From: Lu Baolu <baolu.lu@linux.intel.com> To: Jason Gunthorpe <jgg@nvidia.com>, Christoph Hellwig <hch@lst.de> Cc: baolu.lu@linux.intel.com, Joerg Roedel <joro@8bytes.org>, David Woodhouse <dwmw2@infradead.org>, Alex Williamson <alex.williamson@redhat.com>, Kirti Wankhede <kwankhede@nvidia.com>, ashok.raj@intel.com, sanjay.k.kumar@intel.com, jacob.jun.pan@intel.com, kevin.tian@intel.com, Jean-Philippe Brucker <jean-philippe.brucker@arm.com>, yi.l.liu@intel.com, yi.y.sun@intel.com, peterx@redhat.com, tiwei.bie@intel.com, xin.zeng@intel.com, iommu@lists.linux-foundation.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Jacob Pan <jacob.jun.pan@linux.intel.com> Subject: Re: [PATCH v8 7/9] vfio/mdev: Add iommu related member in mdev_device Date: Wed, 7 Apr 2021 09:58:05 +0800 [thread overview] Message-ID: <1cbe97fb-5595-8cf5-9e0c-1a2edf8c5d9a@linux.intel.com> (raw) In-Reply-To: <20210406200030.GA425310@nvidia.com> Hi Jason, On 4/7/21 4:00 AM, Jason Gunthorpe wrote: > On Mon, Mar 25, 2019 at 09:30:34AM +0800, Lu Baolu wrote: >> A parent device might create different types of mediated >> devices. For example, a mediated device could be created >> by the parent device with full isolation and protection >> provided by the IOMMU. One usage case could be found on >> Intel platforms where a mediated device is an assignable >> subset of a PCI, the DMA requests on behalf of it are all >> tagged with a PASID. Since IOMMU supports PASID-granular >> translations (scalable mode in VT-d 3.0), this mediated >> device could be individually protected and isolated by an >> IOMMU. >> >> This patch adds a new member in the struct mdev_device to >> indicate that the mediated device represented by mdev could >> be isolated and protected by attaching a domain to a device >> represented by mdev->iommu_device. It also adds a helper to >> add or set the iommu device. >> >> * mdev_device->iommu_device >> - This, if set, indicates that the mediated device could >> be fully isolated and protected by IOMMU via attaching >> an iommu domain to this device. If empty, it indicates >> using vendor defined isolation, hence bypass IOMMU. >> >> * mdev_set/get_iommu_device(dev, iommu_device) >> - Set or get the iommu device which represents this mdev >> in IOMMU's device scope. Drivers don't need to set the >> iommu device if it uses vendor defined isolation. >> >> Cc: Ashok Raj <ashok.raj@intel.com> >> Cc: Jacob Pan <jacob.jun.pan@linux.intel.com> >> Cc: Kevin Tian <kevin.tian@intel.com> >> Cc: Liu Yi L <yi.l.liu@intel.com> >> Suggested-by: Kevin Tian <kevin.tian@intel.com> >> Suggested-by: Alex Williamson <alex.williamson@redhat.com> >> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> >> Reviewed-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com> >> --- >> drivers/vfio/mdev/mdev_core.c | 18 ++++++++++++++++++ >> drivers/vfio/mdev/mdev_private.h | 1 + >> include/linux/mdev.h | 14 ++++++++++++++ >> 3 files changed, 33 insertions(+) >> >> diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c >> index b96fedc77ee5..1b6435529166 100644 >> +++ b/drivers/vfio/mdev/mdev_core.c >> @@ -390,6 +390,24 @@ int mdev_device_remove(struct device *dev, bool force_remove) >> return 0; >> } >> >> +int mdev_set_iommu_device(struct device *dev, struct device *iommu_device) >> +{ >> + struct mdev_device *mdev = to_mdev_device(dev); >> + >> + mdev->iommu_device = iommu_device; >> + >> + return 0; >> +} >> +EXPORT_SYMBOL(mdev_set_iommu_device); > > I was looking at these functions when touching the mdev stuff and I > have some concerns. > > 1) Please don't merge dead code. It is a year later and there is still > no in-tree user for any of this. This is not our process. Even > worse it was exported so it looks like this dead code is supporting > out of tree modules. > > 2) Why is this like this? Every struct device already has a connection > to the iommu layer and every mdev has a struct device all its own. > > Why did we need to add special 'if (mdev)' stuff all over the > place? This smells like the same abuse Thomas > and I pointed out for the interrupt domains. I've ever tried to implement a bus iommu_ops for mdev devices. https://lore.kernel.org/lkml/20201030045809.957927-1-baolu.lu@linux.intel.com/ Any comments? Best regards, baolu > > After my next series the mdev drivers will have direct access to > the vfio_device. So an alternative to using the struct device, or > adding 'if mdev' is to add an API to the vfio_device world to > inject what iommu configuration is needed from that direction > instead of trying to discover it from a struct device. > > 3) The vfio_bus_is_mdev() and related symbol_get() nonsense in > drivers/vfio/vfio_iommu_type1.c has to go, for the same reasons > it was not acceptable to do this for the interrupt side either. > > 4) It seems pretty clear to me this will be heavily impacted by the > /dev/ioasid discussion. Please consider removing the dead code now. > > Basically, please fix this before trying to get idxd mdev merged as > the first user. > > Jason >
WARNING: multiple messages have this Message-ID (diff)
From: Lu Baolu <baolu.lu@linux.intel.com> To: Jason Gunthorpe <jgg@nvidia.com>, Christoph Hellwig <hch@lst.de> Cc: kevin.tian@intel.com, ashok.raj@intel.com, tiwei.bie@intel.com, Jean-Philippe Brucker <jean-philippe.brucker@arm.com>, sanjay.k.kumar@intel.com, Kirti Wankhede <kwankhede@nvidia.com>, linux-kernel@vger.kernel.org, Alex Williamson <alex.williamson@redhat.com>, iommu@lists.linux-foundation.org, jacob.jun.pan@intel.com, kvm@vger.kernel.org, David Woodhouse <dwmw2@infradead.org>, yi.y.sun@intel.com Subject: Re: [PATCH v8 7/9] vfio/mdev: Add iommu related member in mdev_device Date: Wed, 7 Apr 2021 09:58:05 +0800 [thread overview] Message-ID: <1cbe97fb-5595-8cf5-9e0c-1a2edf8c5d9a@linux.intel.com> (raw) In-Reply-To: <20210406200030.GA425310@nvidia.com> Hi Jason, On 4/7/21 4:00 AM, Jason Gunthorpe wrote: > On Mon, Mar 25, 2019 at 09:30:34AM +0800, Lu Baolu wrote: >> A parent device might create different types of mediated >> devices. For example, a mediated device could be created >> by the parent device with full isolation and protection >> provided by the IOMMU. One usage case could be found on >> Intel platforms where a mediated device is an assignable >> subset of a PCI, the DMA requests on behalf of it are all >> tagged with a PASID. Since IOMMU supports PASID-granular >> translations (scalable mode in VT-d 3.0), this mediated >> device could be individually protected and isolated by an >> IOMMU. >> >> This patch adds a new member in the struct mdev_device to >> indicate that the mediated device represented by mdev could >> be isolated and protected by attaching a domain to a device >> represented by mdev->iommu_device. It also adds a helper to >> add or set the iommu device. >> >> * mdev_device->iommu_device >> - This, if set, indicates that the mediated device could >> be fully isolated and protected by IOMMU via attaching >> an iommu domain to this device. If empty, it indicates >> using vendor defined isolation, hence bypass IOMMU. >> >> * mdev_set/get_iommu_device(dev, iommu_device) >> - Set or get the iommu device which represents this mdev >> in IOMMU's device scope. Drivers don't need to set the >> iommu device if it uses vendor defined isolation. >> >> Cc: Ashok Raj <ashok.raj@intel.com> >> Cc: Jacob Pan <jacob.jun.pan@linux.intel.com> >> Cc: Kevin Tian <kevin.tian@intel.com> >> Cc: Liu Yi L <yi.l.liu@intel.com> >> Suggested-by: Kevin Tian <kevin.tian@intel.com> >> Suggested-by: Alex Williamson <alex.williamson@redhat.com> >> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> >> Reviewed-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com> >> --- >> drivers/vfio/mdev/mdev_core.c | 18 ++++++++++++++++++ >> drivers/vfio/mdev/mdev_private.h | 1 + >> include/linux/mdev.h | 14 ++++++++++++++ >> 3 files changed, 33 insertions(+) >> >> diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c >> index b96fedc77ee5..1b6435529166 100644 >> +++ b/drivers/vfio/mdev/mdev_core.c >> @@ -390,6 +390,24 @@ int mdev_device_remove(struct device *dev, bool force_remove) >> return 0; >> } >> >> +int mdev_set_iommu_device(struct device *dev, struct device *iommu_device) >> +{ >> + struct mdev_device *mdev = to_mdev_device(dev); >> + >> + mdev->iommu_device = iommu_device; >> + >> + return 0; >> +} >> +EXPORT_SYMBOL(mdev_set_iommu_device); > > I was looking at these functions when touching the mdev stuff and I > have some concerns. > > 1) Please don't merge dead code. It is a year later and there is still > no in-tree user for any of this. This is not our process. Even > worse it was exported so it looks like this dead code is supporting > out of tree modules. > > 2) Why is this like this? Every struct device already has a connection > to the iommu layer and every mdev has a struct device all its own. > > Why did we need to add special 'if (mdev)' stuff all over the > place? This smells like the same abuse Thomas > and I pointed out for the interrupt domains. I've ever tried to implement a bus iommu_ops for mdev devices. https://lore.kernel.org/lkml/20201030045809.957927-1-baolu.lu@linux.intel.com/ Any comments? Best regards, baolu > > After my next series the mdev drivers will have direct access to > the vfio_device. So an alternative to using the struct device, or > adding 'if mdev' is to add an API to the vfio_device world to > inject what iommu configuration is needed from that direction > instead of trying to discover it from a struct device. > > 3) The vfio_bus_is_mdev() and related symbol_get() nonsense in > drivers/vfio/vfio_iommu_type1.c has to go, for the same reasons > it was not acceptable to do this for the interrupt side either. > > 4) It seems pretty clear to me this will be heavily impacted by the > /dev/ioasid discussion. Please consider removing the dead code now. > > Basically, please fix this before trying to get idxd mdev merged as > the first user. > > Jason > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2021-04-07 2:07 UTC|newest] Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-03-25 1:30 [PATCH v8 0/9] vfio/mdev: IOMMU aware mediated device Lu Baolu 2019-03-25 1:30 ` Lu Baolu 2019-03-25 1:30 ` [PATCH v8 1/9] iommu: Add APIs for multiple domains per device Lu Baolu 2019-03-25 1:30 ` Lu Baolu 2019-03-25 1:30 ` [PATCH v8 2/9] iommu/vt-d: Make intel_iommu_enable_pasid() more generic Lu Baolu 2019-03-25 1:30 ` [PATCH v8 3/9] iommu/vt-d: Add per-device IOMMU feature ops entries Lu Baolu 2019-03-25 1:30 ` [PATCH v8 4/9] iommu/vt-d: Move common code out of iommu_attch_device() Lu Baolu 2019-03-25 1:30 ` [PATCH v8 5/9] iommu/vt-d: Aux-domain specific domain attach/detach Lu Baolu 2019-03-25 1:30 ` [PATCH v8 6/9] iommu/vt-d: Return ID associated with an auxiliary domain Lu Baolu 2019-03-25 1:30 ` Lu Baolu 2019-03-25 1:30 ` [PATCH v8 7/9] vfio/mdev: Add iommu related member in mdev_device Lu Baolu 2019-03-26 9:32 ` Kirti Wankhede 2019-03-27 14:17 ` Parav Pandit 2019-03-27 18:16 ` Alex Williamson 2019-03-27 18:16 ` Alex Williamson 2019-03-26 17:42 ` Alex Williamson 2021-04-06 20:00 ` Jason Gunthorpe 2021-04-06 20:00 ` Jason Gunthorpe 2021-04-07 1:58 ` Lu Baolu [this message] 2021-04-07 1:58 ` Lu Baolu 2021-04-07 11:34 ` Jason Gunthorpe 2021-04-07 11:34 ` Jason Gunthorpe 2021-05-11 6:56 ` Lu Baolu 2021-05-11 6:56 ` Lu Baolu 2021-05-11 17:37 ` Jason Gunthorpe 2021-05-11 17:37 ` Jason Gunthorpe 2021-05-12 7:46 ` Tian, Kevin 2021-05-12 7:46 ` Tian, Kevin 2021-05-17 14:03 ` Jason Gunthorpe 2021-05-17 14:03 ` Jason Gunthorpe 2019-03-25 1:30 ` [PATCH v8 8/9] vfio/type1: Add domain at(de)taching group helpers Lu Baolu 2019-03-26 17:42 ` Alex Williamson 2019-03-26 17:42 ` Alex Williamson 2019-03-25 1:30 ` [PATCH v8 9/9] vfio/type1: Handle different mdev isolation type Lu Baolu 2019-03-26 9:33 ` Kirti Wankhede 2019-03-26 17:42 ` Alex Williamson 2019-04-11 15:19 ` [PATCH v8 0/9] vfio/mdev: IOMMU aware mediated device Joerg Roedel 2019-04-11 15:19 ` Joerg Roedel 2019-04-12 1:36 ` Lu Baolu 2019-04-12 1:36 ` Lu Baolu
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