[PATCH] content: document the behaviours for SR-IOV

[Tiwei Bie <tiwei.bie@intel.com>]

Document the device and driver behaviours for 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/13
---
 content.tex | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/content.tex b/content.tex
index 73981b7..3b45a6c 100644
--- a/content.tex
+++ b/content.tex
@@ -5387,6 +5387,18 @@ 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 checking the FEATURES_OK \field{status} bit) before
+the first time to enable virtual functions through the device's
+PCI SR-IOV capability structure, and the driver MAY remember
+the VIRTIO_F_SR_IOV feature bit negotiation result until it
+unbinds from the device.
+
 \devicenormative{\section}{Reserved Feature Bits}{Reserved Feature Bits}
 
 A device MUST offer VIRTIO_F_VERSION_1.  A device MAY fail to operate further
@@ -5403,6 +5415,10 @@ 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