>-----Original Message----- >From: Daniel Drake [mailto:drake at endlessm.com] >Sent: Monday, March 27, 2017 5:56 PM >To: Nath, Arindam >Cc: joro at 8bytes.org; Deucher, Alexander; Bridgman, John; amd- >gfx at lists.freedesktop.org; iommu at lists.linux-foundation.org; Suthikulpanit, >Suravee; Linux Upstreaming Team >Subject: Re: [PATCH] iommu/amd: flush IOTLB for specific domains only > >Hi Arindam, > >You CC'd me on this - does this mean that it is a fix for the issue >described in the thread "amd-iommu: can't boot with amdgpu, AMD-Vi: >Completion-Wait loop timed out" ? Yes Daniel, please test this patch to confirm if the issue gets resolved. Thanks, Arindam > >Thanks >Daniel > > >On Mon, Mar 27, 2017 at 12:17 AM, <arindam.nath at amd.com> wrote: >> From: Arindam Nath <arindam.nath at amd.com> >> >> 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 for domains for which the mappings are no longer valid.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. >> >> Signed-off-by: Arindam Nath <arindam.nath at amd.com> >> --- >> drivers/iommu/amd_iommu.c | 15 ++++++++------- >> 1 file changed, 8 insertions(+), 7 deletions(-) >> >> diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c >> index 98940d1..6a9a048 100644 >> --- a/drivers/iommu/amd_iommu.c >> +++ b/drivers/iommu/amd_iommu.c >> @@ -2227,15 +2227,16 @@ 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; >> + >> + domain_flush_tlb(&entry->dma_dom->domain); >> + } >> >> /* Wait until flushes have completed */ >> domain_flush_complete(NULL); >> -- >> 1.9.1 >>
