[PATCH v3 07/18] x86/reboot: Hoist "disable virt" helpers above "emergency reboot" path

Sean Christopherson
2023-05-12T23:51:30Z

Move the various "disable virtualization" helpers above the emergency
reboot path so that emergency_reboot_disable_virtualization() can be
stubbed out in a future patch if neither KVM_INTEL nor KVM_AMD is enabled,
i.e. if there is no in-tree user of CPU virtualization.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kernel/reboot.c | 90 ++++++++++++++++++++--------------------
1 file changed, 45 insertions(+), 45 deletions(-)

diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index fddfea5f1d20..493d66e59a4f 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -529,6 +529,51 @@ static inline void kb_wait(void)

static inline void nmi_shootdown_cpus_on_restart(void);

+/* RCU-protected callback to disable virtualization prior to reboot. */
+static cpu_emergency_virt_cb __rcu *cpu_emergency_virt_callback;
+
+void cpu_emergency_register_virt_callback(cpu_emergency_virt_cb *callback)
+{
+ if (WARN_ON_ONCE(rcu_access_pointer(cpu_emergency_virt_callback)))
+ return;
+
+ rcu_assign_pointer(cpu_emergency_virt_callback, callback);
+}
+EXPORT_SYMBOL_GPL(cpu_emergency_register_virt_callback);
+
+void cpu_emergency_unregister_virt_callback(cpu_emergency_virt_cb *callback)
+{
+ if (WARN_ON_ONCE(rcu_access_pointer(cpu_emergency_virt_callback) != callback))
+ return;
+
+ rcu_assign_pointer(cpu_emergency_virt_callback, NULL);
+ synchronize_rcu();
+}
+EXPORT_SYMBOL_GPL(cpu_emergency_unregister_virt_callback);
+
+/*
+ * Disable virtualization, i.e. VMX or SVM, to ensure INIT is recognized during
+ * reboot. VMX blocks INIT if the CPU is post-VMXON, and SVM blocks INIT if
+ * GIF=0, i.e. if the crash occurred between CLGI and STGI.
+ */
+void cpu_emergency_disable_virtualization(void)
+{
+ cpu_emergency_virt_cb *callback;
+
+ /*
+ * IRQs must be disabled as KVM enables virtualization in hardware via
+ * function call IPIs, i.e. IRQs need to be disabled to guarantee
+ * virtualization stays disabled.
+ */
+ lockdep_assert_irqs_disabled();
+
+ rcu_read_lock();
+ callback = rcu_dereference(cpu_emergency_virt_callback);
+ if (callback)
+ callback();
+ rcu_read_unlock();
+}
+
static void emergency_reboot_disable_virtualization(void)
{
local_irq_disable();
@@ -785,54 +830,9 @@ void machine_crash_shutdown(struct pt_regs *regs)
}
#endif

-/* RCU-protected callback to disable virtualization prior to reboot. */
-static cpu_emergency_virt_cb __rcu *cpu_emergency_virt_callback;
-
-void cpu_emergency_register_virt_callback(cpu_emergency_virt_cb *callback)
-{
- if (WARN_ON_ONCE(rcu_access_pointer(cpu_emergency_virt_callback)))
- return;
-
- rcu_assign_pointer(cpu_emergency_virt_callback, callback);
-}
-EXPORT_SYMBOL_GPL(cpu_emergency_register_virt_callback);
-
-void cpu_emergency_unregister_virt_callback(cpu_emergency_virt_cb *callback)
-{
- if (WARN_ON_ONCE(rcu_access_pointer(cpu_emergency_virt_callback) != callback))
- return;
-
- rcu_assign_pointer(cpu_emergency_virt_callback, NULL);
- synchronize_rcu();
-}
-EXPORT_SYMBOL_GPL(cpu_emergency_unregister_virt_callback);
-
/* This is the CPU performing the emergency shutdown work. */
int crashing_cpu = -1;

-/*
- * Disable virtualization, i.e. VMX or SVM, to ensure INIT is recognized during
- * reboot. VMX blocks INIT if the CPU is post-VMXON, and SVM blocks INIT if
- * GIF=0, i.e. if the crash occurred between CLGI and STGI.
- */
-void cpu_emergency_disable_virtualization(void)
-{
- cpu_emergency_virt_cb *callback;
-
- /*
- * IRQs must be disabled as KVM enables virtualization in hardware via
- * function call IPIs, i.e. IRQs need to be disabled to guarantee
- * virtualization stays disabled.
- */
- lockdep_assert_irqs_disabled();
-
- rcu_read_lock();
- callback = rcu_dereference(cpu_emergency_virt_callback);
- if (callback)
- callback();
- rcu_read_unlock();
-}
-
#if defined(CONFIG_SMP)

static nmi_shootdown_cb shootdown_callback;
--
2.40.1.606.ga4b1b128d6-goog