[virtio-comment] [PATCH v2 5/8] admin: Add requirements of device migration commands

[Parav Pandit <parav@nvidia.com>]

Add device and driver side requirements for the device migration
commands.

Fixes: https://github.com/oasis-tcs/virtio-spec/issues/176
Signed-off-by: Parav Pandit <parav@nvidia.com>
---
changelog:
v1->v2:
- fixed spelling from membe to member
- removed device requirement line of FLR making the device active
  as it was incorrectly written to mix operational and admin state
- added requirements to clarify flr, device reset, pm and admin commands
- group sriov requirements
- added description for device config space access in stop mode
- removed stale requirement around pci ids
- made device context write command requirements more robust
  for future and backward compatibility
---
 admin-cmds-device-migration.tex | 141 ++++++++++++++++++++++++++++++++
 1 file changed, 141 insertions(+)

diff --git a/admin-cmds-device-migration.tex b/admin-cmds-device-migration.tex
index bbe5902..5cd9ec7 100644
--- a/admin-cmds-device-migration.tex
+++ b/admin-cmds-device-migration.tex
@@ -324,3 +324,144 @@ \subsubsection{Device Migration}\label{sec:Basic Facilities of a Virtio Device /
 the device returns new device context entry. Once the device context is
 discarded, subsequent VIRTIO_ADMIN_CMD_DEV_CTX_WRITE command writes a new device
 context.
+
+\devicenormative{\paragraph}{Device Migration}{Basic Facilities of a Virtio Device / Device groups / Group administration commands / Device Migration}
+
+A device MUST either support all of, or none of
+VIRTIO_ADMIN_CMD_DEV_MODE_GET,
+VIRTIO_ADMIN_CMD_DEV_MODE_SET,
+VIRTIO_ADMIN_CMD_DEV_CTX_SIZE_GET,
+VIRTIO_ADMIN_CMD_DEV_READ,
+VIRTIO_ADMIN_CMD_DEV_WRITE and
+VIRTIO_ADMIN_CMD_DEV_CTX_DISCARD commands.
+
+When the device \field{mode} supplied in the command
+VIRTIO_ADMIN_CMD_DEV_MODE_SET is same as what the mode in the device, the device
+MUST complete the command successfully.
+
+The device MUST fail the command VIRTIO_ADMIN_CMD_DEV_MODE_SET when the \field{mode}
+is other than \field{Active} or \field{Stop} or \field{Freeze}.
+
+When changing the device mode using the command VIRTIO_ADMIN_CMD_DEV_MODE_SET,
+if the command fails, the device MUST retain the current device mode.
+
+The device MUST fail VIRTIO_ADMIN_CMD_DEV_MODE_SET command when \field{mode}
+is set to \field{Active} or \field{Stop} and if the device context is
+partially read or written using VIRTIO_ADMIN_CMD_DEV_CTX_READ and
+VIRTIO_ADMIN_CMD_DEV_CTX_WRITE commands respectively.
+
+When VIRTIO_ADMIN_CMD_DEV_CTX_READ command is received multiple times
+in a given mode, and when the complete device context is already read by the
+driver, on subsequent reception of command VIRTIO_ADMIN_CMD_DEV_CTX_READ,
+the device MUST complete the command successfully with
+\field{context_len} set to zero.
+
+The device MUST support reading the device context when the device is
+in any mode \field{Active} or \field{Stop} or \field{Freeze} using command
+VIRTIO_ADMIN_CMD_DEV_CTX_READ.
+
+When the device is in any of the mode, and if the device context is read
+partially using VIRTIO_ADMIN_CMD_DEV_CTX_READ command, the device MUST discard
+the device context when VIRTIO_ADMIN_CMD_DEV_CTX_DISCARD command is executed;
+In subsequent execution of VIRTIO_ADMIN_CMD_DEV_CTX_READ and
+VIRTIO_ADMIN_CMD_DEV_CTX_SIZE_GET, the device MUST return the remaining
+estimated device context size and the device context respectively for the
+current mode as if VIRTIO_ADMIN_CMD_DEV_CTX_READ was never received by the
+device for the current device mode.
+
+The device MUST support writing the complete device context multiple times
+by the command VIRTIO_ADMIN_CMD_DEV_CTX_WRITE.
+
+The device MUST fail VIRTIO_ADMIN_CMD_DEV_CTX_WRITE command when the device
+mode is not \field{Freeze}.
+
+For the SR-IOV group type,
+\begin{itemize}
+\item the device MUST not initiate any PCI transaction
+      when the device mode is not \field{Active}.
+\item the device MUST finish all the outstanding PCI transactions before completing
+      the command VIRTIO_ADMIN_CMD_DEV_MODE_SET.
+\item when the device mode is \field{Stop}, the device MUST accept driver
+       notifications and the device MAY update any fields of the device context.
+\item the device MUST respond with valid values for PCI read requests when
+      the device mode is \field{Stop}.
+\item the device MUST function same for the PCI architected interfaces
+      regardless of the device mode.
+\item the device MUST not generate any PCI PME when the device is
+      not in \field{Active} state.
+\item the device MUST NOT update any fields of the device context when the
+      device is in \field{Freeze} mode, the device MAY update fields of the
+      device context when the device transitions from \field{Stop} to
+      \field{Freeze} mode.
+\end{itemize}
+
+When the device mode is not \field{Active},
+\begin{itemize}
+\item the device MUST not access any virtqueue memory or any memory referred
+      by the virtqueue when the device mode is not \field{Active}.
+
+\item the device MUST not generate any configuration change notification. 
+\end{itemize}
+
+When the device is in \field{Freeze} mode, and if any device context is
+written partially by VIRTIO_ADMIN_CMD_DEV_CTX_WRITE, the device MUST discard
+the device context when VIRTIO_ADMIN_CMD_DEV_CTX_DISCARD
+command is executed, i.e. the device functions as if the command
+VIRTIO_ADMIN_CMD_DEV_CTX_WRITE was never received.
+
+For the SR-IOV group type,
+\begin{itemize}
+\item when the device is in \field{Freeze} mode, any
+write access to virtio configuration space MUST not update any fields and any
+configuration space read MAY return any value.
+
+\item for the VIRTIO_PCI_CAP_PCI_CFG capability area,
+the device MUST ignore writes when the device mode is set to \field{Freeze}
+and on receiving the reads, the device MUST function same regardless of the
+device mode is \field{Active} or \field{Stop} or \field{Freeze}.
+
+\item the VF device MUST respond to commands
+VIRTIO_ADMIN_CMD_DEV_MODE_SET, VIRTIO_ADMIN_CMD_DEV_CTX_WRITE and
+VIRTIO_ADMIN_CMD_DEV_CTX_READ after the VF FLR completes in the device, if the VF FLR
+is in progress when the device receives any of these commands.
+
+\item the VF device MUST respond to commands
+VIRTIO_ADMIN_CMD_DEV_MODE_SET, VIRTIO_ADMIN_CMD_DEV_CTX_WRITE and
+VIRTIO_ADMIN_CMD_DEV_CTX_READ after the device reset completes in the device, if the
+device reset is in progress when the device receives any of these commands.
+
+\item the VF device MUST respond to commands
+VIRTIO_ADMIN_CMD_DEV_MODE_SET, VIRTIO_ADMIN_CMD_DEV_CTX_WRITE and
+VIRTIO_ADMIN_CMD_DEV_CTX_READ after the device power management state transition completes
+in the device, if the power management state transition is in progress
+when the device receives any of these commands.
+\end{itemize}
+
+The device MUST respond with an error for the command
+VIRTIO_ADMIN_CMD_DEV_CTX_WRITE, if there is a mismatch in the
+device context field length between the field provided in the
+VIRTIO_ADMIN_CMD_DEV_CTX_WRITE data and the length of the field
+in the device.
+
+\drivernormative{\paragraph}{Device Migration}{Basic Facilities of a Virtio Device / Device groups / Group administration commands / Device Migration}
+
+The driver SHOULD read the complete device context using one or multiple
+VIRTIO_ADMIN_CMD_DEV_CTX_READ commands.
+
+The driver MAY write the device context before changing the device mode from
+\field{Freeze} to \field{Stop} or from \field{Freeze} to \field{Active};
+the driver MUST write a complete device context using one or multiple
+VIRTIO_ADMIN_CMD_DEV_CTX_WRITE commands.
+
+The driver MUST NOT change the device mode to \field{Stop} or \field{Active}
+in the command VIRTIO_ADMIN_CMD_DEV_MODE_SET when device context is
+partially written.
+
+For the SR-IOV group type, the driver SHOULD NOT access device configuration
+space described in section
+\ref{sec:Basic Facilities of a Virtio Device / Device Configuration Space}
+when the device mode is set to \field{Freeze} or \field{Stop}.
+
+For the SR-IOV group type, the driver MUST NOT write into the
+VIRTIO_PCI_CAP_PCI_CFG capability area when the device mode is set to
+\field{Freeze}.
-- 
2.34.1


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