[PATCHv3 1/2] kvm: add PM-notifier

[Sergey Senozhatsky <senozhatsky@chromium.org>]

Add KVM PM-notifier so that architectures can have arch-specific
VM suspend/resume routines. Such architectures need to select
CONFIG_HAVE_KVM_PM_NOTIFIER and implement kvm_arch_pm_notifier().

Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
---
 include/linux/kvm_host.h |  9 +++++++++
 virt/kvm/Kconfig         |  3 +++
 virt/kvm/kvm_main.c      | 35 +++++++++++++++++++++++++++++++++++
 3 files changed, 47 insertions(+)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 76102efbf079..3db4c22e93cd 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -28,6 +28,7 @@
 #include <linux/rcuwait.h>
 #include <linux/refcount.h>
 #include <linux/nospec.h>
+#include <linux/notifier.h>
 #include <asm/signal.h>
 
 #include <linux/kvm.h>
@@ -585,6 +586,10 @@ struct kvm {
 	pid_t userspace_pid;
 	unsigned int max_halt_poll_ns;
 	u32 dirty_ring_size;
+
+#ifdef CONFIG_HAVE_KVM_PM_NOTIFIER
+	struct notifier_block pm_notifier;
+#endif
 };
 
 #define kvm_err(fmt, ...) \
@@ -998,6 +1003,10 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu);
 void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu);
 void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu);
 
+#ifdef CONFIG_HAVE_KVM_PM_NOTIFIER
+int kvm_arch_pm_notifier(struct kvm *kvm, unsigned long state);
+#endif
+
 #ifdef __KVM_HAVE_ARCH_VCPU_DEBUGFS
 void kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu, struct dentry *debugfs_dentry);
 #endif
diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
index 1c37ccd5d402..62b39149b8c8 100644
--- a/virt/kvm/Kconfig
+++ b/virt/kvm/Kconfig
@@ -63,3 +63,6 @@ config HAVE_KVM_NO_POLL
 
 config KVM_XFER_TO_GUEST_WORK
        bool
+
+config HAVE_KVM_PM_NOTIFIER
+       bool
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index eb440eb1225a..1cceead1af46 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -51,6 +51,7 @@
 #include <linux/io.h>
 #include <linux/lockdep.h>
 #include <linux/kthread.h>
+#include <linux/suspend.h>
 
 #include <asm/processor.h>
 #include <asm/ioctl.h>
@@ -780,6 +781,38 @@ static int kvm_init_mmu_notifier(struct kvm *kvm)
 
 #endif /* CONFIG_MMU_NOTIFIER && KVM_ARCH_WANT_MMU_NOTIFIER */
 
+#ifdef CONFIG_HAVE_KVM_PM_NOTIFIER
+static int kvm_pm_notifier_call(struct notifier_block *bl,
+				unsigned long state,
+				void *unused)
+{
+	struct kvm *kvm = container_of(bl, struct kvm, pm_notifier);
+
+	return kvm_arch_pm_notifier(kvm, state);
+}
+
+static void kvm_init_pm_notifier(struct kvm *kvm)
+{
+	kvm->pm_notifier.notifier_call = kvm_pm_notifier_call;
+	/* Suspend KVM before we suspend ftrace, RCU, etc. */
+	kvm->pm_notifier.priority = INT_MAX;
+	register_pm_notifier(&kvm->pm_notifier);
+}
+
+static void kvm_destroy_pm_notifier(struct kvm *kvm)
+{
+	unregister_pm_notifier(&kvm->pm_notifier);
+}
+#else /* !CONFIG_HAVE_KVM_PM_NOTIFIER */
+static void kvm_init_pm_notifier(struct kvm *kvm)
+{
+}
+
+static void kvm_destroy_pm_notifier(struct kvm *kvm)
+{
+}
+#endif /* CONFIG_HAVE_KVM_PM_NOTIFIER */
+
 static struct kvm_memslots *kvm_alloc_memslots(void)
 {
 	int i;
@@ -963,6 +996,7 @@ static struct kvm *kvm_create_vm(unsigned long type)
 	mutex_unlock(&kvm_lock);
 
 	preempt_notifier_inc();
+	kvm_init_pm_notifier(kvm);
 
 	return kvm;
 
@@ -1010,6 +1044,7 @@ static void kvm_destroy_vm(struct kvm *kvm)
 	int i;
 	struct mm_struct *mm = kvm->mm;
 
+	kvm_destroy_pm_notifier(kvm);
 	kvm_uevent_notify_change(KVM_EVENT_DESTROY_VM, kvm);
 	kvm_destroy_vm_debugfs(kvm);
 	kvm_arch_sync_events(kvm);
-- 
2.32.0.rc1.229.g3e70b5a671-goog