From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: virtio-comment-return-1108-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 E75E4985E3D for ; Thu, 27 Feb 2020 10:11:11 +0000 (UTC) Date: Thu, 27 Feb 2020 05:11:01 -0500 From: "Michael S. Tsirkin" Message-ID: <20200227050623-mutt-send-email-mst@kernel.org> References: <20200226120948-mutt-send-email-mst@kernel.org> <84e330dc-cd7b-1521-ad04-e4dcafdc951b@redhat.com> MIME-Version: 1.0 In-Reply-To: <84e330dc-cd7b-1521-ad04-e4dcafdc951b@redhat.com> 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: Jason Wang Cc: Vitaly Mireyno , "virtio-comment@lists.oasis-open.org" , Ariel Elior List-ID: On Thu, Feb 27, 2020 at 06:05:30PM +0800, Jason Wang wrote: >=20 > On 2020/2/27 =E4=B8=8A=E5=8D=881:10, Michael S. Tsirkin wrote: > > On Wed, Feb 26, 2020 at 02:54:36PM +0000, Vitaly Mireyno wrote: > > > > -----Original Message----- > > > > From: Jason Wang > > > > Sent: Wednesday, 26 February, 2020 5:13 > > > > To: Vitaly Mireyno ; virtio-comment@lists.oas= is-open.org > > > > Cc: Michael S. Tsirkin ; Ariel Elior > > > > Subject: [EXT] Re: [virtio-comment] [PATCH v3] virtio-net: Add supp= ort for the flexible driver > > > > notification structure > > > >=20 > > > > -------------------------------------------------------------------= --- > > > >=20 > > > > 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: v= qn, next_off and next_wrap. > > > > > If notify_off_multiplier > 0, the VQ number can be derived by the= device from the Queue Notify > > > > address, so vqn may be redundant. > > > > > Some devices benefit from receiving an additional data with drive= r notifications. This data can > > > > optionally replace the vqn field in the driver notification structu= re. > > > > > In its simplest form, it would be sufficient for this data to be = a per-device constant value. > > > > >=20 > > > > > Changes from v2 - Defined a new feature flag instead of a PCI-spe= cific flag. > > > > >=20 > > > > > Signed-off-by: Vitaly Mireyno > > > > > --- > > > > > content.tex | 34 ++++++++++++++++++++++++++++++++++ > > > > > 1 file changed, 34 insertions(+) > > > > >=20 > > > > > diff --git a/content.tex b/content.tex index b91a132..5223d5c 100= 644 > > > > > --- a/content.tex > > > > > +++ b/content.tex > > > > > @@ -965,6 +965,8 @@ \subsubsection{Notification structure layout}= \label{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} > > > > >=20 > > > > > @@ -984,6 +986,21 @@ \subsubsection{Notification structure layout= }\label{sec:Virtio Transport > > > > Options > > > > > the same Queue Notify address for all queues. > > > > > \end{note} > > > > >=20 > > > > > +\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 addre= ss, > > > > > +so \field{vqn} may be redundant. Some devices benefit from recei= ving > > > > > +the additional data with driver notifications. An example could = be a > > > > > +hardware device implementing multiple protocols (with virtio bei= ng > > > > > +one of them), so extra notification data could serve as a notifi= cation 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 en= vironment. > > > > > +\end{note} > > > > > + > > > > > \devicenormative{\paragraph}{Notification capability}{Virtio T= ransport Options / Virtio Over PCI Bus > > > > / PCI Device Layout / Notification capability} > > > > > The device MUST present at least one notification capability. > > > > >=20 > > > > > @@ -1020,6 +1037,10 @@ \subsubsection{Notification structure layo= ut}\label{sec:Virtio Transport > > > > Options > > > > > cap.length >=3D queue_notify_off * notify_off_multiplier + 4 > > > > > \end{lstlisting} > > > > >=20 > > > > > +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 Transpo= rt > > > > > Options / Virtio Over PCI Bus / PCI Device Layout / ISR status > > > > > capability} > > > > >=20 > > > > > The VIRTIO_PCI_CAP_ISR_CFG capability @@ -1519,6 +1540,14 @@ > > > > > \subsubsection{Available Buffer Notifications}\label{sec:Virtio T= ransport Option > > > > > See \ref{sec:Virtio Transport Options / Virtio Over PCI Bus / = PCI Device Layout / Notification > > > > capability} > > > > > for how to calculate the Queue Notify address. > > > > >=20 > > > > > +\drivernormative{\paragraph}{Available Buffer Notifications}{Vir= tio > > > > > +Transport Options / Virtio Over PCI Bus / PCI-specific Initializ= ation > > > > > +And Device Operation / Available Buffer Notifications} The drive= r SHOULD accept the > > > > VIRTIO_NET_F_NOTIF_EXTRA_DATA feature if it has been offered. > > > >=20 > > > >=20 > > > > 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 >=20 > I may miss something but I think device won't work correctly if this feat= ure > is not negotiated? >=20 > Thanks That would depend on the device. Device can always fail FEATURES_OK if it doesn't support existing drivers. I really need to address https://github.com/oasis-tcs/virtio-spec/issues/71 so people know what to expect ... >=20 > >=20 > >=20 > > > > Other looks good to me. > > > >=20 > > > > Thanks > > > >=20 > > > >=20 > > > > > + > > > > > +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 Tra= nsport > > > > > Options / Virtio Over PCI Bus / PCI-specific Initialization And D= evice > > > > > Operation / Used Buffer Notifications} > > > > >=20 > > > > > If a used buffer notification is necessary for a virtqueue, th= e device would typically act as follows: > > > > > @@ -2895,6 +2924,10 @@ \subsection{Feature bits}\label{sec:Device= Types / Network Device / > > > > Feature bits > > > > > \item[VIRTIO_NET_F_CTRL_MAC_ADDR(23)] Set MAC address through = control > > > > > channel. > > > > >=20 > > > > > +\item[VIRTIO_NET_F_NOTIF_EXTRA_DATA(57)] Driver provides an extr= a data with > > > > > + available buffer notifications, to aid in notification proce= ssing by the > > > > > + device. > > > > > + > > > > > \item[VIRTIO_NET_F_GUEST_HDRLEN(59)] Driver can provide the ex= act \field{hdr_len} > > > > > value. Device benefits from knowing the exact header lengt= h. > > > > >=20 > > > > > @@ -2934,6 +2967,7 @@ \subsubsection{Feature bit requirements}\la= bel{sec:Device Types / > > > > Network Device > > > > > \item[VIRTIO_NET_F_CTRL_MAC_ADDR] Requires VIRTIO_NET_F_CTRL_V= Q. > > > > > \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_NOTIFICAT= ION_DATA. > > > > > \end{description} > > > > >=20 > > > > > \subsubsection{Legacy Interface: Feature bits}\label{sec:Devic= e > > > > > Types / Network Device / Feature bits / Legacy Interface: Feature > > > > > bits} > > > > > -- > > > > >=20 > > > > > This publicly archived list offers a means to provide input to th= e > > > > > OASIS Virtual I/O Device (VIRTIO) TC. > > > > >=20 > > > > > In order to verify user consent to the Feedback License terms and= to > > > > > minimize spam in the list archive, subscription is required befor= e > > > > > posting. > > > > >=20 > > > > > 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.oasi= s-2Dope > > > > > n.org_archives_virtio-2Dcomment_&d=3DDwIFaQ&c=3DnKjWec2b6R0mOyPaz= 7xtfQ&r=3Dl > > > > > DHJ2FW52oJ3lqqsArgFRdcevq01tbLQAw4A_NO7xgI&m=3D94BRvyqIARqVJ-yyds= IqG25_z > > > > > AUHjeENww-NxeMs_s8&s=3DfspKS4uA_CyM-S4HrR6GdJbvttjkX5iCygZvcybe_q= s&e=3D > > > > > Feedback License: > > > > > https://urldefense.proofpoint.com/v2/url?u=3Dhttps-3A__www.oasis-= 2Dopen. > > > > > org_who_ipr_feedback-5Flicense.pdf&d=3DDwIFaQ&c=3DnKjWec2b6R0mOyP= az7xtfQ&r > > > > > =3DlDHJ2FW52oJ3lqqsArgFRdcevq01tbLQAw4A_NO7xgI&m=3D94BRvyqIARqVJ-= yydsIqG25 > > > > > _zAUHjeENww-NxeMs_s8&s=3DsskV_Q0nV6odmu9tb3_QO4sJgxQQfA7SDNkDbhCP= gZ0&e=3D > > > > > List Guidelines: > > > > > https://urldefense.proofpoint.com/v2/url?u=3Dhttps-3A__www.oasis-= 2Dopen. > > > > > org_policies-2Dguidelines_mailing-2Dlists&d=3DDwIFaQ&c=3DnKjWec2b= 6R0mOyPaz > > > > > 7xtfQ&r=3DlDHJ2FW52oJ3lqqsArgFRdcevq01tbLQAw4A_NO7xgI&m=3D94BRvyq= IARqVJ-yy > > > > > dsIqG25_zAUHjeENww-NxeMs_s8&s=3D0FDuoPUSirLgEwBf7ATkyVMaalFeB6N0-= vhpOnkB > > > > > vWY&e=3D > > > > > Committee: > > > > > https://urldefense.proofpoint.com/v2/url?u=3Dhttps-3A__www.oasis-= 2Dopen. > > > > > org_committees_virtio_&d=3DDwIFaQ&c=3DnKjWec2b6R0mOyPaz7xtfQ&r=3D= lDHJ2FW52oJ > > > > > 3lqqsArgFRdcevq01tbLQAw4A_NO7xgI&m=3D94BRvyqIARqVJ-yydsIqG25_zAUH= jeENww- > > > > > NxeMs_s8&s=3DraC15yZMnr9y9Iv5_woorP7Bq2OQiO-uybPhgqzNtlE&e=3D > > > > > Join OASIS: > > > > > https://urldefense.proofpoint.com/v2/url?u=3Dhttps-3A__www.oasis-= 2Dopen. > > > > > org_join_&d=3DDwIFaQ&c=3DnKjWec2b6R0mOyPaz7xtfQ&r=3DlDHJ2FW52oJ3l= qqsArgFRdce > > > > > vq01tbLQAw4A_NO7xgI&m=3D94BRvyqIARqVJ-yydsIqG25_zAUHjeENww-NxeMs_= s8&s=3DGw > > > > > VYWNwNZr7MFb5jJ7acLULJni1uMlwLgWBgiTSrp74&e=3D > > > > >=20 > >=20 > > This publicly archived list offers a means to provide input to the > > OASIS Virtual I/O Device (VIRTIO) TC. > >=20 > > In order to verify user consent to the Feedback License terms and > > to minimize spam in the list archive, subscription is required > > before posting. > >=20 > > 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://lists.oasis-open.org/archives/virtio-comment/ > > Feedback License: https://www.oasis-open.org/who/ipr/feedback_license.p= df > > List Guidelines: https://www.oasis-open.org/policies-guidelines/mailing= -lists > > Committee: https://www.oasis-open.org/committees/virtio/ > > Join OASIS: https://www.oasis-open.org/join/ > >=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/