FAILED: patch "[PATCH] KVM: VMX: Unregister posted interrupt wakeup handler on" failed to apply to 4.9-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From ec5a4919fa7b7d8c7a2af1c7e799b1fe4be84343 Mon Sep 17 00:00:00 2001
From: Sean Christopherson <seanjc@google.com>
Date: Fri, 8 Oct 2021 17:11:05 -0700
Subject: [PATCH] KVM: VMX: Unregister posted interrupt wakeup handler on
 hardware unsetup

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>

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 2f677e72d864..c11688f64e80 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7555,6 +7555,8 @@ static void vmx_migrate_timers(struct kvm_vcpu *vcpu)
 
 static void hardware_unsetup(void)
 {
+	kvm_set_posted_intr_wakeup_handler(NULL);
+
 	if (nested)
 		nested_vmx_hardware_unsetup();
 
@@ -7885,8 +7887,6 @@ static __init int hardware_setup(void)
 		vmx_x86_ops.request_immediate_exit = __kvm_request_immediate_exit;
 	}
 
-	kvm_set_posted_intr_wakeup_handler(pi_wakeup_handler);
-
 	kvm_mce_cap_supported |= MCG_LMCE_P;
 
 	if (pt_mode != PT_MODE_SYSTEM && pt_mode != PT_MODE_HOST_GUEST)
@@ -7910,6 +7910,9 @@ static __init int hardware_setup(void)
 	r = alloc_kvm_area();
 	if (r)
 		nested_vmx_hardware_unsetup();
+
+	kvm_set_posted_intr_wakeup_handler(pi_wakeup_handler);
+
 	return r;
 }