dax: support for transparent PUD pages for device DAX

Add transparent huge PUD pages support for device DAX by adding a
pud_fault handler.

Link: http://lkml.kernel.org/r/148545060002.17912.6765687780007547551.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Nilesh Choudhury <nilesh.choudhury@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/dax/dax.c b/drivers/dax/dax.c
index 922ec46..b90bb30 100644 (file)
--- a/drivers/dax/dax.c
+++ b/drivers/dax/dax.c
@@ -493,6 +493,51 @@ static int __dax_dev_pmd_fault(struct dax_dev *dax_dev, struct vm_fault *vmf)
                        vmf->flags & FAULT_FLAG_WRITE);
 }
 
+#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
+static int __dax_dev_pud_fault(struct dax_dev *dax_dev, struct vm_fault *vmf)
+{
+       unsigned long pud_addr = vmf->address & PUD_MASK;
+       struct device *dev = &dax_dev->dev;
+       struct dax_region *dax_region;
+       phys_addr_t phys;
+       pgoff_t pgoff;
+       pfn_t pfn;
+
+       if (check_vma(dax_dev, vmf->vma, __func__))
+               return VM_FAULT_SIGBUS;
+
+       dax_region = dax_dev->region;
+       if (dax_region->align > PUD_SIZE) {
+               dev_dbg(dev, "%s: alignment > fault size\n", __func__);
+               return VM_FAULT_SIGBUS;
+       }
+
+       /* dax pud mappings require pfn_t_devmap() */
+       if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) != (PFN_DEV|PFN_MAP)) {
+               dev_dbg(dev, "%s: alignment > fault size\n", __func__);
+               return VM_FAULT_SIGBUS;
+       }
+
+       pgoff = linear_page_index(vmf->vma, pud_addr);
+       phys = pgoff_to_phys(dax_dev, pgoff, PUD_SIZE);
+       if (phys == -1) {
+               dev_dbg(dev, "%s: phys_to_pgoff(%#lx) failed\n", __func__,
+                               pgoff);
+               return VM_FAULT_SIGBUS;
+       }
+
+       pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
+
+       return vmf_insert_pfn_pud(vmf->vma, vmf->address, vmf->pud, pfn,
+                       vmf->flags & FAULT_FLAG_WRITE);
+}
+#else
+static int __dax_dev_pud_fault(struct dax_dev *dax_dev, struct vm_fault *vmf)
+{
+       return VM_FAULT_FALLBACK;
+}
+#endif /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
+
 static int dax_dev_fault(struct vm_fault *vmf)
 {
        int rc;
@@ -512,6 +557,9 @@ static int dax_dev_fault(struct vm_fault *vmf)
        case FAULT_FLAG_SIZE_PMD:
                rc = __dax_dev_pmd_fault(dax_dev, vmf);
                break;
+       case FAULT_FLAG_SIZE_PUD:
+               rc = __dax_dev_pud_fault(dax_dev, vmf);
+               break;
        default:
                return VM_FAULT_FALLBACK;
        }