From 310a5ab93cb4ce29367238f682affd9ac352f4d0 Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Sun, 28 Jun 2009 18:52:20 +0100 Subject: [PATCH] intel-iommu: Performance improvement for dma_pte_clear_range() It's a bit silly to repeatedly call domain_flush_cache() for each PTE individually, as we clear it. Instead, batch them up and flush a whole range at a time. We might as well refrain from recalculating the PTE address from scratch each time round the loop too. Signed-off-by: David Woodhouse --- drivers/pci/intel-iommu.c | 31 +++++++++++++++---------------- 1 file changed, 15 insertions(+), 16 deletions(-) diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c index c5caf7d63a0..ba7e37f7111 100644 --- a/drivers/pci/intel-iommu.c +++ b/drivers/pci/intel-iommu.c @@ -761,34 +761,33 @@ static struct dma_pte *dma_pfn_level_pte(struct dmar_domain *domain, return NULL; } -/* clear one page's page table */ -static void dma_pte_clear_one(struct dmar_domain *domain, unsigned long pfn) -{ - struct dma_pte *pte = NULL; - - /* get last level pte */ - pte = dma_pfn_level_pte(domain, pfn, 1); - - if (pte) { - dma_clear_pte(pte); - domain_flush_cache(domain, pte, sizeof(*pte)); - } -} - /* clear last level pte, a tlb flush should be followed */ static void dma_pte_clear_range(struct dmar_domain *domain, unsigned long start_pfn, unsigned long last_pfn) { int addr_width = agaw_to_width(domain->agaw) - VTD_PAGE_SHIFT; + struct dma_pte *first_pte, *pte; BUG_ON(addr_width < BITS_PER_LONG && start_pfn >> addr_width); BUG_ON(addr_width < BITS_PER_LONG && last_pfn >> addr_width); /* we don't need lock here; nobody else touches the iova range */ while (start_pfn <= last_pfn) { - dma_pte_clear_one(domain, start_pfn); - start_pfn++; + first_pte = pte = dma_pfn_level_pte(domain, start_pfn, 1); + if (!pte) { + start_pfn = align_to_level(start_pfn + 1, 2); + continue; + } + while (start_pfn <= last_pfn && + (unsigned long)pte >> VTD_PAGE_SHIFT == + (unsigned long)first_pte >> VTD_PAGE_SHIFT) { + dma_clear_pte(pte); + start_pfn++; + pte++; + } + domain_flush_cache(domain, first_pte, + (void *)pte - (void *)first_pte); } } -- 2.44.2