On Tue, Aug 09, 2016 at 10:54:29AM +0100, Andre Przywara wrote:
> When userspace provides the doorbell address for an MSI to be
> injected into the guest, we find a KVM device which feels responsible.
> Lets check that this device is really an emulated ITS before we make
> real use of the container_of-ed pointer.
>
> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
> ---
> virt/kvm/arm/vgic/vgic-its.c | 25 +++++++++++++++++++++----
> 1 file changed, 21 insertions(+), 4 deletions(-)
>
> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
> index 18a6871..9aeb3a4 100644
> --- a/virt/kvm/arm/vgic/vgic-its.c
> +++ b/virt/kvm/arm/vgic/vgic-its.c
> @@ -471,6 +471,24 @@ static int vgic_its_trigger_msi(struct kvm *kvm, struct vgic_its *its,
> return 0;
> }
>
> +static struct vgic_io_device *vgic_get_its_iodev(struct kvm_io_device *dev)
> +{
> + struct vgic_io_device *iodev;
> +
> + if (!dev)
> + return NULL;
this feels defensive. Wouldn't it make more sense to check the return
of kvm_io_bus_get_dev where its' called, and then conditionally call
this function?
Otherwise:
Reviewed-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
> +
> + if (dev->ops != &kvm_io_gic_ops)
> + return NULL;
> +
> + iodev = container_of(dev, struct vgic_io_device, dev);
> +
> + if (iodev->iodev_type != IODEV_ITS)
> + return NULL;
> +
> + return iodev;
> +}
> +
> /*
> * Queries the KVM IO bus framework to get the ITS pointer from the given
> * doorbell address.
> @@ -493,10 +511,9 @@ int vgic_its_inject_msi(struct kvm *kvm, struct kvm_msi *msi)
> address = (u64)msi->address_hi << 32 | msi->address_lo;
>
> kvm_io_dev = kvm_io_bus_get_dev(kvm, KVM_MMIO_BUS, address);
> - if (!kvm_io_dev)
> - return -ENODEV;
> -
> - iodev = container_of(kvm_io_dev, struct vgic_io_device, dev);
> + iodev = vgic_get_its_iodev(kvm_io_dev);
> + if (!iodev)
> + return -EINVAL;
>
> mutex_lock(&iodev->its->its_lock);
> ret = vgic_its_trigger_msi(kvm, iodev->its, msi->devid, msi->data);
> --
> 2.9.0
>
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