1/*- 2 * SPDX-License-Identifier: BSD-2-Clause 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/* 43 * svm_launch(uint64_t vmcb, struct svm_regctx *gctx, struct pcpu *pcpu) 44 * %rdi: physical address of VMCB 45 * %rsi: pointer to guest context 46 * %rdx: pointer to the pcpu data 47 */ 48ENTRY(svm_launch) 49 VENTER 50 51 /* save pointer to the pcpu data */ 52 push %rdx 53 54 /* 55 * Host register state saved across a VMRUN. 56 * 57 * All "callee saved registers" except: 58 * %rsp: because it is preserved by the processor across VMRUN. 59 * %rbp: because it is saved/restored by the function prologue/epilogue. 60 */ 61 push %rbx 62 push %r12 63 push %r13 64 push %r14 65 push %r15 66 67 /* Save the physical address of the VMCB in %rax */ 68 movq %rdi, %rax 69 70 push %rsi /* push guest context pointer on the stack */ 71 72 /* 73 * Restore guest state. 74 */ 75 movq SCTX_R8(%rsi), %r8 76 movq SCTX_R9(%rsi), %r9 77 movq SCTX_R10(%rsi), %r10 78 movq SCTX_R11(%rsi), %r11 79 movq SCTX_R12(%rsi), %r12 80 movq SCTX_R13(%rsi), %r13 81 movq SCTX_R14(%rsi), %r14 82 movq SCTX_R15(%rsi), %r15 83 movq SCTX_RBP(%rsi), %rbp 84 movq SCTX_RBX(%rsi), %rbx 85 movq SCTX_RCX(%rsi), %rcx 86 movq SCTX_RDX(%rsi), %rdx 87 movq SCTX_RDI(%rsi), %rdi 88 movq SCTX_RSI(%rsi), %rsi /* %rsi must be restored last */ 89 90 vmload %rax 91 vmrun %rax 92 vmsave %rax 93 94 pop %rax /* pop guest context pointer from the stack */ 95 96 /* 97 * Save guest state. 98 */ 99 movq %r8, SCTX_R8(%rax) 100 movq %r9, SCTX_R9(%rax) 101 movq %r10, SCTX_R10(%rax) 102 movq %r11, SCTX_R11(%rax) 103 movq %r12, SCTX_R12(%rax) 104 movq %r13, SCTX_R13(%rax) 105 movq %r14, SCTX_R14(%rax) 106 movq %r15, SCTX_R15(%rax) 107 movq %rbp, SCTX_RBP(%rax) 108 movq %rbx, SCTX_RBX(%rax) 109 movq %rcx, SCTX_RCX(%rax) 110 movq %rdx, SCTX_RDX(%rax) 111 movq %rdi, SCTX_RDI(%rax) 112 movq %rsi, SCTX_RSI(%rax) 113 114 /* 115 * To prevent malicious branch target predictions from 116 * affecting the host, overwrite all entries in the RSB upon 117 * exiting a guest. 118 */ 119 mov $16, %ecx /* 16 iterations, two calls per loop */ 120 mov %rsp, %rax 1210: call 2f /* create an RSB entry. */ 1221: pause 123 call 1b /* capture rogue speculation. */ 1242: call 2f /* create an RSB entry. */ 1251: pause 126 call 1b /* capture rogue speculation. */ 1272: sub $1, %ecx 128 jnz 0b 129 mov %rax, %rsp 130 131 /* Restore host state */ 132 pop %r15 133 pop %r14 134 pop %r13 135 pop %r12 136 pop %rbx 137 138 /* Restore %GS.base to point to the host's pcpu data */ 139 pop %rdx 140 mov %edx, %eax 141 shr $32, %rdx 142 mov $MSR_GSBASE, %rcx 143 wrmsr 144 145 /* 146 * Clobber the remaining registers with guest contents so they 147 * can't be misused. 148 */ 149 xor %rbp, %rbp 150 xor %rdi, %rdi 151 xor %rsi, %rsi 152 xor %r8, %r8 153 xor %r9, %r9 154 xor %r10, %r10 155 xor %r11, %r11 156 157 VLEAVE 158 ret 159END(svm_launch) 160