[Xen-devel] [PATCH] x86/ptwr: Misc cleanup to ptwr_emulated_update()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

All but one user wants mfn as mfn_t, so switch its type.  offset is only ever
used when multipled by 8, so fold that into its initial calculation.  Fold all
the pointer arithmic on pl1e together, to avoid needless casts.

No functional change.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
 xen/arch/x86/pv/ro-page-fault.c | 26 ++++++++++++--------------
 1 file changed, 12 insertions(+), 14 deletions(-)

diff --git a/xen/arch/x86/pv/ro-page-fault.c b/xen/arch/x86/pv/ro-page-fault.c
index aa8d5a7..efb5c1a 100644
--- a/xen/arch/x86/pv/ro-page-fault.c
+++ b/xen/arch/x86/pv/ro-page-fault.c
@@ -67,7 +67,7 @@ static int ptwr_emulated_update(unsigned long addr, intpte_t 
*p_old,
                                 intpte_t val, unsigned int bytes,
                                 struct x86_emulate_ctxt *ctxt)
 {
-    unsigned long mfn;
+    mfn_t mfn;
     unsigned long unaligned_addr = addr;
     struct page_info *page;
     l1_pgentry_t pte, ol1e, nl1e, *pl1e;
@@ -93,7 +93,7 @@ static int ptwr_emulated_update(unsigned long addr, intpte_t 
*p_old,
         intpte_t full;
         unsigned int rc;
 
-        offset = addr & (sizeof(full) - 1);
+        offset = (addr & (sizeof(full) - 1)) * 8;
 
         /* Align address; read full word. */
         addr &= ~(sizeof(full) - 1);
@@ -105,24 +105,24 @@ static int ptwr_emulated_update(unsigned long addr, 
intpte_t *p_old,
             return X86EMUL_EXCEPTION;
         }
         /* Mask out bits provided by caller. */
-        full &= ~((((intpte_t)1 << (bytes * 8)) - 1) << (offset * 8));
+        full &= ~((((intpte_t)1 << (bytes * 8)) - 1) << offset);
         /* Shift the caller value and OR in the missing bits. */
         val  &= (((intpte_t)1 << (bytes * 8)) - 1);
-        val <<= (offset) * 8;
+        val <<= offset;
         val  |= full;
         /* Also fill in missing parts of the cmpxchg old value. */
         old  &= (((intpte_t)1 << (bytes * 8)) - 1);
-        old <<= (offset) * 8;
+        old <<= offset;
         old  |= full;
     }
 
     pte  = ptwr_ctxt->pte;
-    mfn  = l1e_get_pfn(pte);
-    page = mfn_to_page(_mfn(mfn));
+    mfn  = l1e_get_mfn(pte);
+    page = mfn_to_page(mfn);
 
     /* We are looking only for read-only mappings of p.t. pages. */
     ASSERT((l1e_get_flags(pte) & (_PAGE_RW|_PAGE_PRESENT)) == _PAGE_PRESENT);
-    ASSERT(mfn_valid(_mfn(mfn)));
+    ASSERT(mfn_valid(mfn));
     ASSERT((page->u.inuse.type_info & PGT_type_mask) == PGT_l1_page_table);
     ASSERT((page->u.inuse.type_info & PGT_count_mask) != 0);
     ASSERT(page_get_owner(page) == d);
@@ -162,20 +162,18 @@ static int ptwr_emulated_update(unsigned long addr, 
intpte_t *p_old,
     nl1e = adjust_guest_l1e(nl1e, d);
 
     /* Checked successfully: do the update (write or cmpxchg). */
-    pl1e = map_domain_page(_mfn(mfn));
-    pl1e = (l1_pgentry_t *)((unsigned long)pl1e + (addr & ~PAGE_MASK));
+    pl1e = map_domain_page(mfn) + (addr & ~PAGE_MASK);
     if ( p_old )
     {
-
         ol1e = l1e_from_intpte(old);
         if ( !paging_cmpxchg_guest_entry(v, &l1e_get_intpte(*pl1e),
-                                         &old, l1e_get_intpte(nl1e), 
_mfn(mfn)) )
+                                         &old, l1e_get_intpte(nl1e), mfn) )
             ret = X86EMUL_UNHANDLEABLE;
         else if ( l1e_get_intpte(ol1e) == old )
             ret = X86EMUL_OKAY;
         else
         {
-            *p_old = old >> (offset * 8);
+            *p_old = old >> offset;
             ret = X86EMUL_CMPXCHG_FAILED;
         }
 
@@ -189,7 +187,7 @@ static int ptwr_emulated_update(unsigned long addr, 
intpte_t *p_old,
     else
     {
         ol1e = *pl1e;
-        if ( !UPDATE_ENTRY(l1, pl1e, ol1e, nl1e, mfn, v, 0) )
+        if ( !UPDATE_ENTRY(l1, pl1e, ol1e, nl1e, mfn_x(mfn), v, 0) )
             BUG();
     }
 
-- 
2.1.4


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