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| 1 | +/* |
| 2 | + * Copyright (c) NVIDIA CORPORATION. All rights reserved. |
| 3 | + * |
| 4 | + * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | + * you may not use this file except in compliance with the License. |
| 6 | + * You may obtain a copy of the License at |
| 7 | + * |
| 8 | + * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | + * |
| 10 | + * Unless required by applicable law or agreed to in writing, software |
| 11 | + * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | + * See the License for the specific language governing permissions and |
| 14 | + * limitations under the License. |
| 15 | + */ |
| 16 | + |
| 17 | +package nvpassthrough |
| 18 | + |
| 19 | +import ( |
| 20 | + "fmt" |
| 21 | + "math" |
| 22 | + "reflect" |
| 23 | + "strings" |
| 24 | + |
| 25 | + "golang.org/x/sys/unix" |
| 26 | +) |
| 27 | + |
| 28 | +const ( |
| 29 | + vfioPciAliasPrefix string = "alias vfio_pci:" |
| 30 | +) |
| 31 | + |
| 32 | +// modAlias is a decomposed version of string like this |
| 33 | +// |
| 34 | +// vNNNNNNNNdNNNNNNNNsvNNNNNNNNsdNNNNNNNNbcNNscNNiNN |
| 35 | +// |
| 36 | +// The "NNNN" are always of the length in the example |
| 37 | +// unless replaced with a wildcard ("*"). |
| 38 | +type modAlias struct { |
| 39 | + vendor string // v |
| 40 | + device string // d |
| 41 | + subvendor string // sv |
| 42 | + subdevice string // sd |
| 43 | + baseClass string // bc |
| 44 | + subClass string // sc |
| 45 | + programmingInterface string // i |
| 46 | +} |
| 47 | + |
| 48 | +// vfioAlias represents an entry from the modules.alias file for a vfio driver. |
| 49 | +type vfioAlias struct { |
| 50 | + modAlias *modAlias // The modalias pattern |
| 51 | + driver string // The vfio driver name |
| 52 | +} |
| 53 | + |
| 54 | +func parseModAliasString(input string) (*modAlias, error) { |
| 55 | + if input == "" { |
| 56 | + return nil, fmt.Errorf("modalias string is empty") |
| 57 | + } |
| 58 | + |
| 59 | + input = strings.TrimSpace(input) |
| 60 | + |
| 61 | + // Trim the leading "pci:" prefix in the modalias file |
| 62 | + split := strings.SplitN(input, ":", 2) |
| 63 | + if len(split) != 2 { |
| 64 | + return nil, fmt.Errorf("unexpected number of parts in modalias after trimming 'pci:' prefix: %s", input) |
| 65 | + } |
| 66 | + input = split[1] |
| 67 | + |
| 68 | + if !strings.HasPrefix(input, "v") { |
| 69 | + return nil, fmt.Errorf("modalias must start with 'v', got: %s", input) |
| 70 | + } |
| 71 | + |
| 72 | + ma := &modAlias{} |
| 73 | + var before, after string |
| 74 | + var found bool |
| 75 | + after = input[1:] // cut leading 'v' |
| 76 | + |
| 77 | + before, after, found = strings.Cut(after, "d") |
| 78 | + if !found { |
| 79 | + return nil, fmt.Errorf("failed to find delimiter 'd' in %q", input) |
| 80 | + } |
| 81 | + ma.vendor = before |
| 82 | + |
| 83 | + before, after, found = strings.Cut(after, "sv") |
| 84 | + if !found { |
| 85 | + return nil, fmt.Errorf("failed to find delimiter 'sv' in %q", input) |
| 86 | + } |
| 87 | + ma.device = before |
| 88 | + |
| 89 | + before, after, found = strings.Cut(after, "sd") |
| 90 | + if !found { |
| 91 | + return nil, fmt.Errorf("failed to find delimiter 'sd' in %q", input) |
| 92 | + } |
| 93 | + ma.subvendor = before |
| 94 | + |
| 95 | + before, after, found = strings.Cut(after, "bc") |
| 96 | + if !found { |
| 97 | + return nil, fmt.Errorf("failed to find delimiter 'bc' in %q", input) |
| 98 | + } |
| 99 | + ma.subdevice = before |
| 100 | + |
| 101 | + before, after, found = strings.Cut(after, "sc") |
| 102 | + if !found { |
| 103 | + return nil, fmt.Errorf("failed to find delimiter 'sc' in input %q", input) |
| 104 | + } |
| 105 | + ma.baseClass = before |
| 106 | + |
| 107 | + before, after, found = strings.Cut(after, "i") |
| 108 | + if !found { |
| 109 | + return nil, fmt.Errorf("failed to find delimiter 'i' in %q", input) |
| 110 | + } |
| 111 | + ma.subClass = before |
| 112 | + ma.programmingInterface = after |
| 113 | + |
| 114 | + return ma, nil |
| 115 | +} |
| 116 | + |
| 117 | +func getKernelVersion() (string, error) { |
| 118 | + var uname unix.Utsname |
| 119 | + if err := unix.Uname(&uname); err != nil { |
| 120 | + return "", err |
| 121 | + } |
| 122 | + |
| 123 | + // Convert C-style byte array to Go string |
| 124 | + release := make([]byte, 0, len(uname.Release)) |
| 125 | + for _, c := range uname.Release { |
| 126 | + if c == 0 { |
| 127 | + break |
| 128 | + } |
| 129 | + release = append(release, c) |
| 130 | + } |
| 131 | + |
| 132 | + return string(release), nil |
| 133 | +} |
| 134 | + |
| 135 | +// getVFIOAliases returns the vfio driver aliases from the input string. |
| 136 | +// The input string is expected to be the content of a modules.alias file. |
| 137 | +// Only lines that begin with 'alias vfio_pci:' are parsed, with the |
| 138 | +// format being: alias vfio_pci:<modalias string> <driver_name>. |
| 139 | +func getVFIOAliases(input string) []vfioAlias { |
| 140 | + var aliases []vfioAlias |
| 141 | + |
| 142 | + lines := strings.Split(input, "\n") |
| 143 | + for _, line := range lines { |
| 144 | + line = strings.TrimSpace(line) |
| 145 | + |
| 146 | + if !strings.HasPrefix(line, vfioPciAliasPrefix) { |
| 147 | + continue |
| 148 | + } |
| 149 | + |
| 150 | + split := strings.SplitN(line, " ", 3) |
| 151 | + if len(split) != 3 { |
| 152 | + continue |
| 153 | + } |
| 154 | + modAliasStr := split[1] |
| 155 | + modAlias, err := parseModAliasString(modAliasStr) |
| 156 | + if err != nil { |
| 157 | + continue |
| 158 | + } |
| 159 | + |
| 160 | + driver := split[2] |
| 161 | + aliases = append(aliases, vfioAlias{ |
| 162 | + modAlias: modAlias, |
| 163 | + driver: driver, |
| 164 | + }) |
| 165 | + } |
| 166 | + |
| 167 | + return aliases |
| 168 | +} |
| 169 | + |
| 170 | +// findBestMatch finds the best matching VFIO driver for the given modalias |
| 171 | +// by comparing against all available vfio alias patterns. The best match |
| 172 | +// is the one with the fewest wildcard characters. |
| 173 | +func findBestMatch(deviceModAlias *modAlias, aliases []vfioAlias) string { |
| 174 | + var bestDriver string |
| 175 | + bestWildcardCount := math.MaxInt |
| 176 | + |
| 177 | + for _, alias := range aliases { |
| 178 | + if matches, wildcardCount := matchModalias(deviceModAlias, alias.modAlias); matches { |
| 179 | + if wildcardCount < bestWildcardCount { |
| 180 | + bestDriver = alias.driver |
| 181 | + bestWildcardCount = wildcardCount |
| 182 | + } |
| 183 | + } |
| 184 | + } |
| 185 | + |
| 186 | + return bestDriver |
| 187 | +} |
| 188 | + |
| 189 | +// matchModalias checks if a device modalias matches a pattern from modules.alias |
| 190 | +// Returns true if it matches and the number of wildcards |
| 191 | +func matchModalias(deviceModAlias, patternModAlias *modAlias) (bool, int) { |
| 192 | + wildcardCount := 0 |
| 193 | + |
| 194 | + modAliasType := reflect.TypeOf(*deviceModAlias) |
| 195 | + deviceModAliasValue := reflect.ValueOf(*deviceModAlias) |
| 196 | + patternModAliasValue := reflect.ValueOf(*patternModAlias) |
| 197 | + |
| 198 | + // iterate over both modAlias structs, comparing each field |
| 199 | + for i := 0; i < modAliasType.NumField(); i++ { |
| 200 | + deviceValue := deviceModAliasValue.Field(i).String() |
| 201 | + patternValue := patternModAliasValue.Field(i).String() |
| 202 | + |
| 203 | + if patternValue == "*" { |
| 204 | + wildcardCount++ |
| 205 | + continue |
| 206 | + } |
| 207 | + |
| 208 | + if deviceValue != patternValue { |
| 209 | + return false, wildcardCount |
| 210 | + } |
| 211 | + } |
| 212 | + return true, wildcardCount |
| 213 | +} |
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