From: Peter Maydell <peter.maydell@linaro.org>
To: qemu-devel@nongnu.org
Subject: [Qemu-devel] [PULL 05/24] target/arm: Allow VFP and Neon to be disabled via a CPU property
Date: Mon, 17 Jun 2019 15:33:53 +0100 [thread overview]
Message-ID: <20190617143412.5734-6-peter.maydell@linaro.org> (raw)
In-Reply-To: <20190617143412.5734-1-peter.maydell@linaro.org>
Allow VFP and neon to be disabled via a CPU property. As with
the "pmu" property, we only allow these features to be removed
from CPUs which have it by default, not added to CPUs which
don't have it.
The primary motivation here is to be able to optionally
create Cortex-M33 CPUs with no FPU, but we provide switches
for both VFP and Neon because the two interact:
* AArch64 can't have one without the other
* Some ID register fields only change if both are disabled
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 20190517174046.11146-2-peter.maydell@linaro.org
---
target/arm/cpu.h | 4 ++
target/arm/cpu.c | 150 +++++++++++++++++++++++++++++++++++++++++++++--
2 files changed, 148 insertions(+), 6 deletions(-)
diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 92298624215..cf2496aeeec 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -786,6 +786,10 @@ struct ARMCPU {
bool has_el3;
/* CPU has PMU (Performance Monitor Unit) */
bool has_pmu;
+ /* CPU has VFP */
+ bool has_vfp;
+ /* CPU has Neon */
+ bool has_neon;
/* CPU has memory protection unit */
bool has_mpu;
diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index 2335659a852..af879d5311e 100644
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -763,6 +763,12 @@ static Property arm_cpu_cfgend_property =
static Property arm_cpu_has_pmu_property =
DEFINE_PROP_BOOL("pmu", ARMCPU, has_pmu, true);
+static Property arm_cpu_has_vfp_property =
+ DEFINE_PROP_BOOL("vfp", ARMCPU, has_vfp, true);
+
+static Property arm_cpu_has_neon_property =
+ DEFINE_PROP_BOOL("neon", ARMCPU, has_neon, true);
+
static Property arm_cpu_has_mpu_property =
DEFINE_PROP_BOOL("has-mpu", ARMCPU, has_mpu, true);
@@ -803,6 +809,13 @@ void arm_cpu_post_init(Object *obj)
if (arm_feature(&cpu->env, ARM_FEATURE_M)) {
set_feature(&cpu->env, ARM_FEATURE_PMSA);
}
+ /* Similarly for the VFP feature bits */
+ if (arm_feature(&cpu->env, ARM_FEATURE_VFP4)) {
+ set_feature(&cpu->env, ARM_FEATURE_VFP3);
+ }
+ if (arm_feature(&cpu->env, ARM_FEATURE_VFP3)) {
+ set_feature(&cpu->env, ARM_FEATURE_VFP);
+ }
if (arm_feature(&cpu->env, ARM_FEATURE_CBAR) ||
arm_feature(&cpu->env, ARM_FEATURE_CBAR_RO)) {
@@ -847,6 +860,27 @@ void arm_cpu_post_init(Object *obj)
&error_abort);
}
+ /*
+ * Allow user to turn off VFP and Neon support, but only for TCG --
+ * KVM does not currently allow us to lie to the guest about its
+ * ID/feature registers, so the guest always sees what the host has.
+ */
+ if (arm_feature(&cpu->env, ARM_FEATURE_VFP)) {
+ cpu->has_vfp = true;
+ if (!kvm_enabled()) {
+ qdev_property_add_static(DEVICE(obj), &arm_cpu_has_vfp_property,
+ &error_abort);
+ }
+ }
+
+ if (arm_feature(&cpu->env, ARM_FEATURE_NEON)) {
+ cpu->has_neon = true;
+ if (!kvm_enabled()) {
+ qdev_property_add_static(DEVICE(obj), &arm_cpu_has_neon_property,
+ &error_abort);
+ }
+ }
+
if (arm_feature(&cpu->env, ARM_FEATURE_PMSA)) {
qdev_property_add_static(DEVICE(obj), &arm_cpu_has_mpu_property,
&error_abort);
@@ -956,6 +990,116 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
return;
}
+ if (arm_feature(env, ARM_FEATURE_AARCH64) &&
+ cpu->has_vfp != cpu->has_neon) {
+ /*
+ * This is an architectural requirement for AArch64; AArch32 is
+ * more flexible and permits VFP-no-Neon and Neon-no-VFP.
+ */
+ error_setg(errp,
+ "AArch64 CPUs must have both VFP and Neon or neither");
+ return;
+ }
+
+ if (!cpu->has_vfp) {
+ uint64_t t;
+ uint32_t u;
+
+ unset_feature(env, ARM_FEATURE_VFP);
+ unset_feature(env, ARM_FEATURE_VFP3);
+ unset_feature(env, ARM_FEATURE_VFP4);
+
+ t = cpu->isar.id_aa64isar1;
+ t = FIELD_DP64(t, ID_AA64ISAR1, JSCVT, 0);
+ cpu->isar.id_aa64isar1 = t;
+
+ t = cpu->isar.id_aa64pfr0;
+ t = FIELD_DP64(t, ID_AA64PFR0, FP, 0xf);
+ cpu->isar.id_aa64pfr0 = t;
+
+ u = cpu->isar.id_isar6;
+ u = FIELD_DP32(u, ID_ISAR6, JSCVT, 0);
+ cpu->isar.id_isar6 = u;
+
+ 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);
+ 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);
+ cpu->isar.mvfr1 = u;
+
+ u = cpu->isar.mvfr2;
+ u = FIELD_DP32(u, MVFR2, FPMISC, 0);
+ cpu->isar.mvfr2 = u;
+ }
+
+ if (!cpu->has_neon) {
+ uint64_t t;
+ uint32_t u;
+
+ unset_feature(env, ARM_FEATURE_NEON);
+
+ t = cpu->isar.id_aa64isar0;
+ t = FIELD_DP64(t, ID_AA64ISAR0, DP, 0);
+ cpu->isar.id_aa64isar0 = t;
+
+ t = cpu->isar.id_aa64isar1;
+ t = FIELD_DP64(t, ID_AA64ISAR1, FCMA, 0);
+ cpu->isar.id_aa64isar1 = t;
+
+ t = cpu->isar.id_aa64pfr0;
+ t = FIELD_DP64(t, ID_AA64PFR0, ADVSIMD, 0xf);
+ cpu->isar.id_aa64pfr0 = t;
+
+ u = cpu->isar.id_isar5;
+ u = FIELD_DP32(u, ID_ISAR5, RDM, 0);
+ u = FIELD_DP32(u, ID_ISAR5, VCMA, 0);
+ cpu->isar.id_isar5 = u;
+
+ u = cpu->isar.id_isar6;
+ u = FIELD_DP32(u, ID_ISAR6, DP, 0);
+ 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);
+ u = FIELD_DP32(u, MVFR1, SIMDFMAC, 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) {
+ uint64_t t;
+ uint32_t u;
+
+ t = cpu->isar.id_aa64isar0;
+ t = FIELD_DP64(t, ID_AA64ISAR0, FHM, 0);
+ cpu->isar.id_aa64isar0 = t;
+
+ t = cpu->isar.id_aa64isar1;
+ t = FIELD_DP64(t, ID_AA64ISAR1, FRINTTS, 0);
+ cpu->isar.id_aa64isar1 = t;
+
+ u = cpu->isar.mvfr0;
+ u = FIELD_DP32(u, MVFR0, SIMDREG, 0);
+ cpu->isar.mvfr0 = u;
+ }
+
/* Some features automatically imply others: */
if (arm_feature(env, ARM_FEATURE_V8)) {
if (arm_feature(env, ARM_FEATURE_M)) {
@@ -1016,12 +1160,6 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
if (arm_feature(env, ARM_FEATURE_V5)) {
set_feature(env, ARM_FEATURE_V4T);
}
- if (arm_feature(env, ARM_FEATURE_VFP4)) {
- set_feature(env, ARM_FEATURE_VFP3);
- }
- if (arm_feature(env, ARM_FEATURE_VFP3)) {
- set_feature(env, ARM_FEATURE_VFP);
- }
if (arm_feature(env, ARM_FEATURE_LPAE)) {
set_feature(env, ARM_FEATURE_V7MP);
set_feature(env, ARM_FEATURE_PXN);
--
2.20.1
next prev parent reply other threads:[~2019-06-17 14:47 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-17 14:33 [Qemu-devel] [PULL 00/24] target-arm queue Peter Maydell
2019-06-17 14:33 ` [Qemu-devel] [PULL 01/24] hw/arm/boot: Don't assume RAM starts at address zero Peter Maydell
2019-06-17 14:33 ` [Qemu-devel] [PULL 02/24] hw/arm/boot: Diagnose layouts that put initrd or DTB off the end of RAM Peter Maydell
2019-06-17 14:33 ` [Qemu-devel] [PULL 03/24] hw/arm/boot: Avoid placing the initrd on top of the kernel Peter Maydell
2019-06-17 14:33 ` [Qemu-devel] [PULL 04/24] hw/arm/boot: Honour image size field in AArch64 Image format kernels Peter Maydell
2019-06-17 14:33 ` Peter Maydell [this message]
2019-06-17 14:33 ` [Qemu-devel] [PULL 06/24] target/arm: Allow M-profile CPUs to disable the DSP extension via CPU property Peter Maydell
2019-06-17 14:33 ` [Qemu-devel] [PULL 07/24] hw/arm/armv7m: Forward "vfp" and "dsp" properties to CPU Peter Maydell
2019-06-17 14:33 ` [Qemu-devel] [PULL 08/24] hw/arm: Correctly disable FPU/DSP for some ARMSSE-based boards Peter Maydell
2019-06-17 14:33 ` [Qemu-devel] [PULL 09/24] hw/intc/arm_gicv3: Fix decoding of ID register range Peter Maydell
2019-06-17 14:33 ` [Qemu-devel] [PULL 10/24] hw/intc/arm_gicv3: GICD_TYPER.SecurityExtn is RAZ if GICD_CTLR.DS == 1 Peter Maydell
2019-06-17 14:33 ` [Qemu-devel] [PULL 11/24] target/arm: Move vfp_expand_imm() to translate.[ch] Peter Maydell
2019-06-17 14:34 ` [Qemu-devel] [PULL 12/24] target/arm: Use vfp_expand_imm() for AArch32 VFP VMOV_imm Peter Maydell
2019-06-17 14:34 ` [Qemu-devel] [PULL 13/24] target/arm: Stop using cpu_F0s for NEON_2RM_VABS_F Peter Maydell
2019-06-17 14:34 ` [Qemu-devel] [PULL 14/24] target/arm: Stop using cpu_F0s for NEON_2RM_VNEG_F Peter Maydell
2019-06-17 14:34 ` [Qemu-devel] [PULL 15/24] target/arm: Stop using cpu_F0s for NEON_2RM_VRINT* Peter Maydell
2019-06-17 14:34 ` [Qemu-devel] [PULL 16/24] target/arm: Stop using cpu_F0s for NEON_2RM_VCVT[ANPM][US] Peter Maydell
2019-06-17 14:34 ` [Qemu-devel] [PULL 17/24] target/arm: Stop using cpu_F0s for NEON_2RM_VRECPE_F and NEON_2RM_VRSQRTE_F Peter Maydell
2019-06-17 14:34 ` [Qemu-devel] [PULL 18/24] target/arm: Stop using cpu_F0s for Neon f32/s32 VCVT Peter Maydell
2019-06-17 14:34 ` [Qemu-devel] [PULL 19/24] target/arm: Stop using cpu_F0s in Neon VCVT fixed-point ops Peter Maydell
2019-06-17 14:34 ` [Qemu-devel] [PULL 20/24] target/arm: stop using deprecated functions in NEON_2RM_VCVT_F16_F32 Peter Maydell
2019-06-17 14:34 ` [Qemu-devel] [PULL 21/24] target/arm: Stop using deprecated functions in NEON_2RM_VCVT_F32_F16 Peter Maydell
2019-06-17 14:34 ` [Qemu-devel] [PULL 22/24] target/arm: Remove unused cpu_F0s, cpu_F0d, cpu_F1s, cpu_F1d Peter Maydell
2019-06-17 14:34 ` [Qemu-devel] [PULL 23/24] target/arm: Fix typos in trans function prototypes Peter Maydell
2019-06-17 14:34 ` [Qemu-devel] [PULL 24/24] target/arm: Only implement doubles if the FPU supports them Peter Maydell
2019-06-17 15:41 ` [Qemu-devel] [PULL 00/24] target-arm queue Peter Maydell
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