Patch "KVM: x86: flush pending lapic jump label updates on module unload" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

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

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     kvm-x86-flush-pending-lapic-jump-label-updates-on-module-unload.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From cef84c302fe051744b983a92764d3fcca933415d Mon Sep 17 00:00:00 2001
From: David Matlack <dmatlack@google.com>
Date: Fri, 16 Dec 2016 14:30:36 -0800
Subject: KVM: x86: flush pending lapic jump label updates on module unload

From: David Matlack <dmatlack@google.com>

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>

---
 arch/x86/kvm/lapic.c |    6 ++++++
 arch/x86/kvm/lapic.h |    1 +
 arch/x86/kvm/x86.c   |    1 +
 3 files changed, 8 insertions(+)

--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -2187,3 +2187,9 @@ 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);
+}
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -95,6 +95,7 @@ static inline bool kvm_hv_vapic_assist_p
 
 int kvm_lapic_enable_pv_eoi(struct kvm_vcpu *vcpu, u64 data);
 void kvm_lapic_init(void);
+void kvm_lapic_exit(void);
 
 static inline u32 kvm_apic_get_reg(struct kvm_lapic *apic, int reg_off)
 {
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5842,6 +5842,7 @@ 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))


Patches currently in stable-queue which might be from dmatlack@google.com are

queue-4.4/kvm-x86-flush-pending-lapic-jump-label-updates-on-module-unload.patch