[PATCH] KVM: x86: Zero the IOAPIC scan request dest vCPUs bitmap

[PATCH] KVM: x86: Zero the IOAPIC scan request dest vCPUs bitmap

[Nitesh Narayan Lal]

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@redhat.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 ||
-- 
2.18.1

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

[Paolo Bonzini]

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@redhat.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