1/*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2013, Anish Gupta (akgupt3@gmail.com) 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice unmodified, this list of conditions, and the following 12 * disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 * 28 * $FreeBSD$ 29 */ 30#include <machine/asmacros.h> 31 32#include "svm_assym.h" 33 34/* 35 * Be friendly to DTrace FBT's prologue/epilogue pattern matching. 36 * 37 * They are also responsible for saving/restoring the host %rbp across VMRUN. 38 */ 39#define VENTER push %rbp ; mov %rsp,%rbp 40#define VLEAVE pop %rbp 41 42#define VMLOAD .byte 0x0f, 0x01, 0xda 43#define VMRUN .byte 0x0f, 0x01, 0xd8 44#define VMSAVE .byte 0x0f, 0x01, 0xdb 45 46/* 47 * svm_launch(uint64_t vmcb, struct svm_regctx *gctx, struct pcpu *pcpu) 48 * %rdi: physical address of VMCB 49 * %rsi: pointer to guest context 50 * %rdx: pointer to the pcpu data 51 */ 52ENTRY(svm_launch) 53 VENTER 54 55 /* save pointer to the pcpu data */ 56 push %rdx 57 58 /* 59 * Host register state saved across a VMRUN. 60 * 61 * All "callee saved registers" except: 62 * %rsp: because it is preserved by the processor across VMRUN. 63 * %rbp: because it is saved/restored by the function prologue/epilogue. 64 */ 65 push %rbx 66 push %r12 67 push %r13 68 push %r14 69 push %r15 70 71 /* Save the physical address of the VMCB in %rax */ 72 movq %rdi, %rax 73 74 push %rsi /* push guest context pointer on the stack */ 75 76 /* 77 * Restore guest state. 78 */ 79 movq SCTX_R8(%rsi), %r8 80 movq SCTX_R9(%rsi), %r9 81 movq SCTX_R10(%rsi), %r10 82 movq SCTX_R11(%rsi), %r11 83 movq SCTX_R12(%rsi), %r12 84 movq SCTX_R13(%rsi), %r13 85 movq SCTX_R14(%rsi), %r14 86 movq SCTX_R15(%rsi), %r15 87 movq SCTX_RBP(%rsi), %rbp 88 movq SCTX_RBX(%rsi), %rbx 89 movq SCTX_RCX(%rsi), %rcx 90 movq SCTX_RDX(%rsi), %rdx 91 movq SCTX_RDI(%rsi), %rdi 92 movq SCTX_RSI(%rsi), %rsi /* %rsi must be restored last */ 93 94 VMLOAD 95 VMRUN 96 VMSAVE 97 98 pop %rax /* pop guest context pointer from the stack */ 99 100 /* 101 * Save guest state. 102 */ 103 movq %r8, SCTX_R8(%rax) 104 movq %r9, SCTX_R9(%rax) 105 movq %r10, SCTX_R10(%rax) 106 movq %r11, SCTX_R11(%rax) 107 movq %r12, SCTX_R12(%rax) 108 movq %r13, SCTX_R13(%rax) 109 movq %r14, SCTX_R14(%rax) 110 movq %r15, SCTX_R15(%rax) 111 movq %rbp, SCTX_RBP(%rax) 112 movq %rbx, SCTX_RBX(%rax) 113 movq %rcx, SCTX_RCX(%rax) 114 movq %rdx, SCTX_RDX(%rax) 115 movq %rdi, SCTX_RDI(%rax) 116 movq %rsi, SCTX_RSI(%rax) 117 118 /* 119 * To prevent malicious branch target predictions from 120 * affecting the host, overwrite all entries in the RSB upon 121 * exiting a guest. 122 */ 123 mov $16, %ecx /* 16 iterations, two calls per loop */ 124 mov %rsp, %rax 1250: call 2f /* create an RSB entry. */ 1261: pause 127 call 1b /* capture rogue speculation. */ 1282: call 2f /* create an RSB entry. */ 1291: pause 130 call 1b /* capture rogue speculation. */ 1312: sub $1, %ecx 132 jnz 0b 133 mov %rax, %rsp 134 135 /* Restore host state */ 136 pop %r15 137 pop %r14 138 pop %r13 139 pop %r12 140 pop %rbx 141 142 /* Restore %GS.base to point to the host's pcpu data */ 143 pop %rdx 144 mov %edx, %eax 145 shr $32, %rdx 146 mov $MSR_GSBASE, %rcx 147 wrmsr 148 149 /* 150 * Clobber the remaining registers with guest contents so they 151 * can't be misused. 152 */ 153 xor %rbp, %rbp 154 xor %rdi, %rdi 155 xor %rsi, %rsi 156 xor %r8, %r8 157 xor %r9, %r9 158 xor %r10, %r10 159 xor %r11, %r11 160 161 VLEAVE 162 ret 163END(svm_launch) 164