daa1ea522b
Details about CimFs project are discussed in #8346 Signed-off-by: Amit Barve <ambarve@microsoft.com>
108 lines
4.1 KiB
Go
108 lines
4.1 KiB
Go
//go:build windows
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package cim
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import (
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"bytes"
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"fmt"
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"os/exec"
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"github.com/Microsoft/go-winio/pkg/guid"
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)
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const (
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bcdFilePath = "UtilityVM\\Files\\EFI\\Microsoft\\Boot\\BCD"
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cimfsDeviceOptionsID = "{763e9fea-502d-434f-aad9-5fabe9c91a7b}"
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vmbusDeviceID = "{c63c9bdf-5fa5-4208-b03f-6b458b365592}"
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compositeDeviceOptionsID = "{e1787220-d17f-49e7-977a-d8fe4c8537e2}"
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bootContainerID = "{b890454c-80de-4e98-a7ab-56b74b4fbd0c}"
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)
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func bcdExec(storePath string, args ...string) error {
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var out bytes.Buffer
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argsArr := []string{"/store", storePath, "/offline"}
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argsArr = append(argsArr, args...)
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cmd := exec.Command("bcdedit.exe", argsArr...)
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cmd.Stdout = &out
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if err := cmd.Run(); err != nil {
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return fmt.Errorf("bcd command (%s) failed: %w", cmd, err)
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}
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return nil
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}
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// A registry configuration required for the uvm.
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func setBcdRestartOnFailure(storePath string) error {
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return bcdExec(storePath, "/set", "{default}", "restartonfailure", "yes")
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}
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func setBcdCimBootDevice(storePath, cimPathRelativeToVSMB string, diskID, partitionID guid.GUID) error {
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// create options for cimfs boot device
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if err := bcdExec(storePath, "/create", cimfsDeviceOptionsID, "/d", "CimFS Device Options", "/device"); err != nil {
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return err
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}
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// Set options. For now we need to set 2 options. First is the parent device i.e the device under
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// which all cim files will be available. Second is the path of the cim (from which this UVM should
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// boot) relative to the parent device. Note that even though the 2nd option is named
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// `cimfsrootdirectory` it expects a path to the cim file and not a directory path.
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if err := bcdExec(storePath, "/set", cimfsDeviceOptionsID, "cimfsparentdevice", fmt.Sprintf("vmbus=%s", vmbusDeviceID)); err != nil {
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return err
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}
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if err := bcdExec(storePath, "/set", cimfsDeviceOptionsID, "cimfsrootdirectory", fmt.Sprintf("\\%s", cimPathRelativeToVSMB)); err != nil {
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return err
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}
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// create options for the composite device
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if err := bcdExec(storePath, "/create", compositeDeviceOptionsID, "/d", "Composite Device Options", "/device"); err != nil {
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return err
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}
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// We need to specify the diskID & the partition ID of the boot disk and we need to set the cimfs boot
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// options ID
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partitionStr := fmt.Sprintf("gpt_partition={%s};{%s}", diskID, partitionID)
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if err := bcdExec(storePath, "/set", compositeDeviceOptionsID, "primarydevice", partitionStr); err != nil {
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return err
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}
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if err := bcdExec(storePath, "/set", compositeDeviceOptionsID, "secondarydevice", fmt.Sprintf("cimfs=%s,%s", bootContainerID, cimfsDeviceOptionsID)); err != nil {
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return err
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}
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if err := bcdExec(storePath, "/set", "{default}", "device", fmt.Sprintf("composite=0,%s", compositeDeviceOptionsID)); err != nil {
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return err
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}
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if err := bcdExec(storePath, "/set", "{default}", "osdevice", fmt.Sprintf("composite=0,%s", compositeDeviceOptionsID)); err != nil {
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return err
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}
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// Since our UVM file are stored under UtilityVM\Files directory inside the CIM we must prepend that
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// directory in front of paths used by bootmgr
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if err := bcdExec(storePath, "/set", "{default}", "path", "\\UtilityVM\\Files\\Windows\\System32\\winload.efi"); err != nil {
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return err
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}
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if err := bcdExec(storePath, "/set", "{default}", "systemroot", "\\UtilityVM\\Files\\Windows"); err != nil {
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return err
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}
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return nil
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}
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// updateBcdStoreForBoot Updates the bcd store at path layerPath + UtilityVM\Files\EFI\Microsoft\Boot\BCD` to
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// boot with the disk with given ID and given partitionID. cimPathRelativeToVSMB is the path of the cim which
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// will be used for booting this UVM relative to the VSMB share. (Usually, the entire snapshots directory will
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// be shared over VSMB, so if this is the cim-layers\1.cim under that directory, the value of
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// `cimPathRelativeToVSMB` should be cim-layers\1.cim)
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func updateBcdStoreForBoot(storePath string, cimPathRelativeToVSMB string, diskID, partitionID guid.GUID) error {
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if err := setBcdRestartOnFailure(storePath); err != nil {
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return err
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}
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if err := setBcdCimBootDevice(storePath, cimPathRelativeToVSMB, diskID, partitionID); err != nil {
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return err
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}
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return nil
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}
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