linux-kernel - Re: [PATCH] KVM: x86: Zero the IOAPIC scan request dest vCPUs bitmap

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Message-ID: <24c18608-2731-c560-8677-26498e848a39@redhat.com>
Date:   Wed, 20 Nov 2019 13:33:51 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Nitesh Narayan Lal <nitesh@...hat.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, mtosatti@...hat.com,
        rkrcmar@...hat.com, vkuznets@...hat.com,
        sean.j.christopherson@...el.com, wanpengli@...cent.com,
        jmattson@...gle.com, joro@...tes.org
Subject: Re: [PATCH] KVM: x86: Zero the IOAPIC scan request dest vCPUs bitmap

On 20/11/19 13:12, Nitesh Narayan Lal wrote:
> Not zeroing the bitmap used for identifying the destination vCPUs for an
> IOAPIC scan request in fixed delivery mode could lead to waking up unwanted
> vCPUs. This patch zeroes the vCPU bitmap before passing it to
> kvm_bitmap_or_dest_vcpus(), which is responsible for setting the bitmap
> with the bits corresponding to the destination vCPUs.
> 
> Fixes: 7ee30bc132c6("KVM: x86: deliver KVM IOAPIC scan request to target vCPUs")
> Signed-off-by: Nitesh Narayan Lal <nitesh@...hat.com>
> ---
>  arch/x86/kvm/ioapic.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/x86/kvm/ioapic.c b/arch/x86/kvm/ioapic.c
> index ce30ef23c86b..9fd2dd89a1c5 100644
> --- a/arch/x86/kvm/ioapic.c
> +++ b/arch/x86/kvm/ioapic.c
> @@ -332,6 +332,7 @@ static void ioapic_write_indirect(struct kvm_ioapic *ioapic, u32 val)
>  			irq.delivery_mode = e->fields.delivery_mode << 8;
>  			irq.dest_id = e->fields.dest_id;
>  			irq.dest_mode = e->fields.dest_mode;
> +			bitmap_zero(&vcpu_bitmap, 16);
>  			kvm_bitmap_or_dest_vcpus(ioapic->kvm, &irq,
>  						 &vcpu_bitmap);
>  			if (old_dest_mode != e->fields.dest_mode ||
> 

Queued, thanks.

Paolo