diff mbox series

[v5,11/30] KVM: Add arch hook for reboot event

Message ID 61dcd6722743bf221f6c612e120a9e2350d5a72f.1663869838.git.isaku.yamahata@intel.com (mailing list archive)
State New, archived
Headers show
Series KVM: hardware enable/disable reorganize | expand

Commit Message

Isaku Yamahata Sept. 22, 2022, 6:20 p.m. UTC 
From: Isaku Yamahata <isaku.yamahata@intel.com>

Factor out the logic on reboot event as arch hook.  Later kvm/x86 overrides
it.

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_main.c      | 18 ++++++++++++++++--
 2 files changed, 18 insertions(+), 2 deletions(-)

Comments

Sean Christopherson Oct. 12, 2022, 8:47 p.m. UTC | #1 
On Thu, Sep 22, 2022, isaku.yamahata@intel.com wrote:
> From: Isaku Yamahata <isaku.yamahata@intel.com>
> 
> Factor out the logic on reboot event as arch hook.  Later kvm/x86 overrides
> it.
> 
> Suggested-by: Sean Christopherson <seanjc@google.com>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
> ---

...

> @@ -5135,6 +5141,8 @@ static void kvm_del_vm(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.
> @@ -5143,8 +5151,14 @@ static int kvm_reboot(struct notifier_block *notifier, unsigned long val,
>  	 */
>  	pr_info("kvm: exiting hardware virtualization\n");
>  	kvm_rebooting = true;
> -	on_each_cpu(hardware_disable_nolock, NULL, 1);
> -	return NOTIFY_OK;
> +
> +	/* This hook is called without cpuhotplug disabled.  */
> +	cpus_read_lock();
> +	mutex_lock(&kvm_lock);
> +	r = kvm_arch_reboot(val);

Unless there's a valid use case for rejecting/stopping reboot, which I'm pretty
sure there isn't, don't allow arch code to return a value.  I.e. return NOTIFY_OK
unconditionally from kvm_reboot() and drop the return from kvm_arch_reboot().

> +	mutex_unlock(&kvm_lock);
> +	cpus_read_unlock();
> +	return r;
>  }
>  
>  static struct notifier_block kvm_reboot_notifier = {
> -- 
> 2.25.1
>
diff mbox series

Patch

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 3fbb01bbac98..084ee8a13e9f 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1434,6 +1434,8 @@  void kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu, struct dentry *debugfs_
 static inline void kvm_create_vcpu_debugfs(struct kvm_vcpu *vcpu) {}
 #endif
 
+int kvm_arch_reboot(int val);
+
 int kvm_arch_hardware_enable(void);
 void kvm_arch_hardware_disable(void);
 int kvm_arch_hardware_setup(void *opaque);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index e2c8823786ff..58385000b73f 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1142,6 +1142,12 @@  int __weak kvm_arch_del_vm(int usage_count)
 	return 0;
 }
 
+int __weak kvm_arch_reboot(int val)
+{
+	on_each_cpu(hardware_disable_nolock, NULL, 1);
+	return NOTIFY_OK;
+}
+
 /*
  * Called just after removing the VM from the vm_list, but before doing any
  * other destruction.
@@ -5135,6 +5141,8 @@  static void kvm_del_vm(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.
@@ -5143,8 +5151,14 @@  static int kvm_reboot(struct notifier_block *notifier, unsigned long val,
 	 */
 	pr_info("kvm: exiting hardware virtualization\n");
 	kvm_rebooting = true;
-	on_each_cpu(hardware_disable_nolock, NULL, 1);
-	return NOTIFY_OK;
+
+	/* This hook is called without cpuhotplug disabled.  */
+	cpus_read_lock();
+	mutex_lock(&kvm_lock);
+	r = kvm_arch_reboot(val);
+	mutex_unlock(&kvm_lock);
+	cpus_read_unlock();
+	return r;
 }
 
 static struct notifier_block kvm_reboot_notifier = {