Re: [libvirt] [PATCH v2 2/2] drm/i915/gvt: export mdev device version to sysfs for Intel vGPU

On Sun, 5 May 2019 21:51:02 -0400 Yan Zhao <yan.y.zhao(a)intel.com&gt; wrote: > This feature implements the version attribute for Intel's vGPU mdev > devices. > > version attribute is rw. > It's used to check device compatibility for two mdev devices. > version string format and length are private for vendor driver. vendor > driver is able to define them freely. > > For Intel vGPU of gen8 and gen9, the mdev device version > consists of 3 fields: "vendor id" + "device id" + "mdev type". > > Reading from a vGPU's version attribute, a string is returned in below > format: <vendor id>-<device id>-<mdev type>. e.g. > 8086-193b-i915-GVTg_V5_2. > > Writing a string to a vGPU's version attribute will trigger GVT to check > whether a vGPU identified by the written string is compatible with > current vGPU owning this version attribute. errno is returned if the two > vGPUs are incompatible. The length of written string is returned in > compatible case. > > For other platforms, and for GVT not supporting vGPU live migration > feature, errnos are returned when read/write of mdev devices' version > attributes. > > For old GVT versions where no version attributes exposed in sysfs, it is > regarded as not supporting vGPU live migration. > > For future platforms, besides the current 2 fields in vendor proprietary > part, more fields may be added to identify Intel vGPU well for live > migration purpose. > > 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) Should go below '---'.

> > Cc: Alex Williamson <alex.williamson(a)redhat.com&gt; > Cc: Erik Skultety <eskultet(a)redhat.com&gt; > Cc: "Dr. David Alan Gilbert" <dgilbert(a)redhat.com&gt; > Cc: Cornelia Huck <cohuck(a)redhat.com&gt; > Cc: "Tian, Kevin" <kevin.tian(a)intel.com&gt; > Cc: Zhenyu Wang <zhenyuw(a)linux.intel.com&gt; > Cc: "Wang, Zhi A" <zhi.a.wang(a)intel.com&gt; > c: Neo Jia <cjia(a)nvidia.com&gt; > Cc: Kirti Wankhede <kwankhede(a)nvidia.com&gt; > > Signed-off-by: Yan Zhao <yan.y.zhao(a)intel.com&gt; > --- > drivers/gpu/drm/i915/gvt/Makefile | 2 +- > drivers/gpu/drm/i915/gvt/device_version.c | 87 +++++++++++++++++++++++ > drivers/gpu/drm/i915/gvt/gvt.c | 51 +++++++++++++ > drivers/gpu/drm/i915/gvt/gvt.h | 6 ++ > 4 files changed, 145 insertions(+), 1 deletion(-) > create mode 100644 drivers/gpu/drm/i915/gvt/device_version.c > (...) > diff --git a/drivers/gpu/drm/i915/gvt/device_version.c b/drivers/gpu/drm/i915/gvt/device_version.c > new file mode 100644 > index 000000000000..bd4cdcbdba95 > --- /dev/null > +++ b/drivers/gpu/drm/i915/gvt/device_version.c > @@ -0,0 +1,87 @@ > +/* > + * 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(a)intel.com&gt; > + */ > +#include <linux/vfio.h> > +#include "i915_drv.h" > + > +static bool is_compatible(const char *self, const char *remote) > +{ > + if (strlen(remote) != strlen(self)) > + return false; > + > + return (strncmp(self, remote, strlen(self))) ? false : true; > +} > + > +ssize_t intel_gvt_get_vfio_device_version_len(struct drm_i915_private *dev_priv) > +{ > + if (!IS_GEN(dev_priv, 8) && !IS_GEN(dev_priv, 9)) > + return -ENODEV; > + > + return PAGE_SIZE; > +} > + > +ssize_t intel_gvt_get_vfio_device_version(struct drm_i915_private *dev_priv, > + char *buf, const char *mdev_type) > +{ > + int cnt = 0, ret = 0; > + const char *str = NULL; > + > + /* currently only gen8 & gen9 are supported */ > + if (!IS_GEN(dev_priv, 8) && !IS_GEN(dev_priv, 9)) > + return -ENODEV; > + > + /* vendor id + device id + mdev type */ > + /* vendor id */ > + cnt = snprintf(buf, 5, "%04x", PCI_VENDOR_ID_INTEL); > + buf += cnt; > + ret += cnt; > + > + /* device id */ > + cnt = snprintf(buf, 6, "-%04x", INTEL_DEVID(dev_priv)); > + buf += cnt; > + ret += cnt; > + > + /* mdev type */ > + str = mdev_type; > + cnt = snprintf(buf, strlen(str) + 3, "-%s\n", mdev_type); > + buf += cnt; > + ret += cnt; > + > + return ret; I'm not familiar with this driver; but would it make sense to pre-build the version on init? It does not look to me like the values could change dynamically.

> +} > + > +ssize_t intel_gvt_check_vfio_device_version(struct drm_i915_private *dev_priv, > + const char *self, const char *remote) > +{ > + > + /* currently only gen8 & gen9 are supported */ > + if (!IS_GEN(dev_priv, 8) && !IS_GEN(dev_priv, 9)) > + return -ENODEV; > + > + if (!is_compatible(self, remote)) > + return -EINVAL; > + > + return 0; > +} Return values look reasonable to me. I'll leave discussions regarding where the attribute should go to folks familiar with this driver.