[Intel-gfx] [PATCH i-g-t 2/4 v6] lib/igt_gvt: Make use of libkmod helpers and fix reading gvt parameter.

[Chris Wilson]

On Thu, Nov 24, 2016 at 02:04:38PM +0200, Marius Vlad wrote:
> On Wed, Nov 23, 2016 at 01:31:21PM +0000, Chris Wilson wrote:
> > On Wed, Nov 23, 2016 at 02:35:10PM +0200, Marius Vlad wrote:
> > > v2:
> > > - use igt_sysfs_get_boolean() to get gvt status (Chris Wilson)
> > > - do not hard-fail when i915 module could not be loaded/unloaded (Chris
> > > Wilson)
> > > 
> > > Signed-off-by: Marius Vlad <marius.c.vlad at intel.com>
> > > ---
> > >  lib/igt_gvt.c     | 37 ++++++++++++++++++-------------------
> > >  tests/gvt_basic.c |  2 +-
> > >  2 files changed, 19 insertions(+), 20 deletions(-)
> > > 
> > > diff --git a/lib/igt_gvt.c b/lib/igt_gvt.c
> > > index 8bbf9bd..4ab7433 100644
> > > --- a/lib/igt_gvt.c
> > > +++ b/lib/igt_gvt.c
> > > @@ -24,35 +24,30 @@
> > >  #include "igt.h"
> > >  #include "igt_gvt.h"
> > >  #include "igt_sysfs.h"
> > > +#include "igt_kmod.h"
> > >  
> > > +#include <signal.h>
> > >  #include <dirent.h>
> > >  #include <unistd.h>
> > >  #include <fcntl.h>
> > >  
> > >  static bool is_gvt_enabled(void)
> > >  {
> > > -	FILE *file;
> > > -	int value;
> > >  	bool enabled = false;
> > > +	int dir, fd;
> > >  
> > > -	file = fopen("/sys/module/i915/parameters/enable_gvt", "r");
> > > -	if (!file)
> > > +	fd = __drm_open_driver(DRIVER_INTEL);
> > > +	dir = igt_sysfs_open_parameters(fd);
> > > +	if (dir < 0)
> > >  		return false;
> > >  
> > > -	if (fscanf(file, "%d", &value) == 1)
> > > -		enabled = value;
> > > -	fclose(file);
> > > +	enabled = igt_sysfs_get_boolean(dir, "enable_gvt");
> > >  
> > > -	errno = 0;
> > > -	return enabled;
> > > -}
> > > +	close(dir);
> > > +	close(fd);
> > >  
> > > -static void unload_i915(void)
> > > -{
> > > -	kick_fbcon(false);
> > > -	/* pkill alsact */
> > > +	return enabled;
> > >  
> > > -	igt_ignore_warn(system("/sbin/modprobe -s -r i915"));
> > >  }
> > >  
> > >  bool igt_gvt_load_module(void)
> > > @@ -60,8 +55,11 @@ bool igt_gvt_load_module(void)
> > >  	if (is_gvt_enabled())
> > >  		return true;
> > >  
> > > -	unload_i915();
> > > -	igt_ignore_warn(system("/sbin/modprobe -s i915 enable_gvt=1"));
> > > +	if (igt_i915_driver_unload())
> > > +		return false;
> > > +
> > > +	if (igt_i915_driver_load("enable_gvt=1"))
> > > +		return false;
> > >  
> > >  	return is_gvt_enabled();
> > >  }
> > > @@ -71,8 +69,9 @@ void igt_gvt_unload_module(void)
> > >  	if (!is_gvt_enabled())
> > >  		return;
> > >  
> > > -	unload_i915();
> > > -	igt_ignore_warn(system("/sbin/modprobe -s i915 enable_gvt=0"));
> > > +	igt_i915_driver_unload();
> > > +
> > > +	igt_i915_driver_load(NULL);
> > >  
> > >  	igt_assert(!is_gvt_enabled());
> > >  }
> > > diff --git a/tests/gvt_basic.c b/tests/gvt_basic.c
> > > index 48b853a..4e909a5 100644
> > > --- a/tests/gvt_basic.c
> > > +++ b/tests/gvt_basic.c
> > > @@ -32,7 +32,7 @@ igt_main
> > >  
> > >  	igt_fixture {
> > >  		igt_require(igt_gvt_load_module());
> > > -		fd = drm_open_driver(DRIVER_INTEL);
> > > +		fd = __drm_open_driver(DRIVER_INTEL);
> > 
> > I couldn't work out why this needed to switch to the non-checking, bare
> > call to open_driver().
> 
> The last fixture unloads (actually reloads with enable_gvt=0) the driver
> and will fail to do so due the stray fd in drm_open_driver():
> 
> 	at_exit_drm_fd = __drm_open_driver(chipset);
> 
> which is closed atexit by the quiescent_gpu_at_exit().
> 
> Maybe I should document this in lib/igt_kmod that __drm_open_driver() is
> required when reloading/unloading the driver.

Hmm, indeed. Better perhaps might be

fd = igt_open_module(DRIVER_INTEL, "module options") ?

Time will tell.

> There's also igt_set_module_param() which should allow setting
> parameters dynamically without the need of reloading but I don't know if
> there's support for that.

Not all (most in fact do not) support runtime changes. And the ones that
we do change, taint the kernel. Sigh.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre