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>

1 files changed, 17 insertions, 9 deletions

diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index ba7e37f7111a..f8074236bcce 100644
--- 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++;
         }