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authorSean Christopherson <seanjc@google.com>2023-05-13 02:31:26 +0300
committerPaolo Bonzini <pbonzini@redhat.com>2023-05-19 20:56:25 +0300
commit6735150b69978a9f73e3d1bab719e81a5dfafa83 (patch)
treeef516b67d3226182447b70dc00ce6b9a27139b94 /virt
parent39428f6ea9eace95011681628717062ff7f5eb5f (diff)
downloadlinux-6735150b69978a9f73e3d1bab719e81a5dfafa83.tar.xz
KVM: Use syscore_ops instead of reboot_notifier to hook restart/shutdown
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@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> Acked-by: Marc Zyngier <maz@kernel.org> Message-Id: <20230512233127.804012-2-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/kvm_main.c26
1 files changed, 11 insertions, 15 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index cb5c13eee193..2079d6065795 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -5213,26 +5213,24 @@ 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)
{
/*
@@ -5263,6 +5261,7 @@ 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)
@@ -5967,7 +5966,6 @@ 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 +6037,6 @@ err_cpu_kick_mask:
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 +6062,6 @@ 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();