[Xen-devel] [PATCH v4 04/44] x86emul: generalize vector length handling for AVX512/EVEX

["Jan Beulich" <JBeulich@xxxxxxxx>]

To allow for some code sharing where possible, copy VEX.L into EVEX.LR
even for VEX (or XOP) encoded insns. Make operand size determination
use this right away, at the same time adding consistency checks for the
EVEX scalar insn cases (the non-scalar ones aren't uniform enough for
the checking to be done in a central place like this).

Note that the broadcast case is not handled here, but will be taken care
of elsewhere (in just a single place rather than at least two).

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v3: Introduce evex_encoded() to replace open-coded evex.mbs checks.
v2: Don't raise #UD in simd_scalar_opc case when EVEX.W != low-opcode-bit.

--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -191,14 +191,14 @@ enum simd_opsize {
      * Ordinary packed integers:
      * - 64 bits without prefix 66 (MMX)
      * - 128 bits with prefix 66 (SSEn)
-     * - 128/256 bits depending on VEX.L (AVX)
+     * - 128/256/512 bits depending on VEX.L/EVEX.LR (AVX+)
      */
     simd_packed_int,
 
     /*
      * Ordinary packed/scalar floating point:
      * - 128 bits without prefix or with prefix 66 (SSEn)
-     * - 128/256 bits depending on VEX.L (AVX)
+     * - 128/256/512 bits depending on VEX.L/EVEX.LR (AVX+)
      * - 32 bits with prefix F3 (scalar single)
      * - 64 bits with prefix F2 (scalar doubgle)
      */
@@ -207,14 +207,14 @@ enum simd_opsize {
     /*
      * Packed floating point:
      * - 128 bits without prefix or with prefix 66 (SSEn)
-     * - 128/256 bits depending on VEX.L (AVX)
+     * - 128/256/512 bits depending on VEX.L/EVEX.LR (AVX+)
      */
     simd_packed_fp,
 
     /*
      * Single precision packed/scalar floating point:
      * - 128 bits without prefix (SSEn)
-     * - 128/256 bits depending on VEX.L, no prefix (AVX)
+     * - 128/256/512 bits depending on VEX.L/EVEX.LR (AVX+)
      * - 32 bits with prefix F3 (scalar)
      */
     simd_single_fp,
@@ -228,7 +228,7 @@ enum simd_opsize {
 
     /*
      * Scalar floating point:
-     * - 32/64 bits depending on VEX.W
+     * - 32/64 bits depending on VEX.W/EVEX.W
      */
     simd_scalar_vexw,
 
@@ -2249,6 +2249,7 @@ int x86emul_unhandleable_rw(
 #define lock_prefix (state->lock_prefix)
 #define vex (state->vex)
 #define evex (state->evex)
+#define evex_encoded() (evex.mbs)
 #define ea (state->ea)
 
 static int
@@ -2818,6 +2819,9 @@ x86_decode(
 
                 opcode |= b | MASK_INSR(vex.pfx, X86EMUL_OPC_PFX_MASK);
 
+                if ( !evex_encoded() )
+                    evex.lr = vex.l;
+
                 if ( !(d & ModRM) )
                     break;
 
@@ -3148,7 +3152,7 @@ x86_decode(
             }
             /* fall through */
         case vex_66:
-            op_bytes = 16 << vex.l;
+            op_bytes = 16 << evex.lr;
             break;
         default:
             op_bytes = 0;
@@ -3172,9 +3176,17 @@ x86_decode(
     case simd_any_fp:
         switch ( vex.pfx )
         {
-        default:     op_bytes = 16 << vex.l; break;
-        case vex_f3: op_bytes = 4;           break;
-        case vex_f2: op_bytes = 8;           break;
+        default:
+            op_bytes = 16 << evex.lr;
+            break;
+        case vex_f3:
+            generate_exception_if(evex_encoded() && evex.w, EXC_UD);
+            op_bytes = 4;
+            break;
+        case vex_f2:
+            generate_exception_if(evex_encoded() && !evex.w, EXC_UD);
+            op_bytes = 8;
+            break;
         }
         break;
 





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