[PULL 023/114] target/arm: Add ID_AA64ZFR0 fields and isar_feature_aa64_sve2

[Peter Maydell]

From: Richard Henderson <richard.henderson@linaro.org>

Will be used for SVE2 isa subset enablement.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210525010358.152808-2-richard.henderson@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 target/arm/cpu.h    | 16 ++++++++++++++++
 target/arm/helper.c |  3 +--
 target/arm/kvm64.c  | 21 +++++++++++++++------
 3 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 7986a217acd..b7ce3b1e89b 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -947,6 +947,7 @@ struct ARMCPU {
         uint64_t id_aa64mmfr2;
         uint64_t id_aa64dfr0;
         uint64_t id_aa64dfr1;
+        uint64_t id_aa64zfr0;
     } isar;
     uint64_t midr;
     uint32_t revidr;
@@ -2034,6 +2035,16 @@ FIELD(ID_AA64DFR0, DOUBLELOCK, 36, 4)
 FIELD(ID_AA64DFR0, TRACEFILT, 40, 4)
 FIELD(ID_AA64DFR0, MTPMU, 48, 4)
 
+FIELD(ID_AA64ZFR0, SVEVER, 0, 4)
+FIELD(ID_AA64ZFR0, AES, 4, 4)
+FIELD(ID_AA64ZFR0, BITPERM, 16, 4)
+FIELD(ID_AA64ZFR0, BFLOAT16, 20, 4)
+FIELD(ID_AA64ZFR0, SHA3, 32, 4)
+FIELD(ID_AA64ZFR0, SM4, 40, 4)
+FIELD(ID_AA64ZFR0, I8MM, 44, 4)
+FIELD(ID_AA64ZFR0, F32MM, 52, 4)
+FIELD(ID_AA64ZFR0, F64MM, 56, 4)
+
 FIELD(ID_DFR0, COPDBG, 0, 4)
 FIELD(ID_DFR0, COPSDBG, 4, 4)
 FIELD(ID_DFR0, MMAPDBG, 8, 4)
@@ -4225,6 +4236,11 @@ static inline bool isar_feature_aa64_ssbs(const 
ARMISARegisters *id)
     return FIELD_EX64(id->id_aa64pfr1, ID_AA64PFR1, SSBS) != 0;
 }
 
+static inline bool isar_feature_aa64_sve2(const ARMISARegisters *id)
+{
+    return FIELD_EX64(id->id_aa64zfr0, ID_AA64ZFR0, SVEVER) != 0;
+}
+
 /*
  * Feature tests for "does this exist in either 32-bit or 64-bit?"
  */
diff --git a/target/arm/helper.c b/target/arm/helper.c
index 59e9847133a..a66c1f0b9eb 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -7879,8 +7879,7 @@ void register_cp_regs_for_features(ARMCPU *cpu)
               .opc0 = 3, .opc1 = 0, .crn = 0, .crm = 4, .opc2 = 4,
               .access = PL1_R, .type = ARM_CP_CONST,
               .accessfn = access_aa64_tid3,
-              /* At present, only SVEver == 0 is defined anyway.  */
-              .resetvalue = 0 },
+              .resetvalue = cpu->isar.id_aa64zfr0 },
             { .name = "ID_AA64PFR5_EL1_RESERVED", .state = ARM_CP_STATE_AA64,
               .opc0 = 3, .opc1 = 0, .crn = 0, .crm = 4, .opc2 = 5,
               .access = PL1_R, .type = ARM_CP_CONST,
diff --git a/target/arm/kvm64.c b/target/arm/kvm64.c
index dff85f6db94..37ceadd9a9d 100644
--- a/target/arm/kvm64.c
+++ b/target/arm/kvm64.c
@@ -647,17 +647,26 @@ bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures 
*ahcf)
 
     sve_supported = ioctl(fdarray[0], KVM_CHECK_EXTENSION, KVM_CAP_ARM_SVE) > 
0;
 
-    kvm_arm_destroy_scratch_host_vcpu(fdarray);
-
-    if (err < 0) {
-        return false;
-    }
-
     /* Add feature bits that can't appear until after VCPU init. */
     if (sve_supported) {
         t = ahcf->isar.id_aa64pfr0;
         t = FIELD_DP64(t, ID_AA64PFR0, SVE, 1);
         ahcf->isar.id_aa64pfr0 = t;
+
+        /*
+         * Before v5.1, KVM did not support SVE and did not expose
+         * ID_AA64ZFR0_EL1 even as RAZ.  After v5.1, KVM still does
+         * not expose the register to "user" requests like this
+         * unless the host supports SVE.
+         */
+        err |= read_sys_reg64(fdarray[2], &ahcf->isar.id_aa64zfr0,
+                              ARM64_SYS_REG(3, 0, 0, 4, 4));
+    }
+
+    kvm_arm_destroy_scratch_host_vcpu(fdarray);
+
+    if (err < 0) {
+        return false;
     }
 
     /*
-- 
2.20.1