Re: [Intel-gfx] [PATCH v3 1/2] vfio: Replace the DMA unmapping notifier with a callback
On 2022.07.04 21:59:03 -0300, Jason Gunthorpe wrote: > Instead of having drivers register the notifier with explicit code just > have them provide a dma_unmap callback op in their driver ops and rely on > the core code to wire it up. > > Suggested-by: Christoph Hellwig > Reviewed-by: Christoph Hellwig > Reviewed-by: Kevin Tian > Reviewed-by: Tony Krowiak > Reviewed-by: Eric Farman > Signed-off-by: Jason Gunthorpe > --- > drivers/gpu/drm/i915/gvt/gvt.h| 1 - > drivers/gpu/drm/i915/gvt/kvmgt.c | 75 --- gvt change looks fine to me. Reviewed-by: Zhenyu Wang > drivers/s390/cio/vfio_ccw_ops.c | 41 ++-- > drivers/s390/cio/vfio_ccw_private.h | 2 - > drivers/s390/crypto/vfio_ap_ops.c | 53 ++- > drivers/s390/crypto/vfio_ap_private.h | 3 - > drivers/vfio/vfio.c | 129 +- > drivers/vfio/vfio.h | 3 + > include/linux/vfio.h | 21 + > 9 files changed, 88 insertions(+), 240 deletions(-) > > diff --git a/drivers/gpu/drm/i915/gvt/gvt.h b/drivers/gpu/drm/i915/gvt/gvt.h > index aee1a45da74bcb..705689e6401197 100644 > --- a/drivers/gpu/drm/i915/gvt/gvt.h > +++ b/drivers/gpu/drm/i915/gvt/gvt.h > @@ -226,7 +226,6 @@ struct intel_vgpu { > unsigned long nr_cache_entries; > struct mutex cache_lock; > > - struct notifier_block iommu_notifier; > atomic_t released; > > struct kvm_page_track_notifier_node track_node; > diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c > b/drivers/gpu/drm/i915/gvt/kvmgt.c > index e2f6c56ab3420c..ecd5bb37b63a2a 100644 > --- a/drivers/gpu/drm/i915/gvt/kvmgt.c > +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c > @@ -729,34 +729,25 @@ int intel_gvt_set_edid(struct intel_vgpu *vgpu, int > port_num) > return ret; > } > > -static int intel_vgpu_iommu_notifier(struct notifier_block *nb, > - unsigned long action, void *data) > +static void intel_vgpu_dma_unmap(struct vfio_device *vfio_dev, u64 iova, > + u64 length) > { > - struct intel_vgpu *vgpu = > - container_of(nb, struct intel_vgpu, iommu_notifier); > - > - if (action == VFIO_IOMMU_NOTIFY_DMA_UNMAP) { > - struct vfio_iommu_type1_dma_unmap *unmap = data; > - struct gvt_dma *entry; > - unsigned long iov_pfn, end_iov_pfn; > + struct intel_vgpu *vgpu = vfio_dev_to_vgpu(vfio_dev); > + struct gvt_dma *entry; > + u64 iov_pfn = iova >> PAGE_SHIFT; > + u64 end_iov_pfn = iov_pfn + length / PAGE_SIZE; > > - iov_pfn = unmap->iova >> PAGE_SHIFT; > - end_iov_pfn = iov_pfn + unmap->size / PAGE_SIZE; > + mutex_lock(&vgpu->cache_lock); > + for (; iov_pfn < end_iov_pfn; iov_pfn++) { > + entry = __gvt_cache_find_gfn(vgpu, iov_pfn); > + if (!entry) > + continue; > > - mutex_lock(&vgpu->cache_lock); > - for (; iov_pfn < end_iov_pfn; iov_pfn++) { > - entry = __gvt_cache_find_gfn(vgpu, iov_pfn); > - if (!entry) > - continue; > - > - gvt_dma_unmap_page(vgpu, entry->gfn, entry->dma_addr, > -entry->size); > - __gvt_cache_remove_entry(vgpu, entry); > - } > - mutex_unlock(&vgpu->cache_lock); > + gvt_dma_unmap_page(vgpu, entry->gfn, entry->dma_addr, > +entry->size); > + __gvt_cache_remove_entry(vgpu, entry); > } > - > - return NOTIFY_OK; > + mutex_unlock(&vgpu->cache_lock); > } > > static bool __kvmgt_vgpu_exist(struct intel_vgpu *vgpu) > @@ -783,36 +774,20 @@ static bool __kvmgt_vgpu_exist(struct intel_vgpu *vgpu) > static int intel_vgpu_open_device(struct vfio_device *vfio_dev) > { > struct intel_vgpu *vgpu = vfio_dev_to_vgpu(vfio_dev); > - unsigned long events; > - int ret; > - > - vgpu->iommu_notifier.notifier_call = intel_vgpu_iommu_notifier; > > - events = VFIO_IOMMU_NOTIFY_DMA_UNMAP; > - ret = vfio_register_notifier(vfio_dev, VFIO_IOMMU_NOTIFY, &events, > - &vgpu->iommu_notifier); > - if (ret != 0) { > - gvt_vgpu_err("vfio_register_notifier for iommu failed: %d\n", > - ret); > - goto out; > - } > - > - ret = -EEXIST; > if (vgpu->attached) > - goto undo_iommu; > + return -EEXIST; > > - ret = -ESRCH; > if (!vgpu->vfio_device.kvm || > vgpu->vfio_device.kvm->mm != current->mm) { > gvt_vgpu_err("KVM is required to use Intel vGPU\n"); > - goto undo_iommu; > + return -ESRCH; > } > > kvm_get_kvm(vgpu->vfio_device.kvm); > > - ret = -EEXIST; > if (__kvmgt_vgpu_exist(vgpu)) > - goto un
Re: [Intel-gfx] [PATCH v3 1/2] vfio: Replace the DMA unmapping notifier with a callback
On Mon, 4 Jul 2022 21:59:03 -0300 Jason Gunthorpe wrote: > diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c > index b49e2e9db2dc6f..09e0ce7b72324c 100644 > --- a/drivers/s390/cio/vfio_ccw_ops.c > +++ b/drivers/s390/cio/vfio_ccw_ops.c > @@ -44,31 +44,19 @@ static int vfio_ccw_mdev_reset(struct vfio_ccw_private > *private) > return ret; > } > > -static int vfio_ccw_mdev_notifier(struct notifier_block *nb, > - unsigned long action, > - void *data) > +static void vfio_ccw_dma_unmap(struct vfio_device *vdev, u64 iova, u64 > length) > { > struct vfio_ccw_private *private = > - container_of(nb, struct vfio_ccw_private, nb); > - > - /* > - * Vendor drivers MUST unpin pages in response to an > - * invalidation. > - */ > - if (action == VFIO_IOMMU_NOTIFY_DMA_UNMAP) { > - struct vfio_iommu_type1_dma_unmap *unmap = data; > - > - if (!cp_iova_pinned(&private->cp, unmap->iova)) > - return NOTIFY_OK; > + container_of(vdev, struct vfio_ccw_private, vdev); > > - if (vfio_ccw_mdev_reset(private)) > - return NOTIFY_BAD; > + /* Drivers MUST unpin pages in response to an invalidation. */ > + if (!cp_iova_pinned(&private->cp, iova)) > + return; > > - cp_free(&private->cp); > - return NOTIFY_OK; > - } > + if (vfio_ccw_mdev_reset(private)) > + return; > > - return NOTIFY_DONE; > + cp_free(&private->cp); > } The cp_free() call is gone here with [1], so I think this function now just ends with: ... vfio_ccw_mdev_reset(private); } There are also minor contextual differences elsewhere from that series, so a quick respin to record the changes on list would be appreciated. However the above kind of highlights that NOTIFY_BAD that silently gets dropped here. I realize we weren't testing the return value of the notifier call chain and really we didn't intend that notifiers could return a failure here, but does this warrant some logging or suggest future work to allow a device to go offline here? Thanks. Alex [1]https://lore.kernel.org/all/20220707135737.720765-1-far...@linux.ibm.com/
Re: [Intel-gfx] [PATCH v3 1/2] vfio: Replace the DMA unmapping notifier with a callback
On Tue, Jul 19 2022, Jason Gunthorpe wrote: > On Thu, Jul 07, 2022 at 03:37:16PM -0600, Alex Williamson wrote: >> On Mon, 4 Jul 2022 21:59:03 -0300 >> Jason Gunthorpe wrote: >> > diff --git a/drivers/s390/cio/vfio_ccw_ops.c >> > b/drivers/s390/cio/vfio_ccw_ops.c >> > index b49e2e9db2dc6f..09e0ce7b72324c 100644 >> > --- a/drivers/s390/cio/vfio_ccw_ops.c >> > +++ b/drivers/s390/cio/vfio_ccw_ops.c >> > @@ -44,31 +44,19 @@ static int vfio_ccw_mdev_reset(struct vfio_ccw_private >> > *private) >> >return ret; >> > } >> > >> > -static int vfio_ccw_mdev_notifier(struct notifier_block *nb, >> > -unsigned long action, >> > -void *data) >> > +static void vfio_ccw_dma_unmap(struct vfio_device *vdev, u64 iova, u64 >> > length) >> > { >> >struct vfio_ccw_private *private = >> > - container_of(nb, struct vfio_ccw_private, nb); >> > - >> > - /* >> > - * Vendor drivers MUST unpin pages in response to an >> > - * invalidation. >> > - */ >> > - if (action == VFIO_IOMMU_NOTIFY_DMA_UNMAP) { >> > - struct vfio_iommu_type1_dma_unmap *unmap = data; >> > - >> > - if (!cp_iova_pinned(&private->cp, unmap->iova)) >> > - return NOTIFY_OK; >> > + container_of(vdev, struct vfio_ccw_private, vdev); >> > >> > - if (vfio_ccw_mdev_reset(private)) >> > - return NOTIFY_BAD; >> > + /* Drivers MUST unpin pages in response to an invalidation. */ >> > + if (!cp_iova_pinned(&private->cp, iova)) >> > + return; >> > >> > - cp_free(&private->cp); >> > - return NOTIFY_OK; >> > - } >> > + if (vfio_ccw_mdev_reset(private)) >> > + return; >> > >> > - return NOTIFY_DONE; >> > + cp_free(&private->cp); >> > } >> >> >> The cp_free() call is gone here with [1], so I think this function now >> just ends with: >> >> ... >> vfio_ccw_mdev_reset(private); >> } >> >> There are also minor contextual differences elsewhere from that series, >> so a quick respin to record the changes on list would be appreciated. >> >> However the above kind of highlights that NOTIFY_BAD that silently gets >> dropped here. I realize we weren't testing the return value of the >> notifier call chain and really we didn't intend that notifiers could >> return a failure here, but does this warrant some logging or suggest >> future work to allow a device to go offline here? Thanks. > > It looks like no. > > If the FSM trapped in a bad state here, such as > VFIO_CCW_STATE_NOT_OPER, then it means it should have already unpinned > the pages and this is considered a success for this purpose A rather pathological case would be a subchannel that cannot be quiesced and does not end up being non-operational; in theory, the hardware could still try to access the buffers we provided for I/O. I'd say that is extremely unlikely, we might log it, but really cannot do anything else. > > The return code here exists only to return to userspace so it can > detect during a VFIO_DEVICE_RESET that the device has crashed > irrecoverably. Does it imply only that ("it's dead, Jim"), or can it also imply a runaway device? Not that userspace can do much in any case. > > Thus just continuing to silently ignore it seems like the best thing. > > Jason