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x86/reboot: Hoist "disable virt" helpers above "emergency reboot" path

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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.

Reviewed-by: Kai Huang <kai.huang@intel.com>
Link: https://lore.kernel.org/r/20230721201859.2307736-7-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2023-07-21 13:18:46 -07:00
parent ad93c1a7c0
commit edc8deb087
1 changed files with 45 additions and 45 deletions
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90
arch/x86/kernel/reboot.c
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@ -530,6 +530,51 @@ 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();
@ -786,54 +831,9 @@ 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;