target/arm: Add zt0_excp_el to DisasContext

Pipe the value through from SMCR_ELx through hflags and into
the disassembly context.  Enable EZT0 in smcr_write.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250704142112.1018902-17-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index 626562776254bc21cb2652d503a9f04dda17cc7d..08c43f674a2a3146398a22423452f2db06c5700b 100644 (file)
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -635,6 +635,9 @@ void arm_emulate_firmware_reset(CPUState *cpustate, int target_el)
                 env->cp15.cptr_el[3] |= R_CPTR_EL3_ESM_MASK;
                 env->cp15.scr_el3 |= SCR_ENTP2;
                 env->vfp.smcr_el[3] = 0xf;
+                if (cpu_isar_feature(aa64_sme2, cpu)) {
+                    env->vfp.smcr_el[3] |= R_SMCR_EZT0_MASK;
+                }
             }
             if (cpu_isar_feature(aa64_hcx, cpu)) {
                 env->cp15.scr_el3 |= SCR_HXEN;

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index cbc20434836acf5528c0854242369fc6bd9e3aec..39a9234ff285e4eb355d2b1ce15e31eda5d2662c 100644 (file)
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -1513,6 +1513,7 @@ FIELD(SVCR, ZA, 1, 1)
 
 /* Fields for SMCR_ELx. */
 FIELD(SMCR, LEN, 0, 4)
+FIELD(SMCR, EZT0, 30, 1)
 FIELD(SMCR, FA64, 31, 1)
 
 /* Write a new value to v7m.exception, thus transitioning into or out
@@ -3084,6 +3085,7 @@ FIELD(TBFLAG_A64, NV2_MEM_E20, 35, 1)
 FIELD(TBFLAG_A64, NV2_MEM_BE, 36, 1)
 FIELD(TBFLAG_A64, AH, 37, 1)   /* FPCR.AH */
 FIELD(TBFLAG_A64, NEP, 38, 1)   /* FPCR.NEP */
+FIELD(TBFLAG_A64, ZT0EXC_EL, 39, 2)
 
 /*
  * Helpers for using the above. Note that only the A64 accessors use

diff --git a/target/arm/helper.c b/target/arm/helper.c
index 3879bce848924c63365d8829d5327f6490a6436a..b3f0d6f17a8cbfc771344676fef95caa7bbcc6eb 100644 (file)
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -6682,10 +6682,14 @@ static void smcr_write(CPUARMState *env, const ARMCPRegInfo *ri,
 {
     int cur_el = arm_current_el(env);
     int old_len = sve_vqm1_for_el(env, cur_el);
+    uint64_t valid_mask = R_SMCR_LEN_MASK | R_SMCR_FA64_MASK;
     int new_len;
 
     QEMU_BUILD_BUG_ON(ARM_MAX_VQ > R_SMCR_LEN_MASK + 1);
-    value &= R_SMCR_LEN_MASK | R_SMCR_FA64_MASK;
+    if (cpu_isar_feature(aa64_sme2, env_archcpu(env))) {
+        valid_mask |= R_SMCR_EZT0_MASK;
+    }
+    value &= valid_mask;
     raw_write(env, ri, value);
 
     /*

diff --git a/target/arm/tcg/hflags.c b/target/arm/tcg/hflags.c
index 1ccec63bbd431ab37734c85eca79670b99f5855d..59ab5263753aec497385376ffc549cc495397f73 100644 (file)
--- a/target/arm/tcg/hflags.c
+++ b/target/arm/tcg/hflags.c
@@ -214,6 +214,31 @@ static CPUARMTBFlags rebuild_hflags_a32(CPUARMState *env, int fp_el,
     return rebuild_hflags_common_32(env, fp_el, mmu_idx, flags);
 }
 
+/*
+ * Return the exception level to which exceptions should be taken for ZT0.
+ * C.f. the ARM pseudocode function CheckSMEZT0Enabled, after the ZA check.
+ */
+static int zt0_exception_el(CPUARMState *env, int el)
+{
+#ifndef CONFIG_USER_ONLY
+    if (el <= 1
+        && !el_is_in_host(env, el)
+        && !FIELD_EX64(env->vfp.smcr_el[1], SMCR, EZT0)) {
+        return 1;
+    }
+    if (el <= 2
+        && arm_is_el2_enabled(env)
+        && !FIELD_EX64(env->vfp.smcr_el[2], SMCR, EZT0)) {
+        return 2;
+    }
+    if (arm_feature(env, ARM_FEATURE_EL3)
+        && !FIELD_EX64(env->vfp.smcr_el[3], SMCR, EZT0)) {
+        return 3;
+    }
+#endif
+    return 0;
+}
+
 static CPUARMTBFlags rebuild_hflags_a64(CPUARMState *env, int el, int fp_el,
                                         ARMMMUIdx mmu_idx)
 {
@@ -269,7 +294,14 @@ static CPUARMTBFlags rebuild_hflags_a64(CPUARMState *env, int el, int fp_el,
             DP_TBFLAG_A64(flags, PSTATE_SM, 1);
             DP_TBFLAG_A64(flags, SME_TRAP_NONSTREAMING, !sme_fa64(env, el));
         }
-        DP_TBFLAG_A64(flags, PSTATE_ZA, FIELD_EX64(env->svcr, SVCR, ZA));
+
+        if (FIELD_EX64(env->svcr, SVCR, ZA)) {
+            DP_TBFLAG_A64(flags, PSTATE_ZA, 1);
+            if (cpu_isar_feature(aa64_sme2, env_archcpu(env))) {
+                int zt0_el = zt0_exception_el(env, el);
+                DP_TBFLAG_A64(flags, ZT0EXC_EL, zt0_el);
+            }
+        }
     }
 
     sctlr = regime_sctlr(env, stage1);

diff --git a/target/arm/tcg/translate-a64.c b/target/arm/tcg/translate-a64.c
index b0caccca46edcec7fa8b228776112a4b6f77ff1e..ad293c088582e5e1bbc5457c38a00c8bbcb1698a 100644 (file)
--- a/target/arm/tcg/translate-a64.c
+++ b/target/arm/tcg/translate-a64.c
@@ -10139,6 +10139,7 @@ static void aarch64_tr_init_disas_context(DisasContextBase *dcbase,
     dc->trap_eret = EX_TBFLAG_A64(tb_flags, TRAP_ERET);
     dc->sve_excp_el = EX_TBFLAG_A64(tb_flags, SVEEXC_EL);
     dc->sme_excp_el = EX_TBFLAG_A64(tb_flags, SMEEXC_EL);
+    dc->zt0_excp_el = EX_TBFLAG_A64(tb_flags, ZT0EXC_EL);
     dc->vl = (EX_TBFLAG_A64(tb_flags, VL) + 1) * 16;
     dc->svl = (EX_TBFLAG_A64(tb_flags, SVL) + 1) * 16;
     dc->pauth_active = EX_TBFLAG_A64(tb_flags, PAUTH_ACTIVE);

diff --git a/target/arm/tcg/translate.h b/target/arm/tcg/translate.h
index 0004a97219ba6aa4d1485dc28ec3f2cf3eb1aa0d..b03956a79379f7e4be1021c06e2ce771ee6e64d1 100644 (file)
--- a/target/arm/tcg/translate.h
+++ b/target/arm/tcg/translate.h
@@ -70,6 +70,7 @@ typedef struct DisasContext {
     int fp_excp_el; /* FP exception EL or 0 if enabled */
     int sve_excp_el; /* SVE exception EL or 0 if enabled */
     int sme_excp_el; /* SME exception EL or 0 if enabled */
+    int zt0_excp_el; /* ZT0 exception EL or 0 if enabled */
     int vl;          /* current vector length in bytes */
     int svl;         /* current streaming vector length in bytes */
     bool vfp_enabled; /* FP enabled via FPSCR.EN */