virtio — archive

[Michael S. Tsirkin <parav@nvidia.com>]

On Wed, Apr 27, 2022 at 01:58:20AM +0300, Max Gurtovoy wrote: > Introduce a new mechanism to issue commands with dst_type field that is > not "self". With the new mechanism, driver can set dst_type to 1 > and use the vdev_id common field to describe the designated vdev_id. > > This mechanism is useful for device groups with multiple devices > with various different capabilities. For example, a type 1 device group > that contains a PCI PF and its VF. For this group, a clever system > administrator can use admin commands to manipulate the PF/VF resources. > > Reviewed-by: Parav Pandit <parav@nvidia.com> > Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com> > --- > admin.tex | 18 ++++++++++++++---- > 1 file changed, 14 insertions(+), 4 deletions(-) > > diff --git a/admin.tex b/admin.tex > index 6725daa..f816c3b 100644 > --- a/admin.tex > +++ b/admin.tex > @@ -11,11 +11,13 @@ \section{Administration command set}\label{sec:Basic Facilities of a Virtio Devi > le16 command; > /* > * 0 - self > - * 1 - 65535 are reserved > + * 1 - other virtio device (identified by vdev_id) in the same device group > + * 2 - 65535 are reserved > */ > le16 dst_type; > + le64 vdev_id; Alignment problems. Proposal: vdev_id dst_type command > /* reserved for common cmd fields */ > - u8 reserved[20]; > + u8 reserved[12]; > u8 command_specific_data[]; > > /* Device-writable part */ > @@ -39,9 +41,11 @@ \section{Administration command set}\label{sec:Basic Facilities of a Virtio Devi > \hline > 03h & VIRTIO_ADMIN_STATUS_INVALID_FIELD & invalid field was set \\ > \hline > +04h & VIRTIO_ADMIN_STATUS_INVALID_VDEV_ID & invalid vdev_id was set \\ > +\hline > \end{tabular} > > -The \field{command}, \field{dst_type} and \field{command_specific_data} are > +The \field{command}, \field{dst_type}, \field{vdev_id} and \field{command_specific_data} are > set by the driver, and the device sets the \field{status}, the > \field{command_specific_error} and the \field{command_specific_result}, > if needed. > @@ -50,9 +54,15 @@ \section{Administration command set}\label{sec:Basic Facilities of a Virtio Devi > > The mandatory fields to be set by the driver, for all admin commands, are \field{command} and \field{dst_type}. > > +The optional unused fields to be zeroed by the driver. > + > The \field{command} defines the opcode for the command. The value for each command can be found in each command section. > > -The \field{dst_type} defines the designated virtio device for the command. This value should be set to 0 (self). > +The \field{dst_type} defines the designated virtio device for the command. This value can be set to 0 (self) or 1 (other virtio device in the same device > +group) by the driver. Not all the commands allow setting \field{dst_type} to 1. Refer to each command description explicitly to check whether this operation is allowed. > +If \field{dst_type} is set to 0 by the driver, the \field{vdev_id} isn't valid, should be zeroed by the driver and should be ignored by the device. > +If \field{dst_type} is set to 1 by the driver, the \field{vdev_id} is valid and used to describe the vdev_id of the designated virtio device (see section > +\ref{sec:Introduction / Terminology / Device group} for vdev_id numbering for type 1 device groups). > > The \field{command_specific_error} should be inspected by the driver only if \field{status} is set to > VIRTIO_ADMIN_STATUS_CS_ERR by the device. In this case, the content of \field{command_specific_error} teminology is a bit inconsistent. would dst_id be better? it goes together with dst_type after all. > -- > 2.21.0