- Xen PVM PTE breakage fixed upstream

diff --git a/kernel-small_fixes.patch b/kernel-small_fixes.patch
index ab5a074bde8d3e7ba5e1aceef3383925f3ef3991..c64eee1927bf2b6b2ee051afcb1c82b843ffebf3 100644 (file)
--- a/kernel-small_fixes.patch
+++ b/kernel-small_fixes.patch
@@ -71,112 +71,6 @@ index 3b1ea34..eaa808e 100644
        result = scsi_vpd_inquiry(sdev, buf, 0, buf_len);
        if (result)
 
-David Vrabel identified a regression when using automatic NUMA balancing
-under Xen whereby page table entries were getting corrupted due to the
-use of native PTE operations. Quoting him
-
-       Xen PV guest page tables require that their entries use machine
-       addresses if the preset bit (_PAGE_PRESENT) is set, and (for
-       successful migration) non-present PTEs must use pseudo-physical
-       addresses.  This is because on migration MFNs in present PTEs are
-       translated to PFNs (canonicalised) so they may be translated back
-       to the new MFN in the destination domain (uncanonicalised).
-
-       pte_mknonnuma(), pmd_mknonnuma(), pte_mknuma() and pmd_mknuma()
-       set and clear the _PAGE_PRESENT bit using pte_set_flags(),
-       pte_clear_flags(), etc.
-
-       In a Xen PV guest, these functions must translate MFNs to PFNs
-       when clearing _PAGE_PRESENT and translate PFNs to MFNs when setting
-       _PAGE_PRESENT.
-
-His suggested fix converted p[te|md]_[set|clear]_flags to using
-paravirt-friendly ops but this is overkill. He suggested an alternative of
-using p[te|md]_modify in the NUMA page table operations but this is does
-more work than necessary and would require looking up a VMA for protections.
-
-This patch modifies the NUMA page table operations to use paravirt friendly
-operations to set/clear the flags of interest. Unfortunately this will take
-a performance hit when updating the PTEs on CONFIG_PARAVIRT but I do not
-see a way around it that does not break Xen.
-
-Cc: stable@vger.kernel.org
-Signed-off-by: Mel Gorman <mgorman@suse.de>
-Acked-by: David Vrabel <david.vrabel@citrix.com>
-Tested-by: David Vrabel <david.vrabel@citrix.com>
----
- include/asm-generic/pgtable.h | 31 +++++++++++++++++++++++--------
- 1 file changed, 23 insertions(+), 8 deletions(-)
-
-diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
-index 34c7bdc..38a7437 100644
---- a/include/asm-generic/pgtable.h
-+++ b/include/asm-generic/pgtable.h
-@@ -680,24 +680,35 @@ static inline int pmd_numa(pmd_t pmd)
- #ifndef pte_mknonnuma
- static inline pte_t pte_mknonnuma(pte_t pte)
- {
--      pte = pte_clear_flags(pte, _PAGE_NUMA);
--      return pte_set_flags(pte, _PAGE_PRESENT|_PAGE_ACCESSED);
-+      pteval_t val = pte_val(pte);
-+
-+      val &= ~_PAGE_NUMA;
-+      val |= (_PAGE_PRESENT|_PAGE_ACCESSED);
-+      return __pte(val);
- }
- #endif
- 
- #ifndef pmd_mknonnuma
- static inline pmd_t pmd_mknonnuma(pmd_t pmd)
- {
--      pmd = pmd_clear_flags(pmd, _PAGE_NUMA);
--      return pmd_set_flags(pmd, _PAGE_PRESENT|_PAGE_ACCESSED);
-+      pmdval_t val = pmd_val(pmd);
-+
-+      val &= ~_PAGE_NUMA;
-+      val |= (_PAGE_PRESENT|_PAGE_ACCESSED);
-+
-+      return __pmd(val);
- }
- #endif
- 
- #ifndef pte_mknuma
- static inline pte_t pte_mknuma(pte_t pte)
- {
--      pte = pte_set_flags(pte, _PAGE_NUMA);
--      return pte_clear_flags(pte, _PAGE_PRESENT);
-+      pteval_t val = pte_val(pte);
-+
-+      val &= ~_PAGE_PRESENT;
-+      val |= _PAGE_NUMA;
-+
-+      return __pte(val);
- }
- #endif
- 
-@@ -716,8 +727,12 @@ static inline void ptep_set_numa(struct mm_struct *mm, unsigned long addr,
- #ifndef pmd_mknuma
- static inline pmd_t pmd_mknuma(pmd_t pmd)
- {
--      pmd = pmd_set_flags(pmd, _PAGE_NUMA);
--      return pmd_clear_flags(pmd, _PAGE_PRESENT);
-+      pmdval_t val = pmd_val(pmd);
-+
-+      val &= ~_PAGE_PRESENT;
-+      val |= _PAGE_NUMA;
-+
-+      return __pmd(val);
- }
- #endif
- 
--- 
-1.8.4.5
-
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 From 1e2ee49f7f1b79f0b14884fe6a602f0411b39552 Mon Sep 17 00:00:00 2001
 From: Will Woods <wwoods@redhat.com>
 Date: Tue, 6 May 2014 12:50:10 -0700