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Subject[PATCH v2 02/10] x86, pat: separate the pfn attribute tracking for remap_pfn_range and vm_insert_pfn
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From: Suresh Siddha <suresh.b.siddha@intel.com>

With PAT enabled, vm_insert_pfn() looks up the existing pfn memory attribute
and uses it. Expectation is that the driver reserves the memory attributes
for the pfn before calling vm_insert_pfn().

remap_pfn_range() (when called for the whole vma) will setup a
new attribute (based on the prot argument) for the specified pfn range. This
addresses the legacy usage which typically calls remap_pfn_range() with
a desired memory attribute. For ranges smaller than the vma size (which
is typically not the case), remap_pfn_range() will use the
existing memory attribute for the pfn range.

Expose two different API's for these different behaviors.
track_pfn_insert() for tracking the pfn attribute set by
vm_insert_pfn() and track_pfn_remap() for the remap_pfn_range().

This cleanup also prepares the ground for the track/untrack pfn vma routines
to take over the ownership of setting PAT specific vm_flag in the 'vma'.

[khlebnikov@openvz.org: Clear checks in track_pfn_remap()]

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Venkatesh Pallipadi <venki@google.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Ingo Molnar <mingo@redhat.com>
---
arch/x86/mm/pat.c | 49 ++++++++++++++++++++++++++++---------
include/asm-generic/pgtable.h | 55 ++++++++++++++++++++++++-----------------
mm/memory.c | 13 ++++------
3 files changed, 75 insertions(+), 42 deletions(-)

diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 86d6590..d5b6759 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -652,13 +652,13 @@ static void free_pfn_range(u64 paddr, unsigned long size)
}

/*
- * track_pfn_vma_copy is called when vma that is covering the pfnmap gets
+ * track_pfn_copy is called when vma that is covering the pfnmap gets
* copied through copy_page_range().
*
* If the vma has a linear pfn mapping for the entire range, we get the prot
* from pte and reserve the entire vma range with single reserve_pfn_range call.
*/
-int track_pfn_vma_copy(struct vm_area_struct *vma)
+int track_pfn_copy(struct vm_area_struct *vma)
{
resource_size_t paddr;
unsigned long prot;
@@ -682,15 +682,12 @@ int track_pfn_vma_copy(struct vm_area_struct *vma)
}

/*
- * track_pfn_vma_new is called when a _new_ pfn mapping is being established
- * for physical range indicated by pfn and size.
- *
* prot is passed in as a parameter for the new mapping. If the vma has a
* linear pfn mapping for the entire range reserve the entire vma range with
* single reserve_pfn_range call.
*/
-int track_pfn_vma_new(struct vm_area_struct *vma, pgprot_t *prot,
- unsigned long pfn, unsigned long size)
+int track_pfn_remap(struct vm_area_struct *vma, pgprot_t *prot,
+ unsigned long pfn, unsigned long size)
{
resource_size_t paddr = (resource_size_t)pfn << PAGE_SHIFT;
unsigned long flags;
@@ -702,8 +699,38 @@ int track_pfn_vma_new(struct vm_area_struct *vma, pgprot_t *prot,
if (!pat_enabled)
return 0;

- /* for vm_insert_pfn and friends, we set prot based on lookup */
+ /*
+ * for anything smaller than the vma size,
+ * we set prot based on the lookup.
+ */
flags = lookup_memtype(paddr);
+
+ /*
+ * Check memtype for the rest pages
+ */
+ while (size > PAGE_SIZE) {
+ size -= PAGE_SIZE;
+ paddr += PAGE_SIZE;
+ if (flags != lookup_memtype(paddr))
+ return -EINVAL;
+ }
+
+ *prot = __pgprot((pgprot_val(vma->vm_page_prot) & (~_PAGE_CACHE_MASK)) |
+ flags);
+
+ return 0;
+}
+
+int track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot,
+ unsigned long pfn)
+{
+ unsigned long flags;
+
+ if (!pat_enabled)
+ return 0;
+
+ /* we set prot based on lookup */
+ flags = lookup_memtype((resource_size_t)pfn << PAGE_SHIFT);
*prot = __pgprot((pgprot_val(vma->vm_page_prot) & (~_PAGE_CACHE_MASK)) |
flags);

@@ -711,12 +738,12 @@ int track_pfn_vma_new(struct vm_area_struct *vma, pgprot_t *prot,
}

/*
- * untrack_pfn_vma is called while unmapping a pfnmap for a region.
+ * untrack_pfn is called while unmapping a pfnmap for a region.
* untrack can be called for a specific region indicated by pfn and size or
* can be for the entire vma (in which case pfn, size are zero).
*/
-void untrack_pfn_vma(struct vm_area_struct *vma, unsigned long pfn,
- unsigned long size)
+void untrack_pfn(struct vm_area_struct *vma, unsigned long pfn,
+ unsigned long size)
{
resource_size_t paddr;
unsigned long prot;
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 125c54e..a877649 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -382,48 +382,57 @@ static inline void ptep_modify_prot_commit(struct mm_struct *mm,

#ifndef __HAVE_PFNMAP_TRACKING
/*
- * Interface that can be used by architecture code to keep track of
- * memory type of pfn mappings (remap_pfn_range, vm_insert_pfn)
- *
- * track_pfn_vma_new is called when a _new_ pfn mapping is being established
- * for physical range indicated by pfn and size.
+ * Interfaces that can be used by architecture code to keep track of
+ * memory type of pfn mappings specified by the remap_pfn_range,
+ * vm_insert_pfn.
+ */
+
+/*
+ * track_pfn_remap is called when a _new_ pfn mapping is being established
+ * by remap_pfn_range() for physical range indicated by pfn and size.
*/
-static inline int track_pfn_vma_new(struct vm_area_struct *vma, pgprot_t *prot,
- unsigned long pfn, unsigned long size)
+static inline int track_pfn_remap(struct vm_area_struct *vma, pgprot_t *prot,
+ unsigned long pfn, unsigned long size)
{
return 0;
}

/*
- * Interface that can be used by architecture code to keep track of
- * memory type of pfn mappings (remap_pfn_range, vm_insert_pfn)
- *
- * track_pfn_vma_copy is called when vma that is covering the pfnmap gets
+ * track_pfn_insert is called when a _new_ single pfn is established
+ * by vm_insert_pfn().
+ */
+static inline int track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot,
+ unsigned long pfn)
+{
+ return 0;
+}
+
+/*
+ * track_pfn_copy is called when vma that is covering the pfnmap gets
* copied through copy_page_range().
*/
-static inline int track_pfn_vma_copy(struct vm_area_struct *vma)
+static inline int track_pfn_copy(struct vm_area_struct *vma)
{
return 0;
}

/*
- * Interface that can be used by architecture code to keep track of
- * memory type of pfn mappings (remap_pfn_range, vm_insert_pfn)
- *
* untrack_pfn_vma is called while unmapping a pfnmap for a region.
* untrack can be called for a specific region indicated by pfn and size or
- * can be for the entire vma (in which case size can be zero).
+ * can be for the entire vma (in which case pfn, size are zero).
*/
-static inline void untrack_pfn_vma(struct vm_area_struct *vma,
- unsigned long pfn, unsigned long size)
+static inline void untrack_pfn(struct vm_area_struct *vma,
+ unsigned long pfn, unsigned long size)
{
}
#else
-extern int track_pfn_vma_new(struct vm_area_struct *vma, pgprot_t *prot,
- unsigned long pfn, unsigned long size);
-extern int track_pfn_vma_copy(struct vm_area_struct *vma);
-extern void untrack_pfn_vma(struct vm_area_struct *vma, unsigned long pfn,
- unsigned long size);
+extern int track_pfn_remap(struct vm_area_struct *vma, pgprot_t *prot,
+ unsigned long pfn, unsigned long size);
+extern int track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot,
+ unsigned long pfn);
+extern int track_pfn_copy(struct vm_area_struct *vma);
+extern void untrack_pfn(struct vm_area_struct *vma, unsigned long pfn,
+ unsigned long size);
#endif

#ifdef CONFIG_MMU
diff --git a/mm/memory.c b/mm/memory.c
index 6105f47..4cdcf53 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1056,7 +1056,7 @@ int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
* We do not free on error cases below as remove_vma
* gets called on error from higher level routine
*/
- ret = track_pfn_vma_copy(vma);
+ ret = track_pfn_copy(vma);
if (ret)
return ret;
}
@@ -1311,7 +1311,7 @@ static void unmap_single_vma(struct mmu_gather *tlb,
*nr_accounted += (end - start) >> PAGE_SHIFT;

if (unlikely(is_pfn_mapping(vma)))
- untrack_pfn_vma(vma, 0, 0);
+ untrack_pfn(vma, 0, 0);

if (start != end) {
if (unlikely(is_vm_hugetlb_page(vma))) {
@@ -2145,14 +2145,11 @@ int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,

if (addr < vma->vm_start || addr >= vma->vm_end)
return -EFAULT;
- if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE))
+ if (track_pfn_insert(vma, &pgprot, pfn))
return -EINVAL;

ret = insert_pfn(vma, addr, pfn, pgprot);

- if (ret)
- untrack_pfn_vma(vma, pfn, PAGE_SIZE);
-
return ret;
}
EXPORT_SYMBOL(vm_insert_pfn);
@@ -2294,7 +2291,7 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,

vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;

- err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size));
+ err = track_pfn_remap(vma, &prot, pfn, PAGE_ALIGN(size));
if (err) {
/*
* To indicate that track_pfn related cleanup is not
@@ -2318,7 +2315,7 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
} while (pgd++, addr = next, addr != end);

if (err)
- untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size));
+ untrack_pfn(vma, pfn, PAGE_ALIGN(size));

return err;
}


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