The patch below does not apply to the 4.0-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 <[email protected]>.

thanks,

greg k-h

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

>From 4839ddc27b7212ec58874f62c97da7400c8523be Mon Sep 17 00:00:00 2001
From: Marc Zyngier <[email protected]>
Date: Wed, 17 Jun 2015 14:43:35 +0100
Subject: [PATCH] KVM: arm/arm64: vgic: Avoid injecting reserved IRQ numbers

Commit fd1d0ddf2ae9 (KVM: arm/arm64: check IRQ number on userland
injection) rightly limited the range of interrupts userspace can
inject in a guest, but failed to consider the (unlikely) case where
a guest is configured with 1024 interrupts.

In this case, interrupts ranging from 1020 to 1023 are unuseable,
as they have a special meaning for the GIC CPU interface.

Make sure that these number cannot be used as an IRQ. Also delete
a redundant (and similarily buggy) check in kvm_set_irq.

Reported-by: Peter Maydell <[email protected]>
Cc: Andre Przywara <[email protected]>
Cc: <[email protected]> # 4.1, 4.0, 3.19, 3.18
Signed-off-by: Marc Zyngier <[email protected]>

diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 78fb8201014f..950064a0942d 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -1561,7 +1561,7 @@ int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, 
unsigned int irq_num,
                        goto out;
        }
 
-       if (irq_num >= kvm->arch.vgic.nr_irqs)
+       if (irq_num >= min(kvm->arch.vgic.nr_irqs, 1020))
                return -EINVAL;
 
        vcpu_id = vgic_update_irq_pending(kvm, cpuid, irq_num, level);
@@ -2161,10 +2161,7 @@ int kvm_set_irq(struct kvm *kvm, int irq_source_id,
 
        BUG_ON(!vgic_initialized(kvm));
 
-       if (spi > kvm->arch.vgic.nr_irqs)
-               return -EINVAL;
        return kvm_vgic_inject_irq(kvm, 0, spi, level);
-
 }
 
 /* MSI not implemented yet */

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