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Subject: Re: [PATCH v1 5/5] Add miscellaneous configuration structure for PCI
On Mon, Apr 04, 2022 at 06:52:27PM +0300, Max Gurtovoy wrote: > > On 4/4/2022 4:04 PM, Michael S. Tsirkin wrote: > > On Wed, Mar 02, 2022 at 05:56:08PM +0200, Max Gurtovoy wrote: > > > This new structure will be used for adding new miscellaneous registers > > > for a virtio device configuration layout. > > > > > > For now, only admin_queue_index register is added. Admin virtqueue index > > > does not depend on the device type. Hence, add a PCI capability to read > > > the admin virtqueue index. > > > > > > Reviewed-by: Parav Pandit <parav@nvidia.com> > > > Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com> > > > --- > > > conformance.tex | 2 ++ > > > content.tex | 25 +++++++++++++++++++++++++ > > > 2 files changed, 27 insertions(+) > > > > > > diff --git a/conformance.tex b/conformance.tex > > > index 129831c..e31645e 100644 > > > --- a/conformance.tex > > > +++ b/conformance.tex > > > @@ -102,6 +102,7 @@ \section{Conformance Targets}\label{sec:Conformance / Conformance Targets} > > > \item \ref{drivernormative:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / PCI configuration access capability} > > > \item \ref{drivernormative:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Device Initialization / MSI-X Vector Configuration} > > > \item \ref{drivernormative:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Notification of Device Configuration Changes} > > > +\item \ref{drivernormative:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Miscellaneous configuration structure layout} > > > \end{itemize} > > > \conformance{\subsection}{MMIO Driver Conformance}\label{sec:Conformance / Driver Conformance / MMIO Driver Conformance} > > > @@ -363,6 +364,7 @@ \section{Conformance Targets}\label{sec:Conformance / Conformance Targets} > > > \item \ref{devicenormative:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Device Initialization / MSI-X Vector Configuration} > > > \item \ref{devicenormative:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Used Buffer Notifications} > > > \item \ref{devicenormative:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Notification of Device Configuration Changes} > > > +\item \ref{devicenormative:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Miscellaneous configuration structure layout} > > > \end{itemize} > > > \conformance{\subsection}{MMIO Device Conformance}\label{sec:Conformance / Device Conformance / MMIO Device Conformance} > > > diff --git a/content.tex b/content.tex > > > index 163cb34..bf46192 100644 > > > --- a/content.tex > > > +++ b/content.tex > > > @@ -712,6 +712,7 @@ \subsection{Virtio Structure PCI Capabilities}\label{sec:Virtio Transport Option > > > \item ISR Status > > > \item Device-specific configuration (optional) > > > \item PCI configuration access > > > +\item Miscellaneous configuration > > > \end{itemize} > > > Each structure can be mapped by a Base Address register (BAR) belonging to > > > @@ -771,6 +772,8 @@ \subsection{Virtio Structure PCI Capabilities}\label{sec:Virtio Transport Option > > > #define VIRTIO_PCI_CAP_SHARED_MEMORY_CFG 8 > > > /* Vendor-specific data */ > > > #define VIRTIO_PCI_CAP_VENDOR_CFG 9 > > > +/* Miscellaneous configuration */ > > > +#define VIRTIO_PCI_CAP_MISC_CFG 10 > > > \end{lstlisting} > > > Any other value is reserved for future use. > > > @@ -1352,6 +1355,28 @@ \subsubsection{PCI configuration access capability}\label{sec:Virtio Transport O > > > specified by some other Virtio Structure PCI Capability > > > of type other than \field{VIRTIO_PCI_CAP_PCI_CFG}. > > > +\subsubsection{Miscellaneous configuration structure layout}\label{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Miscellaneous configuration structure layout} > > > + > > > +The miscellaneous configuration structure is found at the bar and offset within the VIRTIO_PCI_CAP_MISC_CFG capability. > > > +Its layout is below. > > > +\begin{lstlisting} > > > +struct virtio_pci_misc_cfg { > > > + le16 admin_queue_index; /* read-only for driver */ > > > +}; > > > +\end{lstlisting} > > > + > > > +\begin{description} > > > +\item[\field{admin_queue_index}] > > > + The device uses this to report the index of the admin virtqueue. > > > + This field is valid only if VIRTIO_F_ADMIN_VQ is set. > > > +\end{description} > > > + > > > +\devicenormative{\paragraph}{Miscellaneous configuration structure layout}{Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Miscellaneous configuration structure layout} > > > +The device MUST present a valid \field{admin_queue_index} when VIRTIO_F_ADMIN_VQ is set. besides, is must have a misc config capability if it has VIRTIO_F_ADMIN_VQ. > > > + > > > +\drivernormative{\paragraph}{Miscellaneous configuration structure layout}{Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Miscellaneous configuration structure layout} > > > +The driver MUST use the value of \field{admin_queue_index} to configure the admin virtqueue. For more details on virtqueue configuration see section \ref{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Device Initialization / Virtqueue Configuration}. > > > + > > > \subsubsection{Legacy Interfaces: A Note on PCI Device Layout}\label{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Legacy Interfaces: A Note on PCI Device Layout} > > > Transitional devices MUST present part of configuration > > This is useful, but I think we'll want this for all transports then. > > I think that adding more transports can be incremental and should be a no-go > for merging this patch set. > > We discussed this in the previous version and nobody had a conclusion on the > right approach for other transports. I think this referred to the msi-x thing not the the misc config capability - this is the first version where that appeared, right? Cornelia what do you think? In any case, in that case maybe besides saying it's transport-specific also mention that it is currently only defined for the PCI transport. > > > > > > > -- > > > 2.21.0
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