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Re: [Qemu-devel] [PATCH RFC 1/7] virtio: relax feature check
From: |
Cornelia Huck |
Subject: |
Re: [Qemu-devel] [PATCH RFC 1/7] virtio: relax feature check |
Date: |
Tue, 12 May 2015 15:14:53 +0200 |
On Wed, 06 May 2015 14:07:37 +0200
Greg Kurz <address@hidden> wrote:
> Unlike with add and clear, there is no valid reason to abort when checking
> for a feature. It makes more sense to return false (i.e. the feature bit
> isn't set). This is exactly what __virtio_has_feature() does if fbit >= 32.
>
> This allows to introduce code that is aware about new 64-bit features like
> VIRTIO_F_VERSION_1, even if they are still not implemented.
>
> Signed-off-by: Greg Kurz <address@hidden>
> ---
> include/hw/virtio/virtio.h | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
> index d95f8b6..6ef70f1 100644
> --- a/include/hw/virtio/virtio.h
> +++ b/include/hw/virtio/virtio.h
> @@ -233,7 +233,6 @@ static inline void virtio_clear_feature(uint32_t
> *features, unsigned int fbit)
>
> static inline bool __virtio_has_feature(uint32_t features, unsigned int fbit)
> {
> - assert(fbit < 32);
> return !!(features & (1 << fbit));
> }
>
>
>
I must say I'm not very comfortable with knowingly passing out-of-rage
values to this function.
Can we perhaps apply at least the feature-bit-size extending patches
prior to your patchset, if the remainder of the virtio-1 patchset still
takes some time?
- [Qemu-devel] [PATCH RFC 0/7] vhost: cross-endian support (vhost-net only), Greg Kurz, 2015/05/06
- [Qemu-devel] [PATCH RFC 2/7] linux-headers: sync vhost.h, Greg Kurz, 2015/05/06
- [Qemu-devel] [PATCH RFC 1/7] virtio: relax feature check, Greg Kurz, 2015/05/06
- Re: [Qemu-devel] [PATCH RFC 1/7] virtio: relax feature check,
Cornelia Huck <=
- Re: [Qemu-devel] [PATCH RFC 1/7] virtio: relax feature check, Michael S. Tsirkin, 2015/05/12
- Re: [Qemu-devel] [PATCH RFC 1/7] virtio: relax feature check, Cornelia Huck, 2015/05/12
- Re: [Qemu-devel] [PATCH RFC 1/7] virtio: relax feature check, Cornelia Huck, 2015/05/12
- Re: [Qemu-devel] [PATCH RFC 1/7] virtio: relax feature check, Michael S. Tsirkin, 2015/05/12
- Re: [Qemu-devel] [PATCH RFC 1/7] virtio: relax feature check, Cornelia Huck, 2015/05/12
- Re: [Qemu-devel] [PATCH RFC 1/7] virtio: relax feature check, Greg Kurz, 2015/05/12
- Re: [Qemu-devel] [PATCH RFC 1/7] virtio: relax feature check, Peter Maydell, 2015/05/12
[Qemu-devel] [PATCH RFC 3/7] virtio: introduce virtio_legacy_is_cross_endian(), Greg Kurz, 2015/05/06
[Qemu-devel] [PATCH RFC 5/7] tap: add VNET_LE/VNET_BE operations, Greg Kurz, 2015/05/06
[Qemu-devel] [PATCH RFC 4/7] vhost: set vring endianness for legacy virtio, Greg Kurz, 2015/05/06