FAILED: patch "[PATCH] KVM: x86: request interrupt window when IRQ chip is split" failed to apply to 4.3-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 4.3-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 62a193edaf90df38356e292f47a17f28e0cee3f1 Mon Sep 17 00:00:00 2001
From: Matt Gingell <gingell@google.com>
Date: Mon, 16 Nov 2015 15:26:07 -0800
Subject: [PATCH] KVM: x86: request interrupt window when IRQ chip is split

Before this patch, we incorrectly enter the guest without requesting an
interrupt window if the IRQ chip is split between user space and the
kernel.

Because lapic_in_kernel no longer implies the PIC is in the kernel, this
patch tests pic_in_kernel to determining whether an interrupt window
should be requested when entering the guest.

If the APIC is in the kernel and we request an interrupt window the
guest will return immediately. If the APIC is masked the guest will not
not make forward progress and unmask it, leading to a loop when KVM
reenters and requests again. This patch adds a check to ensure the APIC
is ready to accept an interrupt before requesting a window.

Reviewed-by: Steve Rutherford <srutherford@google.com>
Signed-off-by: Matt Gingell <gingell@google.com>
[Use the other newly introduced functions. - Paolo]
Fixes: 1c1a9ce973a7863dd46767226bce2a5f12d48bc6
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f254e296d368..eed32283d22c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6360,8 +6360,10 @@ void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
 static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 {
 	int r;
-	bool req_int_win = !lapic_in_kernel(vcpu) &&
-		vcpu->run->request_interrupt_window;
+	bool req_int_win =
+		dm_request_for_irq_injection(vcpu) &&
+		kvm_cpu_accept_dm_intr(vcpu);
+
 	bool req_immediate_exit = false;
 
 	if (vcpu->requests) {