4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dexuan Cui <[email protected]>

commit bf70e5513dfea29c3682e7eb3dbb45f0723bac09 upstream.

"d1cd12108346: x86, pageattr: Prevent overflow in slow_virt_to_phys() for
X86_PAE" was unintentionally removed by the recent "34437e67a672: x86/mm: Fix
slow_virt_to_phys() to handle large PAT bit".

And, the variable 'phys_addr' was defined as "unsigned long" by mistake -- it 
should
be "phys_addr_t".

As a result, Hyper-V network driver in 32-PAE Linux guest can't work again.

Fixes: commit 34437e67a672: "x86/mm: Fix slow_virt_to_phys() to handle large 
PAT bit"
Signed-off-by: Dexuan Cui <[email protected]>
Reviewed-by: Toshi Kani <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: Andrew Morton <[email protected]>
Cc: K. Y. Srinivasan <[email protected]>
Cc: Haiyang Zhang <[email protected]>
Link: 
http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 arch/x86/mm/pageattr.c |   14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -414,24 +414,30 @@ pmd_t *lookup_pmd_address(unsigned long
 phys_addr_t slow_virt_to_phys(void *__virt_addr)
 {
        unsigned long virt_addr = (unsigned long)__virt_addr;
-       unsigned long phys_addr, offset;
+       phys_addr_t phys_addr;
+       unsigned long offset;
        enum pg_level level;
        pte_t *pte;
 
        pte = lookup_address(virt_addr, &level);
        BUG_ON(!pte);
 
+       /*
+        * pXX_pfn() returns unsigned long, which must be cast to phys_addr_t
+        * before being left-shifted PAGE_SHIFT bits -- this trick is to
+        * make 32-PAE kernel work correctly.
+        */
        switch (level) {
        case PG_LEVEL_1G:
-               phys_addr = pud_pfn(*(pud_t *)pte) << PAGE_SHIFT;
+               phys_addr = (phys_addr_t)pud_pfn(*(pud_t *)pte) << PAGE_SHIFT;
                offset = virt_addr & ~PUD_PAGE_MASK;
                break;
        case PG_LEVEL_2M:
-               phys_addr = pmd_pfn(*(pmd_t *)pte) << PAGE_SHIFT;
+               phys_addr = (phys_addr_t)pmd_pfn(*(pmd_t *)pte) << PAGE_SHIFT;
                offset = virt_addr & ~PMD_PAGE_MASK;
                break;
        default:
-               phys_addr = pte_pfn(*pte) << PAGE_SHIFT;
+               phys_addr = (phys_addr_t)pte_pfn(*pte) << PAGE_SHIFT;
                offset = virt_addr & ~PAGE_MASK;
        }
 


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