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

commit cef84c302fe051744b983a92764d3fcca933415d upstream.

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>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 6f69340..3f05c04 100644 (file)
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -2360,3 +2360,9 @@ 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 f60d01c..4dfe4d6 100644 (file)
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -108,6 +108,7 @@ 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 f3648c9..6264669 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5963,6 +5963,7 @@ 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))