KVM: x86: flush pending lapic jump label updates on module unload

KVM's lapic emulation uses static_key_deferred (apic_{hw,sw}_disabled).
These are implemented with delayed_work structs which can still be
pending when the KVM module is unloaded. We've seen this cause kernel
panics when the kvm_intel module is quickly reloaded.

Use the new static_key_deferred_flush() API to flush pending updates on
module unload.

Signed-off-by: David Matlack <dmatlack@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

3 files changed, 8 insertions, 0 deletions

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 5fe290c1b7d8..2f6ef5121a4c 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -2426,3 +2426,9 @@ void kvm_lapic_init(void)
         jump_label_rate_limit(&apic_hw_disabled, HZ);
         jump_label_rate_limit(&apic_sw_disabled, HZ);
 }
+
+void kvm_lapic_exit(void)
+{
+        static_key_deferred_flush(&apic_hw_disabled);
+        static_key_deferred_flush(&apic_sw_disabled);
+}
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index e0c80233b3e1..ff8039d61672 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -110,6 +110,7 @@ static inline bool kvm_hv_vapic_assist_page_enabled(struct kvm_vcpu *vcpu)
 
 int kvm_lapic_enable_pv_eoi(struct kvm_vcpu *vcpu, u64 data);
 void kvm_lapic_init(void);
+void kvm_lapic_exit(void);
 
 #define VEC_POS(v) ((v) & (32 - 1))
 #define REG_POS(v) (((v) >> 5) << 4)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2f22810a7e0c..a0ac6e0060fb 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6045,6 +6045,7 @@ out:
 
 void kvm_arch_exit(void)
 {
+        kvm_lapic_exit();
         perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
 
         if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC))