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/*-
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright (c) 2013, Anish Gupta (akgupt3@gmail.com)
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice unmodified, this list of conditions, and the following
* disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <machine/asmacros.h>
#include "svm_assym.h"
/*
* Be friendly to DTrace FBT's prologue/epilogue pattern matching.
*
* They are also responsible for saving/restoring the host %rbp across VMRUN.
*/
#define VENTER push %rbp ; mov %rsp,%rbp
#define VLEAVE pop %rbp
/*
* svm_launch(uint64_t vmcb, struct svm_regctx *gctx, struct pcpu *pcpu)
* %rdi: physical address of VMCB
* %rsi: pointer to guest context
* %rdx: pointer to the pcpu data
*/
ENTRY(svm_launch)
VENTER
/* save pointer to the pcpu data */
push %rdx
/*
* Host register state saved across a VMRUN.
*
* All "callee saved registers" except:
* %rsp: because it is preserved by the processor across VMRUN.
* %rbp: because it is saved/restored by the function prologue/epilogue.
*/
push %rbx
push %r12
push %r13
push %r14
push %r15
/* Save the physical address of the VMCB in %rax */
movq %rdi, %rax
push %rsi /* push guest context pointer on the stack */
/*
* Restore guest state.
*/
movq SCTX_R8(%rsi), %r8
movq SCTX_R9(%rsi), %r9
movq SCTX_R10(%rsi), %r10
movq SCTX_R11(%rsi), %r11
movq SCTX_R12(%rsi), %r12
movq SCTX_R13(%rsi), %r13
movq SCTX_R14(%rsi), %r14
movq SCTX_R15(%rsi), %r15
movq SCTX_RBP(%rsi), %rbp
movq SCTX_RBX(%rsi), %rbx
movq SCTX_RCX(%rsi), %rcx
movq SCTX_RDX(%rsi), %rdx
movq SCTX_RDI(%rsi), %rdi
movq SCTX_RSI(%rsi), %rsi /* %rsi must be restored last */
vmload %rax
vmrun %rax
vmsave %rax
pop %rax /* pop guest context pointer from the stack */
/*
* Save guest state.
*/
movq %r8, SCTX_R8(%rax)
movq %r9, SCTX_R9(%rax)
movq %r10, SCTX_R10(%rax)
movq %r11, SCTX_R11(%rax)
movq %r12, SCTX_R12(%rax)
movq %r13, SCTX_R13(%rax)
movq %r14, SCTX_R14(%rax)
movq %r15, SCTX_R15(%rax)
movq %rbp, SCTX_RBP(%rax)
movq %rbx, SCTX_RBX(%rax)
movq %rcx, SCTX_RCX(%rax)
movq %rdx, SCTX_RDX(%rax)
movq %rdi, SCTX_RDI(%rax)
movq %rsi, SCTX_RSI(%rax)
/*
* To prevent malicious branch target predictions from
* affecting the host, overwrite all entries in the RSB upon
* exiting a guest.
*/
mov $16, %ecx /* 16 iterations, two calls per loop */
mov %rsp, %rax
0: call 2f /* create an RSB entry. */
1: pause
call 1b /* capture rogue speculation. */
2: call 2f /* create an RSB entry. */
1: pause
call 1b /* capture rogue speculation. */
2: sub $1, %ecx
jnz 0b
mov %rax, %rsp
/* Restore host state */
pop %r15
pop %r14
pop %r13
pop %r12
pop %rbx
/* Restore %GS.base to point to the host's pcpu data */
pop %rdx
mov %edx, %eax
shr $32, %rdx
mov $MSR_GSBASE, %rcx
wrmsr
/*
* Clobber the remaining registers with guest contents so they
* can't be misused.
*/
xor %rbp, %rbp
xor %rdi, %rdi
xor %rsi, %rsi
xor %r8, %r8
xor %r9, %r9
xor %r10, %r10
xor %r11, %r11
VLEAVE
ret
END(svm_launch)
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