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().
Rename KVM's hook to match the syscore op to avoid any possible confusion
from wiring up a "reboot" helper to a "shutdown" hook (neither "shutdown
nor "reboot" is completely accurate as the hook handles both).
Opportunistically rewrite kvm_shutdown()'s comment to make it less VMX
specific, and to explain why kvm_rebooting exists.
Cc: Marc Zyngier <maz@xxxxxxxxxx>
Cc: Oliver Upton <oliver.upton@xxxxxxxxx>
Cc: James Morse <james.morse@xxxxxxx>
Cc: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Cc: Zenghui Yu <yuzenghui@xxxxxxxxxx>
Cc: kvmarm@xxxxxxxxxxxxxxx
Cc: Huacai Chen <chenhuacai@xxxxxxxxxx>
Cc: Aleksandar Markovic <aleksandar.qemu.devel@xxxxxxxxx>
Cc: Anup Patel <anup@xxxxxxxxxxxxxx>
Cc: Atish Patra <atishp@xxxxxxxxxxxxxx>
Cc: kvm-riscv@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
virt/kvm/kvm_main.c | 26 +++++++++++---------------
1 file changed, 11 insertions(+), 15 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index d1abb331ea68..e771b6a013c9 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -5211,26 +5211,24 @@ static int hardware_enable_all(void)
return r;
}
-static int kvm_reboot(struct notifier_block *notifier, unsigned long val,
- void *v)
+static void kvm_shutdown(void)
{
/*
- * Some (well, at least mine) BIOSes hang on reboot if
- * in vmx root mode.
- *
- * And Intel TXT required VMX off for all cpu when system shutdown.
+ * Disable hardware virtualization and set kvm_rebooting to indicate
+ * that KVM has asynchronously disabled hardware virtualization, i.e.
+ * that relevant errors and exceptions aren't entirely unexpected.
+ * Some flavors of hardware virtualization need to be disabled before
+ * transferring control to firmware (to perform shutdown/reboot), e.g.
+ * on x86, virtualization can block INIT interrupts, which are used by
+ * firmware to pull APs back under firmware control. Note, this path
+ * is used for both shutdown and reboot scenarios, i.e. neither name is
+ * 100% comprehensive.
*/
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 +5259,7 @@ static void kvm_resume(void)
static struct syscore_ops kvm_syscore_ops = {
.suspend = kvm_suspend,
.resume = kvm_resume,
+ .shutdown = kvm_shutdown,
};
#else /* CONFIG_KVM_GENERIC_HARDWARE_ENABLING */
static int hardware_enable_all(void)
@@ -5965,7 +5964,6 @@ 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
@@ -6037,7 +6035,6 @@ 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;
@@ -6063,7 +6060,6 @@ 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();
--
2.40.1.606.ga4b1b128d6-goog
