target/arm: Implement FEAT_E0PD

FEAT_E0PD adds new bits E0PD0 and E0PD1 to TCR_EL1, which allow the
OS to forbid EL0 access to half of the address space.  Since this is
an EL0-specific variation on the existing TCR_ELx.{EPD0,EPD1}, we can
implement it entirely in aa64_va_parameters().

This requires moving the existing regime_is_user() to internals.h
so that the code in helper.c can get at it.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20221021160131.3531787-1-peter.maydell@linaro.org

docs/system/arm/emulation.rst

@@ -24,6 +24,7 @@ the following architecture extensions:
 - FEAT_Debugv8p4 (Debug changes for v8.4)
 - FEAT_DotProd (Advanced SIMD dot product instructions)
 - FEAT_DoubleFault (Double Fault Extension)
+- FEAT_E0PD (Preventing EL0 access to halves of address maps)
 - FEAT_ETS (Enhanced Translation Synchronization)
 - FEAT_FCMA (Floating-point complex number instructions)
 - FEAT_FHM (Floating-point half-precision multiplication instructions)

target/arm/cpu.h

@@ -4139,6 +4139,11 @@ static inline bool isar_feature_aa64_lva(const ARMISARegisters *id)
     return FIELD_EX64(id->id_aa64mmfr2, ID_AA64MMFR2, VARANGE) != 0;
 }
 
+static inline bool isar_feature_aa64_e0pd(const ARMISARegisters *id)
+{
+    return FIELD_EX64(id->id_aa64mmfr2, ID_AA64MMFR2, E0PD) != 0;
+}
+
 static inline bool isar_feature_aa64_tts2uxn(const ARMISARegisters *id)
 {
     return FIELD_EX64(id->id_aa64mmfr1, ID_AA64MMFR1, XNX) != 0;

target/arm/cpu64.c

@@ -1185,6 +1185,7 @@ static void aarch64_max_initfn(Object *obj)
     t = FIELD_DP64(t, ID_AA64MMFR2, FWB, 1);      /* FEAT_S2FWB */
     t = FIELD_DP64(t, ID_AA64MMFR2, TTL, 1);      /* FEAT_TTL */
     t = FIELD_DP64(t, ID_AA64MMFR2, BBM, 2);      /* FEAT_BBM at level 2 */
+    t = FIELD_DP64(t, ID_AA64MMFR2, E0PD, 1);     /* FEAT_E0PD */
     cpu->isar.id_aa64mmfr2 = t;
 
     t = cpu->isar.id_aa64zfr0;

target/arm/helper.c

@@ -10491,6 +10491,8 @@ ARMVAParameters aa64_va_parameters(CPUARMState *env, uint64_t va,
         ps = extract32(tcr, 16, 3);
         ds = extract64(tcr, 32, 1);
     } else {
+        bool e0pd;
+
         /*
          * Bit 55 is always between the two regions, and is canonical for
          * determining if address tagging is enabled.
@@ -10502,15 +10504,22 @@ ARMVAParameters aa64_va_parameters(CPUARMState *env, uint64_t va,
             epd = extract32(tcr, 7, 1);
             sh = extract32(tcr, 12, 2);
             hpd = extract64(tcr, 41, 1);
+            e0pd = extract64(tcr, 55, 1);
         } else {
             tsz = extract32(tcr, 16, 6);
             gran = tg1_to_gran_size(extract32(tcr, 30, 2));
             epd = extract32(tcr, 23, 1);
             sh = extract32(tcr, 28, 2);
             hpd = extract64(tcr, 42, 1);
+            e0pd = extract64(tcr, 56, 1);
         }
         ps = extract64(tcr, 32, 3);
         ds = extract64(tcr, 59, 1);
+
+        if (e0pd && cpu_isar_feature(aa64_e0pd, cpu) &&
+            regime_is_user(env, mmu_idx)) {
+            epd = true;
+        }
     }
 
     gran = sanitize_gran_size(cpu, gran, stage2);

target/arm/internals.h

@@ -707,6 +707,25 @@ static inline uint32_t regime_el(CPUARMState *env, ARMMMUIdx mmu_idx)
     }
 }
 
+static inline bool regime_is_user(CPUARMState *env, ARMMMUIdx mmu_idx)
+{
+    switch (mmu_idx) {
+    case ARMMMUIdx_E20_0:
+    case ARMMMUIdx_Stage1_E0:
+    case ARMMMUIdx_MUser:
+    case ARMMMUIdx_MSUser:
+    case ARMMMUIdx_MUserNegPri:
+    case ARMMMUIdx_MSUserNegPri:
+        return true;
+    default:
+        return false;
+    case ARMMMUIdx_E10_0:
+    case ARMMMUIdx_E10_1:
+    case ARMMMUIdx_E10_1_PAN:
+        g_assert_not_reached();
+    }
+}
+
 /* Return the SCTLR value which controls this address translation regime */
 static inline uint64_t regime_sctlr(CPUARMState *env, ARMMMUIdx mmu_idx)
 {

target/arm/ptw.c

@@ -104,25 +104,6 @@ static bool regime_translation_big_endian(CPUARMState *env, ARMMMUIdx mmu_idx)
     return (regime_sctlr(env, mmu_idx) & SCTLR_EE) != 0;
 }
 
-static bool regime_is_user(CPUARMState *env, ARMMMUIdx mmu_idx)
-{
-    switch (mmu_idx) {
-    case ARMMMUIdx_E20_0:
-    case ARMMMUIdx_Stage1_E0:
-    case ARMMMUIdx_MUser:
-    case ARMMMUIdx_MSUser:
-    case ARMMMUIdx_MUserNegPri:
-    case ARMMMUIdx_MSUserNegPri:
-        return true;
-    default:
-        return false;
-    case ARMMMUIdx_E10_0:
-    case ARMMMUIdx_E10_1:
-    case ARMMMUIdx_E10_1_PAN:
-        g_assert_not_reached();
-    }
-}
-
 /* Return the TTBR associated with this translation regime */
 static uint64_t regime_ttbr(CPUARMState *env, ARMMMUIdx mmu_idx, int ttbrn)
 {