linux-kernel - [PATCH 43/44] KVM: Register syscore (suspend/resume) ops early in kvm

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Date:   Wed,  2 Nov 2022 23:19:10 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>, Marc Zyngier <maz@...nel.org>,
        Huacai Chen <chenhuacai@...nel.org>,
        Aleksandar Markovic <aleksandar.qemu.devel@...il.com>,
        Anup Patel <anup@...infault.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        Claudio Imbrenda <imbrenda@...ux.ibm.com>,
        Matthew Rosato <mjrosato@...ux.ibm.com>,
        Eric Farman <farman@...ux.ibm.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>
Cc:     James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Oliver Upton <oliver.upton@...ux.dev>,
        Atish Patra <atishp@...shpatra.org>,
        David Hildenbrand <david@...hat.com>, kvm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
        kvmarm@...ts.cs.columbia.edu, linux-mips@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, kvm-riscv@...ts.infradead.org,
        linux-riscv@...ts.infradead.org, linux-s390@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Isaku Yamahata <isaku.yamahata@...el.com>,
        Fabiano Rosas <farosas@...ux.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Chao Gao <chao.gao@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Yuan Yao <yuan.yao@...el.com>
Subject: [PATCH 43/44] KVM: Register syscore (suspend/resume) ops early in kvm_init()

Register the suspend/resume notifier hooks at the same time KVM registers
its reboot notifier so that all the code in kvm_init() that deals with
enabling/disabling hardware is bundled together.  Opportunstically move
KVM's implementations to reside near the reboot notifier code for the
same reason.

Bunching the code together will allow architectures to opt out of KVM's
generic hardware enable/disable logic with minimal #ifdeffery.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 virt/kvm/kvm_main.c | 64 ++++++++++++++++++++++-----------------------
 1 file changed, 32 insertions(+), 32 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index a18296ee731b..859bc27091cd 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -5142,6 +5142,36 @@ static struct notifier_block kvm_reboot_notifier = {
 	.priority = 0,
 };
 
+static int kvm_suspend(void)
+{
+	/*
+	 * Secondary CPUs and CPU hotplug are disabled across the suspend/resume
+	 * callbacks, i.e. no need to acquire kvm_lock to ensure the usage count
+	 * is stable.  Assert that kvm_lock is not held as a paranoid sanity
+	 * check that the system isn't suspended when KVM is enabling hardware.
+	 */
+	lockdep_assert_not_held(&kvm_lock);
+	lockdep_assert_irqs_disabled();
+
+	if (kvm_usage_count)
+		hardware_disable_nolock(NULL);
+	return 0;
+}
+
+static void kvm_resume(void)
+{
+	lockdep_assert_not_held(&kvm_lock);
+	lockdep_assert_irqs_disabled();
+
+	if (kvm_usage_count)
+		WARN_ON_ONCE(__hardware_enable_nolock());
+}
+
+static struct syscore_ops kvm_syscore_ops = {
+	.suspend = kvm_suspend,
+	.resume = kvm_resume,
+};
+
 static void kvm_io_bus_destroy(struct kvm_io_bus *bus)
 {
 	int i;
@@ -5720,36 +5750,6 @@ static void kvm_init_debug(void)
 	}
 }
 
-static int kvm_suspend(void)
-{
-	/*
-	 * Secondary CPUs and CPU hotplug are disabled across the suspend/resume
-	 * callbacks, i.e. no need to acquire kvm_lock to ensure the usage count
-	 * is stable.  Assert that kvm_lock is not held as a paranoid sanity
-	 * check that the system isn't suspended when KVM is enabling hardware.
-	 */
-	lockdep_assert_not_held(&kvm_lock);
-	lockdep_assert_irqs_disabled();
-
-	if (kvm_usage_count)
-		hardware_disable_nolock(NULL);
-	return 0;
-}
-
-static void kvm_resume(void)
-{
-	lockdep_assert_not_held(&kvm_lock);
-	lockdep_assert_irqs_disabled();
-
-	if (kvm_usage_count)
-		WARN_ON_ONCE(__hardware_enable_nolock());
-}
-
-static struct syscore_ops kvm_syscore_ops = {
-	.suspend = kvm_suspend,
-	.resume = kvm_resume,
-};
-
 static inline
 struct kvm_vcpu *preempt_notifier_to_vcpu(struct preempt_notifier *pn)
 {
@@ -5865,6 +5865,7 @@ int kvm_init(unsigned vcpu_size, unsigned vcpu_align, struct module *module)
 		return r;
 
 	register_reboot_notifier(&kvm_reboot_notifier);
+	register_syscore_ops(&kvm_syscore_ops);
 
 	/* A kmem cache lets us meet the alignment requirements of fx_save. */
 	if (!vcpu_align)
@@ -5899,8 +5900,6 @@ int kvm_init(unsigned vcpu_size, unsigned vcpu_align, struct module *module)
 
 	kvm_chardev_ops.owner = module;
 
-	register_syscore_ops(&kvm_syscore_ops);
-
 	kvm_preempt_ops.sched_in = kvm_sched_in;
 	kvm_preempt_ops.sched_out = kvm_sched_out;
 
@@ -5934,6 +5933,7 @@ int kvm_init(unsigned vcpu_size, unsigned vcpu_align, struct module *module)
 		free_cpumask_var(per_cpu(cpu_kick_mask, cpu));
 	kmem_cache_destroy(kvm_vcpu_cache);
 out_free_3:
+	unregister_syscore_ops(&kvm_syscore_ops);
 	unregister_reboot_notifier(&kvm_reboot_notifier);
 	cpuhp_remove_state_nocalls(CPUHP_AP_KVM_ONLINE);
 	return r;
-- 
2.38.1.431.g37b22c650d-goog