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From:   isaku.yamahata@intel.com
To:     kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     isaku.yamahata@intel.com, isaku.yamahata@gmail.com,
        Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <seanjc@google.com>,
        Kai Huang <kai.huang@intel.com>, Chao Gao <chao.gao@intel.com>,
        Will Deacon <will@kernel.org>
Subject: [RFC PATCH 06/18] KVM: Add arch hook when VM is added/deleted
Date:   Fri, 19 Aug 2022 23:00:12 -0700
Message-Id: <ccbd4117278ae973617918f4adb029d648deb8f3.1660974106.git.isaku.yamahata@intel.com>
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From: Isaku Yamahata <isaku.yamahata@intel.com>

and pass kvm_usage_count with kvm_lock.  Move kvm_arch_post_init_vm() under
kvm_arch_add_vm().  Later kvm_arch_post_init_vm() is deleted once x86
overrides kvm_arch_add_vm().

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
---
 include/linux/kvm_host.h |  2 ++
 virt/kvm/kvm_arch.c      | 12 +++++++++++-
 virt/kvm/kvm_main.c      | 21 +++++++++++++++++----
 3 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index c38f382f3808..5ae66062620c 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1445,6 +1445,8 @@ int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu);
 bool kvm_arch_dy_runnable(struct kvm_vcpu *vcpu);
 bool kvm_arch_dy_has_pending_interrupt(struct kvm_vcpu *vcpu);
 int kvm_arch_post_init_vm(struct kvm *kvm);
+int kvm_arch_add_vm(struct kvm *kvm, int usage_count);
+int kvm_arch_del_vm(int usage_count);
 void kvm_arch_pre_destroy_vm(struct kvm *kvm);
 int kvm_arch_create_vm_debugfs(struct kvm *kvm);
 
diff --git a/virt/kvm/kvm_arch.c b/virt/kvm/kvm_arch.c
index 4748a76bcb03..0eac996f4981 100644
--- a/virt/kvm/kvm_arch.c
+++ b/virt/kvm/kvm_arch.c
@@ -10,11 +10,21 @@
 
 #include <linux/kvm_host.h>
 
+__weak int kvm_arch_post_init_vm(struct kvm *kvm)
+{
+	return 0;
+}
+
 /*
  * 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)
+__weak int kvm_arch_add_vm(struct kvm *kvm, int usage_count)
+{
+	return kvm_arch_post_init_vm(kvm);
+}
+
+__weak int kvm_arch_del_vm(int usage_count)
 {
 	return 0;
 }
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 8d08126e6c74..0ba370acff8d 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -144,6 +144,7 @@ static int kvm_no_compat_open(struct inode *inode, struct file *file)
 #endif
 static int hardware_enable_all(void);
 static void hardware_disable_all(void);
+static void kvm_del_vm(void);
 
 static void kvm_io_bus_destroy(struct kvm_io_bus *bus);
 
@@ -1201,11 +1202,12 @@ static struct kvm *kvm_create_vm(unsigned long type, const char *fdname)
 	if (r)
 		goto out_err_no_mmu_notifier;
 
-	r = kvm_arch_post_init_vm(kvm);
-	if (r)
-		goto out_err_mmu_notifier;
-
 	mutex_lock(&kvm_lock);
+	r = kvm_arch_add_vm(kvm, kvm_usage_count);
+	if (r) {
+		mutex_unlock(&kvm_lock);
+		goto out_err_mmu_notifier;
+	}
 	list_add(&kvm->vm_list, &vm_list);
 	mutex_unlock(&kvm_lock);
 
@@ -1237,6 +1239,7 @@ static struct kvm *kvm_create_vm(unsigned long type, const char *fdname)
 #endif
 out_err_no_mmu_notifier:
 	hardware_disable_all();
+	kvm_del_vm();
 out_err_no_disable:
 	kvm_arch_destroy_vm(kvm);
 out_err_no_arch_destroy_vm:
@@ -1316,6 +1319,7 @@ static void kvm_destroy_vm(struct kvm *kvm)
 	kvm_arch_free_vm(kvm);
 	preempt_notifier_dec();
 	hardware_disable_all();
+	kvm_del_vm();
 	mmdrop(mm);
 	module_put(kvm_chardev_ops.owner);
 }
@@ -5055,6 +5059,15 @@ static void hardware_disable_all(void)
 	cpus_read_unlock();
 }
 
+static void kvm_del_vm(void)
+{
+	cpus_read_lock();
+	mutex_lock(&kvm_lock);
+	kvm_arch_del_vm(kvm_usage_count);
+	mutex_unlock(&kvm_lock);
+	cpus_read_unlock();
+}
+
 static int hardware_enable_all(void)
 {
 	int r = 0;
-- 
2.25.1