diff options
| -rw-r--r-- | arch/powerpc/platforms/powernv/npu-dma.c | 51 |
1 files changed, 42 insertions, 9 deletions
diff --git a/arch/powerpc/platforms/powernv/npu-dma.c b/arch/powerpc/platforms/powernv/npu-dma.c index 69a4f9e8bd55..5ff7c6e0e6da 100644 --- a/arch/powerpc/platforms/powernv/npu-dma.c +++ b/arch/powerpc/platforms/powernv/npu-dma.c @@ -34,6 +34,12 @@ #define npu_to_phb(x) container_of(x, struct pnv_phb, npu) /* + * spinlock to protect initialisation of an npu_context for a particular + * mm_struct. + */ +static DEFINE_SPINLOCK(npu_context_lock); + +/* * Other types of TCE cache invalidation are not functional in the * hardware. */ @@ -696,7 +702,8 @@ static const struct mmu_notifier_ops nv_nmmu_notifier_ops = { * Returns an error if there no contexts are currently available or a * npu_context which should be passed to pnv_npu2_handle_fault(). * - * mmap_sem must be held in write mode. + * mmap_sem must be held in write mode and must not be called from interrupt + * context. */ struct npu_context *pnv_npu2_init_context(struct pci_dev *gpdev, unsigned long flags, @@ -743,7 +750,9 @@ struct npu_context *pnv_npu2_init_context(struct pci_dev *gpdev, /* * Setup the NPU context table for a particular GPU. These need to be * per-GPU as we need the tables to filter ATSDs when there are no - * active contexts on a particular GPU. + * active contexts on a particular GPU. It is safe for these to be + * called concurrently with destroy as the OPAL call takes appropriate + * locks and refcounts on init/destroy. */ rc = opal_npu_init_context(nphb->opal_id, mm->context.id, flags, PCI_DEVID(gpdev->bus->number, gpdev->devfn)); @@ -754,8 +763,19 @@ struct npu_context *pnv_npu2_init_context(struct pci_dev *gpdev, * We store the npu pci device so we can more easily get at the * associated npus. */ + spin_lock(&npu_context_lock); npu_context = mm->context.npu_context; + if (npu_context) + WARN_ON(!kref_get_unless_zero(&npu_context->kref)); + spin_unlock(&npu_context_lock); + if (!npu_context) { + /* + * We can set up these fields without holding the + * npu_context_lock as the npu_context hasn't been returned to + * the caller meaning it can't be destroyed. Parallel allocation + * is protected against by mmap_sem. + */ rc = -ENOMEM; npu_context = kzalloc(sizeof(struct npu_context), GFP_KERNEL); if (npu_context) { @@ -774,8 +794,6 @@ struct npu_context *pnv_npu2_init_context(struct pci_dev *gpdev, } mm->context.npu_context = npu_context; - } else { - WARN_ON(!kref_get_unless_zero(&npu_context->kref)); } npu_context->release_cb = cb; @@ -814,15 +832,16 @@ static void pnv_npu2_release_context(struct kref *kref) mm_context_remove_copro(npu_context->mm); npu_context->mm->context.npu_context = NULL; - mmu_notifier_unregister(&npu_context->mn, - npu_context->mm); - - kfree(npu_context); } +/* + * Destroy a context on the given GPU. May free the npu_context if it is no + * longer active on any GPUs. Must not be called from interrupt context. + */ void pnv_npu2_destroy_context(struct npu_context *npu_context, struct pci_dev *gpdev) { + int removed; struct pnv_phb *nphb; struct npu *npu; struct pci_dev *npdev = pnv_pci_get_npu_dev(gpdev, 0); @@ -844,7 +863,21 @@ void pnv_npu2_destroy_context(struct npu_context *npu_context, WRITE_ONCE(npu_context->npdev[npu->index][nvlink_index], NULL); opal_npu_destroy_context(nphb->opal_id, npu_context->mm->context.id, PCI_DEVID(gpdev->bus->number, gpdev->devfn)); - kref_put(&npu_context->kref, pnv_npu2_release_context); + spin_lock(&npu_context_lock); + removed = kref_put(&npu_context->kref, pnv_npu2_release_context); + spin_unlock(&npu_context_lock); + + /* + * We need to do this outside of pnv_npu2_release_context so that it is + * outside the spinlock as mmu_notifier_destroy uses SRCU. + */ + if (removed) { + mmu_notifier_unregister(&npu_context->mn, + npu_context->mm); + + kfree(npu_context); + } + } EXPORT_SYMBOL(pnv_npu2_destroy_context); |