[RFC PATCH 04/18] KVM: Add arch hooks for PM events with empty stub

[isaku . yamahata]

From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>

Add arch hooks for reboot, suspend, resume, and CPU-online/offline events
with empty stub functions.

Suggested-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
---
 include/linux/kvm_host.h |  6 ++++++
 virt/kvm/Makefile.kvm    |  2 +-
 virt/kvm/kvm_arch.c      | 44 ++++++++++++++++++++++++++++++++++++++++
 virt/kvm/kvm_main.c      | 35 ++++++++++++++++----------------
 4 files changed, 69 insertions(+), 18 deletions(-)
 create mode 100644 virt/kvm/kvm_arch.c

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 1c480b1821e1..c38f382f3808 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1448,6 +1448,12 @@ int kvm_arch_post_init_vm(struct kvm *kvm);
 void kvm_arch_pre_destroy_vm(struct kvm *kvm);
 int kvm_arch_create_vm_debugfs(struct kvm *kvm);
 
+int kvm_arch_suspend(int usage_count);
+void kvm_arch_resume(int usage_count);
+int kvm_arch_reboot(int val);
+int kvm_arch_online_cpu(unsigned int cpu, int usage_count);
+int kvm_arch_offline_cpu(unsigned int cpu, int usage_count);
+
 #ifndef __KVM_HAVE_ARCH_VM_ALLOC
 /*
  * All architectures that want to use vzalloc currently also
diff --git a/virt/kvm/Makefile.kvm b/virt/kvm/Makefile.kvm
index 2c27d5d0c367..c4210acabd35 100644
--- a/virt/kvm/Makefile.kvm
+++ b/virt/kvm/Makefile.kvm
@@ -5,7 +5,7 @@
 
 KVM ?= ../../../virt/kvm
 
-kvm-y := $(KVM)/kvm_main.o $(KVM)/eventfd.o $(KVM)/binary_stats.o
+kvm-y := $(KVM)/kvm_main.o $(KVM)/kvm_arch.o $(KVM)/eventfd.o $(KVM)/binary_stats.o
 kvm-$(CONFIG_KVM_VFIO) += $(KVM)/vfio.o
 kvm-$(CONFIG_KVM_MMIO) += $(KVM)/coalesced_mmio.o
 kvm-$(CONFIG_KVM_ASYNC_PF) += $(KVM)/async_pf.o
diff --git a/virt/kvm/kvm_arch.c b/virt/kvm/kvm_arch.c
new file mode 100644
index 000000000000..4748a76bcb03
--- /dev/null
+++ b/virt/kvm/kvm_arch.c
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * kvm_arch.c: kvm default arch hooks for hardware enabling/disabling
+ * Copyright (c) 2022 Intel Corporation.
+ *
+ * Author:
+ *   Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
+ *                  <isaku.yamahata@xxxxxxxxx>
+ */
+
+#include <linux/kvm_host.h>
+
+/*
+ * Called after the VM is otherwise initialized, but just before adding it to
+ * the vm_list.
+ */
+__weak int kvm_arch_post_init_vm(struct kvm *kvm)
+{
+	return 0;
+}
+
+__weak int kvm_arch_online_cpu(unsigned int cpu, int usage_count)
+{
+	return 0;
+}
+
+__weak int kvm_arch_offline_cpu(unsigned int cpu, int usage_count)
+{
+	return 0;
+}
+
+__weak int kvm_arch_reboot(int val)
+{
+	return NOTIFY_OK;
+}
+
+__weak int kvm_arch_suspend(int usage_count)
+{
+	return 0;
+}
+
+__weak void kvm_arch_resume(int usage_count)
+{
+}
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index c6781fa30461..8d08126e6c74 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1095,15 +1095,6 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, const char *fdname)
 	return ret;
 }
 
-/*
- * Called after the VM is otherwise initialized, but just before adding it to
- * the vm_list.
- */
-int __weak kvm_arch_post_init_vm(struct kvm *kvm)
-{
-	return 0;
-}
-
 /*
  * Called just after removing the VM from the vm_list, but before doing any
  * other destruction.
@@ -5019,6 +5010,7 @@ static int kvm_starting_cpu(unsigned int cpu)
 	mutex_lock(&kvm_lock);
 	if (kvm_usage_count)
 		hardware_enable_nolock(NULL);
+	(void)kvm_arch_online_cpu(cpu, kvm_usage_count);
 	mutex_unlock(&kvm_lock);
 	return 0;
 }
@@ -5040,6 +5032,7 @@ static int kvm_dying_cpu(unsigned int cpu)
 	mutex_lock(&kvm_lock);
 	if (kvm_usage_count)
 		hardware_disable_nolock(NULL);
+	(void)kvm_arch_offline_cpu(cpu, kvm_usage_count);
 	mutex_unlock(&kvm_lock);
 	return 0;
 }
@@ -5089,6 +5082,8 @@ static int hardware_enable_all(void)
 static int kvm_reboot(struct notifier_block *notifier, unsigned long val,
 		      void *v)
 {
+	int r;
+
 	/*
 	 * Some (well, at least mine) BIOSes hang on reboot if
 	 * in vmx root mode.
@@ -5097,8 +5092,15 @@ static int kvm_reboot(struct notifier_block *notifier, unsigned long val,
 	 */
 	pr_info("kvm: exiting hardware virtualization\n");
 	kvm_rebooting = true;
+
+	/* This hook is called without cpuhotplug disabled.  */
+	cpus_read_lock();
+	mutex_lock(&kvm_lock);
 	on_each_cpu(hardware_disable_nolock, NULL, 1);
-	return NOTIFY_OK;
+	r = kvm_arch_reboot(val);
+	mutex_unlock(&kvm_lock);
+	cpus_read_unlock();
+	return r;
 }
 
 static struct notifier_block kvm_reboot_notifier = {
@@ -5692,19 +5694,18 @@ static int kvm_suspend(void)
 	 * cpu_hotplug_disable() and other CPUs are offlined.  No need for
 	 * locking.
 	 */
-	if (kvm_usage_count) {
-		lockdep_assert_not_held(&kvm_lock);
+	lockdep_assert_not_held(&kvm_lock);
+	if (kvm_usage_count)
 		hardware_disable_nolock(NULL);
-	}
-	return 0;
+	return kvm_arch_suspend(kvm_usage_count);
 }
 
 static void kvm_resume(void)
 {
-	if (kvm_usage_count) {
-		lockdep_assert_not_held(&kvm_lock);
+	kvm_arch_resume(kvm_usage_count);
+	lockdep_assert_not_held(&kvm_lock);
+	if (kvm_usage_count)
 		hardware_enable_nolock(NULL);
-	}
 }
 
 static struct syscore_ops kvm_syscore_ops = {
-- 
2.25.1