x86: add movnti emulation

PATCH New Jan Beulich 1 participant 1 message Oct 17, 2008

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Jan Beulich

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2008-10-17 15:16 UTC #0 lore raw

PATCH 1/1 x86: add movnti emulation

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 <[email protected]>

xen/arch/x86/x86_emulate/x86_emulate.c +8 -1

Index: 2008-09-19/xen/arch/x86/x86_emulate/x86_emulate.c
===================================================================
@@ -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;