On Fri, 2017-05-19 at 15:32 +0530, arindam.nath at amd.com wrote: > From: Arindam Nath <arindam.nath at amd.com> > > Change History > -------------- > > v2: changes suggested by Joerg > - add flush flag to improve efficiency of flush operation > > v1: > - The idea behind flush queues is to defer the IOTLB flushing > for domains for which the mappings are no longer valid. We > add such domains in queue_add(), and when the queue size > reaches FLUSH_QUEUE_SIZE, we perform __queue_flush(). > > Since we have already taken lock before __queue_flush() > is called, we need to make sure the IOTLB flushing is > performed as quickly as possible. > > In the current implementation, we perform IOTLB flushing > for all domains irrespective of which ones were actually > added in the flush queue initially. This can be quite > expensive especially for domains for which unmapping is > not required at this point of time. > > This patch makes use of domain information in > 'struct flush_queue_entry' to make sure we only flush > IOTLBs for domains who need it, skipping others. Hi, just a note, the patch also fixes "AMD-Vi: Completion-Wait loop timed out" boot hang on my system (carrizo + iceland) [0,1,2]. Presumably the old loop also tried to flush domains that included powered-off devices. regards, Jan [0] https://github.com/RadeonOpenCompute/ROCK-Kernel-Driver/issues/20 [1] https://bugs.freedesktop.org/show_bug.cgi?id=101029 [2] https://bugzilla.redhat.com/show_bug.cgi?id=1448121 > > Suggested-by: Joerg Roedel <joro at 8bytes.org> > Signed-off-by: Arindam Nath <arindam.nath at amd.com> > --- > drivers/iommu/amd_iommu.c | 27 ++++++++++++++++++++------- > drivers/iommu/amd_iommu_types.h | 2 ++ > 2 files changed, 22 insertions(+), 7 deletions(-) > > diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c > index 63cacf5..1edeebec 100644 > --- a/drivers/iommu/amd_iommu.c > +++ b/drivers/iommu/amd_iommu.c > @@ -2227,15 +2227,26 @@ static struct iommu_group *amd_iommu_device_group(struct device *dev) > > static void __queue_flush(struct flush_queue *queue) > { > - struct protection_domain *domain; > - unsigned long flags; > int idx; > > - /* First flush TLB of all known domains */ > - spin_lock_irqsave(&amd_iommu_pd_lock, flags); > - list_for_each_entry(domain, &amd_iommu_pd_list, list) > - domain_flush_tlb(domain); > - spin_unlock_irqrestore(&amd_iommu_pd_lock, flags); > + /* First flush TLB of all domains which were added to flush queue */ > + for (idx = 0; idx < queue->next; ++idx) { > + struct flush_queue_entry *entry; > + > + entry = queue->entries + idx; > + > + /* > + * There might be cases where multiple IOVA entries for the > + * same domain are queued in the flush queue. To avoid > + * flushing the same domain again, we check whether the > + * flag is set or not. This improves the efficiency of > + * flush operation. > + */ > + if (!entry->dma_dom->domain.already_flushed) { > + entry->dma_dom->domain.already_flushed = true; > + domain_flush_tlb(&entry->dma_dom->domain); > + } > + } > > /* Wait until flushes have completed */ > domain_flush_complete(NULL); > @@ -2289,6 +2300,8 @@ static void queue_add(struct dma_ops_domain *dma_dom, > pages = __roundup_pow_of_two(pages); > address >>= PAGE_SHIFT; > > + dma_dom->domain.already_flushed = false; > + > queue = get_cpu_ptr(&flush_queue); > spin_lock_irqsave(&queue->lock, flags); > > diff --git a/drivers/iommu/amd_iommu_types.h b/drivers/iommu/amd_iommu_types.h > index 4de8f41..4f5519d 100644 > --- a/drivers/iommu/amd_iommu_types.h > +++ b/drivers/iommu/amd_iommu_types.h > @@ -454,6 +454,8 @@ struct protection_domain { > bool updated; /* complete domain flush required */ > unsigned dev_cnt; /* devices assigned to this domain */ > unsigned dev_iommu[MAX_IOMMUS]; /* per-IOMMU reference count */ > + bool already_flushed; /* flag to avoid flushing the same domain again > + in a single invocation of __queue_flush() */ > }; > > /* -- Jan Vesely <jan.vesely at rutgers.edu> -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 833 bytes Desc: This is a digitally signed message part URL: <https://lists.freedesktop.org/archives/amd-gfx/attachments/20170519/31d831cd/attachment.sig>
