sriov: add support

Add support to report SRIOV devices.
Much like GPU devices, support is added using a new top-level package.

SRIOV devices are either Physical Functions or Virtual functions.
The preferred representation for ghw is Physical Functions, whose
dependent devices will be Virtual Functions; however, for the sake of
practicality, the API also exposes soft references to Virtual Functions,
so consumers of the API can access them directly and not navigating
the parent devices.

This patch also adds support in `ghwc`, to report the sriov information,
and in the `snapshot` package, to make sure to capture all the files
in sysfs that ghw cares about.

Last but not least, lacking access to suitable non-linux systems,
support is provided only on linux OS, even though the API tries hard
not to be linux-specific.

Resolves: #92
Signed-off-by: Francesco Romani <fromani@redhat.com>

README.md

@@ -1039,6 +1039,67 @@ information
 `ghw.TopologyNode` struct if you'd like to dig deeper into the NUMA/topology
 subsystem
 
+### SRIOV
+
+*This API is PROVISIONAL! ghw will try hard to not make breaking changes to this API, but still users are advice this new API is not
+declared stable yet. We expect to declare it stable with ghw version 1.0.0*
+
+SRIOV (Single-Root Input/Output Virtualization) is a class of PCI devices that ghw models explicitly, like gpus.
+
+```go
+package main
+
+import (
+	"fmt"
+
+	"github.com/jaypipes/ghw"
+)
+
+func main() {
+	sriov, err := ghw.SRIOV()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error getting SRIOV info: %v", err)
+	}
+
+	fmt.Printf("%v\n", sriov)
+
+	for _, dev := range sriov.PhysicalFunctions {
+		fmt.Printf(" %v\n", dev)
+	}
+}
+```
+
+ghw discovers the SRIOV devices starting from the Physical Function (PF) and exposes them in the `PhysicalFunctions` slice.
+Virtual Function (VF) are exposed as properties of the PF instance with exposes them.
+However, in some cases users are interested in the VFs first, so it's clumsy to navigate the PFs to learn about VFs.
+To make this easier, ghw also exposes a slice of VF instances. These instances are soft references to the very same VF objects
+you can find from the PF objects.
+
+```go
+package main
+
+import (
+	"fmt"
+
+	"github.com/jaypipes/ghw"
+)
+
+func main() {
+	sriov, err := ghw.SRIOV()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error getting SRIOV info: %v", err)
+	}
+
+	fmt.Printf("%v\n", sriov)
+
+	// you will see the very same VF data data you seen from the previous example
+	for _, dev := range sriov.VirtualFunctions {
+		fmt.Printf(" %v\n", dev)
+	}
+}
+```
+
+
 ### Chassis
 
 The host's chassis information is accessible with the `ghw.Chassis()` function.  This

alias.go

@@ -19,6 +19,7 @@ import (
 	"github.com/jaypipes/ghw/pkg/pci"
 	pciaddress "github.com/jaypipes/ghw/pkg/pci/address"
 	"github.com/jaypipes/ghw/pkg/product"
+	"github.com/jaypipes/ghw/pkg/sriov"
 	"github.com/jaypipes/ghw/pkg/topology"
 )
 
@@ -146,3 +147,11 @@ type GraphicsCard = gpu.GraphicsCard
 var (
 	GPU = gpu.New
 )
+
+type SRIOVInfo = sriov.Info
+type PhysicalFunction = sriov.PhysicalFunction
+type VirtualFunction = sriov.VirtualFunction
+
+var (
+	SRIOV = sriov.New
+)

cmd/ghwc/commands/sriov.go

@@ -0,0 +1,48 @@
+//
+// Use and distribution licensed under the Apache license version 2.
+//
+// See the COPYING file in the root project directory for full text.
+//
+
+package commands
+
+import (
+	"fmt"
+
+	"github.com/jaypipes/ghw"
+	"github.com/pkg/errors"
+	"github.com/spf13/cobra"
+)
+
+// sriovCmd represents the listing command
+var sriovCmd = &cobra.Command{
+	Use:   "sriov",
+	Short: "Show SRIOV devices information for the host system",
+	RunE:  showSRIOV,
+}
+
+// showSRIOV show SRIOV physical device information for the host system.
+func showSRIOV(cmd *cobra.Command, args []string) error {
+	sriov, err := ghw.SRIOV()
+	if err != nil {
+		return errors.Wrap(err, "error getting SRIOV info")
+	}
+
+	switch outputFormat {
+	case outputFormatHuman:
+		fmt.Printf("%v\n", sriov)
+
+		for _, dev := range sriov.PhysicalFunctions {
+			fmt.Printf(" %v\n", dev)
+		}
+	case outputFormatJSON:
+		fmt.Printf("%s\n", sriov.JSONString(pretty))
+	case outputFormatYAML:
+		fmt.Printf("%s", sriov.YAMLString())
+	}
+	return nil
+}
+
+func init() {
+	rootCmd.AddCommand(sriovCmd)
+}

host.go

@@ -8,6 +8,7 @@ package ghw
 
 import (
 	"fmt"
+	"strings"
 
 	"github.com/jaypipes/ghw/pkg/context"
 
@@ -22,6 +23,7 @@ import (
 	"github.com/jaypipes/ghw/pkg/net"
 	"github.com/jaypipes/ghw/pkg/pci"
 	"github.com/jaypipes/ghw/pkg/product"
+	"github.com/jaypipes/ghw/pkg/sriov"
 	"github.com/jaypipes/ghw/pkg/topology"
 )
 
@@ -40,6 +42,7 @@ type HostInfo struct {
 	Baseboard *baseboard.Info `json:"baseboard"`
 	Product   *product.Info   `json:"product"`
 	PCI       *pci.Info       `json:"pci"`
+	SRIOV     *sriov.Info     `json:"sriov"`
 }
 
 // Host returns a pointer to a HostInfo struct that contains fields with
@@ -91,6 +94,10 @@ func Host(opts ...*WithOption) (*HostInfo, error) {
 	if err != nil {
 		return nil, err
 	}
+	sriovInfo, err := sriov.New(opts...)
+	if err != nil {
+		return nil, err
+	}
 	return &HostInfo{
 		ctx:       ctx,
 		CPU:       cpuInfo,
@@ -104,26 +111,32 @@ func Host(opts ...*WithOption) (*HostInfo, error) {
 		Baseboard: baseboardInfo,
 		Product:   productInfo,
 		PCI:       pciInfo,
+		SRIOV:     sriovInfo,
 	}, nil
 }
 
 // String returns a newline-separated output of the HostInfo's component
 // structs' String-ified output
 func (info *HostInfo) String() string {
-	return fmt.Sprintf(
-		"%s\n%s\n%s\n%s\n%s\n%s\n%s\n%s\n%s\n%s\n%s\n",
-		info.Block.String(),
-		info.CPU.String(),
-		info.GPU.String(),
-		info.Memory.String(),
-		info.Network.String(),
-		info.Topology.String(),
-		info.Chassis.String(),
-		info.BIOS.String(),
-		info.Baseboard.String(),
-		info.Product.String(),
-		info.PCI.String(),
-	)
+	var b strings.Builder
+	for _, s := range []fmt.Stringer{
+		info.Block,
+		info.CPU,
+		info.GPU,
+		info.Memory,
+		info.Network,
+		info.Topology,
+		info.Chassis,
+		info.BIOS,
+		info.Baseboard,
+		info.Product,
+		info.PCI,
+		info.SRIOV,
+	} {
+		b.WriteString(s.String())
+		b.WriteString("\n")
+	}
+	return b.String()
 }
 
 // YAMLString returns a string with the host information formatted as YAML

pkg/pci/address/address.go

@@ -24,6 +24,17 @@ type Address struct {
 	Function string
 }
 
+// Equal tells if two Addresses are equal or not
+func (addr *Address) Equal(a *Address) bool {
+	if addr == nil && a == nil {
+		return true
+	}
+	if addr != nil && a != nil {
+		return addr.Domain == a.Domain && addr.Bus == a.Bus && addr.Slot == a.Slot && addr.Function == a.Function
+	}
+	return false
+}
+
 // String() returns the canonical [D]BSF representation of this Address
 func (addr *Address) String() string {
 	return addr.Domain + ":" + addr.Bus + ":" + addr.Slot + "." + addr.Function

pkg/pci/address/address_test.go

@@ -80,3 +80,11 @@ func TestPCIAddressFromString(t *testing.T) {
 		}
 	}
 }
+
+func TestPCIAddressEqual(t *testing.T) {
+	addr1 := pciaddr.FromString("0000:03:00.A")
+	addr2 := pciaddr.FromString("03:00.A")
+	if addr1.Equal(addr2) == false {
+		t.Fatalf("addr1 %v and addr2 %v should be equal", addr1, addr2)
+	}
+}

pkg/snapshot/clonetree.go

@@ -7,6 +7,7 @@
 package snapshot
 
 import (
+	"errors"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -197,6 +198,11 @@ func copyLink(path, targetPath string) error {
 		return err
 	}
 	if err := os.Symlink(target, targetPath); err != nil {
+		// multiple sources can link back to the same entry: a notable example is
+		// all the SRIOV VFs linking back to the same driver.
+		if errors.Is(err, os.ErrExist) {
+			return nil
+		}
 		return err
 	}
 

pkg/snapshot/clonetree_pci.go

@@ -67,6 +67,15 @@ func scanPCIDeviceRoot(root string) (fileSpecs []string, pciRoots []string) {
 		"revision",
 		"vendor",
 	}
+
+	perDevEntriesOpt := []string{
+		"driver",
+		"net/*",
+		"physfn",
+		"sriov_*",
+		"virtfn*",
+	}
+
 	entries, err := ioutil.ReadDir(root)
 	if err != nil {
 		return []string{}, []string{}
@@ -93,6 +102,14 @@ func scanPCIDeviceRoot(root string) (fileSpecs []string, pciRoots []string) {
 			fileSpecs = append(fileSpecs, filepath.Join(pciEntry, perNetEntry))
 		}
 
+		for _, perNetEntryOpt := range perDevEntriesOpt {
+			netEntryOptPath := filepath.Join(pciEntry, perNetEntryOpt)
+			if items, err := filepath.Glob(netEntryOptPath); err == nil && len(items) > 0 {
+				fileSpecs = append(fileSpecs, netEntryOptPath)
+			}
+
+		}
+
 		if isPCIBridge(entryPath) {
 			trace("adding new PCI root %q\n", entryName)
 			pciRoots = append(pciRoots, pciEntry)