target/arm: Add SMCR_ELx

These cpregs control the streaming vector length and whether the
full a64 instruction set is allowed while in streaming mode.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220620175235.60881-7-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

2 files changed, 47 insertions, 2 deletions

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index bb8cb959d1..dec52c6c3b 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -669,8 +669,8 @@ typedef struct CPUArchState {
         float_status standard_fp_status;
         float_status standard_fp_status_f16;
 
-        /* ZCR_EL[1-3] */
-        uint64_t zcr_el[4];
+        uint64_t zcr_el[4];   /* ZCR_EL[1-3] */
+        uint64_t smcr_el[4];  /* SMCR_EL[1-3] */
     } vfp;
     uint64_t exclusive_addr;
     uint64_t exclusive_val;
@@ -1434,6 +1434,10 @@ FIELD(CPTR_EL3, TCPAC, 31, 1)
 FIELD(SVCR, SM, 0, 1)
 FIELD(SVCR, ZA, 1, 1)
 
+/* Fields for SMCR_ELx. */
+FIELD(SMCR, LEN, 0, 4)
+FIELD(SMCR, FA64, 31, 1)
+
 /* Write a new value to v7m.exception, thus transitioning into or out
  * of Handler mode; this may result in a change of active stack pointer.
  */
diff --git a/target/arm/helper.c b/target/arm/helper.c
index 3acc1dc378..2072f2a550 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -5879,6 +5879,8 @@ static void define_arm_vh_e2h_redirects_aliases(ARMCPU *cpu)
          */
         { K(3, 0,  1, 2, 0), K(3, 4,  1, 2, 0), K(3, 5, 1, 2, 0),
           "ZCR_EL1", "ZCR_EL2", "ZCR_EL12", isar_feature_aa64_sve },
+        { K(3, 0,  1, 2, 6), K(3, 4,  1, 2, 6), K(3, 5, 1, 2, 6),
+          "SMCR_EL1", "SMCR_EL2", "SMCR_EL12", isar_feature_aa64_sme },
 
         { K(3, 0,  5, 6, 0), K(3, 4,  5, 6, 0), K(3, 5, 5, 6, 0),
           "TFSR_EL1", "TFSR_EL2", "TFSR_EL12", isar_feature_aa64_mte },
@@ -6357,6 +6359,30 @@ static void svcr_write(CPUARMState *env, const ARMCPRegInfo *ri,
     env->svcr = value;
 }
 
+static void smcr_write(CPUARMState *env, const ARMCPRegInfo *ri,
+                       uint64_t value)
+{
+    int cur_el = arm_current_el(env);
+    int old_len = sve_vqm1_for_el(env, cur_el);
+    int new_len;
+
+    QEMU_BUILD_BUG_ON(ARM_MAX_VQ > R_SMCR_LEN_MASK + 1);
+    value &= R_SMCR_LEN_MASK | R_SMCR_FA64_MASK;
+    raw_write(env, ri, value);
+
+    /*
+     * Note that it is CONSTRAINED UNPREDICTABLE what happens to ZA storage
+     * when SVL is widened (old values kept, or zeros).  Choose to keep the
+     * current values for simplicity.  But for QEMU internals, we must still
+     * apply the narrower SVL to the Zregs and Pregs -- see the comment
+     * above aarch64_sve_narrow_vq.
+     */
+    new_len = sve_vqm1_for_el(env, cur_el);
+    if (new_len < old_len) {
+        aarch64_sve_narrow_vq(env, new_len + 1);
+    }
+}
+
 static const ARMCPRegInfo sme_reginfo[] = {
     { .name = "TPIDR2_EL0", .state = ARM_CP_STATE_AA64,
       .opc0 = 3, .opc1 = 3, .crn = 13, .crm = 0, .opc2 = 5,
@@ -6367,6 +6393,21 @@ static const ARMCPRegInfo sme_reginfo[] = {
       .access = PL0_RW, .type = ARM_CP_SME,
       .fieldoffset = offsetof(CPUARMState, svcr),
       .writefn = svcr_write, .raw_writefn = raw_write },
+    { .name = "SMCR_EL1", .state = ARM_CP_STATE_AA64,
+      .opc0 = 3, .opc1 = 0, .crn = 1, .crm = 2, .opc2 = 6,
+      .access = PL1_RW, .type = ARM_CP_SME,
+      .fieldoffset = offsetof(CPUARMState, vfp.smcr_el[1]),
+      .writefn = smcr_write, .raw_writefn = raw_write },
+    { .name = "SMCR_EL2", .state = ARM_CP_STATE_AA64,
+      .opc0 = 3, .opc1 = 4, .crn = 1, .crm = 2, .opc2 = 6,
+      .access = PL2_RW, .type = ARM_CP_SME,
+      .fieldoffset = offsetof(CPUARMState, vfp.smcr_el[2]),
+      .writefn = smcr_write, .raw_writefn = raw_write },
+    { .name = "SMCR_EL3", .state = ARM_CP_STATE_AA64,
+      .opc0 = 3, .opc1 = 6, .crn = 1, .crm = 2, .opc2 = 6,
+      .access = PL3_RW, .type = ARM_CP_SME,
+      .fieldoffset = offsetof(CPUARMState, vfp.smcr_el[3]),
+      .writefn = smcr_write, .raw_writefn = raw_write },
 };
 #endif /* TARGET_AARCH64 */