[v3,2/2] drm/i915/gvt: export migration_version to mdev sysfs for Intel vGPU

This feature implements the migration_version attribute for Intel's vGPU
mdev devices.

migration_version attribute is rw.
It's used to check migration compatibility for two mdev devices of the
same mdev type.
migration_version string is defined by vendor driver and opaque to
userspace.

For Intel vGPU of gen8 and gen9, the format of migration_version string
is:
  <vendor id>-<device id>-<vgpu type>-<software version>.

For future platforms, the format of migration_version string is to be
expanded to include more meta data to identify Intel vGPUs for live
migration compatibility check

For old platforms, and for GVT not supporting vGPU live migration
feature, -ENODEV is returned on read(2)/write(2) of migration_version
attribute.
For vGPUs running old GVT who do not expose migration_version
attribute, live migration is regarded as not supported for those vGPUs.

Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Erik Skultety <eskultet@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Cornelia Huck <cohuck@redhat.com>
Cc: "Tian, Kevin" <kevin.tian@intel.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: "Wang, Zhi A" <zhi.a.wang@intel.com>
c: Neo Jia <cjia@nvidia.com>
Cc: Kirti Wankhede <kwankhede@nvidia.com>

Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>

---
v3:
1. renamed version to migration_version
(Christophe de Dinechin, Cornelia Huck, Alex Williamson)
2. instead of generating migration version strings each time, storing
them in vgpu types generated during initialization.
(Zhenyu Wang, Cornelia Huck)
3. replaced multiple snprintf to one big snprintf in
intel_gvt_get_vfio_migration_version()
(Dr. David Alan Gilbert)
4. printed detailed error log
(Alex Williamson, Erik Skultety, Cornelia Huck, Dr. David Alan Gilbert)
5. incorporated <software version> into migration_version string
(Alex Williamson)
6. do not use ifndef macro to switch off migration_version attribute
(Zhenyu Wang)

v2:
1. removed 32 common part of version string
(Alex Williamson)
2. do not register version attribute for GVT not supporting live
migration.(Cornelia Huck)
3. for platforms out of gen8, gen9, return -EINVAL --> -ENODEV for
incompatible. (Cornelia Huck)
---
 drivers/gpu/drm/i915/gvt/Makefile            |   2 +-
 drivers/gpu/drm/i915/gvt/gvt.c               |  39 +++++
 drivers/gpu/drm/i915/gvt/gvt.h               |   5 +
 drivers/gpu/drm/i915/gvt/migration_version.c | 167 +++++++++++++++++++
 drivers/gpu/drm/i915/gvt/vgpu.c              |  13 +-
 5 files changed, 223 insertions(+), 3 deletions(-)
 create mode 100644 drivers/gpu/drm/i915/gvt/migration_version.c

On Sun, 26 May 2019 23:44:37 -0400
Yan Zhao <yan.y.zhao@intel.com> wrote:

> This feature implements the migration_version attribute for Intel's vGPU
> mdev devices.
> 
> migration_version attribute is rw.
> It's used to check migration compatibility for two mdev devices of the
> same mdev type.
> migration_version string is defined by vendor driver and opaque to
> userspace.
> 
> For Intel vGPU of gen8 and gen9, the format of migration_version string
> is:
>   <vendor id>-<device id>-<vgpu type>-<software version>.
> 
> For future platforms, the format of migration_version string is to be
> expanded to include more meta data to identify Intel vGPUs for live
> migration compatibility check
> 
> For old platforms, and for GVT not supporting vGPU live migration
> feature, -ENODEV is returned on read(2)/write(2) of migration_version
> attribute.
> For vGPUs running old GVT who do not expose migration_version
> attribute, live migration is regarded as not supported for those vGPUs.
> 
> Cc: Alex Williamson <alex.williamson@redhat.com>
> Cc: Erik Skultety <eskultet@redhat.com>
> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> Cc: Cornelia Huck <cohuck@redhat.com>
> Cc: "Tian, Kevin" <kevin.tian@intel.com>
> Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
> Cc: "Wang, Zhi A" <zhi.a.wang@intel.com>
> c: Neo Jia <cjia@nvidia.com>
> Cc: Kirti Wankhede <kwankhede@nvidia.com>
> 
> Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
> 
> ---
> v3:
> 1. renamed version to migration_version
> (Christophe de Dinechin, Cornelia Huck, Alex Williamson)
> 2. instead of generating migration version strings each time, storing
> them in vgpu types generated during initialization.
> (Zhenyu Wang, Cornelia Huck)
> 3. replaced multiple snprintf to one big snprintf in
> intel_gvt_get_vfio_migration_version()
> (Dr. David Alan Gilbert)
> 4. printed detailed error log
> (Alex Williamson, Erik Skultety, Cornelia Huck, Dr. David Alan Gilbert)
> 5. incorporated <software version> into migration_version string
> (Alex Williamson)
> 6. do not use ifndef macro to switch off migration_version attribute
> (Zhenyu Wang)
> 
> v2:
> 1. removed 32 common part of version string
> (Alex Williamson)
> 2. do not register version attribute for GVT not supporting live
> migration.(Cornelia Huck)
> 3. for platforms out of gen8, gen9, return -EINVAL --> -ENODEV for
> incompatible. (Cornelia Huck)
> ---
>  drivers/gpu/drm/i915/gvt/Makefile            |   2 +-
>  drivers/gpu/drm/i915/gvt/gvt.c               |  39 +++++
>  drivers/gpu/drm/i915/gvt/gvt.h               |   5 +
>  drivers/gpu/drm/i915/gvt/migration_version.c | 167 +++++++++++++++++++
>  drivers/gpu/drm/i915/gvt/vgpu.c              |  13 +-
>  5 files changed, 223 insertions(+), 3 deletions(-)
>  create mode 100644 drivers/gpu/drm/i915/gvt/migration_version.c
> 

(...)

> diff --git a/drivers/gpu/drm/i915/gvt/gvt.c b/drivers/gpu/drm/i915/gvt/gvt.c
> index 43f4242062dd..be2980e8ac75 100644
> --- a/drivers/gpu/drm/i915/gvt/gvt.c
> +++ b/drivers/gpu/drm/i915/gvt/gvt.c
> @@ -105,14 +105,53 @@ static ssize_t description_show(struct kobject *kobj, struct device *dev,
>  		       type->weight);
>  }
>  
> +static ssize_t migration_version_show(struct kobject *kobj, struct device *dev,
> +		char *buf)

Indentation looks a bit odd? (Also below.)

> +{
> +	struct intel_vgpu_type *type;
> +	void *gvt = kdev_to_i915(dev)->gvt;
> +
> +	type = intel_gvt_find_vgpu_type(gvt, kobject_name(kobj));
> +	if (!type || !type->migration_version) {
> +		gvt_err("Does not support migraion on type %s. Please search previous detailed log\n",

s/migraion/migration/ (also below)

Or reword to "Migration not supported on type %s."?

> +				kobject_name(kobj));
> +		return -ENODEV;
> +	}
> +
> +	return snprintf(buf, strlen(type->migration_version) + 2,
> +			"%s\n", type->migration_version);
> +}
> +
> +static ssize_t migration_version_store(struct kobject *kobj, struct device *dev,
> +		const char *buf, size_t count)
> +{
> +	int ret = 0;
> +	struct intel_vgpu_type *type;
> +	void *gvt = kdev_to_i915(dev)->gvt;
> +
> +	type = intel_gvt_find_vgpu_type(gvt, kobject_name(kobj));
> +	if (!type || !type->migration_version) {
> +		gvt_err("Does not support migraion on type %s. Please search previous detailed log\n",
> +				kobject_name(kobj));
> +		return -ENODEV;
> +	}
> +
> +	ret = intel_gvt_check_vfio_migration_version(gvt,
> +			type->migration_version, buf);
> +
> +	return (ret < 0 ? ret : count);
> +}
> +
>  static MDEV_TYPE_ATTR_RO(available_instances);
>  static MDEV_TYPE_ATTR_RO(device_api);
>  static MDEV_TYPE_ATTR_RO(description);
> +static MDEV_TYPE_ATTR_RW(migration_version);
>  
>  static struct attribute *gvt_type_attrs[] = {
>  	&mdev_type_attr_available_instances.attr,
>  	&mdev_type_attr_device_api.attr,
>  	&mdev_type_attr_description.attr,
> +	&mdev_type_attr_migration_version.attr,
>  	NULL,
>  };

(...)

> +char *
> +intel_gvt_get_vfio_migration_version(struct intel_gvt *gvt,
> +		const char *vgpu_type)
> +{
> +	int cnt = 0;
> +	struct drm_i915_private *dev_priv = gvt->dev_priv;
> +	char *version = NULL;
> +
> +	/* currently only gen8 & gen9 are supported */
> +	if (!IS_GEN(dev_priv, 8) && !IS_GEN(dev_priv, 9)) {
> +		gvt_err("Local hardware does not support migration on %d\n",
> +				INTEL_INFO(dev_priv)->gen);
> +		return NULL;
> +	}
> +
> +	if (GVT_VFIO_MIGRATION_SOFTWARE_VERSION == INV_SOFTWARE_VERSION) {
> +		gvt_err("Local GVT does not support migration\n");
> +		return NULL;
> +	}
> +
> +	version = kzalloc(MIGRATION_VERSION_TOTAL_LEN, GFP_KERNEL);
> +
> +	if (unlikely(!version)) {
> +		gvt_err("memory allocation failed when get local migraiton version\n");

s/migraiton/migration/

Or "cannot allocate memory for local migration version"?

> +		return NULL;
> +	}
> +
> +	/* vendor id + device id + vgpu type + software version */
> +	cnt = snprintf(version, MIGRATION_VERSION_TOTAL_LEN, PRINTF_FORMAT,
> +			PCI_VENDOR_ID_INTEL,
> +			INTEL_DEVID(dev_priv),
> +			vgpu_type,
> +			GVT_VFIO_MIGRATION_SOFTWARE_VERSION);
> +
> +	if (cnt)
> +		return version;
> +
> +	gvt_err("string generation failed when get local migration version\n");
> +	return NULL;
> +}

(...)

Only some nitpicks from me, but I'm not really familiar with this
driver. Overall, this looks sane to me, so have an

Acked-by: Cornelia Huck <cohuck@redhat.com>

On Tue, May 28, 2019 at 05:01:35PM +0800, Cornelia Huck wrote:
> On Sun, 26 May 2019 23:44:37 -0400
> Yan Zhao <yan.y.zhao@intel.com> wrote:
> 
> > This feature implements the migration_version attribute for Intel's vGPU
> > mdev devices.
> > 
> > migration_version attribute is rw.
> > It's used to check migration compatibility for two mdev devices of the
> > same mdev type.
> > migration_version string is defined by vendor driver and opaque to
> > userspace.
> > 
> > For Intel vGPU of gen8 and gen9, the format of migration_version string
> > is:
> >   <vendor id>-<device id>-<vgpu type>-<software version>.
> > 
> > For future platforms, the format of migration_version string is to be
> > expanded to include more meta data to identify Intel vGPUs for live
> > migration compatibility check
> > 
> > For old platforms, and for GVT not supporting vGPU live migration
> > feature, -ENODEV is returned on read(2)/write(2) of migration_version
> > attribute.
> > For vGPUs running old GVT who do not expose migration_version
> > attribute, live migration is regarded as not supported for those vGPUs.
> > 
> > Cc: Alex Williamson <alex.williamson@redhat.com>
> > Cc: Erik Skultety <eskultet@redhat.com>
> > Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> > Cc: Cornelia Huck <cohuck@redhat.com>
> > Cc: "Tian, Kevin" <kevin.tian@intel.com>
> > Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
> > Cc: "Wang, Zhi A" <zhi.a.wang@intel.com>
> > c: Neo Jia <cjia@nvidia.com>
> > Cc: Kirti Wankhede <kwankhede@nvidia.com>
> > 
> > Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
> > 
> > ---
> > v3:
> > 1. renamed version to migration_version
> > (Christophe de Dinechin, Cornelia Huck, Alex Williamson)
> > 2. instead of generating migration version strings each time, storing
> > them in vgpu types generated during initialization.
> > (Zhenyu Wang, Cornelia Huck)
> > 3. replaced multiple snprintf to one big snprintf in
> > intel_gvt_get_vfio_migration_version()
> > (Dr. David Alan Gilbert)
> > 4. printed detailed error log
> > (Alex Williamson, Erik Skultety, Cornelia Huck, Dr. David Alan Gilbert)
> > 5. incorporated <software version> into migration_version string
> > (Alex Williamson)
> > 6. do not use ifndef macro to switch off migration_version attribute
> > (Zhenyu Wang)
> > 
> > v2:
> > 1. removed 32 common part of version string
> > (Alex Williamson)
> > 2. do not register version attribute for GVT not supporting live
> > migration.(Cornelia Huck)
> > 3. for platforms out of gen8, gen9, return -EINVAL --> -ENODEV for
> > incompatible. (Cornelia Huck)
> > ---
> >  drivers/gpu/drm/i915/gvt/Makefile            |   2 +-
> >  drivers/gpu/drm/i915/gvt/gvt.c               |  39 +++++
> >  drivers/gpu/drm/i915/gvt/gvt.h               |   5 +
> >  drivers/gpu/drm/i915/gvt/migration_version.c | 167 +++++++++++++++++++
> >  drivers/gpu/drm/i915/gvt/vgpu.c              |  13 +-
> >  5 files changed, 223 insertions(+), 3 deletions(-)
> >  create mode 100644 drivers/gpu/drm/i915/gvt/migration_version.c
> > 
> 
> (...)
> 
> > diff --git a/drivers/gpu/drm/i915/gvt/gvt.c b/drivers/gpu/drm/i915/gvt/gvt.c
> > index 43f4242062dd..be2980e8ac75 100644
> > --- a/drivers/gpu/drm/i915/gvt/gvt.c
> > +++ b/drivers/gpu/drm/i915/gvt/gvt.c
> > @@ -105,14 +105,53 @@ static ssize_t description_show(struct kobject *kobj, struct device *dev,
> >  		       type->weight);
> >  }
> >  
> > +static ssize_t migration_version_show(struct kobject *kobj, struct device *dev,
> > +		char *buf)
> 
> Indentation looks a bit odd? (Also below.)
>
yes. Let me correct it in next revision.

> > +{
> > +	struct intel_vgpu_type *type;
> > +	void *gvt = kdev_to_i915(dev)->gvt;
> > +
> > +	type = intel_gvt_find_vgpu_type(gvt, kobject_name(kobj));
> > +	if (!type || !type->migration_version) {
> > +		gvt_err("Does not support migraion on type %s. Please search previous detailed log\n",
> 
> s/migraion/migration/ (also below)
>
Sorry for typos again. I'll be more careful next time. thank you:)

> Or reword to "Migration not supported on type %s."?
>
Yes, better :)

> > +				kobject_name(kobj));
> > +		return -ENODEV;
> > +	}
> > +
> > +	return snprintf(buf, strlen(type->migration_version) + 2,
> > +			"%s\n", type->migration_version);
> > +}
> > +
> > +static ssize_t migration_version_store(struct kobject *kobj, struct device *dev,
> > +		const char *buf, size_t count)
> > +{
> > +	int ret = 0;
> > +	struct intel_vgpu_type *type;
> > +	void *gvt = kdev_to_i915(dev)->gvt;
> > +
> > +	type = intel_gvt_find_vgpu_type(gvt, kobject_name(kobj));
> > +	if (!type || !type->migration_version) {
> > +		gvt_err("Does not support migraion on type %s. Please search previous detailed log\n",
> > +				kobject_name(kobj));
> > +		return -ENODEV;
> > +	}
> > +
> > +	ret = intel_gvt_check_vfio_migration_version(gvt,
> > +			type->migration_version, buf);
> > +
> > +	return (ret < 0 ? ret : count);
> > +}
> > +
> >  static MDEV_TYPE_ATTR_RO(available_instances);
> >  static MDEV_TYPE_ATTR_RO(device_api);
> >  static MDEV_TYPE_ATTR_RO(description);
> > +static MDEV_TYPE_ATTR_RW(migration_version);
> >  
> >  static struct attribute *gvt_type_attrs[] = {
> >  	&mdev_type_attr_available_instances.attr,
> >  	&mdev_type_attr_device_api.attr,
> >  	&mdev_type_attr_description.attr,
> > +	&mdev_type_attr_migration_version.attr,
> >  	NULL,
> >  };
> 
> (...)
> 
> > +char *
> > +intel_gvt_get_vfio_migration_version(struct intel_gvt *gvt,
> > +		const char *vgpu_type)
> > +{
> > +	int cnt = 0;
> > +	struct drm_i915_private *dev_priv = gvt->dev_priv;
> > +	char *version = NULL;
> > +
> > +	/* currently only gen8 & gen9 are supported */
> > +	if (!IS_GEN(dev_priv, 8) && !IS_GEN(dev_priv, 9)) {
> > +		gvt_err("Local hardware does not support migration on %d\n",
> > +				INTEL_INFO(dev_priv)->gen);
> > +		return NULL;
> > +	}
> > +
> > +	if (GVT_VFIO_MIGRATION_SOFTWARE_VERSION == INV_SOFTWARE_VERSION) {
> > +		gvt_err("Local GVT does not support migration\n");
> > +		return NULL;
> > +	}
> > +
> > +	version = kzalloc(MIGRATION_VERSION_TOTAL_LEN, GFP_KERNEL);
> > +
> > +	if (unlikely(!version)) {
> > +		gvt_err("memory allocation failed when get local migraiton version\n");
> 
> s/migraiton/migration/
> 
> Or "cannot allocate memory for local migration version"?
>
Ok.

> > +		return NULL;
> > +	}
> > +
> > +	/* vendor id + device id + vgpu type + software version */
> > +	cnt = snprintf(version, MIGRATION_VERSION_TOTAL_LEN, PRINTF_FORMAT,
> > +			PCI_VENDOR_ID_INTEL,
> > +			INTEL_DEVID(dev_priv),
> > +			vgpu_type,
> > +			GVT_VFIO_MIGRATION_SOFTWARE_VERSION);
> > +
> > +	if (cnt)
> > +		return version;
> > +
> > +	gvt_err("string generation failed when get local migration version\n");
> > +	return NULL;
> > +}
> 
> (...)
> 
> Only some nitpicks from me, but I'm not really familiar with this
> driver. Overall, this looks sane to me, so have an
> 
> Acked-by: Cornelia Huck <cohuck@redhat.com>


Thank you so much Cornelia :)

On 2019.05.26 23:44:37 -0400, Yan Zhao wrote:
> This feature implements the migration_version attribute for Intel's vGPU
> mdev devices.
> 
> migration_version attribute is rw.
> It's used to check migration compatibility for two mdev devices of the
> same mdev type.
> migration_version string is defined by vendor driver and opaque to
> userspace.
> 
> For Intel vGPU of gen8 and gen9, the format of migration_version string
> is:
>   <vendor id>-<device id>-<vgpu type>-<software version>.
> 
> For future platforms, the format of migration_version string is to be
> expanded to include more meta data to identify Intel vGPUs for live
> migration compatibility check
> 
> For old platforms, and for GVT not supporting vGPU live migration
> feature, -ENODEV is returned on read(2)/write(2) of migration_version
> attribute.
> For vGPUs running old GVT who do not expose migration_version
> attribute, live migration is regarded as not supported for those vGPUs.
> 
> Cc: Alex Williamson <alex.williamson@redhat.com>
> Cc: Erik Skultety <eskultet@redhat.com>
> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> Cc: Cornelia Huck <cohuck@redhat.com>
> Cc: "Tian, Kevin" <kevin.tian@intel.com>
> Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
> Cc: "Wang, Zhi A" <zhi.a.wang@intel.com>
> c: Neo Jia <cjia@nvidia.com>
> Cc: Kirti Wankhede <kwankhede@nvidia.com>
> 
> Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
> 
> ---
> v3:
> 1. renamed version to migration_version
> (Christophe de Dinechin, Cornelia Huck, Alex Williamson)
> 2. instead of generating migration version strings each time, storing
> them in vgpu types generated during initialization.
> (Zhenyu Wang, Cornelia Huck)
> 3. replaced multiple snprintf to one big snprintf in
> intel_gvt_get_vfio_migration_version()
> (Dr. David Alan Gilbert)
> 4. printed detailed error log
> (Alex Williamson, Erik Skultety, Cornelia Huck, Dr. David Alan Gilbert)
> 5. incorporated <software version> into migration_version string
> (Alex Williamson)
> 6. do not use ifndef macro to switch off migration_version attribute
> (Zhenyu Wang)
> 
> v2:
> 1. removed 32 common part of version string
> (Alex Williamson)
> 2. do not register version attribute for GVT not supporting live
> migration.(Cornelia Huck)
> 3. for platforms out of gen8, gen9, return -EINVAL --> -ENODEV for
> incompatible. (Cornelia Huck)
> ---
>  drivers/gpu/drm/i915/gvt/Makefile            |   2 +-
>  drivers/gpu/drm/i915/gvt/gvt.c               |  39 +++++
>  drivers/gpu/drm/i915/gvt/gvt.h               |   5 +
>  drivers/gpu/drm/i915/gvt/migration_version.c | 167 +++++++++++++++++++
>  drivers/gpu/drm/i915/gvt/vgpu.c              |  13 +-
>  5 files changed, 223 insertions(+), 3 deletions(-)
>  create mode 100644 drivers/gpu/drm/i915/gvt/migration_version.c
> 
> diff --git a/drivers/gpu/drm/i915/gvt/Makefile b/drivers/gpu/drm/i915/gvt/Makefile
> index 271fb46d4dd0..a9d561c93ab8 100644
> --- a/drivers/gpu/drm/i915/gvt/Makefile
> +++ b/drivers/gpu/drm/i915/gvt/Makefile
> @@ -3,7 +3,7 @@ GVT_DIR := gvt
>  GVT_SOURCE := gvt.o aperture_gm.o handlers.o vgpu.o trace_points.o firmware.o \
>  	interrupt.o gtt.o cfg_space.o opregion.o mmio.o display.o edid.o \
>  	execlist.o scheduler.o sched_policy.o mmio_context.o cmd_parser.o debugfs.o \
> -	fb_decoder.o dmabuf.o page_track.o
> +	fb_decoder.o dmabuf.o page_track.o migration_version.o
>  
>  ccflags-y				+= -I$(src) -I$(src)/$(GVT_DIR)
>  i915-y					+= $(addprefix $(GVT_DIR)/, $(GVT_SOURCE))
> diff --git a/drivers/gpu/drm/i915/gvt/gvt.c b/drivers/gpu/drm/i915/gvt/gvt.c
> index 43f4242062dd..be2980e8ac75 100644
> --- a/drivers/gpu/drm/i915/gvt/gvt.c
> +++ b/drivers/gpu/drm/i915/gvt/gvt.c
> @@ -105,14 +105,53 @@ static ssize_t description_show(struct kobject *kobj, struct device *dev,
>  		       type->weight);
>  }
>  
> +static ssize_t migration_version_show(struct kobject *kobj, struct device *dev,
> +		char *buf)
> +{
> +	struct intel_vgpu_type *type;
> +	void *gvt = kdev_to_i915(dev)->gvt;
> +
> +	type = intel_gvt_find_vgpu_type(gvt, kobject_name(kobj));
> +	if (!type || !type->migration_version) {
> +		gvt_err("Does not support migraion on type %s. Please search previous detailed log\n",
> +				kobject_name(kobj));
> +		return -ENODEV;
> +	}
> +
> +	return snprintf(buf, strlen(type->migration_version) + 2,
> +			"%s\n", type->migration_version);
> +}
> +
> +static ssize_t migration_version_store(struct kobject *kobj, struct device *dev,
> +		const char *buf, size_t count)
> +{
> +	int ret = 0;
> +	struct intel_vgpu_type *type;
> +	void *gvt = kdev_to_i915(dev)->gvt;
> +
> +	type = intel_gvt_find_vgpu_type(gvt, kobject_name(kobj));
> +	if (!type || !type->migration_version) {
> +		gvt_err("Does not support migraion on type %s. Please search previous detailed log\n",
> +				kobject_name(kobj));
> +		return -ENODEV;
> +	}
> +
> +	ret = intel_gvt_check_vfio_migration_version(gvt,
> +			type->migration_version, buf);
> +
> +	return (ret < 0 ? ret : count);
> +}
> +
>  static MDEV_TYPE_ATTR_RO(available_instances);
>  static MDEV_TYPE_ATTR_RO(device_api);
>  static MDEV_TYPE_ATTR_RO(description);
> +static MDEV_TYPE_ATTR_RW(migration_version);
>  
>  static struct attribute *gvt_type_attrs[] = {
>  	&mdev_type_attr_available_instances.attr,
>  	&mdev_type_attr_device_api.attr,
>  	&mdev_type_attr_description.attr,
> +	&mdev_type_attr_migration_version.attr,
>  	NULL,
>  };
>  
> diff --git a/drivers/gpu/drm/i915/gvt/gvt.h b/drivers/gpu/drm/i915/gvt/gvt.h
> index f5a328b5290a..265319d35c25 100644
> --- a/drivers/gpu/drm/i915/gvt/gvt.h
> +++ b/drivers/gpu/drm/i915/gvt/gvt.h
> @@ -296,6 +296,7 @@ struct intel_vgpu_type {
>  	unsigned int fence;
>  	unsigned int weight;
>  	enum intel_vgpu_edid resolution;
> +	char *migration_version;
>  };
>  
>  struct intel_gvt {
> @@ -687,6 +688,10 @@ void intel_gvt_debugfs_remove_vgpu(struct intel_vgpu *vgpu);
>  int intel_gvt_debugfs_init(struct intel_gvt *gvt);
>  void intel_gvt_debugfs_clean(struct intel_gvt *gvt);
>  
> +ssize_t intel_gvt_check_vfio_migration_version(struct intel_gvt *gvt,
> +		const char *self, const char *remote);
> +char *intel_gvt_get_vfio_migration_version(struct intel_gvt *gvt,
> +		const char *vgpu_type);
>  
>  #include "trace.h"
>  #include "mpt.h"
> diff --git a/drivers/gpu/drm/i915/gvt/migration_version.c b/drivers/gpu/drm/i915/gvt/migration_version.c
> new file mode 100644
> index 000000000000..e6acf188b29a
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/gvt/migration_version.c
> @@ -0,0 +1,167 @@
> +/*
> + * Copyright(c) 2011-2017 Intel Corporation. All rights reserved.
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice (including the next
> + * paragraph) shall be included in all copies or substantial portions of the
> + * Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
> + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
> + * SOFTWARE.
> + *
> + * Authors:
> + *    Yan Zhao <yan.y.zhao@intel.com>
> + */
> +#include <linux/vfio.h>
> +#include "i915_drv.h"
> +#include "gvt.h"
> +
> +#define INV_SOFTWARE_VERSION (-1U)
> +#define VENDOR_ID_LEN (4)
> +#define DEVICE_ID_LEN (4)
> +#define VGPU_TYPE_LEN (16)
> +#define SOFTWARE_VER_LEN (8)
> +
> +/* total length of vfio migration version string.
> + * never exceed limit of PATH_MAX (4096)
> + */
> +#define MIGRATION_VERSION_TOTAL_LEN (VENDOR_ID_LEN + DEVICE_ID_LEN + \
> +					VGPU_TYPE_LEN + SOFTWARE_VER_LEN + 4)
> +
> +#define GVT_VFIO_MIGRATION_SOFTWARE_VERSION INV_SOFTWARE_VERSION
> +
> +
> +#define PRINTF_FORMAT "%04x-%04x-%s-%08x"
> +#define SCANF_FORMAT "%x-%x-%16[^-]-%x"
> +
> +enum incompatible_reason {
> +	IREASON_WRONG_REMOTE_FORMAT = 0,
> +	IREASON_HARDWARE_MISMATCH,
> +	IREASON_SOFTWARE_VERSION_MISMATCH,
> +	IREASON_VGPU_TYPE_MISMATCH,
> +};
> +
> +static const char *const incompatible_reason_str[] = {
> +	[IREASON_WRONG_REMOTE_FORMAT] =
> +		"wrong string format. probably wrong GVT version",
> +	[IREASON_HARDWARE_MISMATCH] =
> +		"physical device not matched",
> +	[IREASON_SOFTWARE_VERSION_MISMATCH] =
> +		"migration software version not matched",
> +	[IREASON_VGPU_TYPE_MISMATCH] =
> +		"vgpu type not matched"
> +};
> +
> +static bool is_compatible(const char *local, const char *remote)
> +{
> +	bool ret;
> +
> +	ret = sysfs_streq(local, remote);
> +
> +	if (!ret) {
> +		int vid_l = 0, did_l = 0, vid_r = 0, did_r = 0;
> +		char type_l[VGPU_TYPE_LEN], type_r[VGPU_TYPE_LEN];
> +		u32 sv_l = 0, sv_r = 0;
> +		int rl = 0, rr = 0;
> +		enum incompatible_reason reason = IREASON_WRONG_REMOTE_FORMAT;
> +
> +		memset(type_l, 0, sizeof(type_l));
> +		memset(type_r, 0, sizeof(type_r));
> +
> +		rl = sscanf(local, SCANF_FORMAT,
> +				&vid_l, &did_l, type_l, &sv_l);
> +		rr = sscanf(remote, SCANF_FORMAT,
> +				&vid_r, &did_r, type_r, &sv_r);
> +
> +		if (rl == rr) {
> +			if (vid_l != vid_r || did_l != did_r)
> +				reason = IREASON_HARDWARE_MISMATCH;
> +			else if (sv_l != sv_r)
> +				reason = IREASON_SOFTWARE_VERSION_MISMATCH;
> +			else if (strncmp(type_l, type_r, VGPU_TYPE_LEN))
> +				reason = IREASON_VGPU_TYPE_MISMATCH;
> +		}
> +
> +		gvt_err("Migration version mismatched. Possible reason: %s. Local migration version:%s, Remote migration version:%s\n",
> +				incompatible_reason_str[reason], local,	remote);
> +
> +	}
> +	return ret;
> +
> +}
> +
> +
> +char *
> +intel_gvt_get_vfio_migration_version(struct intel_gvt *gvt,
> +		const char *vgpu_type)
> +{
> +	int cnt = 0;
> +	struct drm_i915_private *dev_priv = gvt->dev_priv;
> +	char *version = NULL;
> +
> +	/* currently only gen8 & gen9 are supported */
> +	if (!IS_GEN(dev_priv, 8) && !IS_GEN(dev_priv, 9)) {
> +		gvt_err("Local hardware does not support migration on %d\n",
> +				INTEL_INFO(dev_priv)->gen);
> +		return NULL;
> +	}
> +
> +	if (GVT_VFIO_MIGRATION_SOFTWARE_VERSION == INV_SOFTWARE_VERSION) {
> +		gvt_err("Local GVT does not support migration\n");
> +		return NULL;
> +	}
> +
> +	version = kzalloc(MIGRATION_VERSION_TOTAL_LEN, GFP_KERNEL);
> +
> +	if (unlikely(!version)) {
> +		gvt_err("memory allocation failed when get local migraiton version\n");
> +		return NULL;
> +	}
> +
> +	/* vendor id + device id + vgpu type + software version */
> +	cnt = snprintf(version, MIGRATION_VERSION_TOTAL_LEN, PRINTF_FORMAT,
> +			PCI_VENDOR_ID_INTEL,
> +			INTEL_DEVID(dev_priv),
> +			vgpu_type,
> +			GVT_VFIO_MIGRATION_SOFTWARE_VERSION);
> +
> +	if (cnt)
> +		return version;
> +
> +	gvt_err("string generation failed when get local migration version\n");
> +	return NULL;

Handle version kfree for possible error here. The approach looks fine to me.
I think some of those messages might be too chatty or maybe debug message instead.
Others are good to me.

Acked-by: Zhenyu Wang <zhenyuw@linux.intel.com>

> +}
> +
> +ssize_t intel_gvt_check_vfio_migration_version(struct intel_gvt *gvt,
> +		const char *self, const char *remote)
> +{
> +	struct drm_i915_private *dev_priv = gvt->dev_priv;
> +
> +	/* currently only gen8 & gen9 are supported */
> +	if (!IS_GEN(dev_priv, 8) && !IS_GEN(dev_priv, 9)) {
> +		gvt_err("Local hardware does not support migration on %d\n",
> +				INTEL_INFO(dev_priv)->gen);
> +		return -ENODEV;
> +	}
> +
> +	if (GVT_VFIO_MIGRATION_SOFTWARE_VERSION == INV_SOFTWARE_VERSION) {
> +		gvt_err("Local GVT does not support migration\n");
> +		return -ENODEV;
> +	}
> +
> +	if (!is_compatible(self, remote))
> +		return -EINVAL;
> +
> +	return 0;
> +}
> diff --git a/drivers/gpu/drm/i915/gvt/vgpu.c b/drivers/gpu/drm/i915/gvt/vgpu.c
> index 44ce3c2b9ac1..7642b21641bd 100644
> --- a/drivers/gpu/drm/i915/gvt/vgpu.c
> +++ b/drivers/gpu/drm/i915/gvt/vgpu.c
> @@ -155,13 +155,18 @@ int intel_gvt_init_vgpu_types(struct intel_gvt *gvt)
>  			sprintf(gvt->types[i].name, "GVTg_V5_%s",
>  						vgpu_types[i].name);
>  
> -		gvt_dbg_core("type[%d]: %s avail %u low %u high %u fence %u weight %u res %s\n",
> +		gvt->types[i].migration_version =
> +			intel_gvt_get_vfio_migration_version(gvt,
> +					gvt->types[i].name);
> +		gvt_dbg_core("type[%d]: %s avail %u low %u high %u fence %u weight %u res %s, migratio_version:%s\n",
>  			     i, gvt->types[i].name,
>  			     gvt->types[i].avail_instance,
>  			     gvt->types[i].low_gm_size,
>  			     gvt->types[i].high_gm_size, gvt->types[i].fence,
>  			     gvt->types[i].weight,
> -			     vgpu_edid_str(gvt->types[i].resolution));
> +			     vgpu_edid_str(gvt->types[i].resolution),
> +			     (gvt->types[i].migration_version ?
> +			     gvt->types[i].migration_version : "null"));
>  	}
>  
>  	gvt->num_types = i;
> @@ -170,6 +175,10 @@ int intel_gvt_init_vgpu_types(struct intel_gvt *gvt)
>  
>  void intel_gvt_clean_vgpu_types(struct intel_gvt *gvt)
>  {
> +	int i;
> +
> +	for (i = 0; i < gvt->num_types; i++)
> +		kfree(gvt->types[i].migration_version);
>  	kfree(gvt->types);
>  }
>  
> -- 
> 2.17.1
>

On Wed, May 29, 2019 at 11:07:50AM +0800, Zhenyu Wang wrote:
> On 2019.05.26 23:44:37 -0400, Yan Zhao wrote:
> > This feature implements the migration_version attribute for Intel's vGPU
> > mdev devices.
> > 
> > migration_version attribute is rw.
> > It's used to check migration compatibility for two mdev devices of the
> > same mdev type.
> > migration_version string is defined by vendor driver and opaque to
> > userspace.
> > 
> > For Intel vGPU of gen8 and gen9, the format of migration_version string
> > is:
> >   <vendor id>-<device id>-<vgpu type>-<software version>.
> > 
> > For future platforms, the format of migration_version string is to be
> > expanded to include more meta data to identify Intel vGPUs for live
> > migration compatibility check
> > 
> > For old platforms, and for GVT not supporting vGPU live migration
> > feature, -ENODEV is returned on read(2)/write(2) of migration_version
> > attribute.
> > For vGPUs running old GVT who do not expose migration_version
> > attribute, live migration is regarded as not supported for those vGPUs.
> > 
> > Cc: Alex Williamson <alex.williamson@redhat.com>
> > Cc: Erik Skultety <eskultet@redhat.com>
> > Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> > Cc: Cornelia Huck <cohuck@redhat.com>
> > Cc: "Tian, Kevin" <kevin.tian@intel.com>
> > Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
> > Cc: "Wang, Zhi A" <zhi.a.wang@intel.com>
> > c: Neo Jia <cjia@nvidia.com>
> > Cc: Kirti Wankhede <kwankhede@nvidia.com>
> > 
> > Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
> > 
> > ---
> > v3:
> > 1. renamed version to migration_version
> > (Christophe de Dinechin, Cornelia Huck, Alex Williamson)
> > 2. instead of generating migration version strings each time, storing
> > them in vgpu types generated during initialization.
> > (Zhenyu Wang, Cornelia Huck)
> > 3. replaced multiple snprintf to one big snprintf in
> > intel_gvt_get_vfio_migration_version()
> > (Dr. David Alan Gilbert)
> > 4. printed detailed error log
> > (Alex Williamson, Erik Skultety, Cornelia Huck, Dr. David Alan Gilbert)
> > 5. incorporated <software version> into migration_version string
> > (Alex Williamson)
> > 6. do not use ifndef macro to switch off migration_version attribute
> > (Zhenyu Wang)
> > 
> > v2:
> > 1. removed 32 common part of version string
> > (Alex Williamson)
> > 2. do not register version attribute for GVT not supporting live
> > migration.(Cornelia Huck)
> > 3. for platforms out of gen8, gen9, return -EINVAL --> -ENODEV for
> > incompatible. (Cornelia Huck)
> > ---
> >  drivers/gpu/drm/i915/gvt/Makefile            |   2 +-
> >  drivers/gpu/drm/i915/gvt/gvt.c               |  39 +++++
> >  drivers/gpu/drm/i915/gvt/gvt.h               |   5 +
> >  drivers/gpu/drm/i915/gvt/migration_version.c | 167 +++++++++++++++++++
> >  drivers/gpu/drm/i915/gvt/vgpu.c              |  13 +-
> >  5 files changed, 223 insertions(+), 3 deletions(-)
> >  create mode 100644 drivers/gpu/drm/i915/gvt/migration_version.c
> > 
> > diff --git a/drivers/gpu/drm/i915/gvt/Makefile b/drivers/gpu/drm/i915/gvt/Makefile
> > index 271fb46d4dd0..a9d561c93ab8 100644
> > --- a/drivers/gpu/drm/i915/gvt/Makefile
> > +++ b/drivers/gpu/drm/i915/gvt/Makefile
> > @@ -3,7 +3,7 @@ GVT_DIR := gvt
> >  GVT_SOURCE := gvt.o aperture_gm.o handlers.o vgpu.o trace_points.o firmware.o \
> >  	interrupt.o gtt.o cfg_space.o opregion.o mmio.o display.o edid.o \
> >  	execlist.o scheduler.o sched_policy.o mmio_context.o cmd_parser.o debugfs.o \
> > -	fb_decoder.o dmabuf.o page_track.o
> > +	fb_decoder.o dmabuf.o page_track.o migration_version.o
> >  
> >  ccflags-y				+= -I$(src) -I$(src)/$(GVT_DIR)
> >  i915-y					+= $(addprefix $(GVT_DIR)/, $(GVT_SOURCE))
> > diff --git a/drivers/gpu/drm/i915/gvt/gvt.c b/drivers/gpu/drm/i915/gvt/gvt.c
> > index 43f4242062dd..be2980e8ac75 100644
> > --- a/drivers/gpu/drm/i915/gvt/gvt.c
> > +++ b/drivers/gpu/drm/i915/gvt/gvt.c
> > @@ -105,14 +105,53 @@ static ssize_t description_show(struct kobject *kobj, struct device *dev,
> >  		       type->weight);
> >  }
> >  
> > +static ssize_t migration_version_show(struct kobject *kobj, struct device *dev,
> > +		char *buf)
> > +{
> > +	struct intel_vgpu_type *type;
> > +	void *gvt = kdev_to_i915(dev)->gvt;
> > +
> > +	type = intel_gvt_find_vgpu_type(gvt, kobject_name(kobj));
> > +	if (!type || !type->migration_version) {
> > +		gvt_err("Does not support migraion on type %s. Please search previous detailed log\n",
> > +				kobject_name(kobj));
> > +		return -ENODEV;
> > +	}
> > +
> > +	return snprintf(buf, strlen(type->migration_version) + 2,
> > +			"%s\n", type->migration_version);
> > +}
> > +
> > +static ssize_t migration_version_store(struct kobject *kobj, struct device *dev,
> > +		const char *buf, size_t count)
> > +{
> > +	int ret = 0;
> > +	struct intel_vgpu_type *type;
> > +	void *gvt = kdev_to_i915(dev)->gvt;
> > +
> > +	type = intel_gvt_find_vgpu_type(gvt, kobject_name(kobj));
> > +	if (!type || !type->migration_version) {
> > +		gvt_err("Does not support migraion on type %s. Please search previous detailed log\n",
> > +				kobject_name(kobj));
> > +		return -ENODEV;
> > +	}
> > +
> > +	ret = intel_gvt_check_vfio_migration_version(gvt,
> > +			type->migration_version, buf);
> > +
> > +	return (ret < 0 ? ret : count);
> > +}
> > +
> >  static MDEV_TYPE_ATTR_RO(available_instances);
> >  static MDEV_TYPE_ATTR_RO(device_api);
> >  static MDEV_TYPE_ATTR_RO(description);
> > +static MDEV_TYPE_ATTR_RW(migration_version);
> >  
> >  static struct attribute *gvt_type_attrs[] = {
> >  	&mdev_type_attr_available_instances.attr,
> >  	&mdev_type_attr_device_api.attr,
> >  	&mdev_type_attr_description.attr,
> > +	&mdev_type_attr_migration_version.attr,
> >  	NULL,
> >  };
> >  
> > diff --git a/drivers/gpu/drm/i915/gvt/gvt.h b/drivers/gpu/drm/i915/gvt/gvt.h
> > index f5a328b5290a..265319d35c25 100644
> > --- a/drivers/gpu/drm/i915/gvt/gvt.h
> > +++ b/drivers/gpu/drm/i915/gvt/gvt.h
> > @@ -296,6 +296,7 @@ struct intel_vgpu_type {
> >  	unsigned int fence;
> >  	unsigned int weight;
> >  	enum intel_vgpu_edid resolution;
> > +	char *migration_version;
> >  };
> >  
> >  struct intel_gvt {
> > @@ -687,6 +688,10 @@ void intel_gvt_debugfs_remove_vgpu(struct intel_vgpu *vgpu);
> >  int intel_gvt_debugfs_init(struct intel_gvt *gvt);
> >  void intel_gvt_debugfs_clean(struct intel_gvt *gvt);
> >  
> > +ssize_t intel_gvt_check_vfio_migration_version(struct intel_gvt *gvt,
> > +		const char *self, const char *remote);
> > +char *intel_gvt_get_vfio_migration_version(struct intel_gvt *gvt,
> > +		const char *vgpu_type);
> >  
> >  #include "trace.h"
> >  #include "mpt.h"
> > diff --git a/drivers/gpu/drm/i915/gvt/migration_version.c b/drivers/gpu/drm/i915/gvt/migration_version.c
> > new file mode 100644
> > index 000000000000..e6acf188b29a
> > --- /dev/null
> > +++ b/drivers/gpu/drm/i915/gvt/migration_version.c
> > @@ -0,0 +1,167 @@
> > +/*
> > + * Copyright(c) 2011-2017 Intel Corporation. All rights reserved.
> > + *
> > + * Permission is hereby granted, free of charge, to any person obtaining a
> > + * copy of this software and associated documentation files (the "Software"),
> > + * to deal in the Software without restriction, including without limitation
> > + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> > + * and/or sell copies of the Software, and to permit persons to whom the
> > + * Software is furnished to do so, subject to the following conditions:
> > + *
> > + * The above copyright notice and this permission notice (including the next
> > + * paragraph) shall be included in all copies or substantial portions of the
> > + * Software.
> > + *
> > + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> > + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> > + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
> > + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> > + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
> > + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
> > + * SOFTWARE.
> > + *
> > + * Authors:
> > + *    Yan Zhao <yan.y.zhao@intel.com>
> > + */
> > +#include <linux/vfio.h>
> > +#include "i915_drv.h"
> > +#include "gvt.h"
> > +
> > +#define INV_SOFTWARE_VERSION (-1U)
> > +#define VENDOR_ID_LEN (4)
> > +#define DEVICE_ID_LEN (4)
> > +#define VGPU_TYPE_LEN (16)
> > +#define SOFTWARE_VER_LEN (8)
> > +
> > +/* total length of vfio migration version string.
> > + * never exceed limit of PATH_MAX (4096)
> > + */
> > +#define MIGRATION_VERSION_TOTAL_LEN (VENDOR_ID_LEN + DEVICE_ID_LEN + \
> > +					VGPU_TYPE_LEN + SOFTWARE_VER_LEN + 4)
> > +
> > +#define GVT_VFIO_MIGRATION_SOFTWARE_VERSION INV_SOFTWARE_VERSION
> > +
> > +
> > +#define PRINTF_FORMAT "%04x-%04x-%s-%08x"
> > +#define SCANF_FORMAT "%x-%x-%16[^-]-%x"
> > +
> > +enum incompatible_reason {
> > +	IREASON_WRONG_REMOTE_FORMAT = 0,
> > +	IREASON_HARDWARE_MISMATCH,
> > +	IREASON_SOFTWARE_VERSION_MISMATCH,
> > +	IREASON_VGPU_TYPE_MISMATCH,
> > +};
> > +
> > +static const char *const incompatible_reason_str[] = {
> > +	[IREASON_WRONG_REMOTE_FORMAT] =
> > +		"wrong string format. probably wrong GVT version",
> > +	[IREASON_HARDWARE_MISMATCH] =
> > +		"physical device not matched",
> > +	[IREASON_SOFTWARE_VERSION_MISMATCH] =
> > +		"migration software version not matched",
> > +	[IREASON_VGPU_TYPE_MISMATCH] =
> > +		"vgpu type not matched"
> > +};
> > +
> > +static bool is_compatible(const char *local, const char *remote)
> > +{
> > +	bool ret;
> > +
> > +	ret = sysfs_streq(local, remote);
> > +
> > +	if (!ret) {
> > +		int vid_l = 0, did_l = 0, vid_r = 0, did_r = 0;
> > +		char type_l[VGPU_TYPE_LEN], type_r[VGPU_TYPE_LEN];
> > +		u32 sv_l = 0, sv_r = 0;
> > +		int rl = 0, rr = 0;
> > +		enum incompatible_reason reason = IREASON_WRONG_REMOTE_FORMAT;
> > +
> > +		memset(type_l, 0, sizeof(type_l));
> > +		memset(type_r, 0, sizeof(type_r));
> > +
> > +		rl = sscanf(local, SCANF_FORMAT,
> > +				&vid_l, &did_l, type_l, &sv_l);
> > +		rr = sscanf(remote, SCANF_FORMAT,
> > +				&vid_r, &did_r, type_r, &sv_r);
> > +
> > +		if (rl == rr) {
> > +			if (vid_l != vid_r || did_l != did_r)
> > +				reason = IREASON_HARDWARE_MISMATCH;
> > +			else if (sv_l != sv_r)
> > +				reason = IREASON_SOFTWARE_VERSION_MISMATCH;
> > +			else if (strncmp(type_l, type_r, VGPU_TYPE_LEN))
> > +				reason = IREASON_VGPU_TYPE_MISMATCH;
> > +		}
> > +
> > +		gvt_err("Migration version mismatched. Possible reason: %s. Local migration version:%s, Remote migration version:%s\n",
> > +				incompatible_reason_str[reason], local,	remote);
> > +
> > +	}
> > +	return ret;
> > +
> > +}
> > +
> > +
> > +char *
> > +intel_gvt_get_vfio_migration_version(struct intel_gvt *gvt,
> > +		const char *vgpu_type)
> > +{
> > +	int cnt = 0;
> > +	struct drm_i915_private *dev_priv = gvt->dev_priv;
> > +	char *version = NULL;
> > +
> > +	/* currently only gen8 & gen9 are supported */
> > +	if (!IS_GEN(dev_priv, 8) && !IS_GEN(dev_priv, 9)) {
> > +		gvt_err("Local hardware does not support migration on %d\n",
> > +				INTEL_INFO(dev_priv)->gen);
> > +		return NULL;
> > +	}
> > +
> > +	if (GVT_VFIO_MIGRATION_SOFTWARE_VERSION == INV_SOFTWARE_VERSION) {
> > +		gvt_err("Local GVT does not support migration\n");
> > +		return NULL;
> > +	}
> > +
> > +	version = kzalloc(MIGRATION_VERSION_TOTAL_LEN, GFP_KERNEL);
> > +
> > +	if (unlikely(!version)) {
> > +		gvt_err("memory allocation failed when get local migraiton version\n");
> > +		return NULL;
> > +	}
> > +
> > +	/* vendor id + device id + vgpu type + software version */
> > +	cnt = snprintf(version, MIGRATION_VERSION_TOTAL_LEN, PRINTF_FORMAT,
> > +			PCI_VENDOR_ID_INTEL,
> > +			INTEL_DEVID(dev_priv),
> > +			vgpu_type,
> > +			GVT_VFIO_MIGRATION_SOFTWARE_VERSION);
> > +
> > +	if (cnt)
> > +		return version;
> > +
> > +	gvt_err("string generation failed when get local migration version\n");
> > +	return NULL;
> 
> Handle version kfree for possible error here. The approach looks fine to me.
> I think some of those messages might be too chatty or maybe debug message instead.
> Others are good to me.
> 
> Acked-by: Zhenyu Wang <zhenyuw@linux.intel.com>
> 
Got it. will add the kfree in next revision.
But debug message is only available for debug version of driver? If that's true,
maybe keep it printed also for non-debug version is better? as it is intended to
be checked by userspace software to see what's going wrong on migration
compatibility test.
Thank you:)

> > +}
> > +
> > +ssize_t intel_gvt_check_vfio_migration_version(struct intel_gvt *gvt,
> > +		const char *self, const char *remote)
> > +{
> > +	struct drm_i915_private *dev_priv = gvt->dev_priv;
> > +
> > +	/* currently only gen8 & gen9 are supported */
> > +	if (!IS_GEN(dev_priv, 8) && !IS_GEN(dev_priv, 9)) {
> > +		gvt_err("Local hardware does not support migration on %d\n",
> > +				INTEL_INFO(dev_priv)->gen);
> > +		return -ENODEV;
> > +	}
> > +
> > +	if (GVT_VFIO_MIGRATION_SOFTWARE_VERSION == INV_SOFTWARE_VERSION) {
> > +		gvt_err("Local GVT does not support migration\n");
> > +		return -ENODEV;
> > +	}
> > +
> > +	if (!is_compatible(self, remote))
> > +		return -EINVAL;
> > +
> > +	return 0;
> > +}
> > diff --git a/drivers/gpu/drm/i915/gvt/vgpu.c b/drivers/gpu/drm/i915/gvt/vgpu.c
> > index 44ce3c2b9ac1..7642b21641bd 100644
> > --- a/drivers/gpu/drm/i915/gvt/vgpu.c
> > +++ b/drivers/gpu/drm/i915/gvt/vgpu.c
> > @@ -155,13 +155,18 @@ int intel_gvt_init_vgpu_types(struct intel_gvt *gvt)
> >  			sprintf(gvt->types[i].name, "GVTg_V5_%s",
> >  						vgpu_types[i].name);
> >  
> > -		gvt_dbg_core("type[%d]: %s avail %u low %u high %u fence %u weight %u res %s\n",
> > +		gvt->types[i].migration_version =
> > +			intel_gvt_get_vfio_migration_version(gvt,
> > +					gvt->types[i].name);
> > +		gvt_dbg_core("type[%d]: %s avail %u low %u high %u fence %u weight %u res %s, migratio_version:%s\n",
> >  			     i, gvt->types[i].name,
> >  			     gvt->types[i].avail_instance,
> >  			     gvt->types[i].low_gm_size,
> >  			     gvt->types[i].high_gm_size, gvt->types[i].fence,
> >  			     gvt->types[i].weight,
> > -			     vgpu_edid_str(gvt->types[i].resolution));
> > +			     vgpu_edid_str(gvt->types[i].resolution),
> > +			     (gvt->types[i].migration_version ?
> > +			     gvt->types[i].migration_version : "null"));
> >  	}
> >  
> >  	gvt->num_types = i;
> > @@ -170,6 +175,10 @@ int intel_gvt_init_vgpu_types(struct intel_gvt *gvt)
> >  
> >  void intel_gvt_clean_vgpu_types(struct intel_gvt *gvt)
> >  {
> > +	int i;
> > +
> > +	for (i = 0; i < gvt->num_types; i++)
> > +		kfree(gvt->types[i].migration_version);
> >  	kfree(gvt->types);
> >  }
> >  
> > -- 
> > 2.17.1
> > 
> 
> -- 
> Open Source Technology Center, Intel ltd.
> 
> $gpg --keyserver wwwkeys.pgp.net --recv-keys 4D781827