sathyanarayanan * 117eb94f1b6SKuppuswamy Sathyanarayanan * On successful completion, return the hypercall error code. 118eb94f1b6SKuppuswamy Sathyanarayanan */ 119eb94f1b6SKuppuswamy SathyanarayananSYM_FUNC_START(__tdx_hypercall) 120eb94f1b6SKuppuswamy Sathyanarayanan FRAME_BEGIN 121eb94f1b6SKuppuswamy Sathyanarayanan 122eb94f1b6SKuppuswamy Sathyanarayanan /* Save callee-saved GPRs as mandated by the x86_64 ABI */ 123eb94f1b6SKuppuswamy Sathyanarayanan push %r15 124eb94f1b6SKuppuswamy Sathyanarayanan push %r14 125eb94f1b6SKuppuswamy Sathyanarayanan push %r13 126eb94f1b6SKuppuswamy Sathyanarayanan push %r12 127eb94f1b6SKuppuswamy Sathyanarayanan 128eb94f1b6SKuppuswamy Sathyanarayanan /* Mangle function call ABI into TDCALL ABI: */ 129eb94f1b6SKuppuswamy Sathyanarayanan /* Set TDCALL leaf ID (TDVMCALL (0)) in RAX */ 130eb94f1b6SKuppuswamy Sathyanarayanan xor %eax, %eax 131eb94f1b6SKuppuswamy Sathyanarayanan 132eb94f1b6SKuppuswamy Sathyanarayanan /* Copy hypercall registers from arg struct: */ 133eb94f1b6SKuppuswamy Sathyanarayanan movq TDX_HYPERCALL_r10(%rdi), %r10 134eb94f1b6SKuppuswamy Sathyanarayanan movq TDX_HYPERCALL_r11(%rdi), %r11 135eb94f1b6SKuppuswamy Sathyanarayanan movq TDX_HYPERCALL_r12(%rdi), %r12 136eb94f1b6SKuppuswamy Sathyanarayanan movq TDX_HYPERCALL_r13(%rdi), %r13 137eb94f1b6SKuppuswamy Sathyanarayanan movq TDX_HYPERCALL_r14(%rdi), %r14 138eb94f1b6SKuppuswamy Sathyanarayanan movq TDX_HYPERCALL_r15(%rdi), %r15 139eb94f1b6SKuppuswamy Sathyanarayanan 140eb94f1b6SKuppuswamy Sathyanarayanan movl $TDVMCALL_EXPOSE_REGS_MASK, %ecx 141eb94f1b6SKuppuswamy Sathyanarayanan 142*bfe6ed0cSKirill A. Shutemov /* 143*bfe6ed0cSKirill A. Shutemov * For the idle loop STI needs to be called directly before the TDCALL 144*bfe6ed0cSKirill A. Shutemov * that enters idle (EXIT_REASON_HLT case). STI instruction enables 145*bfe6ed0cSKirill A. Shutemov * interrupts only one instruction later. If there is a window between 146*bfe6ed0cSKirill A. Shutemov * STI and the instruction that emulates the HALT state, there is a 147*bfe6ed0cSKirill A. Shutemov * chance for interrupts to happen in this window, which can delay the 148*bfe6ed0cSKirill A. Shutemov * HLT operation indefinitely. Since this is the not the desired 149*bfe6ed0cSKirill A. Shutemov * result, conditionally call STI before TDCALL. 150*bfe6ed0cSKirill A. Shutemov */ 151*bfe6ed0cSKirill A. Shutemov testq $TDX_HCALL_ISSUE_STI, %rsi 152*bfe6ed0cSKirill A. Shutemov jz .Lskip_sti 153*bfe6ed0cSKirill A. Shutemov sti 154*bfe6ed0cSKirill A. Shutemov.Lskip_sti: 155eb94f1b6SKuppuswamy Sathyanarayanan tdcall 156eb94f1b6SKuppuswamy Sathyanarayanan 157eb94f1b6SKuppuswamy Sathyanarayanan /* 158eb94f1b6SKuppuswamy Sathyanarayanan * RAX==0 indicates a failure of the TDVMCALL mechanism itself and that 159eb94f1b6SKuppuswamy Sathyanarayanan * something has gone horribly wrong with the TDX module. 160eb94f1b6SKuppuswamy Sathyanarayanan * 161eb94f1b6SKuppuswamy Sathyanarayanan * The return status of the hypercall operation is in a separate 162eb94f1b6SKuppuswamy Sathyanarayanan * register (in R10). Hypercall errors are a part of normal operation 163eb94f1b6SKuppuswamy Sathyanarayanan * and are handled by callers. 164eb94f1b6SKuppuswamy Sathyanarayanan */ 165eb94f1b6SKuppuswamy Sathyanarayanan testq %rax, %rax 166eb94f1b6SKuppuswamy Sathyanarayanan jne .Lpanic 167eb94f1b6SKuppuswamy Sathyanarayanan 168eb94f1b6SKuppuswamy Sathyanarayanan /* TDVMCALL leaf return code is in R10 */ 169eb94f1b6SKuppuswamy Sathyanarayanan movq %r10, %rax 170eb94f1b6SKuppuswamy Sathyanarayanan 171eb94f1b6SKuppuswamy Sathyanarayanan /* Copy hypercall result registers to arg struct if needed */ 172eb94f1b6SKuppuswamy Sathyanarayanan testq $TDX_HCALL_HAS_OUTPUT, %rsi 173eb94f1b6SKuppuswamy Sathyanarayanan jz .Lout 174eb94f1b6SKuppuswamy Sathyanarayanan 175eb94f1b6SKuppuswamy Sathyanarayanan movq %r10, TDX_HYPERCALL_r10(%rdi) 176eb94f1b6SKuppuswamy Sathyanarayanan movq %r11, TDX_HYPERCALL_r11(%rdi) 177eb94f1b6SKuppuswamy Sathyanarayanan movq %r12, TDX_HYPERCALL_r12(%rdi) 178eb94f1b6SKuppuswamy Sathyanarayanan movq %r13, TDX_HYPERCALL_r13(%rdi) 179eb94f1b6SKuppuswamy Sathyanarayanan movq %r14, TDX_HYPERCALL_r14(%rdi) 180eb94f1b6SKuppuswamy Sathyanarayanan movq %r15, TDX_HYPERCALL_r15(%rdi) 181eb94f1b6SKuppuswamy Sathyanarayanan.Lout: 182eb94f1b6SKuppuswamy Sathyanarayanan /* 183eb94f1b6SKuppuswamy Sathyanarayanan * Zero out registers exposed to the VMM to avoid speculative execution 184eb94f1b6SKuppuswamy Sathyanarayanan * with VMM-controlled values. This needs to include all registers 185eb94f1b6SKuppuswamy Sathyanarayanan * present in TDVMCALL_EXPOSE_REGS_MASK (except R12-R15). R12-R15 186eb94f1b6SKuppuswamy Sathyanarayanan * context will be restored. 187eb94f1b6SKuppuswamy Sathyanarayanan */ 188eb94f1b6SKuppuswamy Sathyanarayanan xor %r10d, %r10d 189eb94f1b6SKuppuswamy Sathyanarayanan xor %r11d, %r11d 190eb94f1b6SKuppuswamy Sathyanarayanan 191eb94f1b6SKuppuswamy Sathyanarayanan /* Restore callee-saved GPRs as mandated by the x86_64 ABI */ 192eb94f1b6SKuppuswamy Sathyanarayanan pop %r12 193eb94f1b6SKuppuswamy Sathyanarayanan pop %r13 194eb94f1b6SKuppuswamy Sathyanarayanan pop %r14 195eb94f1b6SKuppuswamy Sathyanarayanan pop %r15 196eb94f1b6SKuppuswamy Sathyanarayanan 197eb94f1b6SKuppuswamy Sathyanarayanan FRAME_END 198eb94f1b6SKuppuswamy Sathyanarayanan 199eb94f1b6SKuppuswamy Sathyanarayanan retq 200eb94f1b6SKuppuswamy Sathyanarayanan.Lpanic: 201eb94f1b6SKuppuswamy Sathyanarayanan call __tdx_hypercall_failed 202eb94f1b6SKuppuswamy Sathyanarayanan /* __tdx_hypercall_failed never returns */ 203eb94f1b6SKuppuswamy Sathyanarayanan jmp .Lpanic 204eb94f1b6SKuppuswamy SathyanarayananSYM_FUNC_END(__tdx_hypercall) 205