[Xen-changelog] [xen master] x86_emulate: fold wide reads

[patchbot@xxxxxxx]

commit ba6059b08219ec841fac95e1a4d067dd1d22f08f
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Fri Sep 20 11:05:28 2013 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Sep 20 11:05:28 2013 +0200

    x86_emulate: fold wide reads
    
    With HVM's MMIO operand handling now being capable of splitting large
    reads, there's no need to issue at most machine word size reads when
    we really need wider operands.
    
    Not that this is not done everywhere - there are a couple of cases
    where keeping the reads separate is more natural (and folding them
    would complicate the code rather than simplifying it).
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Keir Fraser <keir@xxxxxxx>
---
 xen/arch/x86/x86_emulate/x86_emulate.c |   18 +++++-------------
 1 files changed, 5 insertions(+), 13 deletions(-)

diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c 
b/xen/arch/x86/x86_emulate/x86_emulate.c
index d3023de..473500e 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -1116,7 +1116,6 @@ protmode_load_seg(
 {
     struct segment_register desctab, ss, segr;
     struct { uint32_t a, b; } desc;
-    unsigned long val;
     uint8_t dpl, rpl, cpl;
     uint32_t new_desc_b, a_flag = 0x100;
     int rc, fault_type = EXC_GP;
@@ -1143,14 +1142,9 @@ protmode_load_seg(
     if ( ((sel & 0xfff8) + 7) > desctab.limit )
         goto raise_exn;
 
-    if ( (rc = read_ulong(x86_seg_none, desctab.base + (sel & 0xfff8),
-                          &val, 4, ctxt, ops)) )
+    if ( (rc = ops->read(x86_seg_none, desctab.base + (sel & 0xfff8),
+                         &desc, sizeof(desc), ctxt)) )
         return rc;
-    desc.a = val;
-    if ( (rc = read_ulong(x86_seg_none, desctab.base + (sel & 0xfff8) + 4,
-                          &val, 4, ctxt, ops)) )
-        return rc;
-    desc.b = val;
 
     /* Segment present in memory? */
     if ( !(desc.b & (1u<<15)) )
@@ -4454,7 +4448,6 @@ x86_emulate(
 
     case 0xc7: /* Grp9 (cmpxchg8b/cmpxchg16b) */ {
         unsigned long old[2], exp[2], new[2];
-        unsigned int i;
 
         generate_exception_if((modrm_reg & 7) != 1, EXC_UD, -1);
         generate_exception_if(ea.type != OP_MEM, EXC_UD, -1);
@@ -4463,10 +4456,9 @@ x86_emulate(
         op_bytes *= 2;
 
         /* Get actual old value. */
-        for ( i = 0; i < (op_bytes/sizeof(long)); i++ )
-            if ( (rc = read_ulong(ea.mem.seg, ea.mem.off + i*sizeof(long),
-                                  &old[i], sizeof(long), ctxt, ops)) != 0 )
-                goto done;
+        if ( (rc = ops->read(ea.mem.seg, ea.mem.off, old, op_bytes,
+                             ctxt)) != 0 )
+            goto done;
 
         /* Get expected and proposed values. */
         if ( op_bytes == 8 )
--
generated by git-patchbot for /home/xen/git/xen.git#master

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