diff mbox series

[1/2] KVM: Use syscore_ops instead of reboot_notifier to hook restart/shutdown

Message ID 20230310221414.811690-2-seanjc@google.com
State New
Headers
Series KVM: Fix race between reboot and hardware enabling |

Commit Message

Sean Christopherson March 10, 2023, 10:14 p.m. UTC 
  Use syscore_ops.shutdown to disable hardware virtualization during a
reboot instead of using the dedicated reboot_notifier so that KVM disables
virtualization _after_ system_state has been updated.  This will allow
fixing a race in KVM's handling of a forced reboot where KVM can end up
enabling hardware virtualization between kernel_restart_prepare() and
machine_restart().

Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
Cc: James Morse <james.morse@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Zenghui Yu <yuzenghui@huawei.com>
Cc: kvmarm@lists.linux.dev
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>
Cc: Anup Patel <anup@brainfault.org>
Cc: Atish Patra <atishp@atishpatra.org>
Cc: kvm-riscv@lists.infradead.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 virt/kvm/kvm_main.c | 14 +++-----------
 1 file changed, 3 insertions(+), 11 deletions(-)

Comments

Marc Zyngier March 12, 2023, 10:12 a.m. UTC | #1 
On Fri, 10 Mar 2023 22:14:13 +0000,
Sean Christopherson <seanjc@google.com> wrote:
> 
> Use syscore_ops.shutdown to disable hardware virtualization during a
> reboot instead of using the dedicated reboot_notifier so that KVM disables
> virtualization _after_ system_state has been updated.  This will allow
> fixing a race in KVM's handling of a forced reboot where KVM can end up
> enabling hardware virtualization between kernel_restart_prepare() and
> machine_restart().
> 
> Cc: Marc Zyngier <maz@kernel.org>
> Cc: Oliver Upton <oliver.upton@linux.dev>
> Cc: James Morse <james.morse@arm.com>
> Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
> Cc: Zenghui Yu <yuzenghui@huawei.com>
> Cc: kvmarm@lists.linux.dev
> Cc: Huacai Chen <chenhuacai@kernel.org>
> Cc: Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>
> Cc: Anup Patel <anup@brainfault.org>
> Cc: Atish Patra <atishp@atishpatra.org>
> Cc: kvm-riscv@lists.infradead.org
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
>  virt/kvm/kvm_main.c | 14 +++-----------
>  1 file changed, 3 insertions(+), 11 deletions(-)
> 
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index d255964ec331..6cdfbb2c641b 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -5211,8 +5211,7 @@ static int hardware_enable_all(void)
>  	return r;
>  }
>  
> -static int kvm_reboot(struct notifier_block *notifier, unsigned long val,
> -		      void *v)
> +static void kvm_reboot(void)
>  {
>  	/*
>  	 * Some (well, at least mine) BIOSes hang on reboot if
> @@ -5223,14 +5222,8 @@ 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;
>  }
>  
> -static struct notifier_block kvm_reboot_notifier = {
> -	.notifier_call = kvm_reboot,
> -	.priority = 0,
> -};
> -
>  static int kvm_suspend(void)
>  {
>  	/*
> @@ -5261,6 +5254,8 @@ static void kvm_resume(void)
>  static struct syscore_ops kvm_syscore_ops = {
>  	.suspend = kvm_suspend,
>  	.resume = kvm_resume,
> +	.shutdown = kvm_reboot,
> +

nit: consider renaming the kvm_reboot to kvm_shutdown to match the
syscore structure, and drop the spurious blank line.

	M.
diff mbox series

Patch

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index d255964ec331..6cdfbb2c641b 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -5211,8 +5211,7 @@  static int hardware_enable_all(void)
 	return r;
 }
 
-static int kvm_reboot(struct notifier_block *notifier, unsigned long val,
-		      void *v)
+static void kvm_reboot(void)
 {
 	/*
 	 * Some (well, at least mine) BIOSes hang on reboot if
@@ -5223,14 +5222,8 @@  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;
 }
 
-static struct notifier_block kvm_reboot_notifier = {
-	.notifier_call = kvm_reboot,
-	.priority = 0,
-};
-
 static int kvm_suspend(void)
 {
 	/*
@@ -5261,6 +5254,8 @@  static void kvm_resume(void)
 static struct syscore_ops kvm_syscore_ops = {
 	.suspend = kvm_suspend,
 	.resume = kvm_resume,
+	.shutdown = kvm_reboot,
+
 };
 #else /* CONFIG_KVM_GENERIC_HARDWARE_ENABLING */
 static int hardware_enable_all(void)
@@ -5967,7 +5962,6 @@  int kvm_init(unsigned vcpu_size, unsigned vcpu_align, struct module *module)
 	if (r)
 		return r;
 
-	register_reboot_notifier(&kvm_reboot_notifier);
 	register_syscore_ops(&kvm_syscore_ops);
 #endif
 
@@ -6039,7 +6033,6 @@  int kvm_init(unsigned vcpu_size, unsigned vcpu_align, struct module *module)
 err_vcpu_cache:
 #ifdef CONFIG_KVM_GENERIC_HARDWARE_ENABLING
 	unregister_syscore_ops(&kvm_syscore_ops);
-	unregister_reboot_notifier(&kvm_reboot_notifier);
 	cpuhp_remove_state_nocalls(CPUHP_AP_KVM_ONLINE);
 #endif
 	return r;
@@ -6065,7 +6058,6 @@  void kvm_exit(void)
 	kvm_async_pf_deinit();
 #ifdef CONFIG_KVM_GENERIC_HARDWARE_ENABLING
 	unregister_syscore_ops(&kvm_syscore_ops);
-	unregister_reboot_notifier(&kvm_reboot_notifier);
 	cpuhp_remove_state_nocalls(CPUHP_AP_KVM_ONLINE);
 #endif
 	kvm_irqfd_exit();