Re: [PATCH v2] content: support SR-IOV

[Cornelia Huck <cohuck@redhat.com>]

On Tue, 22 May 2018 12:56:23 +0800
Tiwei Bie <tiwei.bie@intel.com> wrote:

> Allocate a feature bit for virtio devices which support SR-IOV.
> 
> Suggested-by: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
> Fixes: https://github.com/oasis-tcs/virtio-spec/issues/11
> ---
> More details can be found from this thread:
> https://patchwork.kernel.org/patch/10285541/
> 
> This patch needs below patch applied first:
> https://github.com/oasis-tcs/virtio-spec/issues/10
> https://lists.oasis-open.org/archives/virtio-dev/201805/msg00046.html
> 
> v1 -> v2:
> - s/Reserve/Allocate/ (MST);
> - Add a Fixes tag (MST);
> - Be more explicit in driver requirement (MST);
> - Remove the "device MAY fail" description (MST);
> - Rebase on IO_BARRIER patch;
> 
> RFC -> v1:
> - Mention PCI in the description (Cornelia);
> 
>  content.tex | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/content.tex b/content.tex
> index 95c243f..1c23274 100644
> --- a/content.tex
> +++ b/content.tex
> @@ -95,10 +95,10 @@ Feature bits are allocated as follows:
>  \begin{description}
>  \item[0 to 23] Feature bits for the specific device type
>  
> -\item[24 to 36] Feature bits reserved for extensions to the queue and
> +\item[24 to 37] Feature bits reserved for extensions to the queue and
>    feature negotiation mechanisms
>  
> -\item[37 and above] Feature bits reserved for future extensions.
> +\item[38 and above] Feature bits reserved for future extensions.
>  \end{description}
>  
>  \begin{note}
> @@ -5357,6 +5357,9 @@ Descriptors} and \ref{sec:Packed Virtqueues / Indirect Flag: Scatter-Gather Supp
>    better performance.  This feature indicates whether
>    a stronger form of barrier suitable for hardware
>    devices is necessary.
> +  \item[VIRTIO_F_SR_IOV(37)] This feature indicates that
> +  the device supports Single Root I/O Virtualization.
> +  Currently only virtio PCI devices support this feature.

Nit: s/virtio PCI devices/PCI devices/

(I'd be fine with keeping 'virtio', though.)

>  \end{description}
>  
>  \drivernormative{\section}{Reserved Feature Bits}{Reserved Feature Bits}
> @@ -5376,6 +5379,11 @@ A driver SHOULD accept VIRTIO_F_IO_BARRIER if it is offered.
>  If VIRTIO_F_IO_BARRIER has been negotiated, a driver MUST use
>  the barriers suitable for hardware devices.
>  
> +A driver SHOULD accept VIRTIO_F_SR_IOV if it is offered.
> +If VIRTIO_F_SR_IOV has been negotiated, a driver can
> +enable virtual functions through device's PCI SR-IOV

s/device's/the device's/

> +capability structure.
> +
>  \devicenormative{\section}{Reserved Feature Bits}{Reserved Feature Bits}
>  
>  A device MUST offer VIRTIO_F_VERSION_1.  A device MAY fail to operate further
> @@ -5392,6 +5400,9 @@ buffers in the same order in which they have been available.
>  A device MAY fail to operate further if VIRTIO_F_IO_BARRIER
>  is not accepted.
>  
> +A device SHOULD offer VIRTIO_F_SR_IOV if it presents a PCI
> +SR-IOV capability structure.
> +
>  \section{Legacy Interface: Reserved Feature Bits}\label{sec:Reserved Feature Bits / Legacy Interface: Reserved Feature Bits}
>  
>  Transitional devices MAY offer the following:

Else LGTM.