[RFC PATCH v3 4/5] dts: add OS abstractions for creating virtual functions

[jspewock@iol.unh.edu]

From: Jeremy Spewock <jspewock@iol.unh.edu>

Virtual functions in the framework are created using SR-IOV. The process
for doing this can vary depending on the operating system, so the
commands to create VFs have to be abstracted into different classes
based on the operating system. This patch adds the stubs for methods
that create VFs and get the PCI addresses of all VFs on a port to the
abstract class as well as a linux implementation for the methods.

Bugzilla ID: 1500

Signed-off-by: Jeremy Spewock <jspewock@iol.unh.edu>
---
 dts/framework/testbed_model/linux_session.py | 40 +++++++++++++++++++-
 dts/framework/testbed_model/os_session.py    | 40 ++++++++++++++++++++
 2 files changed, 79 insertions(+), 1 deletion(-)

diff --git a/dts/framework/testbed_model/linux_session.py b/dts/framework/testbed_model/linux_session.py
index 99abc21353..738ddd7600 100644
--- a/dts/framework/testbed_model/linux_session.py
+++ b/dts/framework/testbed_model/linux_session.py
@@ -15,7 +15,11 @@
 
 from typing_extensions import NotRequired
 
-from framework.exception import ConfigurationError, RemoteCommandExecutionError
+from framework.exception import (
+    ConfigurationError,
+    InternalError,
+    RemoteCommandExecutionError,
+)
 from framework.utils import expand_range
 
 from .cpu import LogicalCore
@@ -210,3 +214,37 @@ def configure_ipv4_forwarding(self, enable: bool) -> None:
         """Overrides :meth:`~.os_session.OSSession.configure_ipv4_forwarding`."""
         state = 1 if enable else 0
         self.send_command(f"sysctl -w net.ipv4.ip_forward={state}", privileged=True)
+
+    def set_num_virtual_functions(self, num: int, pf_port: Port) -> bool:
+        """Overrides :meth:`~.os_session.OSSession.set_num_virtual_functions`."""
+        sys_bus_path = f"/sys/bus/pci/devices/{pf_port.pci}/sriov_numvfs".replace(":", "\\:")
+        curr_num_vfs = int(self.send_command(f"cat {sys_bus_path}").stdout)
+        if num > 0 and curr_num_vfs >= num:
+            self._logger.info(
+                f"{curr_num_vfs} VFs already configured on port {pf_port.identifier.pci} on node "
+                f"{pf_port.identifier.node}."
+            )
+            return False
+        elif num > 0 and curr_num_vfs > 0:
+            self._logger.error(
+                f"Not enough VFs configured on port {pf_port.identifier.pci} on node "
+                f"{pf_port.identifier.node}. Need {num} but only {curr_num_vfs} are configured. "
+                "DTS is unable to modify number of preexisting VFs."
+            )
+            raise InternalError("Failed to create VFs on port.")
+        self.send_command(f"echo {num} > {sys_bus_path}", privileged=True, verify=True)
+        return True
+
+    def get_pci_addr_of_vfs(self, pf_port: Port) -> list[str]:
+        """Overrides :meth:`~.os_session.OSSession.get_pci_addr_of_vfs`."""
+        sys_bus_path = f"/sys/bus/pci/devices/{pf_port.pci}".replace(":", "\\:")
+        curr_num_vfs = int(self.send_command(f"cat {sys_bus_path}/sriov_numvfs").stdout)
+        if curr_num_vfs > 0:
+            pci_addrs = self.send_command(
+                'awk -F "PCI_SLOT_NAME=" "/PCI_SLOT_NAME=/ {print \\$2}" '
+                + f"{sys_bus_path}/virtfn*/uevent",
+                privileged=True,
+            )
+            return pci_addrs.stdout.splitlines()
+        else:
+            return []
diff --git a/dts/framework/testbed_model/os_session.py b/dts/framework/testbed_model/os_session.py
index 79f56b289b..191fc3c0c8 100644
--- a/dts/framework/testbed_model/os_session.py
+++ b/dts/framework/testbed_model/os_session.py
@@ -395,3 +395,43 @@ def configure_ipv4_forwarding(self, enable: bool) -> None:
         Args:
             enable: If :data:`True`, enable the forwarding, otherwise disable it.
         """
+
+    @abstractmethod
+    def set_num_virtual_functions(self, num: int, pf_port: Port) -> bool:
+        """Update the number of virtual functions (VFs) on a port.
+
+        It should be noted that, due to the nature of VFs, if there are already VFs that exist on
+        the physical function (PF) prior to calling this function, additional ones cannot be added.
+        The only way to add more VFs is to remove the existing and then set the desired amount. For
+        this reason, this method will handle creation in the following order:
+
+        1. Use existing VFs on the PF if the number of existing VFs is greater than or equal to
+        `num`
+        2. Throw an exception noting that VFs cannot be created if the PF has some VFs already set
+        on it, but the total VFs that it has are less then `num`.
+        3. Create `num` VFs on the PF if there are none on it already
+
+        Args:
+            num: The number of VFs to set on the port.
+            pf_port: The port to add the VFs to.
+
+        Raises:
+            InternalError: If `pf_port` has less than `num` VFs configured on it
+                already.
+
+        Returns:
+            :data:`True` if this method successfully created VFs, :data:`False` if existing VFs
+            were used instead.
+        """
+
+    @abstractmethod
+    def get_pci_addr_of_vfs(self, pf_port: Port) -> list[str]:
+        """Find the PCI addresses of all virtual functions (VFs) on the port `pf_port`.
+
+        Args:
+            pf_port: The port to find the VFs on.
+
+        Returns:
+            A list containing all of the PCI addresses of the VFs on the port. If the port has no
+            VFs then the list will be empty.
+        """
-- 
2.46.0