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Subject: Re: [PATCH v7 4/4] transport-pci: Introduce group legacy group member config region access
On Wed, Jun 28, 2023 at 12:10:50AM +0300, Parav Pandit wrote: > This patch links how in a PCI transport a group owner can access group > member (PCI VFs) legacy registers using a legacy registers access > commands using administration virtqueue infrastructure. > > Additionally it extend the PCI notification capability through which a > PCI VF device indicates to the driver which PCI BAR region to be used > for driver notifications. > > Fixes: https://github.com/oasis-tcs/virtio-spec/issues/167 > Signed-off-by: Parav Pandit <parav@nvidia.com> > --- > changelog: > v6->v7: > - addressed comments from Michael > - removed driver normative about I/O BAR emulation as it does not > make much sense for the spec > - removed references to administration virtqueue > - rewrote driver legacy region access without guest and hypervisor > wording > - added normative for notification region > - added normative for PCI IDs for device which support legacy commands > v5->v6: > - aligned pci capability to 4B as required by PCI spec > - added text for the PCI capability for the group member device > v4->v5: > - split pci transport and generic command section to new patch > - removed multiple references to the VF > - written the description of the command as generic with member > and group device terminology > - reflected many section names to remove VF > v3->v4: > - moved noted to the conformance section details in next patch > - removed queue notify address query AQ command on Michael's suggestion, > though it is fine. Instead replaced with extending virtio_pci_notify_cap > to indicate that legacy queue notifications can be done on the > notification location. > - fixed spelling errors. > - replaced administrative virtqueue to administration virtqueue > - added queue notification capability register to indicate legacy q > notification supported > v2->v3: > - adddressed Jason and Michael's comment to split single register > access command to common config and device specific commands. > - dropped the suggetion to introduce enable/disable command as > admin command cap bit already covers it. > v1->v2: > - addressed comments from Michael > - added theory of operation > - grammar corrections > - removed group fields description from individual commands as > it is already present in generic section > - added endianness normative for legacy device registers region > - renamed the file to drop vf and add legacy prefix > > - added overview in commit log > - renamed subsection to reflect command > --- > conformance.tex | 1 + > transport-pci-legacy-regs.tex | 43 +++++++++++++++++++++++++++++++++++ > transport-pci.tex | 2 ++ > 3 files changed, 46 insertions(+) > create mode 100644 transport-pci-legacy-regs.tex > > diff --git a/conformance.tex b/conformance.tex > index dc00e84..b3f2c92 100644 > --- a/conformance.tex > +++ b/conformance.tex > @@ -267,6 +267,7 @@ \section{Conformance Targets}\label{sec:Conformance / Conformance Targets} > \item Section \ref{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Legacy Interfaces: A Note on PCI Device Layout} > \item Section \ref{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Device Initialization / Virtio Device Configuration Layout Detection / Legacy Interface: A Note on Device Layout Detection} > \item Section \ref{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Device Initialization / Virtqueue Configuration / Legacy Interface: A Note on Virtqueue Configuration} > +\item Section \ref{devicenormative:Virtio Transport Options / Virtio Over PCI Bus / Legacy Interface: Group Member Device Configuration Region Access} > \item Section \ref{sec:Virtio Transport Options / Virtio Over MMIO / Legacy interface} > \item Section \ref{sec:Virtio Transport Options / Virtio over channel I/O / Device Initialization / Setting the Virtio Revision / Legacy Interfaces: A Note on Setting the Virtio Revision} > \item Section \ref{sec:Virtio Transport Options / Virtio over channel I/O / Device Initialization / Configuring a Virtqueue / Legacy Interface: A Note on Configuring a Virtqueue} > diff --git a/transport-pci-legacy-regs.tex b/transport-pci-legacy-regs.tex > new file mode 100644 > index 0000000..9559768 > --- /dev/null > +++ b/transport-pci-legacy-regs.tex > @@ -0,0 +1,43 @@ > +\subsection{Legacy Interface: Group member device Configuration Region Access}\label{sec:Virtio Transport Options / Virtio Over PCI Bus / Legacy Interface: Group Member Device Configuration Region Access} > + > +The PCI owner device or the member device or both supports driver notifications using > +a notification region defined in the \field{struct virtio_pci_notify_region}. > + > +In \field{struct virtio_virtio_admin_cmd_legacy_notify_query_entry}, > +\field{region} is defined as following: > + > +\begin{lstlisting} > +struct virtio_pci_notify_region { > + u8 owner; /* When set to 1, notification region of the owner device */ > + u8 bar; /* BAR of the member or owner device */ > + u8 padding[2]; > + le32 offset; /* Offset within bar. */ > +}; > +\end{lstlisting} Is this just a legacy thing or somehow generic? If the former please stick _legacy_ in the struct name. > + > +The group owner device hardwire VF BAR0 in the SR-IOV Extended capability. > + > +The group member device does not use PCI BAR0 in various PCI capabilities. what does this mean? what various capabilities? VFs don't have PCI BAR0 at all ... > + > +\devicenormative{\subsubsection}{Legacy Interface: Group Member Device Legacy Configuration Region Access}{Virtio Transport Options / Virtio Over PCI Bus / Legacy Interface: Group Member Device Configuration Region Access} > + > +When a PCI SR-IOV group owner device supports > +VIRTIO_ADMIN_CMD_LEGACY_COMMON_CFG_READ, > +VIRTIO_ADMIN_CMD_LEGACY_COMMON_CFG_WRITE, VIRTIO_ADMIN_CMD_LEGACY_DEV_CFG_READ, > +VIRTIO_ADMIN_CMD_LEGACY_DEV_CFG_WRITE commands, the group owner device MUST > +hardwire VF BAR0 in the SR-IOV Extended capability and the group member device > +MUST NOT use BAR0 in any of the Virtio Structure PCI Capabilities. > + > +The group member driver SHOULD use the notification region supplied by the group > +owner driver. > + > +The group owner device or the group member device or both MAY support driver > +notifications region. why is this text here as opposed to the other file? But really I think for now it's easier to just have everything in admin-cmds-legacy-interface.tex > + > +For the SR-IOV group type, the owner device supporting > +VIRTIO_ADMIN_CMD_LEGACY_COMMON_CFG_READ, > +VIRTIO_ADMIN_CMD_LEGACY_COMMON_CFG_WRITE, VIRTIO_ADMIN_CMD_LEGACY_DEV_CFG_READ, > +VIRTIO_ADMIN_CMD_LEGACY_DEV_CFG_WRITE and VIRTIO_ADMIN_CMD_LEGACY_NOTIFY_QUERY > +commands and its member device SHOULD follow the rules for the PCI Device ID, > +Revision ID and Subsystem Device ID of the non-transitional devices documented in > +section \ref{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Discovery}. > diff --git a/transport-pci.tex b/transport-pci.tex > index a5c6719..72c78f6 100644 > --- a/transport-pci.tex > +++ b/transport-pci.tex > @@ -1212,3 +1212,5 @@ \subsubsection{Driver Handling Interrupts}\label{sec:Virtio Transport Options / > re-examine the configuration space to see what changed. > \end{itemize} > \end{itemize} > + > +\input{transport-pci-legacy-regs.tex} > -- > 2.26.2
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