[Xen-devel] [PATCH] x86: add movnti emulation

["Jan Beulich" <jbeulich@xxxxxxxxxx>]

Linux added the use of movnti for copying from user to kernel space in
certain cases, and as per reports we got this may happen with the
destination being in MMIO.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>

Index: 2008-09-19/xen/arch/x86/x86_emulate/x86_emulate.c
===================================================================
--- 2008-09-19.orig/xen/arch/x86/x86_emulate/x86_emulate.c      2008-08-29 
14:26:56.000000000 +0200
+++ 2008-09-19/xen/arch/x86/x86_emulate/x86_emulate.c   2008-10-17 
16:34:02.000000000 +0200
@@ -236,7 +236,8 @@ static uint8_t twobyte_table[256] = {
     DstReg|SrcMem|ModRM, DstReg|SrcMem|ModRM,
     ByteOp|DstReg|SrcMem|ModRM|Mov, DstReg|SrcMem16|ModRM|Mov,
     /* 0xC0 - 0xC7 */
-    ByteOp|DstMem|SrcReg|ModRM, DstMem|SrcReg|ModRM, 0, 0,
+    ByteOp|DstMem|SrcReg|ModRM, DstMem|SrcReg|ModRM,
+    0, DstMem|SrcReg|ModRM|Mov,
     0, 0, 0, ImplicitOps|ModRM,
     /* 0xC8 - 0xCF */
     ImplicitOps, ImplicitOps, ImplicitOps, ImplicitOps,
@@ -3910,6 +3911,12 @@ x86_emulate(
         }
         goto add;
 
+    case 0xc3: /* movnti */
+        /* Ignore the non-temporal hint for now. */
+        generate_exception_if(dst.bytes <= 2, EXC_UD, -1);
+        dst.val = src.val;
+        break;
+
     case 0xc7: /* Grp9 (cmpxchg8b/cmpxchg16b) */ {
         unsigned long old[2], exp[2], new[2];
         unsigned int i;




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