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

[Zhenyu Wang]

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@xxxxxxxxxx>
> Cc: Erik Skultety <eskultet@xxxxxxxxxx>
> Cc: "Dr. David Alan Gilbert" <dgilbert@xxxxxxxxxx>
> Cc: Cornelia Huck <cohuck@xxxxxxxxxx>
> Cc: "Tian, Kevin" <kevin.tian@xxxxxxxxx>
> Cc: Zhenyu Wang <zhenyuw@xxxxxxxxxxxxxxx>
> Cc: "Wang, Zhi A" <zhi.a.wang@xxxxxxxxx>
> c: Neo Jia <cjia@xxxxxxxxxx>
> Cc: Kirti Wankhede <kwankhede@xxxxxxxxxx>
> 
> Signed-off-by: Yan Zhao <yan.y.zhao@xxxxxxxxx>
> 
> ---
> 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@xxxxxxxxx>
> + */
> +#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@xxxxxxxxxxxxxxx>

> +}
> +
> +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
> 

-- 
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