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Subject: Re: [PATCH v10 4/4] transport-pci: Introduce group legacy group member config region access
On Thu, Jul 06, 2023 at 07:17:14AM +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: > v9->v10: > - addressed comments from Cornelia > - fixed errors related to article > - hardwire to hardwires > - replaced various to all > - added hardwire to zero > v7->v8: > - addressed comments from Michael > - made bar offset 64-bit > - prefix legacy specific structure with _legacy > - moved generic normative from pci to generic section > - added link to virtio pci capabilities when referring to bar 0 > - remove 'should' from generic description > 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 > --- > admin-cmds-legacy-interface.tex | 3 ++- > conformance.tex | 1 + > transport-pci-legacy-regs.tex | 42 +++++++++++++++++++++++++++++++++ > transport-pci.tex | 2 ++ > 4 files changed, 47 insertions(+), 1 deletion(-) > create mode 100644 transport-pci-legacy-regs.tex > > diff --git a/admin-cmds-legacy-interface.tex b/admin-cmds-legacy-interface.tex > index dd01c0a..e67632b 100644 > --- a/admin-cmds-legacy-interface.tex > +++ b/admin-cmds-legacy-interface.tex > @@ -187,7 +187,8 @@ \subsubsection{Legacy Interfaces}\label{sec:Basic Facilities of a Virtio Device > by the device. > > Refer to the specific transport section for the definition of the > -\field{data}. > +\field{data}. For the PCI transport refer to section > +\ref{sec:Virtio Transport Options / Virtio Over PCI Bus / Legacy Interface: Group Member Device Configuration Region Access}. > > This command is currently only defined for the SR-IOV group type. > > 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..ceea28c > --- /dev/null > +++ b/transport-pci-legacy-regs.tex > @@ -0,0 +1,42 @@ > +\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 support driver notifications using > +a notification region defined in \field{struct virtio_pci_legacy_notify_region}. > + > +In \field{struct virtio_virtio_admin_cmd_legacy_notify_query_entry}, > +\field{region_data} is defined as following: > + > +\begin{lstlisting} > +struct virtio_pci_legacy_notify_region { > + u8 owner; /* When set to 1, notification region is of the owner device */ I propose we rename this to flags: 0x0 - end of list (driver should ignore following values until end of list) 0x1 - owner 0x2 - member other values - reserved and prescribe that driver ignores any reserved values. basically we are following how the virtio capabilities work. > + u8 bar; /* BAR of the member or owner device */ > + u8 padding[6]; > + le64 offset; /* Offset within bar. */ > +}; > +\end{lstlisting} > + > +The group owner device hardwires VF BAR0 to zero in the SR-IOV Extended > +capability. > + > +The group member device does not use PCI BAR0 in all the Virtio PCI capabilities > +listed in section \ref{sec:Virtio Transport Options / Virtio Over PCI Bus / Virtio Structure PCI Capabilities}. Just drop this last one. How can they use it if there's no VF BAR0? > + > +\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 to zero in the SR-IOV Extended capability and the group memberi > +device MUST NOT use BAR0 in any of the Virtio Structure PCI Capabilities. > + > +The group owner device or the group member device or both MAY support driver > +notifications region. > + > +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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