target/i386: use separate MMU indexes for 32-bit accesses

Accesses from a 32-bit environment (32-bit code segment for instruction accesses, EFER.LMA==0 for processor accesses) have to mask away the upper 32 bits of the address. While a bit wasteful, the easiest way to do so is to use separate MMU indexes. These days, QEMU anyway is compiled with a fixed value for NB_MMU_MODES. Split MMU_USER_IDX, MMU_KSMAP_IDX and MMU_KNOSMAP_IDX in two. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
qemu · Feb 27, 2024 · 90f6415 · 90f6415
1 parent 5f97afe
commit 90f6415
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Showing 3 changed files with 33 additions and 15 deletions.
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
@@ -7732,13 +7732,16 @@ static bool x86_cpu_has_work(CPUState *cs)
     return x86_cpu_pending_interrupt(cs, cs->interrupt_request) != 0;
 }
 
-static int x86_cpu_mmu_index(CPUState *cs, bool ifetch)
+static int x86_cpu_mmu_index(CPUState *env, bool ifetch)
 {
     CPUX86State *env = cpu_env(cs);
+    int mmu_index_32 = (env->hflags & HF_CS64_MASK) ? 1 : 0;
+    int mmu_index_base =
+        (env->hflags & HF_CPL_MASK) == 3 ? MMU_USER64_IDX :
+        !(env->hflags & HF_SMAP_MASK) ? MMU_KNOSMAP64_IDX :
+        (env->eflags & AC_MASK) ? MMU_KNOSMAP64_IDX : MMU_KSMAP64_IDX;
 
-    return (env->hflags & HF_CPL_MASK) == 3 ? MMU_USER_IDX :
-        (!(env->hflags & HF_SMAP_MASK) || (env->eflags & AC_MASK))
-        ? MMU_KNOSMAP_IDX : MMU_KSMAP_IDX;
+    return mmu_index_base + mmu_index_32;
 }
 
 static void x86_disas_set_info(CPUState *cs, disassemble_info *info)

diff --git a/target/i386/cpu.h b/target/i386/cpu.h
@@ -2299,27 +2299,41 @@ uint64_t cpu_get_tsc(CPUX86State *env);
 #define cpu_list x86_cpu_list
 
 /* MMU modes definitions */
-#define MMU_KSMAP_IDX   0
-#define MMU_USER_IDX    1
-#define MMU_KNOSMAP_IDX 2
-#define MMU_NESTED_IDX  3
-#define MMU_PHYS_IDX    4
+#define MMU_KSMAP64_IDX    0
+#define MMU_KSMAP32_IDX    1
+#define MMU_USER64_IDX     2
+#define MMU_USER32_IDX     3
+#define MMU_KNOSMAP64_IDX  4
+#define MMU_KNOSMAP32_IDX  5
+#define MMU_PHYS_IDX       6
+#define MMU_NESTED_IDX     7
+
+#ifdef CONFIG_USER_ONLY
+#ifdef TARGET_X86_64
+#define MMU_USER_IDX MMU_USER64_IDX
+#else
+#define MMU_USER_IDX MMU_USER32_IDX
+#endif
+#endif
 
 static inline bool is_mmu_index_smap(int mmu_index)
 {
-    return mmu_index == MMU_KSMAP_IDX;
+    return (mmu_index & ~1) == MMU_KSMAP64_IDX;
 }
 
 static inline bool is_mmu_index_user(int mmu_index)
 {
-    return mmu_index == MMU_USER_IDX;
+    return (mmu_index & ~1) == MMU_USER64_IDX;
 }
 
 static inline int cpu_mmu_index_kernel(CPUX86State *env)
 {
-    return !(env->hflags & HF_SMAP_MASK) ? MMU_KNOSMAP_IDX :
-        ((env->hflags & HF_CPL_MASK) < 3 && (env->eflags & AC_MASK))
-        ? MMU_KNOSMAP_IDX : MMU_KSMAP_IDX;
+    int mmu_index_32 = (env->hflags & HF_LMA_MASK) ? 1 : 0;
+    int mmu_index_base =
+        !(env->hflags & HF_SMAP_MASK) ? MMU_KNOSMAP64_IDX :
+        ((env->hflags & HF_CPL_MASK) < 3 && (env->eflags & AC_MASK)) ? MMU_KNOSMAP64_IDX : MMU_KSMAP64_IDX;
+
+    return mmu_index_base + mmu_index_32;
 }
 
 #define CC_DST  (env->cc_dst)

diff --git a/target/i386/tcg/sysemu/excp_helper.c b/target/i386/tcg/sysemu/excp_helper.c
@@ -545,7 +545,8 @@ static bool get_physical_address(CPUX86State *env, vaddr addr,
         if (likely(use_stage2)) {
             in.cr3 = env->nested_cr3;
             in.pg_mode = env->nested_pg_mode;
-            in.mmu_idx = MMU_USER_IDX;
+            in.mmu_idx =
+                env->nested_pg_mode & PG_MODE_LMA ? MMU_USER64_IDX : MMU_USER32_IDX;
             in.ptw_idx = MMU_PHYS_IDX;
 
             if (!mmu_translate(env, &in, out, err)) {