[PATCH] kvm tools: Add 'kvm pause' command

[PATCH] kvm tools: Add 'kvm pause' command

[Sasha Levin]

This patch adds a 'kvm debug' command that's currently an alias for

  kill -USR2 `pidof kvm`

Which pauses a guest (freezes all VCPU threads).

Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
---
 tools/kvm/Makefile                |    1 +
 tools/kvm/include/kvm/kvm-pause.h |    6 ++++++
 tools/kvm/kvm-cmd.c               |    2 ++
 tools/kvm/kvm-pause.c             |   13 +++++++++++++
 4 files changed, 22 insertions(+), 0 deletions(-)
 create mode 100644 tools/kvm/include/kvm/kvm-pause.h
 create mode 100644 tools/kvm/kvm-pause.c

diff --git a/tools/kvm/Makefile b/tools/kvm/Makefile
index a05a6b1..ed82cdf 100644
--- a/tools/kvm/Makefile
+++ b/tools/kvm/Makefile
@@ -42,6 +42,7 @@ OBJS	+= irq.o
 OBJS	+= kvm-cmd.o
 OBJS	+= kvm-debug.o
 OBJS	+= kvm-help.o
+OBJS    += kvm-pause.o
 OBJS	+= kvm-run.o
 OBJS	+= mptable.o
 OBJS	+= rbtree.o
diff --git a/tools/kvm/include/kvm/kvm-pause.h b/tools/kvm/include/kvm/kvm-pause.h
new file mode 100644
index 0000000..0f8e96b
--- /dev/null
+++ b/tools/kvm/include/kvm/kvm-pause.h
@@ -0,0 +1,6 @@
+#ifndef KVM__PAUSE_H
+#define KVM__PAUSE_H
+
+int kvm_cmd_pause(int argc, const char **argv, const char *prefix);
+
+#endif
diff --git a/tools/kvm/kvm-cmd.c b/tools/kvm/kvm-cmd.c
index 2ea51a5..ffbc4ff 100644
--- a/tools/kvm/kvm-cmd.c
+++ b/tools/kvm/kvm-cmd.c
@@ -6,11 +6,13 @@
 
 /* user defined header files */
 #include "kvm/kvm-debug.h"
+#include "kvm/kvm-pause.h"
 #include "kvm/kvm-help.h"
 #include "kvm/kvm-cmd.h"
 #include "kvm/kvm-run.h"
 
 struct cmd_struct kvm_commands[] = {
+	{ "pause", kvm_cmd_pause, NULL,         0 },
 	{ "debug", kvm_cmd_debug, NULL,         0 },
 	{ "help",  kvm_cmd_help,  NULL,         0 },
 	{ "run",   kvm_cmd_run,   kvm_run_help, 0 },
diff --git a/tools/kvm/kvm-pause.c b/tools/kvm/kvm-pause.c
new file mode 100644
index 0000000..fdf8714
--- /dev/null
+++ b/tools/kvm/kvm-pause.c
@@ -0,0 +1,13 @@
+#include <stdio.h>
+#include <string.h>
+#include <signal.h>
+
+#include <kvm/util.h>
+#include <kvm/kvm-cmd.h>
+#include <kvm/kvm-pause.h>
+
+int kvm_cmd_pause(int argc, const char **argv, const char *prefix)
+{
+	signal(SIGUSR2, SIG_IGN);
+	return system("kill -USR2 $(pidof kvm)");
+}
-- 
1.7.5.3

Re: [PATCH] kvm tools: Add 'kvm pause' command

[Prasad Joshi]

On Thu, Jun 2, 2011 at 9:22 PM, Sasha Levin <levinsasha928@gmail.com> wrote:
> This patch adds a 'kvm debug' command that's currently an alias for
>
>  kill -USR2 `pidof kvm`
>
> Which pauses a guest (freezes all VCPU threads).
>
> Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
> ---
>  tools/kvm/Makefile                |    1 +
>  tools/kvm/include/kvm/kvm-pause.h |    6 ++++++
>  tools/kvm/kvm-cmd.c               |    2 ++
>  tools/kvm/kvm-pause.c             |   13 +++++++++++++
>  4 files changed, 22 insertions(+), 0 deletions(-)
>  create mode 100644 tools/kvm/include/kvm/kvm-pause.h
>  create mode 100644 tools/kvm/kvm-pause.c
>
> diff --git a/tools/kvm/Makefile b/tools/kvm/Makefile
> index a05a6b1..ed82cdf 100644
> --- a/tools/kvm/Makefile
> +++ b/tools/kvm/Makefile
> @@ -42,6 +42,7 @@ OBJS  += irq.o
>  OBJS   += kvm-cmd.o
>  OBJS   += kvm-debug.o
>  OBJS   += kvm-help.o
> +OBJS    += kvm-pause.o
>  OBJS   += kvm-run.o
>  OBJS   += mptable.o
>  OBJS   += rbtree.o
> diff --git a/tools/kvm/include/kvm/kvm-pause.h b/tools/kvm/include/kvm/kvm-pause.h
> new file mode 100644
> index 0000000..0f8e96b
> --- /dev/null
> +++ b/tools/kvm/include/kvm/kvm-pause.h
> @@ -0,0 +1,6 @@
> +#ifndef KVM__PAUSE_H
> +#define KVM__PAUSE_H
> +
> +int kvm_cmd_pause(int argc, const char **argv, const char *prefix);
> +
> +#endif
> diff --git a/tools/kvm/kvm-cmd.c b/tools/kvm/kvm-cmd.c
> index 2ea51a5..ffbc4ff 100644
> --- a/tools/kvm/kvm-cmd.c
> +++ b/tools/kvm/kvm-cmd.c
> @@ -6,11 +6,13 @@
>
>  /* user defined header files */
>  #include "kvm/kvm-debug.h"
> +#include "kvm/kvm-pause.h"
>  #include "kvm/kvm-help.h"
>  #include "kvm/kvm-cmd.h"
>  #include "kvm/kvm-run.h"
>
>  struct cmd_struct kvm_commands[] = {
> +       { "pause", kvm_cmd_pause, NULL,         0 },

We automatically generate <include/common-cmds.h> header file that
lists the command options with kvm. Should we ensure 'pause' is added
to the file? I think then './kvm help' will display 'pause' as one of
the possible command.

I think we should ensure 'pause' is added to the file during compilation.

>        { "debug", kvm_cmd_debug, NULL,         0 },
>        { "help",  kvm_cmd_help,  NULL,         0 },
>        { "run",   kvm_cmd_run,   kvm_run_help, 0 },
> diff --git a/tools/kvm/kvm-pause.c b/tools/kvm/kvm-pause.c
> new file mode 100644
> index 0000000..fdf8714
> --- /dev/null
> +++ b/tools/kvm/kvm-pause.c
> @@ -0,0 +1,13 @@
> +#include <stdio.h>
> +#include <string.h>
> +#include <signal.h>
> +
> +#include <kvm/util.h>
> +#include <kvm/kvm-cmd.h>
> +#include <kvm/kvm-pause.h>
> +
> +int kvm_cmd_pause(int argc, const char **argv, const char *prefix)
> +{
> +       signal(SIGUSR2, SIG_IGN);
> +       return system("kill -USR2 $(pidof kvm)");
> +}
> --
> 1.7.5.3
>
>

Re: [PATCH] kvm tools: Add 'kvm pause' command

[Pekka Enberg]

On Thu, Jun 2, 2011 at 11:22 PM, Sasha Levin <levinsasha928@gmail.com> wrote:
> This patch adds a 'kvm debug' command that's currently an alias for
>
>  kill -USR2 `pidof kvm`
>
> Which pauses a guest (freezes all VCPU threads).
>
> Signed-off-by: Sasha Levin <levinsasha928@gmail.com>

What is this useful for? Debugging? Don't we need a command to
unfreeze the guest as well?

Re: [PATCH] kvm tools: Add 'kvm pause' command

[Sasha Levin]

On Fri, 2011-06-03 at 09:29 +0300, Pekka Enberg wrote:
> On Thu, Jun 2, 2011 at 11:22 PM, Sasha Levin <levinsasha928@gmail.com> wrote:
> > This patch adds a 'kvm debug' command that's currently an alias for
> >
> >  kill -USR2 `pidof kvm`
> >
> > Which pauses a guest (freezes all VCPU threads).
> >
> > Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
> 
> What is this useful for? Debugging? Don't we need a command to
> unfreeze the guest as well?

It unfreezes the guest if it's paused. I should have mentioned that in
the commit message.

-- 

Sasha.

Re: [PATCH] kvm tools: Add 'kvm pause' command

[Ingo Molnar]

* Prasad Joshi <prasadjoshi124@gmail.com> wrote:

> >  struct cmd_struct kvm_commands[] = {
> > +       { "pause", kvm_cmd_pause, NULL,         0 },
> 
> We automatically generate <include/common-cmds.h> header file that 
> lists the command options with kvm. Should we ensure 'pause' is 
> added to the file? I think then './kvm help' will display 'pause' 
> as one of the possible command.

That is done by adding the new command to command-list.txt - then the 
Makefile will generate everything correctly.

Thanks,

	Ingo