intel-iommu: Performance improvement for dma_pte_free_pagetable()

As with other functions, batch the CPU data cache flushes and don't keep
recalculating PTE addresses.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index 35bdd2a..ec7e032 100644 (file)
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -797,7 +797,7 @@ static void dma_pte_free_pagetable(struct dmar_domain *domain,
                                   unsigned long last_pfn)
 {
        int addr_width = agaw_to_width(domain->agaw) - VTD_PAGE_SHIFT;
-       struct dma_pte *pte;
+       struct dma_pte *first_pte, *pte;
        int total = agaw_to_level(domain->agaw);
        int level;
        unsigned long tmp;
@@ -805,25 +805,32 @@ static void dma_pte_free_pagetable(struct dmar_domain *domain,
        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 */
+       /* We don't need lock here; nobody else touches the iova range */
        level = 2;
        while (level <= total) {
                tmp = align_to_level(start_pfn, level);
 
-               /* Only clear this pte/pmd if we're asked to clear its
-                  _whole_ range */
+               /* If we can't even clear one PTE at this level, we're done */
                if (tmp + level_size(level) - 1 > last_pfn)
                        return;
 
                while (tmp + level_size(level) - 1 <= last_pfn) {
-                       pte = dma_pfn_level_pte(domain, tmp, level);
-                       if (pte) {
-                               free_pgtable_page(
-                                       phys_to_virt(dma_pte_addr(pte)));
+                       first_pte = pte = dma_pfn_level_pte(domain, tmp, level);
+                       if (!pte) {
+                               tmp = align_to_level(tmp + 1, level + 1);
+                               continue;
+                       }
+                       while (tmp + level_size(level) - 1 <= last_pfn &&
+                              (unsigned long)pte >> VTD_PAGE_SHIFT ==
+                              (unsigned long)first_pte >> VTD_PAGE_SHIFT) {
+                               free_pgtable_page(phys_to_virt(dma_pte_addr(pte)));
                                dma_clear_pte(pte);
-                               domain_flush_cache(domain, pte, sizeof(*pte));
+                               pte++;
+                               tmp += level_size(level);
                        }
-                       tmp += level_size(level);
+                       domain_flush_cache(domain, first_pte,
+                                          (void *)pte - (void *)first_pte);
+                       
                }
                level++;
        }