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target/arm: Disable cryptographic instructions when neon is disabled

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As of now, cryptographic instructions ISAR fields are never cleared so
we can end up with a cpu with cryptographic instructions but no
floating-point/neon instructions which is not a possible configuration
according to Arm specifications.

In QEMU, we have 3 kinds of cpus regarding cryptographic instructions:
+ no support
+ cortex-a57/a72: cryptographic extension is optional,
  floating-point/neon is not.
+ cortex-a53: crytographic extension is optional as well as
  floating-point/neon. But cryptographic requires
  floating-point/neon support.

Therefore we can safely clear the ISAR fields when neon is disabled.

Note that other Arm cpus seem to follow this. For example cortex-a55 is
like cortex-a53 and cortex-a76/cortex-a710 are like cortex-a57/a72.

Signed-off-by: Damien Hedde <damien.hedde@greensocs.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220427090117.6954-1-damien.hedde@greensocs.com
[PMM: fixed commit message typos]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Damien Hedde 2022-04-27 11:01:17 +02:00 committed by Peter Maydell
parent c6a59b559b
commit eb851c1151
1 changed files with 9 additions and 0 deletions
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9
target/arm/cpu.c
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@ -1587,6 +1587,12 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
unset_feature(env, ARM_FEATURE_NEON);
t = cpu->isar.id_aa64isar0;
t = FIELD_DP64(t, ID_AA64ISAR0, AES, 0);
t = FIELD_DP64(t, ID_AA64ISAR0, SHA1, 0);
t = FIELD_DP64(t, ID_AA64ISAR0, SHA2, 0);
t = FIELD_DP64(t, ID_AA64ISAR0, SHA3, 0);
t = FIELD_DP64(t, ID_AA64ISAR0, SM3, 0);
t = FIELD_DP64(t, ID_AA64ISAR0, SM4, 0);
t = FIELD_DP64(t, ID_AA64ISAR0, DP, 0);
cpu->isar.id_aa64isar0 = t;
@ -1601,6 +1607,9 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
cpu->isar.id_aa64pfr0 = t;
u = cpu->isar.id_isar5;
u = FIELD_DP32(u, ID_ISAR5, AES, 0);
u = FIELD_DP32(u, ID_ISAR5, SHA1, 0);
u = FIELD_DP32(u, ID_ISAR5, SHA2, 0);
u = FIELD_DP32(u, ID_ISAR5, RDM, 0);
u = FIELD_DP32(u, ID_ISAR5, VCMA, 0);
cpu->isar.id_isar5 = u;