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#include <machine/asmacros.h> 29 30#include "svm_assym.h" 31 32/* 33 * Be friendly to DTrace FBT's prologue/epilogue pattern matching. 34 * 35 * They are also responsible for saving/restoring the host %rbp across VMRUN. 36 */ 37#define VENTER push %rbp ; mov %rsp,%rbp 38#define VLEAVE pop %rbp 39 40/* 41 * svm_launch(uint64_t vmcb, struct svm_regctx *gctx, struct pcpu *pcpu) 42 * %rdi: physical address of VMCB 43 * %rsi: pointer to guest context 44 * %rdx: pointer to the pcpu data 45 */ 46ENTRY(svm_launch) 47 VENTER 48 49 /* save pointer to the pcpu data */ 50 push %rdx 51 52 /* 53 * Host register state saved across a VMRUN. 54 * 55 * All "callee saved registers" except: 56 * %rsp: because it is preserved by the processor across VMRUN. 57 * %rbp: because it is saved/restored by the function prologue/epilogue. 58 */ 59 push %rbx 60 push %r12 61 push %r13 62 push %r14 63 push %r15 64 65 /* Save the physical address of the VMCB in %rax */ 66 movq %rdi, %rax 67 68 push %rsi /* push guest context pointer on the stack */ 69 70 /* 71 * Restore guest state. 72 */ 73 movq SCTX_R8(%rsi), %r8 74 movq SCTX_R9(%rsi), %r9 75 movq SCTX_R10(%rsi), %r10 76 movq SCTX_R11(%rsi), %r11 77 movq SCTX_R12(%rsi), %r12 78 movq SCTX_R13(%rsi), %r13 79 movq SCTX_R14(%rsi), %r14 80 movq SCTX_R15(%rsi), %r15 81 movq SCTX_RBP(%rsi), %rbp 82 movq SCTX_RBX(%rsi), %rbx 83 movq SCTX_RCX(%rsi), %rcx 84 movq SCTX_RDX(%rsi), %rdx 85 movq SCTX_RDI(%rsi), %rdi 86 movq SCTX_RSI(%rsi), %rsi /* %rsi must be restored last */ 87 88 vmload %rax 89 vmrun %rax 90 vmsave %rax 91 92 pop %rax /* pop guest context pointer from the stack */ 93 94 /* 95 * Save guest state. 96 */ 97 movq %r8, SCTX_R8(%rax) 98 movq %r9, SCTX_R9(%rax) 99 movq %r10, SCTX_R10(%rax) 100 movq %r11, SCTX_R11(%rax) 101 movq %r12, SCTX_R12(%rax) 102 movq %r13, SCTX_R13(%rax) 103 movq %r14, SCTX_R14(%rax) 104 movq %r15, SCTX_R15(%rax) 105 movq %rbp, SCTX_RBP(%rax) 106 movq %rbx, SCTX_RBX(%rax) 107 movq %rcx, SCTX_RCX(%rax) 108 movq %rdx, SCTX_RDX(%rax) 109 movq %rdi, SCTX_RDI(%rax) 110 movq %rsi, SCTX_RSI(%rax) 111 112 /* 113 * To prevent malicious branch target predictions from 114 * affecting the host, overwrite all entries in the RSB upon 115 * exiting a guest. 116 */ 117 mov $16, %ecx /* 16 iterations, two calls per loop */ 118 mov %rsp, %rax 1190: call 2f /* create an RSB entry. */ 1201: pause 121 call 1b /* capture rogue speculation. */ 1222: call 2f /* create an RSB entry. */ 1231: pause 124 call 1b /* capture rogue speculation. */ 1252: sub $1, %ecx 126 jnz 0b 127 mov %rax, %rsp 128 129 /* Restore host state */ 130 pop %r15 131 pop %r14 132 pop %r13 133 pop %r12 134 pop %rbx 135 136 /* Restore %GS.base to point to the host's pcpu data */ 137 pop %rdx 138 mov %edx, %eax 139 shr $32, %rdx 140 mov $MSR_GSBASE, %rcx 141 wrmsr 142 143 /* 144 * Clobber the remaining registers with guest contents so they 145 * can't be misused. 146 */ 147 xor %rbp, %rbp 148 xor %rdi, %rdi 149 xor %rsi, %rsi 150 xor %r8, %r8 151 xor %r9, %r9 152 xor %r10, %r10 153 xor %r11, %r11 154 155 VLEAVE 156 ret 157END(svm_launch) 158