These can wait for 4.4.
Thanks,
Matt
> On Dec 6, 2015, at 11:37 PM, <gregkh@xxxxxxxxxxxxxxxxxxx> <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
>
> 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@xxxxxxxxxxxxxxx>.
>
> thanks,
>
> greg k-h
>
> ------------------ original commit in Linus's tree ------------------
>
> From 127a457acb2131fdb31c68c98cf11eda8ba7b380 Mon Sep 17 00:00:00 2001
> From: Matt Gingell <gingell@xxxxxxxxxx>
> Date: Tue, 17 Nov 2015 17:32:05 +0100
> Subject: [PATCH] KVM: x86: fix interrupt window handling in split IRQ chip
> case
>
> This patch ensures that dm_request_for_irq_injection and
> post_kvm_run_save are in sync, avoiding that an endless ping-pong
> between userspace (who correctly notices that IF=0) and
> the kernel (who insists that userspace handles its request
> for the interrupt window).
>
> To synchronize them, it also adds checks for kvm_arch_interrupt_allowed
> and !kvm_event_needs_reinjection. These are always needed, not
> just for in-kernel LAPIC.
>
> Signed-off-by: Matt Gingell <gingell@xxxxxxxxxx>
> [A collage of two patches from Matt. - Paolo]
> Fixes: 1c1a9ce973a7863dd46767226bce2a5f12d48bc6
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 00462bd63129..46ed8edad793 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -2763,6 +2763,12 @@ static int kvm_vcpu_ioctl_set_lapic(struct kvm_vcpu *vcpu,
> return 0;
> }
>
> +static int kvm_cpu_accept_dm_intr(struct kvm_vcpu *vcpu)
> +{
> + return (!lapic_in_kernel(vcpu) ||
> + kvm_apic_accept_pic_intr(vcpu));
> +}
> +
> static int kvm_vcpu_ioctl_interrupt(struct kvm_vcpu *vcpu,
> struct kvm_interrupt *irq)
> {
> @@ -5921,12 +5927,16 @@ static int dm_request_for_irq_injection(struct kvm_vcpu *vcpu)
> if (!vcpu->run->request_interrupt_window || pic_in_kernel(vcpu->kvm))
> return false;
>
> + if (!kvm_arch_interrupt_allowed(vcpu))
> + return false;
> +
> if (kvm_cpu_has_interrupt(vcpu))
> return false;
>
> - return (irqchip_split(vcpu->kvm)
> - ? kvm_apic_accept_pic_intr(vcpu)
> - : kvm_arch_interrupt_allowed(vcpu));
> + if (kvm_event_needs_reinjection(vcpu))
> + return false;
> +
> + return kvm_cpu_accept_dm_intr(vcpu);
> }
>
> static void post_kvm_run_save(struct kvm_vcpu *vcpu)
> @@ -5937,17 +5947,12 @@ static void post_kvm_run_save(struct kvm_vcpu *vcpu)
> kvm_run->flags = is_smm(vcpu) ? KVM_RUN_X86_SMM : 0;
> kvm_run->cr8 = kvm_get_cr8(vcpu);
> kvm_run->apic_base = kvm_get_apic_base(vcpu);
> - if (!irqchip_in_kernel(vcpu->kvm))
> - kvm_run->ready_for_interrupt_injection =
> - kvm_arch_interrupt_allowed(vcpu) &&
> - !kvm_cpu_has_interrupt(vcpu) &&
> - !kvm_event_needs_reinjection(vcpu);
> - else if (!pic_in_kernel(vcpu->kvm))
> - kvm_run->ready_for_interrupt_injection =
> - kvm_apic_accept_pic_intr(vcpu) &&
> - !kvm_cpu_has_interrupt(vcpu);
> - else
> - kvm_run->ready_for_interrupt_injection = 1;
> + kvm_run->ready_for_interrupt_injection =
> + pic_in_kernel(vcpu->kvm) ||
> + (kvm_arch_interrupt_allowed(vcpu) &&
> + !kvm_cpu_has_interrupt(vcpu) &&
> + !kvm_event_needs_reinjection(vcpu) &&
> + kvm_cpu_accept_dm_intr(vcpu));
> }
>
> static void update_cr8_intercept(struct kvm_vcpu *vcpu)
>
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