Remove lossy vGPU framework detection wrappers

DetectVGPUFramework discarded discovery errors, and its only remaining
caller was the integration test gate via DetectHostGPUMode. Route the
gate through DiscoverVGPU so a discovery failure surfaces in the skip
message, and delete the dead DetectHostGPUMode, DetectVGPUFramework,
and DiscoverVFs wrappers on both platforms.

Also document that least-loaded placement weighs allocated types absent
from the creatable catalog as zero.

Author: yummybomb

integration/vgpu_test.go

@@ -245,10 +245,13 @@ func checkVGPUTestPrerequisites() (string, string) {
 		return "vGPU test requires root (sudo) for mdev creation", ""
 	}
 
-	// Check for vGPU mode (SR-IOV VFs present)
-	mode := devices.DetectHostGPUMode()
-	if mode != devices.GPUModeVGPU {
-		return "vGPU test requires SR-IOV VFs in /sys/class/mdev_bus/", ""
+	// Check for a vGPU framework (SR-IOV VFs present)
+	framework, _, err := devices.DiscoverVGPU()
+	if err != nil {
+		return "vGPU test failed to discover vGPU framework: " + err.Error(), ""
+	}
+	if framework == devices.VGPUFrameworkNone {
+		return "vGPU test requires SR-IOV VFs with an mdev or vendor VFIO vGPU framework", ""
 	}
 
 	// Check for available profiles

lib/devices/gpu_mode.go

@@ -15,21 +15,11 @@ func SetGPUProfileCacheTTL(ttl string) {
 	// No-op on macOS
 }
 
-func DetectVGPUFramework() VGPUFramework {
-	return VGPUFrameworkNone
-}
-
 // DiscoverVGPU reports no vGPU framework on macOS.
 func DiscoverVGPU() (VGPUFramework, []VirtualFunction, error) {
 	return VGPUFrameworkNone, nil, nil
 }
 
-// DiscoverVFs returns an empty list on macOS.
-// SR-IOV Virtual Functions are not available on macOS.
-func DiscoverVFs() ([]VirtualFunction, error) {
-	return []VirtualFunction{}, nil
-}
-
 // ListGPUProfiles returns an empty list on macOS.
 func ListGPUProfiles() ([]GPUProfile, error) {
 	return []GPUProfile{}, nil

lib/devices/mdev_darwin.go

@@ -284,6 +284,9 @@ func (s vendorVFIOSysfs) reconcile(ctx context.Context, protectedDevicePaths map
 }
 
 func (s vendorVFIOSysfs) selectLeastLoadedVF(vfs []VirtualFunction, metadata []profileMetadata, profileType string) (string, error) {
+	// metadata only covers currently creatable types, so an allocated type no
+	// longer creatable anywhere weighs 0 and its GPU can look less loaded than
+	// it is. The driver's creatable lists still bound placement correctness.
 	framebufferByType := make(map[string]int, len(metadata))
 	for _, profile := range metadata {
 		framebufferByType[profile.TypeName] = profile.FramebufferMB

lib/devices/vendor_vfio_linux.go

@@ -34,16 +34,6 @@ func discoverVGPUWith(discoverMdev, discoverVendorVFIO func() ([]VirtualFunction
 	return VGPUFrameworkVendorVFIO, vfs, nil
 }
 
-func DetectVGPUFramework() VGPUFramework {
-	framework, _, _ := DiscoverVGPU()
-	return framework
-}
-
-func DiscoverVFs() ([]VirtualFunction, error) {
-	_, vfs, err := DiscoverVGPU()
-	return vfs, err
-}
-
 func ListGPUProfiles() ([]GPUProfile, error) {
 	framework, vfs, err := DiscoverVGPU()
 	if err != nil {