From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: virtio-comment-return-1104-cohuck=redhat.com@lists.oasis-open.org Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 33D82985E00 for ; Wed, 26 Feb 2020 17:10:45 +0000 (UTC) Date: Wed, 26 Feb 2020 12:10:34 -0500 From: "Michael S. Tsirkin" Message-ID: <20200226120948-mutt-send-email-mst@kernel.org> References: MIME-Version: 1.0 In-Reply-To: Subject: Re: [virtio-comment] [PATCH v3] virtio-net: Add support for the flexible driver notification structure Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline To: Vitaly Mireyno Cc: Jason Wang , "virtio-comment@lists.oasis-open.org" , Ariel Elior List-ID: On Wed, Feb 26, 2020 at 02:54:36PM +0000, Vitaly Mireyno wrote: >=20 > >-----Original Message----- > >From: Jason Wang > >Sent: Wednesday, 26 February, 2020 5:13 > >To: Vitaly Mireyno ; virtio-comment@lists.oasis-op= en.org > >Cc: Michael S. Tsirkin ; Ariel Elior > >Subject: [EXT] Re: [virtio-comment] [PATCH v3] virtio-net: Add support f= or the flexible driver > >notification structure > > > >---------------------------------------------------------------------- > > > >On 2020/2/26 =E4=B8=8A=E5=8D=8812:30, Vitaly Mireyno wrote: > >> Currently, the driver notification (available buffer notification) has= a fixed structure. > >> If VIRTIO_F_NOTIFICATION_DATA has been negotiated, it includes: vqn, n= ext_off and next_wrap. > >> If notify_off_multiplier > 0, the VQ number can be derived by the devi= ce from the Queue Notify > >address, so vqn may be redundant. > >> > >> Some devices benefit from receiving an additional data with driver not= ifications. This data can > >optionally replace the vqn field in the driver notification structure. > >> In its simplest form, it would be sufficient for this data to be a per= -device constant value. > >> > >> Changes from v2 - Defined a new feature flag instead of a PCI-specific= flag. > >> > >> Signed-off-by: Vitaly Mireyno > >> --- > >> content.tex | 34 ++++++++++++++++++++++++++++++++++ > >> 1 file changed, 34 insertions(+) > >> > >> diff --git a/content.tex b/content.tex index b91a132..5223d5c 100644 > >> --- a/content.tex > >> +++ b/content.tex > >> @@ -965,6 +965,8 @@ \subsubsection{Notification structure layout}\labe= l{sec:Virtio Transport > >Options > >> struct virtio_pci_notify_cap { > >> struct virtio_pci_cap cap; > >> le32 notify_off_multiplier; /* Multiplier for > >> queue_notify_off. */ > >> + le16 notify_data; /* Data to be placed in the vqn field */ > >> + le16 padding; /* Pad to a dword */ > >> }; > >> \end{lstlisting} > >> > >> @@ -984,6 +986,21 @@ \subsubsection{Notification structure layout}\lab= el{sec:Virtio Transport > >Options > >> the same Queue Notify address for all queues. > >> \end{note} > >> > >> +\field{notify_data} is the data that the driver will set in the > >> +\field{vqn} field in the available buffer notification, if > >> +VIRTIO_NET_F_NOTIF_EXTRA_DATA has been negotiated. > >> + > >> +\begin{note} > >> +If \field{notify_off_multiplier} > 0, the virtqueue number can > >> +potentially be derived by the device from the Queue Notify address, > >> +so \field{vqn} may be redundant. Some devices benefit from receiving > >> +the additional data with driver notifications. An example could be a > >> +hardware device implementing multiple protocols (with virtio being > >> +one of them), so extra notification data could serve as a notificatio= n type indication or a protocol > >indication. > >> +Another example could be using shared hardware memory space for > >> +driver notifications for multiple virtio devices in a trusted environ= ment. > >> +\end{note} > >> + > >> \devicenormative{\paragraph}{Notification capability}{Virtio Transpo= rt Options / Virtio Over PCI Bus > >/ PCI Device Layout / Notification capability} > >> The device MUST present at least one notification capability. > >> > >> @@ -1020,6 +1037,10 @@ \subsubsection{Notification structure layout}\l= abel{sec:Virtio Transport > >Options > >> cap.length >=3D queue_notify_off * notify_off_multiplier + 4 > >> \end{lstlisting} > >> > >> +If VIRTIO_NET_F_NOTIF_EXTRA_DATA has been negotiated, the device MUST > >> +set \field{notify_data} to a valid value, and SHOULD set > >> +\field{notify_off_multiplier} > 0. > >> + > >> \subsubsection{ISR status capability}\label{sec:Virtio Transport > >> Options / Virtio Over PCI Bus / PCI Device Layout / ISR status > >> capability} > >> > >> The VIRTIO_PCI_CAP_ISR_CFG capability @@ -1519,6 +1540,14 @@ > >> \subsubsection{Available Buffer Notifications}\label{sec:Virtio Transp= ort Option > >> See \ref{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI De= vice Layout / Notification > >capability} > >> for how to calculate the Queue Notify address. > >> > >> +\drivernormative{\paragraph}{Available Buffer Notifications}{Virtio > >> +Transport Options / Virtio Over PCI Bus / PCI-specific Initialization > >> +And Device Operation / Available Buffer Notifications} The driver SHO= ULD accept the > >VIRTIO_NET_F_NOTIF_EXTRA_DATA feature if it has been offered. > > > > > >I think we need use "MUST" here? > > >=20 > Wouldn=E2=80=99t it break the existing drivers then? I agree, we can't declare existing drivers non-conformant by fiat. Certainly not for a boutique feature like this. >=20 > >Other looks good to me. > > > >Thanks > > > > > >> + > >> +If VIRTIO_NET_F_NOTIF_EXTRA_DATA has been negotiated, the driver MUST > >> +set the \field{vqn} field of the available buffer notification > >> +structure to the \field{notify_data} value. > >> + > >> \subsubsection{Used Buffer Notifications}\label{sec:Virtio Transport > >> Options / Virtio Over PCI Bus / PCI-specific Initialization And Device > >> Operation / Used Buffer Notifications} > >> > >> If a used buffer notification is necessary for a virtqueue, the devi= ce would typically act as follows: > >> @@ -2895,6 +2924,10 @@ \subsection{Feature bits}\label{sec:Device Type= s / Network Device / > >Feature bits > >> \item[VIRTIO_NET_F_CTRL_MAC_ADDR(23)] Set MAC address through contro= l > >> channel. > >> > >> +\item[VIRTIO_NET_F_NOTIF_EXTRA_DATA(57)] Driver provides an extra dat= a with > >> + available buffer notifications, to aid in notification processing= by the > >> + device. > >> + > >> \item[VIRTIO_NET_F_GUEST_HDRLEN(59)] Driver can provide the exact \f= ield{hdr_len} > >> value. Device benefits from knowing the exact header length. > >> > >> @@ -2934,6 +2967,7 @@ \subsubsection{Feature bit requirements}\label{s= ec:Device Types / > >Network Device > >> \item[VIRTIO_NET_F_CTRL_MAC_ADDR] Requires VIRTIO_NET_F_CTRL_VQ. > >> \item[VIRTIO_NET_F_RSC_EXT] Requires VIRTIO_NET_F_HOST_TSO4 or > >VIRTIO_NET_F_HOST_TSO6. > >> \item[VIRTIO_NET_F_RSS] Requires VIRTIO_NET_F_CTRL_VQ. > >> +\item[VIRTIO_NET_F_NOTIF_EXTRA_DATA] Requires VIRTIO_F_NOTIFICATION_D= ATA. > >> \end{description} > >> > >> \subsubsection{Legacy Interface: Feature bits}\label{sec:Device > >> Types / Network Device / Feature bits / Legacy Interface: Feature > >> bits} > >> -- > >> > >> This publicly archived list offers a means to provide input to the > >> OASIS Virtual I/O Device (VIRTIO) TC. > >> > >> In order to verify user consent to the Feedback License terms and to > >> minimize spam in the list archive, subscription is required before > >> posting. > >> > >> Subscribe: virtio-comment-subscribe@lists.oasis-open.org > >> Unsubscribe: virtio-comment-unsubscribe@lists.oasis-open.org > >> List help: virtio-comment-help@lists.oasis-open.org > >> List archive: > >> https://urldefense.proofpoint.com/v2/url?u=3Dhttps-3A__lists.oasis-2Do= pe > >> n.org_archives_virtio-2Dcomment_&d=3DDwIFaQ&c=3DnKjWec2b6R0mOyPaz7xtfQ= &r=3Dl > >> DHJ2FW52oJ3lqqsArgFRdcevq01tbLQAw4A_NO7xgI&m=3D94BRvyqIARqVJ-yydsIqG25= _z > >> AUHjeENww-NxeMs_s8&s=3DfspKS4uA_CyM-S4HrR6GdJbvttjkX5iCygZvcybe_qs&e= =3D > >> Feedback License: > >> https://urldefense.proofpoint.com/v2/url?u=3Dhttps-3A__www.oasis-2Dope= n. > >> org_who_ipr_feedback-5Flicense.pdf&d=3DDwIFaQ&c=3DnKjWec2b6R0mOyPaz7xt= fQ&r > >> =3DlDHJ2FW52oJ3lqqsArgFRdcevq01tbLQAw4A_NO7xgI&m=3D94BRvyqIARqVJ-yydsI= qG25 > >> _zAUHjeENww-NxeMs_s8&s=3DsskV_Q0nV6odmu9tb3_QO4sJgxQQfA7SDNkDbhCPgZ0&e= =3D > >> List Guidelines: > >> https://urldefense.proofpoint.com/v2/url?u=3Dhttps-3A__www.oasis-2Dope= n. > >> org_policies-2Dguidelines_mailing-2Dlists&d=3DDwIFaQ&c=3DnKjWec2b6R0mO= yPaz > >> 7xtfQ&r=3DlDHJ2FW52oJ3lqqsArgFRdcevq01tbLQAw4A_NO7xgI&m=3D94BRvyqIARqV= J-yy > >> dsIqG25_zAUHjeENww-NxeMs_s8&s=3D0FDuoPUSirLgEwBf7ATkyVMaalFeB6N0-vhpOn= kB > >> vWY&e=3D > >> Committee: > >> https://urldefense.proofpoint.com/v2/url?u=3Dhttps-3A__www.oasis-2Dope= n. > >> org_committees_virtio_&d=3DDwIFaQ&c=3DnKjWec2b6R0mOyPaz7xtfQ&r=3DlDHJ2= FW52oJ > >> 3lqqsArgFRdcevq01tbLQAw4A_NO7xgI&m=3D94BRvyqIARqVJ-yydsIqG25_zAUHjeENw= w- > >> NxeMs_s8&s=3DraC15yZMnr9y9Iv5_woorP7Bq2OQiO-uybPhgqzNtlE&e=3D > >> Join OASIS: > >> https://urldefense.proofpoint.com/v2/url?u=3Dhttps-3A__www.oasis-2Dope= n. > >> org_join_&d=3DDwIFaQ&c=3DnKjWec2b6R0mOyPaz7xtfQ&r=3DlDHJ2FW52oJ3lqqsAr= gFRdce > >> vq01tbLQAw4A_NO7xgI&m=3D94BRvyqIARqVJ-yydsIqG25_zAUHjeENww-NxeMs_s8&s= =3DGw > >> VYWNwNZr7MFb5jJ7acLULJni1uMlwLgWBgiTSrp74&e=3D > >> >=20 This publicly archived list offers a means to provide input to the=0D OASIS Virtual I/O Device (VIRTIO) TC.=0D =0D In order to verify user consent to the Feedback License terms and=0D to minimize spam in the list archive, subscription is required=0D before posting.=0D =0D Subscribe: virtio-comment-subscribe@lists.oasis-open.org=0D Unsubscribe: virtio-comment-unsubscribe@lists.oasis-open.org=0D List help: virtio-comment-help@lists.oasis-open.org=0D List archive: https://lists.oasis-open.org/archives/virtio-comment/=0D Feedback License: https://www.oasis-open.org/who/ipr/feedback_license.pdf= =0D List Guidelines: https://www.oasis-open.org/policies-guidelines/mailing-lis= ts=0D Committee: https://www.oasis-open.org/committees/virtio/=0D Join OASIS: https://www.oasis-open.org/join/