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 */ 16*752d1330SKirill A. Shutemov#define TDX_RDX BIT(2) 17*752d1330SKirill A. Shutemov#define TDX_RBX BIT(3) 18*752d1330SKirill A. Shutemov#define TDX_RSI BIT(6) 19*752d1330SKirill A. Shutemov#define TDX_RDI BIT(7) 20*752d1330SKirill A. Shutemov#define TDX_R8 BIT(8) 21*752d1330SKirill A. Shutemov#define TDX_R9 BIT(9) 22eb94f1b6SKuppuswamy Sathyanarayanan#define TDX_R10 BIT(10) 23eb94f1b6SKuppuswamy Sathyanarayanan#define TDX_R11 BIT(11) 24eb94f1b6SKuppuswamy Sathyanarayanan#define TDX_R12 BIT(12) 25eb94f1b6SKuppuswamy Sathyanarayanan#define TDX_R13 BIT(13) 26eb94f1b6SKuppuswamy Sathyanarayanan#define TDX_R14 BIT(14) 27eb94f1b6SKuppuswamy Sathyanarayanan#define TDX_R15 BIT(15) 28eb94f1b6SKuppuswamy Sathyanarayanan 29eb94f1b6SKuppuswamy Sathyanarayanan/* 30eb94f1b6SKuppuswamy Sathyanarayanan * These registers are clobbered to hold arguments for each 31eb94f1b6SKuppuswamy Sathyanarayanan * TDVMCALL. They are safe to expose to the VMM. 32eb94f1b6SKuppuswamy Sathyanarayanan * Each bit in this mask represents a register ID. Bit field 33eb94f1b6SKuppuswamy Sathyanarayanan * details can be found in TDX GHCI specification, section 34eb94f1b6SKuppuswamy Sathyanarayanan * titled "TDCALL [TDG.VP.VMCALL] leaf". 35eb94f1b6SKuppuswamy Sathyanarayanan */ 36*752d1330SKirill A. Shutemov#define TDVMCALL_EXPOSE_REGS_MASK \ 37*752d1330SKirill A. Shutemov ( TDX_RDX | TDX_RBX | TDX_RSI | TDX_RDI | TDX_R8 | TDX_R9 | \ 38*752d1330SKirill A. Shutemov TDX_R10 | TDX_R11 | TDX_R12 | TDX_R13 | TDX_R14 | TDX_R15 ) 39eb94f1b6SKuppuswamy Sathyanarayanan 40eb94f1b6SKuppuswamy Sathyanarayanan/* 41eb94f1b6SKuppuswamy Sathyanarayanan * __tdx_module_call() - Used by TDX guests to request services from 42eb94f1b6SKuppuswamy Sathyanarayanan * the TDX module (does not include VMM services) using TDCALL instruction. 43eb94f1b6SKuppuswamy Sathyanarayanan * 44eb94f1b6SKuppuswamy Sathyanarayanan * Transforms function call register arguments into the TDCALL register ABI. 45eb94f1b6SKuppuswamy Sathyanarayanan * After TDCALL operation, TDX module output is saved in @out (if it is 46eb94f1b6SKuppuswamy Sathyanarayanan * provided by the user). 47eb94f1b6SKuppuswamy Sathyanarayanan * 48eb94f1b6SKuppuswamy Sathyanarayanan *------------------------------------------------------------------------- 49eb94f1b6SKuppuswamy Sathyanarayanan * TDCALL ABI: 50eb94f1b6SKuppuswamy Sathyanarayanan *------------------------------------------------------------------------- 51eb94f1b6SKuppuswamy Sathyanarayanan * Input Registers: 52eb94f1b6SKuppuswamy Sathyanarayanan * 53eb94f1b6SKuppuswamy Sathyanarayanan * RAX - TDCALL Leaf number. 54eb94f1b6SKuppuswamy Sathyanarayanan * RCX,RDX,R8-R9 - TDCALL Leaf specific input registers. 55eb94f1b6SKuppuswamy Sathyanarayanan * 56eb94f1b6SKuppuswamy Sathyanarayanan * Output Registers: 57eb94f1b6SKuppuswamy Sathyanarayanan * 58eb94f1b6SKuppuswamy Sathyanarayanan * RAX - TDCALL instruction error code. 59eb94f1b6SKuppuswamy Sathyanarayanan * RCX,RDX,R8-R11 - TDCALL Leaf specific output registers. 60eb94f1b6SKuppuswamy Sathyanarayanan * 61eb94f1b6SKuppuswamy Sathyanarayanan *------------------------------------------------------------------------- 62eb94f1b6SKuppuswamy Sathyanarayanan * 63eb94f1b6SKuppuswamy Sathyanarayanan * __tdx_module_call() function ABI: 64eb94f1b6SKuppuswamy Sathyanarayanan * 65eb94f1b6SKuppuswamy Sathyanarayanan * @fn (RDI) - TDCALL Leaf ID, moved to RAX 66eb94f1b6SKuppuswamy Sathyanarayanan * @rcx (RSI) - Input parameter 1, moved to RCX 67eb94f1b6SKuppuswamy Sathyanarayanan * @rdx (RDX) - Input parameter 2, moved to RDX 68eb94f1b6SKuppuswamy Sathyanarayanan * @r8 (RCX) - Input parameter 3, moved to R8 69eb94f1b6SKuppuswamy Sathyanarayanan * @r9 (R8) - Input parameter 4, moved to R9 70eb94f1b6SKuppuswamy Sathyanarayanan * 71eb94f1b6SKuppuswamy Sathyanarayanan * @out (R9) - struct tdx_module_output pointer 72eb94f1b6SKuppuswamy Sathyanarayanan * stored temporarily in R12 (not 73eb94f1b6SKuppuswamy Sathyanarayanan * shared with the TDX module). It 74eb94f1b6SKuppuswamy Sathyanarayanan * can be NULL. 75eb94f1b6SKuppuswamy Sathyanarayanan * 76eb94f1b6SKuppuswamy Sathyanarayanan * Return status of TDCALL via RAX. 77eb94f1b6SKuppuswamy Sathyanarayanan */ 78eb94f1b6SKuppuswamy SathyanarayananSYM_FUNC_START(__tdx_module_call) 79eb94f1b6SKuppuswamy Sathyanarayanan FRAME_BEGIN 80eb94f1b6SKuppuswamy Sathyanarayanan TDX_MODULE_CALL host=0 81eb94f1b6SKuppuswamy Sathyanarayanan FRAME_END 82c796f021SPeter Zijlstra RET 83eb94f1b6SKuppuswamy SathyanarayananSYM_FUNC_END(__tdx_module_call) 84eb94f1b6SKuppuswamy Sathyanarayanan 85eb94f1b6SKuppuswamy Sathyanarayanan/* 86eb94f1b6SKuppuswamy Sathyanarayanan * __tdx_hypercall() - Make hypercalls to a TDX VMM using TDVMCALL leaf 87eb94f1b6SKuppuswamy Sathyanarayanan * of TDCALL instruction 88eb94f1b6SKuppuswamy Sathyanarayanan * 89eb94f1b6SKuppuswamy Sathyanarayanan * Transforms values in function call argument struct tdx_hypercall_args @args 90eb94f1b6SKuppuswamy Sathyanarayanan * into the TDCALL register ABI. After TDCALL operation, VMM output is saved 91eb94f1b6SKuppuswamy Sathyanarayanan * back in @args. 92eb94f1b6SKuppuswamy Sathyanarayanan * 93eb94f1b6SKuppuswamy Sathyanarayanan *------------------------------------------------------------------------- 94eb94f1b6SKuppuswamy Sathyanarayanan * TD VMCALL ABI: 95eb94f1b6SKuppuswamy Sathyanarayanan *------------------------------------------------------------------------- 96eb94f1b6SKuppuswamy Sathyanarayanan * 97eb94f1b6SKuppuswamy Sathyanarayanan * Input Registers: 98eb94f1b6SKuppuswamy Sathyanarayanan * 99eb94f1b6SKuppuswamy Sathyanarayanan * RAX - TDCALL instruction leaf number (0 - TDG.VP.VMCALL) 100eb94f1b6SKuppuswamy Sathyanarayanan * RCX - BITMAP which controls which part of TD Guest GPR 101eb94f1b6SKuppuswamy Sathyanarayanan * is passed as-is to the VMM and back. 102eb94f1b6SKuppuswamy Sathyanarayanan * R10 - Set 0 to indicate TDCALL follows standard TDX ABI 103eb94f1b6SKuppuswamy Sathyanarayanan * specification. Non zero value indicates vendor 104eb94f1b6SKuppuswamy Sathyanarayanan * specific ABI. 105eb94f1b6SKuppuswamy Sathyanarayanan * R11 - VMCALL sub function number 106eb94f1b6SKuppuswamy Sathyanarayanan * RBX, RBP, RDI, RSI - Used to pass VMCALL sub function specific arguments. 107eb94f1b6SKuppuswamy Sathyanarayanan * R8-R9, R12-R15 - Same as above. 108eb94f1b6SKuppuswamy Sathyanarayanan * 109eb94f1b6SKuppuswamy Sathyanarayanan * Output Registers: 110eb94f1b6SKuppuswamy Sathyanarayanan * 111eb94f1b6SKuppuswamy Sathyanarayanan * RAX - TDCALL instruction status (Not related to hypercall 112eb94f1b6SKuppuswamy Sathyanarayanan * output). 113eb94f1b6SKuppuswamy Sathyanarayanan * R10 - Hypercall output error code. 114eb94f1b6SKuppuswamy Sathyanarayanan * R11-R15 - Hypercall sub function specific output values. 115eb94f1b6SKuppuswamy Sathyanarayanan * 116eb94f1b6SKuppuswamy Sathyanarayanan *------------------------------------------------------------------------- 117eb94f1b6SKuppuswamy Sathyanarayanan * 118eb94f1b6SKuppuswamy Sathyanarayanan * __tdx_hypercall() function ABI: 119eb94f1b6SKuppuswamy Sathyanarayanan * 120eb94f1b6SKuppuswamy Sathyanarayanan * @args (RDI) - struct tdx_hypercall_args for input and output 121eb94f1b6SKuppuswamy Sathyanarayanan * @flags (RSI) - TDX_HCALL_* flags 122eb94f1b6SKuppuswamy Sathyanarayanan * 123eb94f1b6SKuppuswamy Sathyanarayanan * On successful completion, return the hypercall error code. 124eb94f1b6SKuppuswamy Sathyanarayanan */ 125eb94f1b6SKuppuswamy SathyanarayananSYM_FUNC_START(__tdx_hypercall) 126eb94f1b6SKuppuswamy Sathyanarayanan FRAME_BEGIN 127eb94f1b6SKuppuswamy Sathyanarayanan 128eb94f1b6SKuppuswamy Sathyanarayanan /* Save callee-saved GPRs as mandated by the x86_64 ABI */ 129eb94f1b6SKuppuswamy Sathyanarayanan push %r15 130eb94f1b6SKuppuswamy Sathyanarayanan push %r14 131eb94f1b6SKuppuswamy Sathyanarayanan push %r13 132eb94f1b6SKuppuswamy Sathyanarayanan push %r12 133*752d1330SKirill A. Shutemov push %rbx 134c30c4b25SKirill A. Shutemov push %rbp 135c30c4b25SKirill A. Shutemov 136c30c4b25SKirill A. Shutemov /* Free RDI and RSI to be used as TDVMCALL arguments */ 137c30c4b25SKirill A. Shutemov movq %rdi, %rax 138c30c4b25SKirill A. Shutemov movq %rsi, %rbp 139c30c4b25SKirill A. Shutemov 140c30c4b25SKirill A. Shutemov /* Copy hypercall registers from arg struct: */ 141*752d1330SKirill A. Shutemov movq TDX_HYPERCALL_r8(%rax), %r8 142*752d1330SKirill A. Shutemov movq TDX_HYPERCALL_r9(%rax), %r9 143c30c4b25SKirill A. Shutemov movq TDX_HYPERCALL_r10(%rax), %r10 144c30c4b25SKirill A. Shutemov movq TDX_HYPERCALL_r11(%rax), %r11 145c30c4b25SKirill A. Shutemov movq TDX_HYPERCALL_r12(%rax), %r12 146c30c4b25SKirill A. Shutemov movq TDX_HYPERCALL_r13(%rax), %r13 147c30c4b25SKirill A. Shutemov movq TDX_HYPERCALL_r14(%rax), %r14 148c30c4b25SKirill A. Shutemov movq TDX_HYPERCALL_r15(%rax), %r15 149*752d1330SKirill A. Shutemov movq TDX_HYPERCALL_rdi(%rax), %rdi 150*752d1330SKirill A. Shutemov movq TDX_HYPERCALL_rsi(%rax), %rsi 151*752d1330SKirill A. Shutemov movq TDX_HYPERCALL_rbx(%rax), %rbx 152*752d1330SKirill A. Shutemov movq TDX_HYPERCALL_rdx(%rax), %rdx 153c30c4b25SKirill A. Shutemov 154c30c4b25SKirill A. Shutemov push %rax 155eb94f1b6SKuppuswamy Sathyanarayanan 156eb94f1b6SKuppuswamy Sathyanarayanan /* Mangle function call ABI into TDCALL ABI: */ 157eb94f1b6SKuppuswamy Sathyanarayanan /* Set TDCALL leaf ID (TDVMCALL (0)) in RAX */ 158eb94f1b6SKuppuswamy Sathyanarayanan xor %eax, %eax 159eb94f1b6SKuppuswamy Sathyanarayanan 160eb94f1b6SKuppuswamy Sathyanarayanan movl $TDVMCALL_EXPOSE_REGS_MASK, %ecx 161eb94f1b6SKuppuswamy Sathyanarayanan 162bfe6ed0cSKirill A. Shutemov /* 163bfe6ed0cSKirill A. Shutemov * For the idle loop STI needs to be called directly before the TDCALL 164bfe6ed0cSKirill A. Shutemov * that enters idle (EXIT_REASON_HLT case). STI instruction enables 165bfe6ed0cSKirill A. Shutemov * interrupts only one instruction later. If there is a window between 166bfe6ed0cSKirill A. Shutemov * STI and the instruction that emulates the HALT state, there is a 167bfe6ed0cSKirill A. Shutemov * chance for interrupts to happen in this window, which can delay the 168bfe6ed0cSKirill A. Shutemov * HLT operation indefinitely. Since this is the not the desired 169bfe6ed0cSKirill A. Shutemov * result, conditionally call STI before TDCALL. 170bfe6ed0cSKirill A. Shutemov */ 171c30c4b25SKirill A. Shutemov testq $TDX_HCALL_ISSUE_STI, %rbp 172bfe6ed0cSKirill A. Shutemov jz .Lskip_sti 173bfe6ed0cSKirill A. Shutemov sti 174bfe6ed0cSKirill A. Shutemov.Lskip_sti: 175eb94f1b6SKuppuswamy Sathyanarayanan tdcall 176eb94f1b6SKuppuswamy Sathyanarayanan 177eb94f1b6SKuppuswamy Sathyanarayanan /* 1783543f883SKirill A. Shutemov * RAX!=0 indicates a failure of the TDVMCALL mechanism itself and that 179eb94f1b6SKuppuswamy Sathyanarayanan * something has gone horribly wrong with the TDX module. 180eb94f1b6SKuppuswamy Sathyanarayanan * 181eb94f1b6SKuppuswamy Sathyanarayanan * The return status of the hypercall operation is in a separate 182eb94f1b6SKuppuswamy Sathyanarayanan * register (in R10). Hypercall errors are a part of normal operation 183eb94f1b6SKuppuswamy Sathyanarayanan * and are handled by callers. 184eb94f1b6SKuppuswamy Sathyanarayanan */ 185eb94f1b6SKuppuswamy Sathyanarayanan testq %rax, %rax 186eb94f1b6SKuppuswamy Sathyanarayanan jne .Lpanic 187eb94f1b6SKuppuswamy Sathyanarayanan 188c30c4b25SKirill A. Shutemov pop %rax 189c30c4b25SKirill A. Shutemov 190c30c4b25SKirill A. Shutemov /* Copy hypercall result registers to arg struct if needed */ 191c30c4b25SKirill A. Shutemov testq $TDX_HCALL_HAS_OUTPUT, %rbp 192c30c4b25SKirill A. Shutemov jz .Lout 193c30c4b25SKirill A. Shutemov 194*752d1330SKirill A. Shutemov movq %r8, TDX_HYPERCALL_r8(%rax) 195*752d1330SKirill A. Shutemov movq %r9, TDX_HYPERCALL_r9(%rax) 196c30c4b25SKirill A. Shutemov movq %r10, TDX_HYPERCALL_r10(%rax) 197c30c4b25SKirill A. Shutemov movq %r11, TDX_HYPERCALL_r11(%rax) 198c30c4b25SKirill A. Shutemov movq %r12, TDX_HYPERCALL_r12(%rax) 199c30c4b25SKirill A. Shutemov movq %r13, TDX_HYPERCALL_r13(%rax) 200c30c4b25SKirill A. Shutemov movq %r14, TDX_HYPERCALL_r14(%rax) 201c30c4b25SKirill A. Shutemov movq %r15, TDX_HYPERCALL_r15(%rax) 202*752d1330SKirill A. Shutemov movq %rdi, TDX_HYPERCALL_rdi(%rax) 203*752d1330SKirill A. Shutemov movq %rsi, TDX_HYPERCALL_rsi(%rax) 204*752d1330SKirill A. Shutemov movq %rbx, TDX_HYPERCALL_rbx(%rax) 205*752d1330SKirill A. Shutemov movq %rdx, TDX_HYPERCALL_rdx(%rax) 206c30c4b25SKirill A. Shutemov.Lout: 207eb94f1b6SKuppuswamy Sathyanarayanan /* TDVMCALL leaf return code is in R10 */ 208eb94f1b6SKuppuswamy Sathyanarayanan movq %r10, %rax 209eb94f1b6SKuppuswamy Sathyanarayanan 210eb94f1b6SKuppuswamy Sathyanarayanan /* 211eb94f1b6SKuppuswamy Sathyanarayanan * Zero out registers exposed to the VMM to avoid speculative execution 212eb94f1b6SKuppuswamy Sathyanarayanan * with VMM-controlled values. This needs to include all registers 213*752d1330SKirill A. Shutemov * present in TDVMCALL_EXPOSE_REGS_MASK, except RBX, and R12-R15 which 214*752d1330SKirill A. Shutemov * will be restored. 215eb94f1b6SKuppuswamy Sathyanarayanan */ 216*752d1330SKirill A. Shutemov xor %r8d, %r8d 217*752d1330SKirill A. Shutemov xor %r9d, %r9d 218eb94f1b6SKuppuswamy Sathyanarayanan xor %r10d, %r10d 219eb94f1b6SKuppuswamy Sathyanarayanan xor %r11d, %r11d 220*752d1330SKirill A. Shutemov xor %rdi, %rdi 221*752d1330SKirill A. Shutemov xor %rsi, %rsi 222*752d1330SKirill A. Shutemov xor %rdx, %rdx 223eb94f1b6SKuppuswamy Sathyanarayanan 224eb94f1b6SKuppuswamy Sathyanarayanan /* Restore callee-saved GPRs as mandated by the x86_64 ABI */ 225c30c4b25SKirill A. Shutemov pop %rbp 226*752d1330SKirill A. Shutemov pop %rbx 227eb94f1b6SKuppuswamy Sathyanarayanan pop %r12 228eb94f1b6SKuppuswamy Sathyanarayanan pop %r13 229eb94f1b6SKuppuswamy Sathyanarayanan pop %r14 230eb94f1b6SKuppuswamy Sathyanarayanan pop %r15 231eb94f1b6SKuppuswamy Sathyanarayanan 232eb94f1b6SKuppuswamy Sathyanarayanan FRAME_END 233eb94f1b6SKuppuswamy Sathyanarayanan 234c796f021SPeter Zijlstra RET 235eb94f1b6SKuppuswamy Sathyanarayanan.Lpanic: 236eb94f1b6SKuppuswamy Sathyanarayanan call __tdx_hypercall_failed 237eb94f1b6SKuppuswamy Sathyanarayanan /* __tdx_hypercall_failed never returns */ 2385af14c29SBorislav Petkov REACHABLE 239eb94f1b6SKuppuswamy Sathyanarayanan jmp .Lpanic 240eb94f1b6SKuppuswamy SathyanarayananSYM_FUNC_END(__tdx_hypercall) 241