diff options
| author | Peter Maydell <peter.maydell@linaro.org> | 2020-10-19 16:12:59 +0100 |
|---|---|---|
| committer | Peter Maydell <peter.maydell@linaro.org> | 2020-10-20 16:12:01 +0100 |
| commit | 532a3af5fbd348bca371b4a56b45f8f97c7c5519 (patch) | |
| tree | d4dd8f99b461632a132129d2e7a9ff8109aa21b3 /target/arm | |
| parent | b7226369721896ab9ef71544e4fe95b40710e05a (diff) | |
target/arm: Fix has_vfp/has_neon ID reg squashing for M-profile
In arm_cpu_realizefn(), if the CPU has VFP or Neon disabled then we
squash the ID register fields so that we don't advertise it to the
guest. This code was written for A-profile and needs some tweaks to
work correctly on M-profile:
* A-profile only fields should not be zeroed on M-profile:
- MVFR0.FPSHVEC,FPTRAP
- MVFR1.SIMDLS,SIMDINT,SIMDSP,SIMDHP
- MVFR2.SIMDMISC
* M-profile only fields should be zeroed on M-profile:
- MVFR1.FP16
In particular, because MVFR1.SIMDHP on A-profile is the same field as
MVFR1.FP16 on M-profile this code was incorrectly disabling FP16
support on an M-profile CPU (where has_neon is always false). This
isn't a visible bug yet because we don't have any M-profile CPUs with
FP16 support, but the change is necessary before we introduce any.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20201019151301.2046-9-peter.maydell@linaro.org
Diffstat (limited to 'target/arm')
| -rw-r--r-- | target/arm/cpu.c | 31 |
1 files changed, 19 insertions, 12 deletions
diff --git a/target/arm/cpu.c b/target/arm/cpu.c index 056319859f..186ee621a6 100644 --- a/target/arm/cpu.c +++ b/target/arm/cpu.c @@ -1429,17 +1429,22 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp) u = cpu->isar.mvfr0; u = FIELD_DP32(u, MVFR0, FPSP, 0); u = FIELD_DP32(u, MVFR0, FPDP, 0); - u = FIELD_DP32(u, MVFR0, FPTRAP, 0); u = FIELD_DP32(u, MVFR0, FPDIVIDE, 0); u = FIELD_DP32(u, MVFR0, FPSQRT, 0); - u = FIELD_DP32(u, MVFR0, FPSHVEC, 0); u = FIELD_DP32(u, MVFR0, FPROUND, 0); + if (!arm_feature(env, ARM_FEATURE_M)) { + u = FIELD_DP32(u, MVFR0, FPTRAP, 0); + u = FIELD_DP32(u, MVFR0, FPSHVEC, 0); + } cpu->isar.mvfr0 = u; u = cpu->isar.mvfr1; u = FIELD_DP32(u, MVFR1, FPFTZ, 0); u = FIELD_DP32(u, MVFR1, FPDNAN, 0); u = FIELD_DP32(u, MVFR1, FPHP, 0); + if (arm_feature(env, ARM_FEATURE_M)) { + u = FIELD_DP32(u, MVFR1, FP16, 0); + } cpu->isar.mvfr1 = u; u = cpu->isar.mvfr2; @@ -1475,16 +1480,18 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp) u = FIELD_DP32(u, ID_ISAR6, FHM, 0); cpu->isar.id_isar6 = u; - u = cpu->isar.mvfr1; - u = FIELD_DP32(u, MVFR1, SIMDLS, 0); - u = FIELD_DP32(u, MVFR1, SIMDINT, 0); - u = FIELD_DP32(u, MVFR1, SIMDSP, 0); - u = FIELD_DP32(u, MVFR1, SIMDHP, 0); - cpu->isar.mvfr1 = u; - - u = cpu->isar.mvfr2; - u = FIELD_DP32(u, MVFR2, SIMDMISC, 0); - cpu->isar.mvfr2 = u; + if (!arm_feature(env, ARM_FEATURE_M)) { + u = cpu->isar.mvfr1; + u = FIELD_DP32(u, MVFR1, SIMDLS, 0); + u = FIELD_DP32(u, MVFR1, SIMDINT, 0); + u = FIELD_DP32(u, MVFR1, SIMDSP, 0); + u = FIELD_DP32(u, MVFR1, SIMDHP, 0); + cpu->isar.mvfr1 = u; + + u = cpu->isar.mvfr2; + u = FIELD_DP32(u, MVFR2, SIMDMISC, 0); + cpu->isar.mvfr2 = u; + } } if (!cpu->has_neon && !cpu->has_vfp) { |