KVM: VMX: Unregister posted interrupt wakeup handler on hardware unsetup

KVM: VMX: Unregister posted interrupt wakeup handler on hardware unsetup

BugLink: https://bugs.launchpad.net/bugs/1951822
commit ec5a4919fa7b7d8c7a2af1c7e799b1fe4be84343 upstream.

Unregister KVM's posted interrupt wakeup handler during unsetup so that a
spurious interrupt that arrives after kvm_intel.ko is unloaded doesn't
call into freed memory.

Fixes: bf9f6ac8d749 ("KVM: Update Posted-Interrupts Descriptor when vCPU is blocked")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009001107.3936588-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>