b7416438b8
In KVM, a virtual machine implementation like Qemu can access a vcpu via ioctl. KVM_RUN is an ioctl command to enter vcpu. The command returns control for various reasons: needs of device emulation or consuming time slices are the typical ones. The vmi takes a different action for the reason. We, strace users, want to know the reason to understand kvm. This change prints the reason as auxstr if "-e kvm=vcpu" option is given, and if strace runs on Linux 4.16.0 or higher, which includes commit e46b469278a59781f9b25ff608af84892963821b, "kvm: embed vcpu id to dentry of vcpu anon inode." The way to get the reason is a bit complicated because the ioctl does not return it to the userspace directly. Instead, the vmi and kvm communicate via an area of the process virtual memory where the fd of vcpu is mmap'ed. strace must peek the area to know the reason. The change does three things: (1) recording the area for the given vcpu when the target calls VCPU_CREATE to vcpu_info_list per tcb data field, (2) verifying the data recorded in vcpu_info_list before doing (3), and (3) decoding the exit reason field of the area. The change is complicated because there is a case that strace does not have a chance to do (1) if -p option is used. In this case, vcpu_info data created in the step (2). The area has more fields than "exit reason", dumping them may be implemented in the future. * defs.h (struct tcb) [HAVE_LINUX_KVM_H]: Add vcpu_info_list field. [HAVE_LINUX_KVM_H]: (kvm_run_structure_decoder_init, kvm_vcpu_info_free): New declarations. * strace.c (usage): Add "kvm" as a new expression for -e option. (droptcb): Call kvm_vcpu_info_free. * filter_qualify.c (qualify_kvm): New function calling kvm_run_structure_decoder_init to enable for attaching the exit reason to auxstr. (qual_options): Add "kvm" as an entry. * xlat/kvm_exit_reason.in: New file. * kvm.c: Include xmalloc.h and mmap_cache.h. (dump_kvm_run_structure): New static variable. (kvm_run_structure_decoder_init): New function. (vcpu_info): New struct definition representing the 3-tuple: vcpu file descriptor, id of the vcpu, and mmap'ed entry. (vcpu_find, vcpu_alloc, vcpu_register, vcpu_getinfo, kvm_vcpu_info_free): New functions to access tcb's vcpu_info_list field and vcpu_info data type. (is_map_for_file, map_len): New helper functions. (kvm_ioclt_run_attach_auxstr, kvm_ioctl_decode_run): New functions decoding vcpu exit reason and attaching the decoded data to auxstr field of tcb. (kvm_ioctl_create_vcpu): Call vcpu_register to make an entry mapping a file descriptor and the vcpu id associated with the fd. (kvm_ioctl): Call kvm_ioctl_decode_run. Signed-off-by: Masatake YAMATO <yamato@redhat.com> Co-Authored-by: Dmitry V. Levin <ldv@altlinux.org>
426 lines
10 KiB
C
426 lines
10 KiB
C
/*
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* Support for decoding of KVM_* ioctl commands.
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*
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* Copyright (c) 2017 Masatake YAMATO <yamato@redhat.com>
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* Copyright (c) 2017 Red Hat, Inc.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "defs.h"
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#ifdef HAVE_LINUX_KVM_H
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# include <linux/kvm.h>
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# include "print_fields.h"
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# include "arch_kvm.c"
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# include "xmalloc.h"
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# include "mmap_cache.h"
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struct vcpu_info {
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struct vcpu_info *next;
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int fd;
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int cpuid;
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long mmap_addr;
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unsigned long mmap_len;
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bool resolved;
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};
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static bool dump_kvm_run_structure;
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static struct vcpu_info *
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vcpu_find(struct tcb *const tcp, int fd)
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{
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for (struct vcpu_info *vcpu_info = tcp->vcpu_info_list;
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vcpu_info;
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vcpu_info = vcpu_info->next)
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if (vcpu_info->fd == fd)
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return vcpu_info;
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return NULL;
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}
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static struct vcpu_info *
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vcpu_alloc(struct tcb *const tcp, int fd, int cpuid)
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{
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struct vcpu_info *vcpu_info = xcalloc(1, sizeof(*vcpu_info));
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vcpu_info->fd = fd;
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vcpu_info->cpuid = cpuid;
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vcpu_info->next = tcp->vcpu_info_list;
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tcp->vcpu_info_list = vcpu_info;
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return vcpu_info;
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}
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void
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kvm_vcpu_info_free(struct tcb *tcp)
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{
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struct vcpu_info *head, *next;
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for (head = tcp->vcpu_info_list; head; head = next) {
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next = head->next;
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free(head);
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}
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tcp->vcpu_info_list = NULL;
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}
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static void
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vcpu_register(struct tcb *const tcp, int fd, int cpuid)
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{
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if (fd < 0)
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return;
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struct vcpu_info *vcpu_info = vcpu_find(tcp, fd);
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if (!vcpu_info)
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vcpu_info = vcpu_alloc(tcp, fd, cpuid);
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else if (vcpu_info->cpuid != cpuid)
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{
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vcpu_info->cpuid = cpuid;
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vcpu_info->resolved = false;
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}
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}
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static bool
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is_map_for_file(struct mmap_cache_entry_t *map_info, void *data)
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{
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/* major version for anon inode may be given in get_anon_bdev()
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* in linux kernel.
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*
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* *p = MKDEV(0, dev & MINORMASK);
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*-----------------^
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*/
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return map_info->binary_filename &&
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map_info->major == 0 &&
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strcmp(map_info->binary_filename, data) == 0;
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}
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static unsigned long
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map_len(struct mmap_cache_entry_t *map_info)
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{
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return map_info->start_addr < map_info->end_addr
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? map_info->end_addr - map_info->start_addr
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: 0;
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}
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#define VCPU_DENTRY_PREFIX "anon_inode:kvm-vcpu:"
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static struct vcpu_info*
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vcpu_get_info(struct tcb *const tcp, int fd)
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{
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struct vcpu_info *vcpu_info = vcpu_find(tcp, fd);
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struct mmap_cache_entry_t *map_info;
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const char *cpuid_str;
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enum mmap_cache_rebuild_result mc_stat =
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mmap_cache_rebuild_if_invalid(tcp, __func__);
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if (mc_stat == MMAP_CACHE_REBUILD_NOCACHE)
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return NULL;
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if (vcpu_info && vcpu_info->resolved) {
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if (mc_stat == MMAP_CACHE_REBUILD_READY)
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return vcpu_info;
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else {
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map_info = mmap_cache_search(tcp, vcpu_info->mmap_addr);
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if (map_info) {
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cpuid_str =
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STR_STRIP_PREFIX(map_info->binary_filename,
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VCPU_DENTRY_PREFIX);
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if (cpuid_str != map_info->binary_filename) {
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int cpuid = string_to_uint(cpuid_str);
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if (cpuid < 0)
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return NULL;
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if (vcpu_info->cpuid == cpuid)
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return vcpu_info;
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}
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}
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/* The vcpu vma may be mremap'ed. */
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vcpu_info->resolved = false;
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}
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}
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/* Slow path: !vcpu_info || !vcpu_info->resolved */
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char path[PATH_MAX + 1];
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cpuid_str = path;
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if (getfdpath(tcp, fd, path, sizeof(path)) >= 0)
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cpuid_str = STR_STRIP_PREFIX(path, VCPU_DENTRY_PREFIX);
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if (cpuid_str == path)
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map_info = NULL;
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else
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map_info = mmap_cache_search_custom(tcp, is_map_for_file, path);
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if (map_info) {
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int cpuid = string_to_uint(cpuid_str);
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if (cpuid < 0)
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return NULL;
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if (!vcpu_info)
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vcpu_info = vcpu_alloc(tcp, fd, cpuid);
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else if (vcpu_info->cpuid != cpuid)
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vcpu_info->cpuid = cpuid;
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vcpu_info->mmap_addr = map_info->start_addr;
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vcpu_info->mmap_len = map_len(map_info);
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vcpu_info->resolved = true;
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return vcpu_info;
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}
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return NULL;
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}
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static int
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kvm_ioctl_create_vcpu(struct tcb *const tcp, const kernel_ulong_t arg)
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{
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uint32_t cpuid = arg;
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if (entering(tcp)) {
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tprintf(", %u", cpuid);
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if (dump_kvm_run_structure)
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return 0;
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} else if (!syserror(tcp)) {
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vcpu_register(tcp, tcp->u_rval, cpuid);
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}
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return RVAL_IOCTL_DECODED | RVAL_FD;
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}
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# ifdef HAVE_STRUCT_KVM_USERSPACE_MEMORY_REGION
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# include "xlat/kvm_mem_flags.h"
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static int
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kvm_ioctl_set_user_memory_region(struct tcb *const tcp, const kernel_ulong_t arg)
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{
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struct kvm_userspace_memory_region u_memory_region;
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tprints(", ");
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if (umove_or_printaddr(tcp, arg, &u_memory_region))
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return RVAL_IOCTL_DECODED;
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PRINT_FIELD_U("{", u_memory_region, slot);
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PRINT_FIELD_FLAGS(", ", u_memory_region, flags, kvm_mem_flags,
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"KVM_MEM_???");
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PRINT_FIELD_X(", ", u_memory_region, guest_phys_addr);
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PRINT_FIELD_U(", ", u_memory_region, memory_size);
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PRINT_FIELD_X(", ", u_memory_region, userspace_addr);
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tprints("}");
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return RVAL_IOCTL_DECODED;
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}
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# endif /* HAVE_STRUCT_KVM_USERSPACE_MEMORY_REGION */
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# ifdef HAVE_STRUCT_KVM_REGS
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static int
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kvm_ioctl_decode_regs(struct tcb *const tcp, const unsigned int code,
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const kernel_ulong_t arg)
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{
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struct kvm_regs regs;
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if (code == KVM_GET_REGS && entering(tcp))
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return 0;
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tprints(", ");
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if (!umove_or_printaddr(tcp, arg, ®s))
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arch_print_kvm_regs(tcp, arg, ®s);
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return RVAL_IOCTL_DECODED;
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}
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# endif /* HAVE_STRUCT_KVM_REGS */
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# ifdef HAVE_STRUCT_KVM_CPUID2
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# include "xlat/kvm_cpuid_flags.h"
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static bool
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print_kvm_cpuid_entry(struct tcb *const tcp,
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void* elem_buf, size_t elem_size, void* data)
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{
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const struct kvm_cpuid_entry2 *entry = elem_buf;
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PRINT_FIELD_X("{", *entry, function);
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PRINT_FIELD_X(", ", *entry, index);
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PRINT_FIELD_FLAGS(", ", *entry, flags, kvm_cpuid_flags,
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"KVM_CPUID_FLAG_???");
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PRINT_FIELD_X(", ", *entry, eax);
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PRINT_FIELD_X(", ", *entry, ebx);
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PRINT_FIELD_X(", ", *entry, ecx);
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PRINT_FIELD_X(", ", *entry, edx);
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tprints("}");
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return true;
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}
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static int
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kvm_ioctl_decode_cpuid2(struct tcb *const tcp, const unsigned int code,
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const kernel_ulong_t arg)
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{
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struct kvm_cpuid2 cpuid;
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if (entering(tcp) && (code == KVM_GET_SUPPORTED_CPUID
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# ifdef KVM_GET_EMULATED_CPUID
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|| code == KVM_GET_EMULATED_CPUID
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# endif
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))
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return 0;
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tprints(", ");
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if (!umove_or_printaddr(tcp, arg, &cpuid)) {
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PRINT_FIELD_U("{", cpuid, nent);
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tprints(", entries=");
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if (abbrev(tcp)) {
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tprints("[");
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if (cpuid.nent)
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tprints("...");
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tprints("]");
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} else {
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struct kvm_cpuid_entry2 entry;
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print_array(tcp, arg + sizeof(cpuid), cpuid.nent,
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&entry, sizeof(entry), tfetch_mem,
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print_kvm_cpuid_entry, NULL);
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}
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tprints("}");
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}
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return RVAL_IOCTL_DECODED;
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}
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# endif /* HAVE_STRUCT_KVM_CPUID2 */
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# ifdef HAVE_STRUCT_KVM_SREGS
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static int
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kvm_ioctl_decode_sregs(struct tcb *const tcp, const unsigned int code,
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const kernel_ulong_t arg)
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{
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struct kvm_sregs sregs;
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if (code == KVM_GET_SREGS && entering(tcp))
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return 0;
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tprints(", ");
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if (!umove_or_printaddr(tcp, arg, &sregs))
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arch_print_kvm_sregs(tcp, arg, &sregs);
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return RVAL_IOCTL_DECODED;
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}
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# endif /* HAVE_STRUCT_KVM_SREGS */
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# include "xlat/kvm_exit_reason.h"
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static void
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kvm_ioctl_run_attach_auxstr(struct tcb *const tcp,
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struct vcpu_info *info)
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{
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static struct kvm_run vcpu_run_struct;
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if (info->mmap_len < sizeof(vcpu_run_struct))
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return;
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if (umove(tcp, info->mmap_addr, &vcpu_run_struct) < 0)
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return;
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tcp->auxstr = xlat_idx(kvm_exit_reason, ARRAY_SIZE(kvm_exit_reason) - 1,
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vcpu_run_struct.exit_reason);
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if (!tcp->auxstr)
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tcp->auxstr = "KVM_EXIT_???";
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}
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static int
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kvm_ioctl_decode_run(struct tcb *const tcp)
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{
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if (entering(tcp))
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return 0;
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int r = RVAL_DECODED;
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if (syserror(tcp))
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return r;
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if (dump_kvm_run_structure) {
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tcp->auxstr = NULL;
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int fd = tcp->u_arg[0];
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struct vcpu_info *info = vcpu_get_info(tcp, fd);
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if (info) {
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kvm_ioctl_run_attach_auxstr(tcp, info);
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if (tcp->auxstr)
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r |= RVAL_STR;
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}
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}
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return r;
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}
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int
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kvm_ioctl(struct tcb *const tcp, const unsigned int code, const kernel_ulong_t arg)
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{
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switch (code) {
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case KVM_CREATE_VCPU:
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return kvm_ioctl_create_vcpu(tcp, arg);
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# ifdef HAVE_STRUCT_KVM_USERSPACE_MEMORY_REGION
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case KVM_SET_USER_MEMORY_REGION:
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return kvm_ioctl_set_user_memory_region(tcp, arg);
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# endif
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# ifdef HAVE_STRUCT_KVM_REGS
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case KVM_SET_REGS:
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case KVM_GET_REGS:
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return kvm_ioctl_decode_regs(tcp, code, arg);
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# endif
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# ifdef HAVE_STRUCT_KVM_SREGS
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case KVM_SET_SREGS:
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case KVM_GET_SREGS:
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return kvm_ioctl_decode_sregs(tcp, code, arg);
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# endif
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# ifdef HAVE_STRUCT_KVM_CPUID2
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case KVM_SET_CPUID2:
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case KVM_GET_SUPPORTED_CPUID:
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# ifdef KVM_GET_EMULATED_CPUID
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case KVM_GET_EMULATED_CPUID:
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# endif
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return kvm_ioctl_decode_cpuid2(tcp, code, arg);
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# endif
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case KVM_CREATE_VM:
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return RVAL_DECODED | RVAL_FD;
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case KVM_RUN:
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return kvm_ioctl_decode_run(tcp);
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case KVM_GET_VCPU_MMAP_SIZE:
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case KVM_GET_API_VERSION:
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default:
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return RVAL_DECODED;
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}
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}
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void
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kvm_run_structure_decoder_init(void)
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{
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dump_kvm_run_structure = true;
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mmap_cache_enable();
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}
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#endif /* HAVE_LINUX_KVM_H */
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