On Mon, Jun 04, 2018 at 04:01:56PM +0300, Michael S. Tsirkin wrote: > 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 <m...@redhat.com> > > Signed-off-by: Tiwei Bie <tiwei....@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?
I think a reset doesn't have to disable IOV. Because PF and VFs are managed by PCI core. They are independent from the driver's point of view. Once VFs are allocated, PF and VFs can be bound to different drivers and used independently. So a driver reset on PF doesn't have to disable IOV. The proposal is just to provide a feature bit based virtio way for virtio drivers to know whether a virtio device is SR-IOV capable (and virtio drivers can support configuring SR-IOV based on the feature bit negotiation result). Best regards, Tiwei Bie > > > --- > > 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 --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscr...@lists.oasis-open.org For additional commands, e-mail: virtio-dev-h...@lists.oasis-open.org
