Re: [libvirt] PATCH: recent qemu-kvm requires -enable-kvm flag to activate VT optimization

[Steve Yarmie <steve.yarmie@xxxxxxxxx>]

Thanks for pointing that out. I made the changes you suggested.
An updated patch is attached.

btw - I'm using qemu-kvm-0.11.0, but this patch would be relevant when running
any version of qemu/qemu-kvm that was released after the upstream merge of the
kvm userspace..

-Steve


Daniel P. Berrange wrote:

On Mon, Nov 16, 2009 at 02:15:28AM -0800, Steve Yarmie wrote

 
+    /* Should explicitly enable KVM if
+     * 1. Guest domain is 'qemu'

Surely 'kvm' here
    

+     * 2. The qemu binary has the -enable-kvm flag
+     * NOTE: user must be responsible to load the kvm modules
+     */
+    if ((qemuCmdFlags & QEMUD_CMD_FLAG_ENABLE_KVM) &&
+        def->virtType == VIR_DOMAIN_VIRT_QEMU)
    

Again, this should be VIR_DOMAIN_VIRT_KVM here - 'qemu' is intended
to be pure emulation only


Regards,
Daniel
  

diff -upr libvirt/src/qemu/qemu_conf.c libvirt-enableKVM/src/qemu/qemu_conf.c
--- libvirt/src/qemu/qemu_conf.c	2009-11-17 05:37:23.973599362 -0800
+++ libvirt-enableKVM/src/qemu/qemu_conf.c	2009-11-17 05:41:40.755832169 -0800
@@ -878,6 +878,8 @@ static unsigned int qemudComputeCmdFlags
         flags |= QEMUD_CMD_FLAG_KQEMU;
     if (strstr(help, "-no-kvm"))
         flags |= QEMUD_CMD_FLAG_KVM;
+    if (strstr(help, "-enable-kvm"))
+        flags |= QEMUD_CMD_FLAG_ENABLE_KVM;
     if (strstr(help, "-no-reboot"))
         flags |= QEMUD_CMD_FLAG_NO_REBOOT;
     if (strstr(help, "-name"))
@@ -1595,6 +1597,7 @@ int qemudBuildCommandLine(virConnectPtr 
     struct utsname ut;
     int disableKQEMU = 0;
     int disableKVM = 0;
+    int enableKVM = 0;
     int qargc = 0, qarga = 0;
     const char **qargv = NULL;
     int qenvc = 0, qenva = 0;
@@ -1653,6 +1656,15 @@ int qemudBuildCommandLine(virConnectPtr 
         def->virtType == VIR_DOMAIN_VIRT_QEMU)
         disableKVM = 1;
 
+    /* Should explicitly enable KVM if
+     * 1. Guest domain is 'kvm'
+     * 2. The qemu binary has the -enable-kvm flag
+     * NOTE: user must be responsible for loading the kvm modules
+     */
+    if ((qemuCmdFlags & QEMUD_CMD_FLAG_ENABLE_KVM) &&
+        def->virtType == VIR_DOMAIN_VIRT_KVM)
+        enableKVM = 1;
+
     /*
      * Need to force a 32-bit guest CPU type if
      *
@@ -1780,6 +1792,8 @@ int qemudBuildCommandLine(virConnectPtr 
         ADD_ARG_LIT("-no-kqemu");
     if (disableKVM)
         ADD_ARG_LIT("-no-kvm");
+    if (enableKVM)
+        ADD_ARG_LIT("-enable-kvm");
     ADD_ARG_LIT("-m");
     ADD_ARG_LIT(memory);
     if (def->hugepage_backed) {
diff -upr libvirt/src/qemu/qemu_conf.h libvirt-enableKVM/src/qemu/qemu_conf.h
--- libvirt/src/qemu/qemu_conf.h	2009-11-17 05:37:23.973599362 -0800
+++ libvirt-enableKVM/src/qemu/qemu_conf.h	2009-11-17 05:41:40.755832169 -0800
@@ -73,6 +73,7 @@ enum qemud_cmd_flags {
     QEMUD_CMD_FLAG_XEN_DOMID     = (1 << 20), /* -xen-domid (new style xen integration) */
     QEMUD_CMD_FLAG_MIGRATE_QEMU_UNIX = (1 << 21), /* Does qemu support unix domain sockets for migration? */
     QEMUD_CMD_FLAG_CHARDEV       = (1 << 22), /* Is the new -chardev arg available */
+    QEMUD_CMD_FLAG_ENABLE_KVM    = (1 << 23), /* Is the -enable-kvm flag available to "enable KVM full virtualization support" */
 };
 
 /* Main driver state */

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