x86, PAT: Remove duplicate memtype reserve in pci mmap

pci mmap code was doing memtype reserve for a while now. Recently we
added memtype tracking in remap_pfn_range, and pci code indirectly calls
remap_pfn_range. So, we don't need seperate tracking in pci code
anymore. Which means a patch that removes ~50 lines of code :-).

Also, recently we found out that the pci tracking is not working as we expect
it to work in some cases. Specifically, userlevel X mmap of pci, with some
recent version of X, is having a problem with vm_page_prot getting reset.
The pci tracking uses vm_page_prot to pass on the protection type from parent
to child during fork.
a) Parent does a pci mmap
b) We look at PAT and get either UC_MINUS or WC mapping for parent
c) Store that mapping type in vma vm_page_prot for future use
d) This thread does a fork
e) Fork results in mmap_ops ->open for the child process
f) We get the vm_page_prot from vma and reserve that type for the child process

But, between c) and e) above, the vma vm_page_prot is getting reset to zero.
This results in PAT reserve failing at the time of fork as in here.
http://marc.info/?l=linux-kernel&m=123858163103240&w=2

This cleanup makes the above problem go away as we do not depend on
vm_page_prot in our PAT code anymore.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/x86/pci/i386.c

@@ -258,24 +258,7 @@ 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,
 	.access = generic_access_phys,
 };
 
@@ -283,11 +266,6 @@ 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;
-	int retval;
 
 	/* I/O space cannot be accessed via normal processor loads and
 	 * stores on this platform.
@@ -308,30 +286,6 @@ int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
 
 	vma->vm_page_prot = __pgprot(prot);
 
-	flags = pgprot_val(vma->vm_page_prot) & _PAGE_CACHE_MASK;
-	retval = reserve_memtype(addr, addr + len, flags, &new_flags);
-	if (retval)
-		return retval;
-
-	if (flags != new_flags) {
-		if (!is_new_memtype_allowed(flags, new_flags)) {
-			free_memtype(addr, addr+len);
-			return -EINVAL;
-		}
-		flags = new_flags;
-		vma->vm_page_prot = __pgprot(
-			(pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK) |
-			flags);
-	}
-
-	if (((vma->vm_pgoff < max_low_pfn_mapped) ||
-	     (vma->vm_pgoff >= (1UL<<(32 - PAGE_SHIFT)) &&
-	      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))