vm/vmware: improve kernel log collection and VM management

* Collecting kernel logs with dmesg over ssh doesn't work well and
sometimes we miss call traces when a crash occurs. Getting the kernel
log from a virtual serial port is much more effective.
* Creating linked clone VMs is faster then full clone VMs but it
requires snapshot management and this will bring more complexity to
syzkaller. Keep it simple and create full clone VMs for now.
* Use host-only networking because the VM gets its IP faster that way

1 files changed, 16 insertions, 26 deletions

diff --git a/vm/vmware/vmware.go b/vm/vmware/vmware.go
index 05d06e0a6..25f4eb4ec 100644
--- a/vm/vmware/vmware.go
+++ b/vm/vmware/vmware.go
@@ -6,6 +6,7 @@ package vmware
 import (
 	"fmt"
 	"io"
+	"net"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -38,7 +39,6 @@ type instance struct {
 	baseVMX     string
 	vmx         string
 	ipAddr      string
-	snapshot    string
 	closed      chan bool
 	debug       bool
 	sshuser     string
@@ -76,18 +76,18 @@ func (pool *Pool) Count() int {
 }
 
 func (pool *Pool) Create(workdir string, index int) (vmimpl.Instance, error) {
-	vmx := filepath.Join(workdir, "syzkaller.vmx")
+	createTime := strconv.FormatInt(time.Now().UnixNano(), 10)
+	vmx := filepath.Join(workdir, createTime, "syzkaller.vmx")
 	sshkey := pool.env.SSHKey
 	sshuser := pool.env.SSHUser
 	inst := &instance{
-		cfg:      pool.cfg,
-		debug:    pool.env.Debug,
-		baseVMX:  pool.cfg.BaseVMX,
-		vmx:      vmx,
-		sshkey:   sshkey,
-		sshuser:  sshuser,
-		snapshot: strconv.FormatInt(time.Now().Unix(), 10),
-		closed:   make(chan bool),
+		cfg:     pool.cfg,
+		debug:   pool.env.Debug,
+		baseVMX: pool.cfg.BaseVMX,
+		vmx:     vmx,
+		sshkey:  sshkey,
+		sshuser: sshuser,
+		closed:  make(chan bool),
 	}
 	if err := inst.clone(); err != nil {
 		return nil, err
@@ -100,16 +100,9 @@ func (pool *Pool) Create(workdir string, index int) (vmimpl.Instance, error) {
 
 func (inst *instance) clone() error {
 	if inst.debug {
-		log.Logf(0, "snapshotting %v (%v)", inst.baseVMX, inst.snapshot)
-	}
-	if _, err := osutil.RunCmd(2*time.Minute, "", "vmrun", "snapshot", inst.baseVMX, inst.snapshot); err != nil {
-		return err
-	}
-	if inst.debug {
 		log.Logf(0, "cloning %v to %v", inst.baseVMX, inst.vmx)
 	}
-	if _, err := osutil.RunCmd(2*time.Minute, "", "vmrun", "clone", inst.baseVMX, inst.vmx, "linked",
-		"-snapshot="+inst.snapshot); err != nil {
+	if _, err := osutil.RunCmd(2*time.Minute, "", "vmrun", "clone", inst.baseVMX, inst.vmx, "full"); err != nil {
 		return err
 	}
 	return nil
@@ -151,15 +144,11 @@ func (inst *instance) Close() {
 	if inst.debug {
 		log.Logf(0, "stopping %v", inst.vmx)
 	}
-	osutil.RunCmd(2*time.Minute, "", "vmrun", "stop", inst.vmx)
+	osutil.RunCmd(2*time.Minute, "", "vmrun", "stop", inst.vmx, "hard")
 	if inst.debug {
 		log.Logf(0, "deleting %v", inst.vmx)
 	}
 	osutil.RunCmd(2*time.Minute, "", "vmrun", "deleteVM", inst.vmx)
-	if inst.debug {
-		log.Logf(0, "deleting snapshot %v", inst.snapshot)
-	}
-	osutil.RunCmd(2*time.Minute, "", "vmrun", "deleteSnapshot", inst.baseVMX, inst.snapshot)
 	close(inst.closed)
 }
 
@@ -183,8 +172,9 @@ func (inst *instance) Copy(hostSrc string) (string, error) {
 
 func (inst *instance) Run(timeout time.Duration, stop <-chan bool, command string) (
 	<-chan []byte, <-chan error, error) {
-	args := append(vmimpl.SSHArgs(inst.debug, inst.sshkey, 22), inst.sshuser+"@"+inst.ipAddr)
-	dmesg, err := vmimpl.OpenRemoteConsole("ssh", args...)
+	vmxDir := filepath.Dir(inst.vmx)
+	serial := filepath.Join(vmxDir, "serial")
+	dmesg, err := net.Dial("unix", serial)
 	if err != nil {
 		return nil, nil, err
 	}
@@ -195,7 +185,7 @@ func (inst *instance) Run(timeout time.Duration, stop <-chan bool, command strin
 		return nil, nil, err
 	}
 
-	args = vmimpl.SSHArgs(inst.debug, inst.sshkey, 22)
+	args := vmimpl.SSHArgs(inst.debug, inst.sshkey, 22)
 	// Forward target port as part of the ssh connection (reverse proxy)
 	if inst.forwardPort != 0 {
 		proxy := fmt.Sprintf("%v:127.0.0.1:%v", inst.forwardPort, inst.forwardPort)