Messages in this thread | | | Date | Thu, 2 Feb 2023 14:00:59 -0800 | Subject | Re: [PATCH v2 4/7] virtio: VIRTIO_DEVICE_F_MASK for all per-device features | From | Si-Wei Liu <> |
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On 2/2/2023 9:29 AM, Michael S. Tsirkin wrote: > On Tue, Jan 31, 2023 at 03:22:22PM -0800, Si-Wei Liu wrote: >> Introduce VIRTIO_DEVICE_F_MASK bitmask used for identification >> of per-device features. Feature bits VIRTIO_TRANSPORT_F_START >> through VIRTIO_TRANSPORT_F_END are reserved for transport >> features hence are not counted as per-device features against >> the 64bit feature space. >> >> Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com> >> --- >> include/uapi/linux/virtio_config.h | 8 ++++++++ >> 1 file changed, 8 insertions(+) > Pls don't add this in uapi, people tend to depend on this and then > things fail when we extend virtio. For example this won't work with >64 > feature bits. Good point. Then keep this macro private to vdpa.c for now?
-Siwei > >> diff --git a/include/uapi/linux/virtio_config.h b/include/uapi/linux/virtio_config.h >> index 3c05162..3bdc7ed 100644 >> --- a/include/uapi/linux/virtio_config.h >> +++ b/include/uapi/linux/virtio_config.h >> @@ -54,6 +54,14 @@ >> #define VIRTIO_TRANSPORT_F_START 28 >> #define VIRTIO_TRANSPORT_F_END 41 >> >> +/* >> + * Bitmask for all per-device features: feature bits VIRTIO_TRANSPORT_F_START >> + * through VIRTIO_TRANSPORT_F_END are unset, i.e. 0xfffffc000fffffff for >> + * all 64bit features >> + */ >> +#define VIRTIO_DEVICE_F_MASK (~0ULL << (VIRTIO_TRANSPORT_F_END + 1) | \ >> + ((1ULL << VIRTIO_TRANSPORT_F_START) - 1)) >> + >> #ifndef VIRTIO_CONFIG_NO_LEGACY >> /* Do we get callbacks when the ring is completely used, even if we've >> * suppressed them? */ >> -- >> 1.8.3.1
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