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Date: Wed, 20 Apr 2016 18:18:58 +0200 From: Eric Auger <eric.auger@...aro.org> To: Robin Murphy <robin.murphy@....com>, eric.auger@...com, alex.williamson@...hat.com, will.deacon@....com, joro@...tes.org, tglx@...utronix.de, jason@...edaemon.net, marc.zyngier@....com, christoffer.dall@...aro.org, linux-arm-kernel@...ts.infradead.org Cc: patches@...aro.org, linux-kernel@...r.kernel.org, Bharat.Bhushan@...escale.com, pranav.sawargaonkar@...il.com, p.fedin@...sung.com, iommu@...ts.linux-foundation.org, Jean-Philippe.Brucker@....com, julien.grall@....com Subject: Re: [PATCH v7 05/10] iommu/dma-reserved-iommu: reserved binding rb-tree and helpers Robin, On 04/20/2016 03:12 PM, Robin Murphy wrote: > On 19/04/16 17:56, Eric Auger wrote: >> we will need to track which host physical addresses are mapped to >> reserved IOVA. In that prospect we introduce a new RB tree indexed >> by physical address. This RB tree only is used for reserved IOVA >> bindings. >> >> It is expected this RB tree will contain very few bindings. > > Sounds like a good reason in favour of using a list, and thus having > rather less code here ;) OK will move to a simple list. > >> Those >> generally correspond to single page mapping one MSI frame (GICv2m >> frame or ITS GITS_TRANSLATER frame). >> >> Signed-off-by: Eric Auger <eric.auger@...aro.org> >> >> --- >> v5 -> v6: >> - add comment about @d->reserved_lock to be held >> >> v3 -> v4: >> - that code was formerly in "iommu/arm-smmu: add a reserved binding RB >> tree" >> --- >> drivers/iommu/dma-reserved-iommu.c | 63 >> ++++++++++++++++++++++++++++++++++++++ >> 1 file changed, 63 insertions(+) >> >> diff --git a/drivers/iommu/dma-reserved-iommu.c >> b/drivers/iommu/dma-reserved-iommu.c >> index 2562af0..f6fa18e 100644 >> --- a/drivers/iommu/dma-reserved-iommu.c >> +++ b/drivers/iommu/dma-reserved-iommu.c >> @@ -23,6 +23,69 @@ struct reserved_iova_domain { >> int prot; /* iommu protection attributes to be obeyed */ >> }; >> >> +struct iommu_reserved_binding { >> + struct kref kref; >> + struct rb_node node; >> + struct iommu_domain *domain; > > Hang on, the tree these are in is already embedded in a domain. Ergo we > can't look them up without first knowing the domain they belong to, so > what purpose does this guy serve? this is used on the kref_put. The release function takes a kref; then we get the container to retrieve the binding and storing the domain here enables to unlink the node. Best Regards Eric > > Robin. > >> + phys_addr_t addr; >> + dma_addr_t iova; >> + size_t size; >> +}; >> + >> +/* Reserved binding RB-tree manipulation */ >> + >> +/* @d->reserved_lock must be held */ >> +static struct iommu_reserved_binding *find_reserved_binding( >> + struct iommu_domain *d, >> + phys_addr_t start, size_t size) >> +{ >> + struct rb_node *node = d->reserved_binding_list.rb_node; >> + >> + while (node) { >> + struct iommu_reserved_binding *binding = >> + rb_entry(node, struct iommu_reserved_binding, node); >> + >> + if (start + size <= binding->addr) >> + node = node->rb_left; >> + else if (start >= binding->addr + binding->size) >> + node = node->rb_right; >> + else >> + return binding; >> + } >> + >> + return NULL; >> +} >> + >> +/* @d->reserved_lock must be held */ >> +static void link_reserved_binding(struct iommu_domain *d, >> + struct iommu_reserved_binding *new) >> +{ >> + struct rb_node **link = &d->reserved_binding_list.rb_node; >> + struct rb_node *parent = NULL; >> + struct iommu_reserved_binding *binding; >> + >> + while (*link) { >> + parent = *link; >> + binding = rb_entry(parent, struct iommu_reserved_binding, >> + node); >> + >> + if (new->addr + new->size <= binding->addr) >> + link = &(*link)->rb_left; >> + else >> + link = &(*link)->rb_right; >> + } >> + >> + rb_link_node(&new->node, parent, link); >> + rb_insert_color(&new->node, &d->reserved_binding_list); >> +} >> + >> +/* @d->reserved_lock must be held */ >> +static void unlink_reserved_binding(struct iommu_domain *d, >> + struct iommu_reserved_binding *old) >> +{ >> + rb_erase(&old->node, &d->reserved_binding_list); >> +} >> + >> int iommu_alloc_reserved_iova_domain(struct iommu_domain *domain, >> dma_addr_t iova, size_t size, int prot, >> unsigned long order) >> >
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