x86: PAT use reserve free memtype in pci_mmap_page_range

Add reserve_memtype and free_memtype wrapper for pci_mmap_page_range. Free
is called on unmap, but identity map continues to be mapped as per
pci_mmap_page_range request, until next request for the same region calls
ioremap_change_attr(), which will go through without conflict. This way of
mapping is identical to one used in ioremap/iounmap.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 60 insertions, 8 deletions

diff --git a/arch/x86/pci/i386.c b/arch/x86/pci/i386.c
index 103b9dff1213..4ebf52f6b1fd 100644
--- a/arch/x86/pci/i386.c
+++ b/arch/x86/pci/i386.c
@@ -30,6 +30,9 @@
 #include <linux/init.h>
 #include <linux/ioport.h>
 #include <linux/errno.h>
+#include <linux/bootmem.h>
+
+#include <asm/pat.h>
 
 #include "pci.h"
 
@@ -297,10 +300,34 @@ void pcibios_set_master(struct pci_dev *dev)
         pci_write_config_byte(dev, PCI_LATENCY_TIMER, lat);
 }
 
+static void pci_unmap_page_range(struct vm_area_struct *vma)
+{
+        u64 addr = (u64)vma->vm_pgoff << PAGE_SHIFT;
+        free_memtype(addr, addr + vma->vm_end - vma->vm_start);
+}
+
+static void pci_track_mmap_page_range(struct vm_area_struct *vma)
+{
+        u64 addr = (u64)vma->vm_pgoff << PAGE_SHIFT;
+        unsigned long flags = pgprot_val(vma->vm_page_prot)
+                                                & _PAGE_CACHE_MASK;
+
+        reserve_memtype(addr, addr + vma->vm_end - vma->vm_start, flags, NULL);
+}
+
+static struct vm_operations_struct pci_mmap_ops = {
+        .open  = pci_track_mmap_page_range,
+        .close = pci_unmap_page_range,
+};
+
 int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
                         enum pci_mmap_state mmap_state, int write_combine)
 {
         unsigned long prot;
+        u64 addr = vma->vm_pgoff << PAGE_SHIFT;
+        unsigned long len = vma->vm_end - vma->vm_start;
+        unsigned long flags;
+        unsigned long new_flags;
 
         /* I/O space cannot be accessed via normal processor loads and
          * stores on this platform.
@@ -308,21 +335,46 @@ int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
         if (mmap_state == pci_mmap_io)
                 return -EINVAL;
 
-        /* Leave vm_pgoff as-is, the PCI space address is the physical
-         * address on this platform.
-         */
         prot = pgprot_val(vma->vm_page_prot);
-        if (boot_cpu_data.x86 > 3)
-                prot |= _PAGE_PCD | _PAGE_PWT;
+        if (pat_wc_enabled && write_combine)
+                prot |= _PAGE_CACHE_WC;
+        else if (boot_cpu_data.x86 > 3)
+                prot |= _PAGE_CACHE_UC;
+
         vma->vm_page_prot = __pgprot(prot);
 
-        /* Write-combine setting is ignored, it is changed via the mtrr
-         * interfaces on this platform.
-         */
+        flags = pgprot_val(vma->vm_page_prot) & _PAGE_CACHE_MASK;
+        if (reserve_memtype(addr, addr + len, flags, &new_flags)) {
+                /*
+                 * Do not fallback to certain memory types with certain
+                 * requested type:
+                 * - request is uncached, return cannot be write-back
+                 * - request is uncached, return cannot be write-combine
+                 * - request is write-combine, return cannot be write-back
+                 */
+                if ((flags == _PAGE_CACHE_UC &&
+                     (new_flags == _PAGE_CACHE_WB ||
+                      new_flags == _PAGE_CACHE_WC)) ||
+                    (flags == _PAGE_CACHE_WC &&
+                     new_flags == _PAGE_CACHE_WB)) {
+                        free_memtype(addr, addr+len);
+                        return -EINVAL;
+                }
+                flags = new_flags;
+        }
+
+        if (vma->vm_pgoff <= max_pfn_mapped &&
+            ioremap_change_attr((unsigned long)__va(addr), len, flags)) {
+                free_memtype(addr, addr + len);
+                return -EINVAL;
+        }
+
         if (io_remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
                                vma->vm_end - vma->vm_start,
                                vma->vm_page_prot))
                 return -EAGAIN;
 
+        vma->vm_ops = &pci_mmap_ops;
+
         return 0;
 }