diff --git a/.gitmodules b/.gitmodules
index ef9e75a..80ab83c 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -2,6 +2,9 @@
 	path = prebuilts
 	url = https://hafnium.googlesource.com/hafnium/prebuilts
 	shallow = true
+[submodule "driver/linux"]
+	path = driver/linux
+	url = https://hafnium.googlesource.com/hafnium/driver/linux
 [submodule "project/reference"]
 	path = project/reference
 	url = https://hafnium.googlesource.com/hafnium/project/reference
diff --git a/driver/linux b/driver/linux
new file mode 160000
index 0000000..81b9069
--- /dev/null
+++ b/driver/linux
@@ -0,0 +1 @@
+Subproject commit 81b90698b40fdcdd886e733a597ced435bd108b9
diff --git a/driver/linux/.gitignore b/driver/linux/.gitignore
deleted file mode 100644
index 8fd2089..0000000
--- a/driver/linux/.gitignore
+++ /dev/null
@@ -1,7 +0,0 @@
-*.ko
-*.mod.c
-*.o
-.*o.cmd
-.tmp_versions/
-Module.symvers
-modules.order
diff --git a/driver/linux/BUILD.gn b/driver/linux/BUILD.gn
deleted file mode 100644
index 6c7d688..0000000
--- a/driver/linux/BUILD.gn
+++ /dev/null
@@ -1,21 +0,0 @@
-# Copyright 2019 The Hafnium Authors.
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     https://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-import("//build/linux/linux.gni")
-
-linux_kernel_module("linux") {
-  module_name = "hafnium"
-  kernel_target = "//third_party/linux:linux"
-  kernel_dir = "//third_party/linux"
-}
diff --git a/driver/linux/LICENSE b/driver/linux/LICENSE
deleted file mode 100644
index d159169..0000000
--- a/driver/linux/LICENSE
+++ /dev/null
@@ -1,339 +0,0 @@
-                    GNU GENERAL PUBLIC LICENSE
-                       Version 2, June 1991
-
- Copyright (C) 1989, 1991 Free Software Foundation, Inc.,
- 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- Everyone is permitted to copy and distribute verbatim copies
- of this license document, but changing it is not allowed.
-
-                            Preamble
-
-  The licenses for most software are designed to take away your
-freedom to share and change it.  By contrast, the GNU General Public
-License is intended to guarantee your freedom to share and change free
-software--to make sure the software is free for all its users.  This
-General Public License applies to most of the Free Software
-Foundation's software and to any other program whose authors commit to
-using it.  (Some other Free Software Foundation software is covered by
-the GNU Lesser General Public License instead.)  You can apply it to
-your programs, too.
-
-  When we speak of free software, we are referring to freedom, not
-price.  Our General Public Licenses are designed to make sure that you
-have the freedom to distribute copies of free software (and charge for
-this service if you wish), that you receive source code or can get it
-if you want it, that you can change the software or use pieces of it
-in new free programs; and that you know you can do these things.
-
-  To protect your rights, we need to make restrictions that forbid
-anyone to deny you these rights or to ask you to surrender the rights.
-These restrictions translate to certain responsibilities for you if you
-distribute copies of the software, or if you modify it.
-
-  For example, if you distribute copies of such a program, whether
-gratis or for a fee, you must give the recipients all the rights that
-you have.  You must make sure that they, too, receive or can get the
-source code.  And you must show them these terms so they know their
-rights.
-
-  We protect your rights with two steps: (1) copyright the software, and
-(2) offer you this license which gives you legal permission to copy,
-distribute and/or modify the software.
-
-  Also, for each author's protection and ours, we want to make certain
-that everyone understands that there is no warranty for this free
-software.  If the software is modified by someone else and passed on, we
-want its recipients to know that what they have is not the original, so
-that any problems introduced by others will not reflect on the original
-authors' reputations.
-
-  Finally, any free program is threatened constantly by software
-patents.  We wish to avoid the danger that redistributors of a free
-program will individually obtain patent licenses, in effect making the
-program proprietary.  To prevent this, we have made it clear that any
-patent must be licensed for everyone's free use or not licensed at all.
-
-  The precise terms and conditions for copying, distribution and
-modification follow.
-
-                    GNU GENERAL PUBLIC LICENSE
-   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
-
-  0. This License applies to any program or other work which contains
-a notice placed by the copyright holder saying it may be distributed
-under the terms of this General Public License.  The "Program", below,
-refers to any such program or work, and a "work based on the Program"
-means either the Program or any derivative work under copyright law:
-that is to say, a work containing the Program or a portion of it,
-either verbatim or with modifications and/or translated into another
-language.  (Hereinafter, translation is included without limitation in
-the term "modification".)  Each licensee is addressed as "you".
-
-Activities other than copying, distribution and modification are not
-covered by this License; they are outside its scope.  The act of
-running the Program is not restricted, and the output from the Program
-is covered only if its contents constitute a work based on the
-Program (independent of having been made by running the Program).
-Whether that is true depends on what the Program does.
-
-  1. You may copy and distribute verbatim copies of the Program's
-source code as you receive it, in any medium, provided that you
-conspicuously and appropriately publish on each copy an appropriate
-copyright notice and disclaimer of warranty; keep intact all the
-notices that refer to this License and to the absence of any warranty;
-and give any other recipients of the Program a copy of this License
-along with the Program.
-
-You may charge a fee for the physical act of transferring a copy, and
-you may at your option offer warranty protection in exchange for a fee.
-
-  2. You may modify your copy or copies of the Program or any portion
-of it, thus forming a work based on the Program, and copy and
-distribute such modifications or work under the terms of Section 1
-above, provided that you also meet all of these conditions:
-
-    a) You must cause the modified files to carry prominent notices
-    stating that you changed the files and the date of any change.
-
-    b) You must cause any work that you distribute or publish, that in
-    whole or in part contains or is derived from the Program or any
-    part thereof, to be licensed as a whole at no charge to all third
-    parties under the terms of this License.
-
-    c) If the modified program normally reads commands interactively
-    when run, you must cause it, when started running for such
-    interactive use in the most ordinary way, to print or display an
-    announcement including an appropriate copyright notice and a
-    notice that there is no warranty (or else, saying that you provide
-    a warranty) and that users may redistribute the program under
-    these conditions, and telling the user how to view a copy of this
-    License.  (Exception: if the Program itself is interactive but
-    does not normally print such an announcement, your work based on
-    the Program is not required to print an announcement.)
-
-These requirements apply to the modified work as a whole.  If
-identifiable sections of that work are not derived from the Program,
-and can be reasonably considered independent and separate works in
-themselves, then this License, and its terms, do not apply to those
-sections when you distribute them as separate works.  But when you
-distribute the same sections as part of a whole which is a work based
-on the Program, the distribution of the whole must be on the terms of
-this License, whose permissions for other licensees extend to the
-entire whole, and thus to each and every part regardless of who wrote it.
-
-Thus, it is not the intent of this section to claim rights or contest
-your rights to work written entirely by you; rather, the intent is to
-exercise the right to control the distribution of derivative or
-collective works based on the Program.
-
-In addition, mere aggregation of another work not based on the Program
-with the Program (or with a work based on the Program) on a volume of
-a storage or distribution medium does not bring the other work under
-the scope of this License.
-
-  3. You may copy and distribute the Program (or a work based on it,
-under Section 2) in object code or executable form under the terms of
-Sections 1 and 2 above provided that you also do one of the following:
-
-    a) Accompany it with the complete corresponding machine-readable
-    source code, which must be distributed under the terms of Sections
-    1 and 2 above on a medium customarily used for software interchange; or,
-
-    b) Accompany it with a written offer, valid for at least three
-    years, to give any third party, for a charge no more than your
-    cost of physically performing source distribution, a complete
-    machine-readable copy of the corresponding source code, to be
-    distributed under the terms of Sections 1 and 2 above on a medium
-    customarily used for software interchange; or,
-
-    c) Accompany it with the information you received as to the offer
-    to distribute corresponding source code.  (This alternative is
-    allowed only for noncommercial distribution and only if you
-    received the program in object code or executable form with such
-    an offer, in accord with Subsection b above.)
-
-The source code for a work means the preferred form of the work for
-making modifications to it.  For an executable work, complete source
-code means all the source code for all modules it contains, plus any
-associated interface definition files, plus the scripts used to
-control compilation and installation of the executable.  However, as a
-special exception, the source code distributed need not include
-anything that is normally distributed (in either source or binary
-form) with the major components (compiler, kernel, and so on) of the
-operating system on which the executable runs, unless that component
-itself accompanies the executable.
-
-If distribution of executable or object code is made by offering
-access to copy from a designated place, then offering equivalent
-access to copy the source code from the same place counts as
-distribution of the source code, even though third parties are not
-compelled to copy the source along with the object code.
-
-  4. You may not copy, modify, sublicense, or distribute the Program
-except as expressly provided under this License.  Any attempt
-otherwise to copy, modify, sublicense or distribute the Program is
-void, and will automatically terminate your rights under this License.
-However, parties who have received copies, or rights, from you under
-this License will not have their licenses terminated so long as such
-parties remain in full compliance.
-
-  5. You are not required to accept this License, since you have not
-signed it.  However, nothing else grants you permission to modify or
-distribute the Program or its derivative works.  These actions are
-prohibited by law if you do not accept this License.  Therefore, by
-modifying or distributing the Program (or any work based on the
-Program), you indicate your acceptance of this License to do so, and
-all its terms and conditions for copying, distributing or modifying
-the Program or works based on it.
-
-  6. Each time you redistribute the Program (or any work based on the
-Program), the recipient automatically receives a license from the
-original licensor to copy, distribute or modify the Program subject to
-these terms and conditions.  You may not impose any further
-restrictions on the recipients' exercise of the rights granted herein.
-You are not responsible for enforcing compliance by third parties to
-this License.
-
-  7. If, as a consequence of a court judgment or allegation of patent
-infringement or for any other reason (not limited to patent issues),
-conditions are imposed on you (whether by court order, agreement or
-otherwise) that contradict the conditions of this License, they do not
-excuse you from the conditions of this License.  If you cannot
-distribute so as to satisfy simultaneously your obligations under this
-License and any other pertinent obligations, then as a consequence you
-may not distribute the Program at all.  For example, if a patent
-license would not permit royalty-free redistribution of the Program by
-all those who receive copies directly or indirectly through you, then
-the only way you could satisfy both it and this License would be to
-refrain entirely from distribution of the Program.
-
-If any portion of this section is held invalid or unenforceable under
-any particular circumstance, the balance of the section is intended to
-apply and the section as a whole is intended to apply in other
-circumstances.
-
-It is not the purpose of this section to induce you to infringe any
-patents or other property right claims or to contest validity of any
-such claims; this section has the sole purpose of protecting the
-integrity of the free software distribution system, which is
-implemented by public license practices.  Many people have made
-generous contributions to the wide range of software distributed
-through that system in reliance on consistent application of that
-system; it is up to the author/donor to decide if he or she is willing
-to distribute software through any other system and a licensee cannot
-impose that choice.
-
-This section is intended to make thoroughly clear what is believed to
-be a consequence of the rest of this License.
-
-  8. If the distribution and/or use of the Program is restricted in
-certain countries either by patents or by copyrighted interfaces, the
-original copyright holder who places the Program under this License
-may add an explicit geographical distribution limitation excluding
-those countries, so that distribution is permitted only in or among
-countries not thus excluded.  In such case, this License incorporates
-the limitation as if written in the body of this License.
-
-  9. The Free Software Foundation may publish revised and/or new versions
-of the General Public License from time to time.  Such new versions will
-be similar in spirit to the present version, but may differ in detail to
-address new problems or concerns.
-
-Each version is given a distinguishing version number.  If the Program
-specifies a version number of this License which applies to it and "any
-later version", you have the option of following the terms and conditions
-either of that version or of any later version published by the Free
-Software Foundation.  If the Program does not specify a version number of
-this License, you may choose any version ever published by the Free Software
-Foundation.
-
-  10. If you wish to incorporate parts of the Program into other free
-programs whose distribution conditions are different, write to the author
-to ask for permission.  For software which is copyrighted by the Free
-Software Foundation, write to the Free Software Foundation; we sometimes
-make exceptions for this.  Our decision will be guided by the two goals
-of preserving the free status of all derivatives of our free software and
-of promoting the sharing and reuse of software generally.
-
-                            NO WARRANTY
-
-  11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
-FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN
-OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
-PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
-OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
-MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE RISK AS
-TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE
-PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
-REPAIR OR CORRECTION.
-
-  12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
-WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
-REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
-INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
-OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
-TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
-YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
-PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
-POSSIBILITY OF SUCH DAMAGES.
-
-                     END OF TERMS AND CONDITIONS
-
-            How to Apply These Terms to Your New Programs
-
-  If you develop a new program, and you want it to be of the greatest
-possible use to the public, the best way to achieve this is to make it
-free software which everyone can redistribute and change under these terms.
-
-  To do so, attach the following notices to the program.  It is safest
-to attach them to the start of each source file to most effectively
-convey the exclusion of warranty; and each file should have at least
-the "copyright" line and a pointer to where the full notice is found.
-
-    <one line to give the program's name and a brief idea of what it does.>
-    Copyright (C) <year>  <name of author>
-
-    This program is free software; you can redistribute it and/or modify
-    it under the terms of the GNU General Public License as published by
-    the Free Software Foundation; either version 2 of the License, or
-    (at your option) any later version.
-
-    This program is distributed in the hope that it will be useful,
-    but WITHOUT ANY WARRANTY; without even the implied warranty of
-    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-    GNU General Public License for more details.
-
-    You should have received a copy of the GNU General Public License along
-    with this program; if not, write to the Free Software Foundation, Inc.,
-    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
-
-Also add information on how to contact you by electronic and paper mail.
-
-If the program is interactive, make it output a short notice like this
-when it starts in an interactive mode:
-
-    Gnomovision version 69, Copyright (C) year name of author
-    Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
-    This is free software, and you are welcome to redistribute it
-    under certain conditions; type `show c' for details.
-
-The hypothetical commands `show w' and `show c' should show the appropriate
-parts of the General Public License.  Of course, the commands you use may
-be called something other than `show w' and `show c'; they could even be
-mouse-clicks or menu items--whatever suits your program.
-
-You should also get your employer (if you work as a programmer) or your
-school, if any, to sign a "copyright disclaimer" for the program, if
-necessary.  Here is a sample; alter the names:
-
-  Yoyodyne, Inc., hereby disclaims all copyright interest in the program
-  `Gnomovision' (which makes passes at compilers) written by James Hacker.
-
-  <signature of Ty Coon>, 1 April 1989
-  Ty Coon, President of Vice
-
-This General Public License does not permit incorporating your program into
-proprietary programs.  If your program is a subroutine library, you may
-consider it more useful to permit linking proprietary applications with the
-library.  If this is what you want to do, use the GNU Lesser General
-Public License instead of this License.
diff --git a/driver/linux/Makefile b/driver/linux/Makefile
deleted file mode 100644
index 0add537..0000000
--- a/driver/linux/Makefile
+++ /dev/null
@@ -1,45 +0,0 @@
-# Copyright 2018 The Hafnium Authors.
-#
-# This program is free software; you can redistribute it and/or
-# modify it under the terms of the GNU General Public License
-# version 2 as published by the Free Software Foundation.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-# GNU General Public License for more details.
-
-# By default, assume this was checked out as a submodule of the Hafnium repo
-# and that Linux was checked out along side that checkout. These paths can be
-# overridden if that assumption is incorrect.
-HAFNIUM_PATH ?= $(CURDIR)/../..
-
-ifneq ($(KERNELRELEASE),)
-
-obj-m += hafnium.o
-
-hafnium-y += main.o
-hafnium-y += vmlib/aarch64/call.o
-hafnium-y += vmlib/spci.o
-
-ccflags-y = -I$(HAFNIUM_PATH)/inc/vmapi -I$(M)/inc
-
-else
-
-KERNEL_PATH ?= $(HAFNIUM_PATH)/third_party/linux
-ARCH ?= arm64
-CROSS_COMPILE ?= aarch64-linux-gnu-
-CHECKPATCH ?= $(KERNEL_PATH)/scripts/checkpatch.pl -q
-
-all:
-	cp -r $(HAFNIUM_PATH)/vmlib/ $(CURDIR)
-	make -C $(KERNEL_PATH) HAFNIUM_PATH=$(HAFNIUM_PATH) M=$(CURDIR) O=$(O) ARCH=$(ARCH) CROSS_COMPILE=$(CROSS_COMPILE) modules
-
-clean:
-	make -C $(KERNEL_PATH) HAFNIUM_PATH=$(HAFNIUM_PATH) M=$(CURDIR) O=$(O) clean
-	rm -rf vmlib
-
-checkpatch:
-	$(CHECKPATCH) -f main.c
-
-endif
diff --git a/driver/linux/inc/uapi/hf/socket.h b/driver/linux/inc/uapi/hf/socket.h
deleted file mode 100644
index 26d6432..0000000
--- a/driver/linux/inc/uapi/hf/socket.h
+++ /dev/null
@@ -1,32 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * Copyright 2019 The Hafnium Authors.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * version 2 as published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- */
-
-#pragma once
-
-#include <linux/socket.h>
-
-#include <hf/spci.h>
-
-/* TODO: Reusing AF_ECONET for now as it's otherwise unused. */
-#define AF_HF AF_ECONET
-#define PF_HF AF_HF
-
-/*
- * Address of a Hafnium socket
- */
-struct hf_sockaddr {
-	__kernel_sa_family_t family;
-	spci_vm_id_t vm_id;
-	uint64_t port;
-};
diff --git a/driver/linux/main.c b/driver/linux/main.c
deleted file mode 100644
index 5bd5709..0000000
--- a/driver/linux/main.c
+++ /dev/null
@@ -1,1162 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * Copyright 2018 The Hafnium Authors.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * version 2 as published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- */
-
-#include <clocksource/arm_arch_timer.h>
-#include <linux/atomic.h>
-#include <linux/cpuhotplug.h>
-#include <linux/hrtimer.h>
-#include <linux/init.h>
-#include <linux/interrupt.h>
-#include <linux/irq.h>
-#include <linux/kernel.h>
-#include <linux/kthread.h>
-#include <linux/mm.h>
-#include <linux/module.h>
-#include <linux/net.h>
-#include <linux/of.h>
-#include <linux/platform_device.h>
-#include <linux/sched/task.h>
-#include <linux/slab.h>
-#include <net/sock.h>
-
-#include <hf/call.h>
-#include <hf/spci.h>
-#include <hf/transport.h>
-
-#include "uapi/hf/socket.h"
-
-#define HYPERVISOR_TIMER_NAME "el2_timer"
-
-#define CONFIG_HAFNIUM_MAX_VMS   16
-#define CONFIG_HAFNIUM_MAX_VCPUS 32
-
-#define FIRST_SECONDARY_VM_ID (HF_VM_ID_OFFSET + 1)
-
-struct hf_vcpu {
-	struct hf_vm *vm;
-	spci_vcpu_index_t vcpu_index;
-	struct task_struct *task;
-	atomic_t abort_sleep;
-	atomic_t waiting_for_message;
-	struct hrtimer timer;
-};
-
-struct hf_vm {
-	spci_vm_id_t id;
-	spci_vcpu_count_t vcpu_count;
-	struct hf_vcpu *vcpu;
-};
-
-struct hf_sock {
-	/* This needs to be the first field. */
-	struct sock sk;
-
-	/*
-	 * The following fields are immutable after the socket transitions to
-	 * SS_CONNECTED state.
-	 */
-	uint64_t local_port;
-	uint64_t remote_port;
-	struct hf_vm *peer_vm;
-};
-
-static struct proto hf_sock_proto = {
-	.name = "hafnium",
-	.owner = THIS_MODULE,
-	.obj_size = sizeof(struct hf_sock),
-};
-
-static struct hf_vm *hf_vms;
-static spci_vm_count_t hf_vm_count;
-static struct page *hf_send_page;
-static struct page *hf_recv_page;
-static atomic64_t hf_next_port = ATOMIC64_INIT(0);
-static DEFINE_SPINLOCK(hf_send_lock);
-static DEFINE_HASHTABLE(hf_local_port_hash, 7);
-static DEFINE_SPINLOCK(hf_local_port_hash_lock);
-static int hf_irq;
-static enum cpuhp_state hf_cpuhp_state;
-static spci_vm_id_t current_vm_id;
-
-/**
- * Retrieves a VM from its ID, returning NULL if the VM doesn't exist.
- */
-static struct hf_vm *hf_vm_from_id(spci_vm_id_t vm_id)
-{
-	if (vm_id < FIRST_SECONDARY_VM_ID ||
-	    vm_id >= FIRST_SECONDARY_VM_ID + hf_vm_count)
-		return NULL;
-
-	return &hf_vms[vm_id - FIRST_SECONDARY_VM_ID];
-}
-
-/**
- * Wakes up the kernel thread responsible for running the given vcpu.
- *
- * Returns 0 if the thread was already running, 1 otherwise.
- */
-static int hf_vcpu_wake_up(struct hf_vcpu *vcpu)
-{
-	/* Set a flag indicating that the thread should not go to sleep. */
-	atomic_set(&vcpu->abort_sleep, 1);
-
-	/* Set the thread to running state. */
-	return wake_up_process(vcpu->task);
-}
-
-/**
- * Puts the current thread to sleep. The current thread must be responsible for
- * running the given vcpu.
- *
- * Going to sleep will fail if hf_vcpu_wake_up() or kthread_stop() was called on
- * this vcpu/thread since the last time it [re]started running.
- */
-static void hf_vcpu_sleep(struct hf_vcpu *vcpu)
-{
-	int abort;
-
-	set_current_state(TASK_INTERRUPTIBLE);
-
-	/* Check the sleep-abort flag after making thread interruptible. */
-	abort = atomic_read(&vcpu->abort_sleep);
-	if (!abort && !kthread_should_stop())
-		schedule();
-
-	/* Set state back to running on the way out. */
-	set_current_state(TASK_RUNNING);
-}
-
-/**
- * Wakes up the thread associated with the vcpu that owns the given timer. This
- * is called when the timer the thread is waiting on expires.
- */
-static enum hrtimer_restart hf_vcpu_timer_expired(struct hrtimer *timer)
-{
-	struct hf_vcpu *vcpu = container_of(timer, struct hf_vcpu, timer);
-	/* TODO: Inject interrupt. */
-	hf_vcpu_wake_up(vcpu);
-	return HRTIMER_NORESTART;
-}
-
-/**
- * This function is called when Hafnium requests that the primary VM wake up a
- * vCPU that belongs to a secondary VM.
- *
- * It wakes up the thread if it's sleeping, or kicks it if it's already running.
- */
-static void hf_handle_wake_up_request(spci_vm_id_t vm_id,
-				      spci_vcpu_index_t vcpu)
-{
-	struct hf_vm *vm = hf_vm_from_id(vm_id);
-
-	if (!vm) {
-		pr_warn("Request to wake up non-existent VM id: %u\n", vm_id);
-		return;
-	}
-
-	if (vcpu >= vm->vcpu_count) {
-		pr_warn("Request to wake up non-existent vCPU: %u.%u\n",
-			vm_id, vcpu);
-		return;
-	}
-
-	if (hf_vcpu_wake_up(&vm->vcpu[vcpu]) == 0) {
-		/*
-		 * The task was already running (presumably on a different
-		 * physical CPU); interrupt it. This gives Hafnium a chance to
-		 * inject any new interrupts.
-		 */
-		kick_process(vm->vcpu[vcpu].task);
-	}
-}
-
-/**
- * Injects an interrupt into a vCPU of the VM and ensures the vCPU will run to
- * handle the interrupt.
- */
-static void hf_interrupt_vm(spci_vm_id_t vm_id, uint64_t int_id)
-{
-	struct hf_vm *vm = hf_vm_from_id(vm_id);
-	spci_vcpu_index_t vcpu;
-	int64_t ret;
-
-	if (!vm) {
-		pr_warn("Request to wake up non-existent VM id: %u\n", vm_id);
-		return;
-	}
-
-	/*
-	 * TODO: For now we're picking the first vcpu to interrupt, but
-	 * we want to be smarter.
-	 */
-	vcpu = 0;
-	ret = hf_interrupt_inject(vm_id, vcpu, int_id);
-
-	if (ret == -1) {
-		pr_warn("Failed to inject interrupt %lld to vCPU %d of VM %d",
-			int_id, vcpu, vm_id);
-		return;
-	}
-
-	if (ret != 1) {
-		/* We don't need to wake up the vcpu. */
-		return;
-	}
-
-	hf_handle_wake_up_request(vm_id, vcpu);
-}
-
-/**
- * Notify all waiters on the given VM.
- */
-static void hf_notify_waiters(spci_vm_id_t vm_id)
-{
-	spci_vm_id_t waiter_vm_id;
-
-	while ((waiter_vm_id = hf_mailbox_waiter_get(vm_id)) != -1) {
-		if (waiter_vm_id == HF_PRIMARY_VM_ID) {
-			/*
-			 * TODO: Use this information when implementing per-vm
-			 * queues.
-			 */
-		} else {
-			hf_interrupt_vm(waiter_vm_id,
-					HF_MAILBOX_WRITABLE_INTID);
-		}
-	}
-}
-
-/**
- * Delivers a message to a VM.
- */
-static void hf_deliver_message(spci_vm_id_t vm_id)
-{
-	struct hf_vm *vm = hf_vm_from_id(vm_id);
-	spci_vcpu_index_t i;
-
-	if (!vm) {
-		pr_warn("Tried to deliver message to non-existent VM id: %u\n",
-			vm_id);
-		return;
-	}
-
-	/* Try to wake a vCPU that is waiting for a message. */
-	for (i = 0; i < vm->vcpu_count; i++) {
-		if (atomic_read(&vm->vcpu[i].waiting_for_message)) {
-			hf_handle_wake_up_request(vm->id,
-						  vm->vcpu[i].vcpu_index);
-			return;
-		}
-	}
-
-	/* None were waiting for a message so interrupt one. */
-	hf_interrupt_vm(vm->id, HF_MAILBOX_READABLE_INTID);
-}
-
-/**
- * Handles a message delivered to this VM by validating that it's well-formed
- * and then queueing it for delivery to the appropriate socket.
- */
-static void hf_handle_message(struct hf_vm *sender, size_t len,
-			      const void *message)
-{
-	struct hf_sock *hsock;
-	const struct hf_msg_hdr *hdr = (struct hf_msg_hdr *)message;
-	struct sk_buff *skb;
-	int err;
-
-	/* Ignore messages that are too small to hold a header. */
-	if (len < sizeof(struct hf_msg_hdr)) {
-		pr_err("Message received without header of length %d\n", len);
-		spci_rx_release();
-		return;
-	}
-
-	len -= sizeof(struct hf_msg_hdr);
-
-	/* Go through the colliding sockets. */
-	rcu_read_lock();
-	hash_for_each_possible_rcu(hf_local_port_hash, hsock, sk.sk_node,
-				   hdr->dst_port) {
-		if (hsock->peer_vm == sender &&
-		    hsock->remote_port == hdr->src_port) {
-			sock_hold(&hsock->sk);
-			break;
-		}
-	}
-	rcu_read_unlock();
-
-	/* Nothing to do if we couldn't find the target. */
-	if (!hsock) {
-		spci_rx_release();
-		return;
-	}
-
-	/*
-	 * TODO: From this point on, there are two failure paths: when we
-	 * create the skb below, and when we enqueue it to the socket. What
-	 * should we do if they fail? Ideally we would have some form of flow
-	 * control to prevent message loss, but how to do it efficiently?
-	 *
-	 * One option is to have a pre-allocated message that indicates to the
-	 * sender that a message was dropped. This way we guarantee that the
-	 * sender will be aware of loss and should back-off.
-	 */
-	/* Create the skb. */
-	skb = alloc_skb(len, GFP_KERNEL);
-	if (!skb)
-		goto exit;
-
-	memcpy(skb_put(skb, len), hdr + 1, len);
-
-	/*
-	 * Add the skb to the receive queue of the target socket. On success it
-	 * calls sk->sk_data_ready, which is currently set to sock_def_readable,
-	 * which wakes up any waiters.
-	 */
-	err = sock_queue_rcv_skb(&hsock->sk, skb);
-	if (err)
-		kfree_skb(skb);
-
-exit:
-	sock_put(&hsock->sk);
-
-	if (spci_rx_release().func == SPCI_RX_RELEASE_32)
-		hf_notify_waiters(HF_PRIMARY_VM_ID);
-}
-
-/**
- * This is the main loop of each vcpu.
- */
-static int hf_vcpu_thread(void *data)
-{
-	struct hf_vcpu *vcpu = data;
-	struct spci_value ret;
-
-	hrtimer_init(&vcpu->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
-	vcpu->timer.function = &hf_vcpu_timer_expired;
-
-	while (!kthread_should_stop()) {
-		spci_vcpu_index_t i;
-
-		/*
-		 * We're about to run the vcpu, so we can reset the abort-sleep
-		 * flag.
-		 */
-		atomic_set(&vcpu->abort_sleep, 0);
-
-		/* Call into Hafnium to run vcpu. */
-		ret = spci_run(vcpu->vm->id, vcpu->vcpu_index);
-
-		switch (ret.func) {
-		/* Preempted. */
-		case SPCI_INTERRUPT_32:
-			if (need_resched())
-				schedule();
-			break;
-
-		/* Yield. */
-		case SPCI_YIELD_32:
-			if (!kthread_should_stop())
-				schedule();
-			break;
-
-		/* WFI. */
-		case HF_SPCI_RUN_WAIT_FOR_INTERRUPT:
-			if (ret.arg2 != SPCI_SLEEP_INDEFINITE) {
-				hrtimer_start(&vcpu->timer, ret.arg2,
-					      HRTIMER_MODE_REL);
-			}
-			hf_vcpu_sleep(vcpu);
-			hrtimer_cancel(&vcpu->timer);
-			break;
-
-		/* Waiting for a message. */
-		case SPCI_MSG_WAIT_32:
-			atomic_set(&vcpu->waiting_for_message, 1);
-			if (ret.arg2 != SPCI_SLEEP_INDEFINITE) {
-				hrtimer_start(&vcpu->timer, ret.arg2,
-					      HRTIMER_MODE_REL);
-			}
-			hf_vcpu_sleep(vcpu);
-			hrtimer_cancel(&vcpu->timer);
-			atomic_set(&vcpu->waiting_for_message, 0);
-			break;
-
-		/* Wake up another vcpu. */
-		case HF_SPCI_RUN_WAKE_UP:
-			hf_handle_wake_up_request(spci_vm_id(ret),
-						  spci_vcpu_index(ret));
-			break;
-
-		/* Response available. */
-		case SPCI_MSG_SEND_32:
-			if (spci_msg_send_receiver(ret) == HF_PRIMARY_VM_ID) {
-				hf_handle_message(vcpu->vm,
-						  spci_msg_send_size(ret),
-						  page_address(hf_recv_page));
-			} else {
-				hf_deliver_message(spci_msg_send_receiver(ret));
-			}
-			break;
-
-		/* Notify all waiters. */
-		case SPCI_RX_RELEASE_32:
-			hf_notify_waiters(vcpu->vm->id);
-			break;
-
-		case SPCI_ERROR_32:
-			pr_warn("SPCI error %d running VM %d vCPU %d", ret.arg2,
-				vcpu->vm->id, vcpu->vcpu_index);
-			switch (ret.arg2) {
-			/* Abort was triggered. */
-			case SPCI_ABORTED:
-				for (i = 0; i < vcpu->vm->vcpu_count; i++) {
-					if (i == vcpu->vcpu_index)
-						continue;
-					hf_handle_wake_up_request(vcpu->vm->id,
-								  i);
-				}
-				hf_vcpu_sleep(vcpu);
-				break;
-			default:
-				/* Treat as a yield and try again later. */
-				if (!kthread_should_stop())
-					schedule();
-				break;
-			}
-			break;
-		}
-	}
-
-	return 0;
-}
-
-/**
- * Converts a pointer to a struct sock into a pointer to a struct hf_sock. It
- * relies on the fact that the first field of hf_sock is a sock.
- */
-static struct hf_sock *hsock_from_sk(struct sock *sk)
-{
-	return (struct hf_sock *)sk;
-}
-
-/**
- * This is called when the last reference to the outer socket is released. For
- * example, if it's a user-space socket, when the last file descriptor pointing
- * to this socket is closed.
- *
- * It begins cleaning up resources, though some can only be cleaned up after all
- * references to the underlying socket are released, which is handled by
- * hf_sock_destruct().
- */
-static int hf_sock_release(struct socket *sock)
-{
-	struct sock *sk = sock->sk;
-	struct hf_sock *hsock = hsock_from_sk(sk);
-	unsigned long flags;
-
-	if (!sk)
-		return 0;
-
-	/* Shutdown for both send and receive. */
-	lock_sock(sk);
-	sk->sk_shutdown |= RCV_SHUTDOWN | SEND_SHUTDOWN;
-	sk->sk_state_change(sk);
-	release_sock(sk);
-
-	/* Remove from the hash table, so lookups from now on won't find it. */
-	spin_lock_irqsave(&hf_local_port_hash_lock, flags);
-	hash_del_rcu(&hsock->sk.sk_node);
-	spin_unlock_irqrestore(&hf_local_port_hash_lock, flags);
-
-	/*
-	 * TODO: When we implement a tx queue, we need to clear it here so that
-	 * sk_wmem_alloc will not prevent sk from being freed (sk_free).
-	 */
-
-	/*
-	 * Wait for in-flight lookups to finish. We need to do this here because
-	 * in-flight lookups rely on the reference to the socket we're about to
-	 * release.
-	 */
-	synchronize_rcu();
-	sock_put(sk);
-	sock->sk = NULL;
-
-	return 0;
-}
-
-/**
- * This is called when there are no more references to the socket. It frees all
- * resources that haven't been freed during release.
- */
-static void hf_sock_destruct(struct sock *sk)
-{
-	/*
-	 * Clear the receive queue now that the handler cannot add any more
-	 * skbs to it.
-	 */
-	skb_queue_purge(&sk->sk_receive_queue);
-}
-
-/**
- * Connects the Hafnium socket to the provided VM and port. After the socket is
- * connected, it can be used to exchange datagrams with the specified peer.
- */
-static int hf_sock_connect(struct socket *sock, struct sockaddr *saddr, int len,
-			   int connect_flags)
-{
-	struct sock *sk = sock->sk;
-	struct hf_sock *hsock = hsock_from_sk(sk);
-	struct hf_vm *vm;
-	struct hf_sockaddr *addr;
-	int err;
-	unsigned long flags;
-
-	/* Basic address validation. */
-	if (len < sizeof(struct hf_sockaddr) || saddr->sa_family != AF_HF)
-		return -EINVAL;
-
-	addr = (struct hf_sockaddr *)saddr;
-	vm = hf_vm_from_id(addr->vm_id);
-	if (!vm)
-		return -ENETUNREACH;
-
-	/*
-	 * TODO: Once we implement access control in Hafnium, check that the
-	 * caller is allowed to contact the specified VM. Return -ECONNREFUSED
-	 * if access is denied.
-	 */
-
-	/* Take lock to make sure state doesn't change as we connect. */
-	lock_sock(sk);
-
-	/* Only unconnected sockets are allowed to become connected. */
-	if (sock->state != SS_UNCONNECTED) {
-		err = -EISCONN;
-		goto exit;
-	}
-
-	hsock->local_port = atomic64_inc_return(&hf_next_port);
-	hsock->remote_port = addr->port;
-	hsock->peer_vm = vm;
-
-	sock->state = SS_CONNECTED;
-
-	/* Add socket to hash table now that it's fully initialised. */
-	spin_lock_irqsave(&hf_local_port_hash_lock, flags);
-	hash_add_rcu(hf_local_port_hash, &sk->sk_node, hsock->local_port);
-	spin_unlock_irqrestore(&hf_local_port_hash_lock, flags);
-
-	err = 0;
-exit:
-	release_sock(sk);
-	return err;
-}
-
-/**
- * Sends the given skb to the appropriate VM by calling Hafnium. It will also
- * trigger the wake up of a recipient VM.
- *
- * Takes ownership of the skb on success.
- */
-static int hf_send_skb(struct sk_buff *skb)
-{
-	unsigned long flags;
-	struct spci_value ret;
-	struct hf_sock *hsock = hsock_from_sk(skb->sk);
-	struct hf_vm *vm = hsock->peer_vm;
-	void *message = page_address(hf_send_page);
-
-	/*
-	 * Call Hafnium under the send lock so that we serialize the use of the
-	 * global send buffer.
-	 */
-	spin_lock_irqsave(&hf_send_lock, flags);
-	memcpy(message, skb->data, skb->len);
-
-	ret = spci_msg_send(current_vm_id, vm->id, skb->len, 0);
-	spin_unlock_irqrestore(&hf_send_lock, flags);
-
-	if (ret.func == SPCI_ERROR_32) {
-		switch (ret.arg2) {
-		case SPCI_INVALID_PARAMETERS:
-			return -ENXIO;
-		case SPCI_NOT_SUPPORTED:
-			return -EIO;
-		case SPCI_DENIED:
-		case SPCI_BUSY:
-		default:
-			return -EAGAIN;
-		}
-	}
-
-	/* Ensure the VM will run to pick up the message. */
-	hf_deliver_message(vm->id);
-
-	kfree_skb(skb);
-
-	return 0;
-}
-
-/**
- * Determines if the given socket is in the connected state. It acquires and
- * releases the socket lock.
- */
-static bool hf_sock_is_connected(struct socket *sock)
-{
-	bool ret;
-
-	lock_sock(sock->sk);
-	ret = sock->state == SS_CONNECTED;
-	release_sock(sock->sk);
-
-	return ret;
-}
-
-/**
- * Sends a message to the VM & port the socket is connected to. All variants
- * of write/send/sendto/sendmsg eventually call this function.
- */
-static int hf_sock_sendmsg(struct socket *sock, struct msghdr *m, size_t len)
-{
-	struct sock *sk = sock->sk;
-	struct sk_buff *skb;
-	int err;
-	struct hf_msg_hdr *hdr;
-	struct hf_sock *hsock = hsock_from_sk(sk);
-	size_t payload_max_len = HF_MAILBOX_SIZE - sizeof(struct hf_msg_hdr);
-
-	/* Check length. */
-	if (len > payload_max_len)
-		return -EMSGSIZE;
-
-	/* We don't allow the destination address to be specified. */
-	if (m->msg_namelen > 0)
-		return -EISCONN;
-
-	/* We don't support out of band messages. */
-	if (m->msg_flags & MSG_OOB)
-		return -EOPNOTSUPP;
-
-	/*
-	 * Ensure that the socket is connected. We don't need to hold the socket
-	 * lock (acquired and released by hf_sock_is_connected) for the
-	 * remainder of the function because the fields we care about are
-	 * immutable once the state is SS_CONNECTED.
-	 */
-	if (!hf_sock_is_connected(sock))
-		return -ENOTCONN;
-
-	/*
-	 * Allocate an skb for this write. If there isn't enough room in the
-	 * socket's send buffer (sk_wmem_alloc >= sk_sndbuf), this will block
-	 * (if it's a blocking call). On success, it increments sk_wmem_alloc
-	 * and sets up the skb such that sk_wmem_alloc gets decremented when
-	 * the skb is freed (sock_wfree gets called).
-	 */
-	skb = sock_alloc_send_skb(sk, len + sizeof(struct hf_msg_hdr),
-				  m->msg_flags & MSG_DONTWAIT, &err);
-	if (!skb)
-		return err;
-
-	/* Reserve room for the header and initialise it. */
-	skb_reserve(skb, sizeof(struct hf_msg_hdr));
-	hdr = skb_push(skb, sizeof(struct hf_msg_hdr));
-	hdr->src_port = hsock->local_port;
-	hdr->dst_port = hsock->remote_port;
-
-	/* Allocate area for the contents, then copy into skb. */
-	if (!copy_from_iter_full(skb_put(skb, len), len, &m->msg_iter)) {
-		err = -EFAULT;
-		goto err_cleanup;
-	}
-
-	/*
-	 * TODO: We currently do this inline, but when we have support for
-	 * readiness notification from Hafnium, we must add this to a per-VM tx
-	 * queue that can make progress when the VM becomes writable. This will
-	 * fix send buffering and poll readiness notification.
-	 */
-	err = hf_send_skb(skb);
-	if (err)
-		goto err_cleanup;
-
-	return 0;
-
-err_cleanup:
-	kfree_skb(skb);
-	return err;
-}
-
-/**
- * Receives a message originated from the VM & port the socket is connected to.
- * All variants of read/recv/recvfrom/recvmsg eventually call this function.
- */
-static int hf_sock_recvmsg(struct socket *sock, struct msghdr *m, size_t len,
-			   int flags)
-{
-	struct sock *sk = sock->sk;
-	struct sk_buff *skb;
-	int err;
-	size_t copy_len;
-
-	if (!hf_sock_is_connected(sock))
-		return -ENOTCONN;
-
-	/* Grab the next skb from the receive queue. */
-	skb = skb_recv_datagram(sk, flags, flags & MSG_DONTWAIT, &err);
-	if (!skb)
-		return err;
-
-	/* Make sure we don't copy more than what fits in the output buffer. */
-	copy_len = skb->len;
-	if (copy_len > len) {
-		copy_len = len;
-		m->msg_flags |= MSG_TRUNC;
-	}
-
-	/* Make sure we don't overflow the return value type. */
-	if (copy_len > INT_MAX) {
-		copy_len = INT_MAX;
-		m->msg_flags |= MSG_TRUNC;
-	}
-
-	/* Copy skb to output iterator, then free it. */
-	err = skb_copy_datagram_msg(skb, 0, m, copy_len);
-	skb_free_datagram(sk, skb);
-	if (err)
-		return err;
-
-	return copy_len;
-}
-
-/**
- * This function is called when a Hafnium socket is created. It initialises all
- * state such that the caller will be able to connect the socket and then send
- * and receive messages through it.
- */
-static int hf_sock_create(struct net *net, struct socket *sock, int protocol,
-			  int kern)
-{
-	static const struct proto_ops ops = {
-		.family = PF_HF,
-		.owner = THIS_MODULE,
-		.release = hf_sock_release,
-		.bind = sock_no_bind,
-		.connect = hf_sock_connect,
-		.socketpair = sock_no_socketpair,
-		.accept = sock_no_accept,
-		.ioctl = sock_no_ioctl,
-		.listen = sock_no_listen,
-		.shutdown = sock_no_shutdown,
-		.setsockopt = sock_no_setsockopt,
-		.getsockopt = sock_no_getsockopt,
-		.sendmsg = hf_sock_sendmsg,
-		.recvmsg = hf_sock_recvmsg,
-		.mmap = sock_no_mmap,
-		.sendpage = sock_no_sendpage,
-		.poll = datagram_poll,
-	};
-	struct sock *sk;
-
-	if (sock->type != SOCK_DGRAM)
-		return -ESOCKTNOSUPPORT;
-
-	if (protocol != 0)
-		return -EPROTONOSUPPORT;
-
-	/*
-	 * For now we only allow callers with sys admin capability to create
-	 * Hafnium sockets.
-	 */
-	if (!capable(CAP_SYS_ADMIN))
-		return -EPERM;
-
-	/* Allocate and initialise socket. */
-	sk = sk_alloc(net, PF_HF, GFP_KERNEL, &hf_sock_proto, kern);
-	if (!sk)
-		return -ENOMEM;
-
-	sock_init_data(sock, sk);
-
-	sk->sk_destruct = hf_sock_destruct;
-	sock->ops = &ops;
-	sock->state = SS_UNCONNECTED;
-
-	return 0;
-}
-
-/**
- * Frees all resources, including threads, associated with the Hafnium driver.
- */
-static void hf_free_resources(void)
-{
-	uint16_t i;
-	spci_vcpu_index_t j;
-
-	/*
-	 * First stop all worker threads. We need to do this before freeing
-	 * resources because workers may reference each other, so it is only
-	 * safe to free resources after they have all stopped.
-	 */
-	for (i = 0; i < hf_vm_count; i++) {
-		struct hf_vm *vm = &hf_vms[i];
-
-		for (j = 0; j < vm->vcpu_count; j++)
-			kthread_stop(vm->vcpu[j].task);
-	}
-
-	/* Free resources. */
-	for (i = 0; i < hf_vm_count; i++) {
-		struct hf_vm *vm = &hf_vms[i];
-
-		for (j = 0; j < vm->vcpu_count; j++)
-			put_task_struct(vm->vcpu[j].task);
-		kfree(vm->vcpu);
-	}
-
-	kfree(hf_vms);
-}
-
-/**
- * Handles the hypervisor timer interrupt.
- */
-static irqreturn_t hf_nop_irq_handler(int irq, void *dev)
-{
-	/*
-	 * No need to do anything, the interrupt only exists to return to the
-	 * primary vCPU so that the virtual timer will be restored and fire as
-	 * normal.
-	 */
-	return IRQ_HANDLED;
-}
-
-/**
- * Enables the hypervisor timer interrupt on a CPU, when it starts or after the
- * driver is first loaded.
- */
-static int hf_starting_cpu(unsigned int cpu)
-{
-	if (hf_irq != 0) {
-		/* Enable the interrupt, and set it to be edge-triggered. */
-		enable_percpu_irq(hf_irq, IRQ_TYPE_EDGE_RISING);
-	}
-
-	return 0;
-}
-
-/**
- * Disables the hypervisor timer interrupt on a CPU when it is powered down.
- */
-static int hf_dying_cpu(unsigned int cpu)
-{
-	if (hf_irq != 0) {
-		/* Disable the interrupt while the CPU is asleep. */
-		disable_percpu_irq(hf_irq);
-	}
-
-	return 0;
-}
-
-/**
- * Registers for the hypervisor timer interrupt.
- */
-static int hf_int_driver_probe(struct platform_device *pdev)
-{
-	int irq;
-	int ret;
-
-	/*
-	 * Register a handler for the hyperviser timer IRQ, as it is needed for
-	 * Hafnium to emulate the virtual timer for Linux while a secondary vCPU
-	 * is running.
-	 */
-	irq = platform_get_irq(pdev, ARCH_TIMER_HYP_PPI);
-	if (irq < 0) {
-		pr_err("Error getting hypervisor timer IRQ: %d\n", irq);
-		return irq;
-	}
-	hf_irq = irq;
-
-	ret = request_percpu_irq(irq, hf_nop_irq_handler, HYPERVISOR_TIMER_NAME,
-				 pdev);
-	if (ret != 0) {
-		pr_err("Error registering hypervisor timer IRQ %d: %d\n",
-		       irq, ret);
-		return ret;
-	}
-	pr_info("Hafnium registered for IRQ %d\n", irq);
-	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
-				"hafnium/hypervisor_timer:starting",
-				hf_starting_cpu, hf_dying_cpu);
-	if (ret < 0) {
-		pr_err("Error enabling timer on all CPUs: %d\n", ret);
-		free_percpu_irq(irq, pdev);
-		return ret;
-	}
-	hf_cpuhp_state = ret;
-
-	return 0;
-}
-
-/**
- * Unregisters for the hypervisor timer interrupt.
- */
-static int hf_int_driver_remove(struct platform_device *pdev)
-{
-	/*
-	 * This will cause hf_dying_cpu to be called on each CPU, which will
-	 * disable the IRQs.
-	 */
-	cpuhp_remove_state(hf_cpuhp_state);
-	free_percpu_irq(hf_irq, pdev);
-
-	return 0;
-}
-
-static const struct of_device_id hf_int_driver_id[] = {
-	{.compatible = "arm,armv7-timer"},
-	{.compatible = "arm,armv8-timer"},
-	{}
-};
-
-static struct platform_driver hf_int_driver = {
-	.driver = {
-		.name = HYPERVISOR_TIMER_NAME,
-		.owner = THIS_MODULE,
-		.of_match_table = of_match_ptr(hf_int_driver_id),
-	},
-	.probe = hf_int_driver_probe,
-	.remove = hf_int_driver_remove,
-};
-
-/**
- * Initializes the Hafnium driver by creating a thread for each vCPU of each
- * virtual machine.
- */
-static int __init hf_init(void)
-{
-	static const struct net_proto_family proto_family = {
-		.family = PF_HF,
-		.create = hf_sock_create,
-		.owner = THIS_MODULE,
-	};
-	int64_t ret;
-	struct spci_value spci_ret;
-	spci_vm_id_t i;
-	spci_vcpu_index_t j;
-	spci_vm_count_t secondary_vm_count;
-	uint32_t total_vcpu_count;
-
-	/* Allocate a page for send and receive buffers. */
-	hf_send_page = alloc_page(GFP_KERNEL);
-	if (!hf_send_page) {
-		pr_err("Unable to allocate send buffer\n");
-		return -ENOMEM;
-	}
-
-	hf_recv_page = alloc_page(GFP_KERNEL);
-	if (!hf_recv_page) {
-		__free_page(hf_send_page);
-		pr_err("Unable to allocate receive buffer\n");
-		return -ENOMEM;
-	}
-
-	/*
-	 * Configure both addresses. Once configured, we cannot free these pages
-	 * because the hypervisor will use them, even if the module is
-	 * unloaded.
-	 */
-	spci_ret = spci_rxtx_map(page_to_phys(hf_send_page),
-				 page_to_phys(hf_recv_page));
-	if (spci_ret.func != SPCI_SUCCESS_32) {
-		__free_page(hf_send_page);
-		__free_page(hf_recv_page);
-		pr_err("Unable to configure VM\n");
-		if (spci_ret.func == SPCI_ERROR_32)
-			pr_err("SPCI error code %d\n", spci_ret.arg2);
-		else
-			pr_err("Unexpected SPCI function %#x\n", spci_ret.func);
-		return -EIO;
-	}
-
-	/* Get the number of secondary VMs. */
-	secondary_vm_count = hf_vm_get_count() - 1;
-
-	/* Confirm the maximum number of VMs looks sane. */
-	BUILD_BUG_ON(CONFIG_HAFNIUM_MAX_VMS < 1);
-	BUILD_BUG_ON(CONFIG_HAFNIUM_MAX_VMS > U16_MAX);
-
-	/* Validate the number of VMs. There must at least be the primary. */
-	if (secondary_vm_count > CONFIG_HAFNIUM_MAX_VMS - 1) {
-		pr_err("Number of VMs is out of range: %d\n",
-		       secondary_vm_count);
-		return -EDQUOT;
-	}
-
-	/* Only track the secondary VMs. */
-	hf_vms = kmalloc_array(secondary_vm_count, sizeof(struct hf_vm),
-			       GFP_KERNEL);
-	if (!hf_vms)
-		return -ENOMEM;
-
-	/* Cache the VM id for later usage. */
-	current_vm_id = hf_vm_get_id();
-
-	/* Initialize each VM. */
-	total_vcpu_count = 0;
-	for (i = 0; i < secondary_vm_count; i++) {
-		struct hf_vm *vm = &hf_vms[i];
-		spci_vcpu_count_t vcpu_count;
-
-		/* Adjust the ID as only the secondaries are tracked. */
-		vm->id = i + FIRST_SECONDARY_VM_ID;
-
-		vcpu_count = hf_vcpu_get_count(vm->id);
-		if (vcpu_count < 0) {
-			pr_err("HF_VCPU_GET_COUNT failed for vm=%u: %d",
-			       vm->id, vcpu_count);
-			ret = -EIO;
-			goto fail_with_cleanup;
-		}
-
-		/* Avoid overflowing the vcpu count. */
-		if (vcpu_count > (U32_MAX - total_vcpu_count)) {
-			pr_err("Too many vcpus: %u\n", total_vcpu_count);
-			ret = -EDQUOT;
-			goto fail_with_cleanup;
-		}
-
-		/* Confirm the maximum number of VCPUs looks sane. */
-		BUILD_BUG_ON(CONFIG_HAFNIUM_MAX_VCPUS < 1);
-		BUILD_BUG_ON(CONFIG_HAFNIUM_MAX_VCPUS > U16_MAX);
-
-		/* Enforce the limit on vcpus. */
-		total_vcpu_count += vcpu_count;
-		if (total_vcpu_count > CONFIG_HAFNIUM_MAX_VCPUS) {
-			pr_err("Too many vcpus: %u\n", total_vcpu_count);
-			ret = -EDQUOT;
-			goto fail_with_cleanup;
-		}
-
-		vm->vcpu_count = vcpu_count;
-		vm->vcpu = kmalloc_array(vm->vcpu_count, sizeof(struct hf_vcpu),
-					 GFP_KERNEL);
-		if (!vm->vcpu) {
-			ret = -ENOMEM;
-			goto fail_with_cleanup;
-		}
-
-		/* Update the number of initialized VMs. */
-		hf_vm_count = i + 1;
-
-		/* Create a kernel thread for each vcpu. */
-		for (j = 0; j < vm->vcpu_count; j++) {
-			struct hf_vcpu *vcpu = &vm->vcpu[j];
-
-			vcpu->task =
-				kthread_create(hf_vcpu_thread, vcpu,
-					       "vcpu_thread_%u_%u", vm->id, j);
-			if (IS_ERR(vcpu->task)) {
-				pr_err("Error creating task (vm=%u,vcpu=%u): %ld\n",
-				       vm->id, j, PTR_ERR(vcpu->task));
-				vm->vcpu_count = j;
-				ret = PTR_ERR(vcpu->task);
-				goto fail_with_cleanup;
-			}
-
-			get_task_struct(vcpu->task);
-			vcpu->vm = vm;
-			vcpu->vcpu_index = j;
-			atomic_set(&vcpu->abort_sleep, 0);
-			atomic_set(&vcpu->waiting_for_message, 0);
-		}
-	}
-
-	/* Register protocol and socket family. */
-	ret = proto_register(&hf_sock_proto, 0);
-	if (ret) {
-		pr_err("Unable to register protocol: %lld\n", ret);
-		goto fail_with_cleanup;
-	}
-
-	ret = sock_register(&proto_family);
-	if (ret) {
-		pr_err("Unable to register Hafnium's socket family: %lld\n",
-		       ret);
-		goto fail_unregister_proto;
-	}
-
-	/*
-	 * Register as a driver for the timer device, so we can register a
-	 * handler for the hyperviser timer IRQ.
-	 */
-	ret = platform_driver_register(&hf_int_driver);
-	if (ret != 0) {
-		pr_err("Error registering timer driver %lld\n", ret);
-		goto fail_unregister_socket;
-	}
-
-	/*
-	 * Start running threads now that all is initialized.
-	 *
-	 * Any failures from this point on must also unregister the driver with
-	 * platform_driver_unregister().
-	 */
-	for (i = 0; i < hf_vm_count; i++) {
-		struct hf_vm *vm = &hf_vms[i];
-
-		for (j = 0; j < vm->vcpu_count; j++)
-			wake_up_process(vm->vcpu[j].task);
-	}
-
-	/* Dump vm/vcpu count info. */
-	pr_info("Hafnium successfully loaded with %u VMs:\n", hf_vm_count);
-	for (i = 0; i < hf_vm_count; i++) {
-		struct hf_vm *vm = &hf_vms[i];
-
-		pr_info("\tVM %u: %u vCPUS\n", vm->id, vm->vcpu_count);
-	}
-
-	return 0;
-
-fail_unregister_socket:
-	sock_unregister(PF_HF);
-fail_unregister_proto:
-	proto_unregister(&hf_sock_proto);
-fail_with_cleanup:
-	hf_free_resources();
-	return ret;
-}
-
-/**
- * Frees up all resources used by the Hafnium driver in preparation for
- * unloading it.
- */
-static void __exit hf_exit(void)
-{
-	pr_info("Preparing to unload Hafnium\n");
-	sock_unregister(PF_HF);
-	proto_unregister(&hf_sock_proto);
-	hf_free_resources();
-	platform_driver_unregister(&hf_int_driver);
-	pr_info("Hafnium ready to unload\n");
-}
-
-MODULE_LICENSE("GPL v2");
-
-module_init(hf_init);
-module_exit(hf_exit);