linux-kernel - Re: [PATCH 1/2] x86/kvm: revert commit 76b4f357d0e7d8f6f00

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Date:   Mon, 8 Nov 2021 12:14:30 -0800
From:   Ben Gardon <bgardon@...gle.com>
To:     Juergen Gross <jgross@...e.com>
Cc:     kvm@...r.kernel.org, x86@...nel.org, linux-kernel@...r.kernel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Eduardo Habkost <ehabkost@...hat.com>
Subject: Re: [PATCH 1/2] x86/kvm: revert commit 76b4f357d0e7d8f6f00

On Mon, Sep 13, 2021 at 7:51 AM Juergen Gross <jgross@...e.com> wrote:
>
> Commit 76b4f357d0e7d8f6f00 ("x86/kvm: fix vcpu-id indexed array sizes")
> has wrong reasoning, as KVM_MAX_VCPU_ID is not defining the maximum
> allowed vcpu-id as its name suggests, but the number of vcpu-ids.
>
> So revert this patch again.
>
> Suggested-by: Eduardo Habkost <ehabkost@...hat.com>
> Signed-off-by: Juergen Gross <jgross@...e.com>

The original commit 76b4f357d0e7d8f6f00 CC'ed Stable but this revert
does not. Looking at the stable branches, I see the original has been
reverted but this hasn't. Should this be added to Stable as well?

> ---
>  arch/x86/kvm/ioapic.c | 2 +-
>  arch/x86/kvm/ioapic.h | 4 ++--
>  2 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kvm/ioapic.c b/arch/x86/kvm/ioapic.c
> index ff005fe738a4..698969e18fe3 100644
> --- a/arch/x86/kvm/ioapic.c
> +++ b/arch/x86/kvm/ioapic.c
> @@ -96,7 +96,7 @@ static unsigned long ioapic_read_indirect(struct kvm_ioapic *ioapic,
>  static void rtc_irq_eoi_tracking_reset(struct kvm_ioapic *ioapic)
>  {
>         ioapic->rtc_status.pending_eoi = 0;
> -       bitmap_zero(ioapic->rtc_status.dest_map.map, KVM_MAX_VCPU_ID + 1);
> +       bitmap_zero(ioapic->rtc_status.dest_map.map, KVM_MAX_VCPU_ID);
>  }
>
>  static void kvm_rtc_eoi_tracking_restore_all(struct kvm_ioapic *ioapic);
> diff --git a/arch/x86/kvm/ioapic.h b/arch/x86/kvm/ioapic.h
> index bbd4a5d18b5d..27e61ff3ac3e 100644
> --- a/arch/x86/kvm/ioapic.h
> +++ b/arch/x86/kvm/ioapic.h
> @@ -39,13 +39,13 @@ struct kvm_vcpu;
>
>  struct dest_map {
>         /* vcpu bitmap where IRQ has been sent */
> -       DECLARE_BITMAP(map, KVM_MAX_VCPU_ID + 1);
> +       DECLARE_BITMAP(map, KVM_MAX_VCPU_ID);
>
>         /*
>          * Vector sent to a given vcpu, only valid when
>          * the vcpu's bit in map is set
>          */
> -       u8 vectors[KVM_MAX_VCPU_ID + 1];
> +       u8 vectors[KVM_MAX_VCPU_ID];
>  };
>
>
> --
> 2.26.2
>