intel-iommu: Performance improvement for domain_pfn_mapping()

As with dma_pte_clear_range(), don't keep flushing a single PTE at a
time. And also micro-optimise the setting of PTE values rather than
using the helper functions to do all the masking.

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

diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index ba7e37f..f807423 100644 (file)
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -1639,7 +1639,7 @@ static int domain_pfn_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
                              unsigned long phys_pfn, unsigned long nr_pages,
                              int prot)
 {
-       struct dma_pte *pte;
+       struct dma_pte *first_pte = NULL, *pte = NULL;
        int addr_width = agaw_to_width(domain->agaw) - VTD_PAGE_SHIFT;
 
        BUG_ON(addr_width < BITS_PER_LONG && (iov_pfn + nr_pages - 1) >> addr_width);
@@ -1647,19 +1647,27 @@ static int domain_pfn_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
        if ((prot & (DMA_PTE_READ|DMA_PTE_WRITE)) == 0)
                return -EINVAL;
 
+       prot &= DMA_PTE_READ | DMA_PTE_WRITE | DMA_PTE_SNP;
+
        while (nr_pages--) {
-               pte = pfn_to_dma_pte(domain, iov_pfn);
-               if (!pte)
-                       return -ENOMEM;
+               if (!pte) {
+                       first_pte = pte = pfn_to_dma_pte(domain, iov_pfn);
+                       if (!pte)
+                               return -ENOMEM;
+               }
                /* We don't need lock here, nobody else
                 * touches the iova range
                 */
                BUG_ON(dma_pte_addr(pte));
-               dma_set_pte_pfn(pte, phys_pfn);
-               dma_set_pte_prot(pte, prot);
-               if (prot & DMA_PTE_SNP)
-                       dma_set_pte_snp(pte);
-               domain_flush_cache(domain, pte, sizeof(*pte));
+               pte->val = (phys_pfn << VTD_PAGE_SHIFT) | prot;
+               pte++;
+               if (!nr_pages ||
+                   (unsigned long)pte >> VTD_PAGE_SHIFT !=
+                   (unsigned long)first_pte >> VTD_PAGE_SHIFT) {
+                       domain_flush_cache(domain, first_pte,
+                                          (void *)pte - (void *)first_pte);
+                       pte = NULL;
+               }
                iov_pfn++;
                phys_pfn++;
        }