From mboxrd@z Thu Jan 1 00:00:00 1970 From: Maxime Coquelin Subject: Re: [PATCH net-next v3 01/13] virtio: add packed ring types and macros Date: Fri, 30 Nov 2018 14:01:06 +0100 Message-ID: <13593b5c-c1dc-3ab3-a843-d62908e0c7e0@redhat.com> References: <20181121100330.24846-1-tiwei.bie@intel.com> <20181121100330.24846-2-tiwei.bie@intel.com> <1928ac96-3684-45c4-1e8c-09dff03bf308@redhat.com> <20181130095339.GA11984@debian> <20181130074720-mutt-send-email-mst@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Cc: Jason Wang , virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, virtio-dev@lists.oasis-open.org, wexu@redhat.com, jfreimann@redhat.com To: "Michael S. Tsirkin" , Tiwei Bie Return-path: In-Reply-To: <20181130074720-mutt-send-email-mst@kernel.org> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 11/30/18 1:47 PM, Michael S. Tsirkin wrote: > On Fri, Nov 30, 2018 at 05:53:40PM +0800, Tiwei Bie wrote: >> On Fri, Nov 30, 2018 at 04:10:55PM +0800, Jason Wang wrote: >>> >>> On 2018/11/21 下午6:03, Tiwei Bie wrote: >>>> Add types and macros for packed ring. >>>> >>>> Signed-off-by: Tiwei Bie >>>> --- >>>> include/uapi/linux/virtio_config.h | 3 +++ >>>> include/uapi/linux/virtio_ring.h | 52 ++++++++++++++++++++++++++++++++++++++ >>>> 2 files changed, 55 insertions(+) >>>> >>>> diff --git a/include/uapi/linux/virtio_config.h b/include/uapi/linux/virtio_config.h >>>> index 449132c76b1c..1196e1c1d4f6 100644 >>>> --- a/include/uapi/linux/virtio_config.h >>>> +++ b/include/uapi/linux/virtio_config.h >>>> @@ -75,6 +75,9 @@ >>>> */ >>>> #define VIRTIO_F_IOMMU_PLATFORM 33 >>>> +/* This feature indicates support for the packed virtqueue layout. */ >>>> +#define VIRTIO_F_RING_PACKED 34 >>>> + >>>> /* >>>> * Does the device support Single Root I/O Virtualization? >>>> */ >>>> diff --git a/include/uapi/linux/virtio_ring.h b/include/uapi/linux/virtio_ring.h >>>> index 6d5d5faa989b..2414f8af26b3 100644 >>>> --- a/include/uapi/linux/virtio_ring.h >>>> +++ b/include/uapi/linux/virtio_ring.h >>>> @@ -44,6 +44,13 @@ >>>> /* This means the buffer contains a list of buffer descriptors. */ >>>> #define VRING_DESC_F_INDIRECT 4 >>>> +/* >>>> + * Mark a descriptor as available or used in packed ring. >>>> + * Notice: they are defined as shifts instead of shifted values. >>> >>> >>> This looks inconsistent to previous flags, any reason for using shifts? >> >> Yeah, it was suggested to use shifts, as _F_ should be a bit >> number, not a shifted value: >> >> https://patchwork.ozlabs.org/patch/942296/#1989390 > > But let's add a _SPLIT_ variant that uses shifts consistently. Maybe we could avoid adding SPLIT and PACKED, but define as follow: #define VRING_DESC_F_INDIRECT_SHIFT 2 #define VRING_DESC_F_INDIRECT (1ull << VRING_DESC_F_INDIRECT_SHIFT) #define VRING_DESC_F_AVAIL_SHIFT 7 #define VRING_DESC_F_AVAIL (1ull << VRING_DESC_F_AVAIL_SHIFT) I think it would be better for consistency. > > >>> >>> >>>> + */ >>>> +#define VRING_PACKED_DESC_F_AVAIL 7 >>>> +#define VRING_PACKED_DESC_F_USED 15 >>>> + >>>> /* The Host uses this in used->flags to advise the Guest: don't kick me when >>>> * you add a buffer. It's unreliable, so it's simply an optimization. Guest >>>> * will still kick if it's out of buffers. */ >>>> @@ -53,6 +60,23 @@ >>>> * optimization. */ >>>> #define VRING_AVAIL_F_NO_INTERRUPT 1 >>>> +/* Enable events in packed ring. */ >>>> +#define VRING_PACKED_EVENT_FLAG_ENABLE 0x0 >>>> +/* Disable events in packed ring. */ >>>> +#define VRING_PACKED_EVENT_FLAG_DISABLE 0x1 >>>> +/* >>>> + * Enable events for a specific descriptor in packed ring. >>>> + * (as specified by Descriptor Ring Change Event Offset/Wrap Counter). >>>> + * Only valid if VIRTIO_RING_F_EVENT_IDX has been negotiated. >>>> + */ >>>> +#define VRING_PACKED_EVENT_FLAG_DESC 0x2 >>> >>> >>> Any reason for using _FLAG_ instead of _F_? >> >> Yeah, it was suggested to not use _F_, as these are values, >> should not have _F_: >> >> https://patchwork.ozlabs.org/patch/942296/#1989390 >> >> Regards, >> Tiwei >> >>> >>> Thanks >>> >>> >>>> + >>>> +/* >>>> + * Wrap counter bit shift in event suppression structure >>>> + * of packed ring. >>>> + */ >>>> +#define VRING_PACKED_EVENT_F_WRAP_CTR 15 >>>> + >>>> /* We support indirect buffer descriptors */ >>>> #define VIRTIO_RING_F_INDIRECT_DESC 28 >>>> @@ -171,4 +195,32 @@ static inline int vring_need_event(__u16 event_idx, __u16 new_idx, __u16 old) >>>> return (__u16)(new_idx - event_idx - 1) < (__u16)(new_idx - old); >>>> } >>>> +struct vring_packed_desc_event { >>>> + /* Descriptor Ring Change Event Offset/Wrap Counter. */ >>>> + __le16 off_wrap; >>>> + /* Descriptor Ring Change Event Flags. */ >>>> + __le16 flags; >>>> +}; >>>> + >>>> +struct vring_packed_desc { >>>> + /* Buffer Address. */ >>>> + __le64 addr; >>>> + /* Buffer Length. */ >>>> + __le32 len; >>>> + /* Buffer ID. */ >>>> + __le16 id; >>>> + /* The flags depending on descriptor type. */ >>>> + __le16 flags; >>>> +}; >>>> + >>>> +struct vring_packed { >>>> + unsigned int num; >>>> + >>>> + struct vring_packed_desc *desc; >>>> + >>>> + struct vring_packed_desc_event *driver; >>>> + >>>> + struct vring_packed_desc_event *device; >>>> +}; >>>> + >>>> #endif /* _UAPI_LINUX_VIRTIO_RING_H */