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Subject: Re: [PATCH v4] content: support SR-IOV
On Fri, May 25, 2018 at 12:49:51AM +0800, Tiwei Bie 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 I have a question on this: how exactly is reset handled? Does reset disable IOV? > --- > More details can be found from this thread: > https://patchwork.kernel.org/patch/10285541/ > > v3 -> v4: > - Limit the feature to PCI devices with SR-IOV cap (MST); > > v2 -> v3: > - Improve the wording (Cornelia); > > 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 | 21 +++++++++++++++++++-- > 1 file changed, 19 insertions(+), 2 deletions(-) > > diff --git a/content.tex b/content.tex > index c4b3b5c..beec6c1 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} > @@ -5365,6 +5365,9 @@ 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 PCI devices support this feature. > \end{description} > > \drivernormative{\section}{Reserved Feature Bits}{Reserved Feature Bits} > @@ -5384,6 +5387,16 @@ 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. > > +If VIRTIO_F_SR_IOV has been negotiated, a driver can enable > +virtual functions through the device's PCI SR-IOV capability > +structure. A driver MUST NOT negotiate VIRTIO_F_SR_IOV if > +the device does not have a PCI SR-IOV capability structure > +or is not a PCI device. A driver MUST negotiate > +VIRTIO_F_SR_IOV and complete the feature negotiation > +(including setting the DRIVER_OK \field{status} bit) before > +enabling virtual functions through the device's PCI SR-IOV > +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 > @@ -5400,6 +5413,10 @@ 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 is a PCI device > +and presents a PCI SR-IOV capability structure, otherwise > +it MUST NOT offer VIRTIO_F_SR_IOV. > + > \section{Legacy Interface: Reserved Feature Bits}\label{sec:Reserved Feature Bits / Legacy Interface: Reserved Feature Bits} > > Transitional devices MAY offer the following: > -- > 2.17.0
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