x86: Implement SMEP and SMAP

This patch implements Supervisor Mode Execution Prevention (SMEP) and
Supervisor Mode Access Prevention (SMAP) for x86.  The purpose of the
patch, obviously, is to help kernel developers debug the support for
those features.

A fair bit of the code relates to the handling of CPUID features.  The
CPUID code probably would get greatly simplified if all the feature
bit words were unified into a single vector object, but in the
interest of producing a minimal patch for SMEP/SMAP, and because I had
very limited time for this project, I followed the existing style.

[ v2: don't change the definition of the qemu64 CPU shorthand, since
  that breaks loading old snapshots.  Per Anthony Liguori this can be
  fixed once the CPU feature set is snapshot.

  Change the coding style slightly to conform to checkpatch.pl. ]

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 22 insertions, 5 deletions

diff --git a/target-i386/translate.c b/target-i386/translate.c
index 323869d..0a7e4e3 100644
--- a/target-i386/translate.c
+++ b/target-i386/translate.c
@@ -107,6 +107,7 @@ typedef struct DisasContext {
     int cpuid_ext_features;
     int cpuid_ext2_features;
     int cpuid_ext3_features;
+    int cpuid_7_0_ebx_features;
 } DisasContext;
 
 static void gen_eob(DisasContext *s);
@@ -6556,7 +6557,7 @@ static target_ulong disas_insn(DisasContext *s, target_ulong pc_start)
             }
             gen_pop_update(s);
             s->cc_op = CC_OP_EFLAGS;
-            /* abort translation because TF flag may change */
+            /* abort translation because TF/AC flag may change */
             gen_jmp_im(s->pc - s->cs_base);
             gen_eob(s);
         }
@@ -7206,6 +7207,24 @@ static target_ulong disas_insn(DisasContext *s, target_ulong pc_start)
                     gen_helper_mwait(cpu_env, tcg_const_i32(s->pc - pc_start));
                     gen_eob(s);
                     break;
+                case 2: /* clac */
+                    if (!(s->cpuid_7_0_ebx_features & CPUID_7_0_EBX_SMAP) ||
+                        s->cpl != 0) {
+                        goto illegal_op;
+                    }
+                    gen_helper_clac(cpu_env);
+                    gen_jmp_im(s->pc - s->cs_base);
+                    gen_eob(s);
+                    break;
+                case 3: /* stac */
+                    if (!(s->cpuid_7_0_ebx_features & CPUID_7_0_EBX_SMAP) ||
+                        s->cpl != 0) {
+                        goto illegal_op;
+                    }
+                    gen_helper_stac(cpu_env);
+                    gen_jmp_im(s->pc - s->cs_base);
+                    gen_eob(s);
+                    break;
                 default:
                     goto illegal_op;
                 }
@@ -7901,15 +7920,13 @@ static inline void gen_intermediate_code_internal(CPUX86State *env,
     /* select memory access functions */
     dc->mem_index = 0;
     if (flags & HF_SOFTMMU_MASK) {
-        if (dc->cpl == 3)
-            dc->mem_index = 2 * 4;
-        else
-            dc->mem_index = 1 * 4;
+        dc->mem_index = (cpu_mmu_index(env) + 1) << 2;
     }
     dc->cpuid_features = env->cpuid_features;
     dc->cpuid_ext_features = env->cpuid_ext_features;
     dc->cpuid_ext2_features = env->cpuid_ext2_features;
     dc->cpuid_ext3_features = env->cpuid_ext3_features;
+    dc->cpuid_7_0_ebx_features = env->cpuid_7_0_ebx_features;
 #ifdef TARGET_X86_64
     dc->lma = (flags >> HF_LMA_SHIFT) & 1;
     dc->code64 = (flags >> HF_CS64_SHIFT) & 1;