Some CPU features aren't strictly required to run guest code (such debugging features), so we don't model them. To prevent the guest to access non-existent system registers, we disable the feature bit in the ID registers (see commit 7d8c283e10 "target/arm: Suppress more TCG unimplemented features in ID registers").
Since it might be useful to know when a CPU supposed to implement a feature has it disabled in QEMU, provide the ability to log disabled features at the UNIMP level: $ qemu-system-aarch64 -M virt -d unimp -S -cpu neoverse-v1 QEMU 8.0.92 monitor - type 'help' for more information CPU#0: Disabling unimplemented feature 'FEAT_SPE (Statistical Profiling Extension)' for neoverse-v1 CPU#0: Disabling unimplemented feature 'FEAT_TRF (Self-hosted Trace Extension)' for neoverse-v1 CPU#0: Disabling unimplemented feature 'FEAT_TRF (Self-hosted Trace Extension)' for neoverse-v1 CPU#0: Disabling unimplemented feature 'Trace Macrocell system register access' for neoverse-v1 CPU#0: Disabling unimplemented feature 'Trace Macrocell system register access' for neoverse-v1 CPU#0: Disabling unimplemented feature 'Memory-mapped Trace' for neoverse-v1 CPU#0: Disabling unimplemented feature 'FEAT_AMU (Activity Monitors Extension)' for neoverse-v1 CPU#0: Disabling unimplemented feature 'FEAT_AMU (Activity Monitors Extension)' for neoverse-v1 CPU#0: Disabling unimplemented feature 'FEAT_MPAM (Memory Partitioning and Monitoring Extension)' for neoverse-v1 CPU#0: Disabling unimplemented feature 'FEAT_NV (Nested Virtualization)' for neoverse-v1 (qemu) q $ qemu-system-aarch64 -M xlnx-zcu102 -trace arm_disable\* -S -d unimp -monitor stdio -cpu cortex-a76 QEMU 8.0.92 monitor - type 'help' for more information CPU#0: Disabling unimplemented feature 'Memory-mapped Trace' for cortex-a53 CPU#1: Disabling unimplemented feature 'Memory-mapped Trace' for cortex-a53 CPU#2: Disabling unimplemented feature 'Memory-mapped Trace' for cortex-a53 CPU#3: Disabling unimplemented feature 'Memory-mapped Trace' for cortex-a53 (qemu) q Refactor the FIELD_DPxx() calls into the DISABLE_UNIMP_CPU_FEATURE() macro where we call qemu_log(UNIMP). Signed-off-by: Philippe Mathieu-Daudé <[email protected]> --- There is another series reworking cpu_typename() helpers, so meanwhile I simply added a static arm_cpu_typename() here. --- target/arm/cpu.c | 60 ++++++++++++++++++++++++++++++++---------------- 1 file changed, 40 insertions(+), 20 deletions(-) diff --git a/target/arm/cpu.c b/target/arm/cpu.c index 93c28d50e5..becd2d2690 100644 --- a/target/arm/cpu.c +++ b/target/arm/cpu.c @@ -1580,6 +1580,24 @@ void arm_cpu_finalize_features(ARMCPU *cpu, Error **errp) } } +/* callers must free the returned string with g_free() */ +static char *arm_cpu_typename(ARMCPU *cpu) +{ + const char *cpu_type = object_get_typename(OBJECT(cpu)); + + return g_strndup(cpu_type, strlen(cpu_type) - strlen(ARM_CPU_TYPE_SUFFIX)); +} + +#define DISABLE_UNIMP_CPU_FEATURE(size, cpu, storage, reg, field, desc) \ + if (FIELD_EX##size(cpu->isar.storage, reg, field)) { \ + g_autofree char *cpu_type = arm_cpu_typename(cpu); \ + \ + qemu_log_mask(LOG_UNIMP, \ + "CPU#%d: Disabling unimplemented feature '%s' for %s\n", \ + CPU(cpu)->cpu_index, desc, cpu_type); \ + cpu->isar.storage = FIELD_DP##size(cpu->isar.storage, reg, field, 0); \ + } + static void arm_cpu_realizefn(DeviceState *dev, Error **errp) { CPUState *cs = CPU(dev); @@ -2075,32 +2093,34 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp) * try to access the non-existent system registers for them. */ /* FEAT_SPE (Statistical Profiling Extension) */ - cpu->isar.id_aa64dfr0 = - FIELD_DP64(cpu->isar.id_aa64dfr0, ID_AA64DFR0, PMSVER, 0); + DISABLE_UNIMP_CPU_FEATURE(64, cpu, id_aa64dfr0, ID_AA64DFR0, PMSVER, + "FEAT_SPE (Statistical Profiling Extension)"); + /* FEAT_TRF (Self-hosted Trace Extension) */ - cpu->isar.id_aa64dfr0 = - FIELD_DP64(cpu->isar.id_aa64dfr0, ID_AA64DFR0, TRACEFILT, 0); - cpu->isar.id_dfr0 = - FIELD_DP32(cpu->isar.id_dfr0, ID_DFR0, TRACEFILT, 0); + DISABLE_UNIMP_CPU_FEATURE(64, cpu, id_aa64dfr0, ID_AA64DFR0, TRACEFILT, + "FEAT_TRF (Self-hosted Trace Extension)"); + DISABLE_UNIMP_CPU_FEATURE(32, cpu, id_dfr0, ID_DFR0, TRACEFILT, + "FEAT_TRF (Self-hosted Trace Extension)"); /* Trace Macrocell system register access */ - cpu->isar.id_aa64dfr0 = - FIELD_DP64(cpu->isar.id_aa64dfr0, ID_AA64DFR0, TRACEVER, 0); - cpu->isar.id_dfr0 = - FIELD_DP32(cpu->isar.id_dfr0, ID_DFR0, COPTRC, 0); + DISABLE_UNIMP_CPU_FEATURE(64, cpu, id_aa64dfr0, ID_AA64DFR0, TRACEVER, + "Trace Macrocell system register access"); + DISABLE_UNIMP_CPU_FEATURE(32, cpu, id_dfr0, ID_DFR0, COPTRC, + "Trace Macrocell system register access"); /* Memory mapped trace */ - cpu->isar.id_dfr0 = - FIELD_DP32(cpu->isar.id_dfr0, ID_DFR0, MMAPTRC, 0); + DISABLE_UNIMP_CPU_FEATURE(32, cpu, id_dfr0, ID_DFR0, MMAPTRC, + "Memory-mapped Trace"); /* FEAT_AMU (Activity Monitors Extension) */ - cpu->isar.id_aa64pfr0 = - FIELD_DP64(cpu->isar.id_aa64pfr0, ID_AA64PFR0, AMU, 0); - cpu->isar.id_pfr0 = - FIELD_DP32(cpu->isar.id_pfr0, ID_PFR0, AMU, 0); + DISABLE_UNIMP_CPU_FEATURE(64, cpu, id_aa64pfr0, ID_AA64PFR0, AMU, + "FEAT_AMU (Activity Monitors Extension)"); + DISABLE_UNIMP_CPU_FEATURE(32, cpu, id_pfr0, ID_PFR0, AMU, + "FEAT_AMU (Activity Monitors Extension)"); /* FEAT_MPAM (Memory Partitioning and Monitoring Extension) */ - cpu->isar.id_aa64pfr0 = - FIELD_DP64(cpu->isar.id_aa64pfr0, ID_AA64PFR0, MPAM, 0); + DISABLE_UNIMP_CPU_FEATURE(64, cpu, id_aa64pfr0, ID_AA64PFR0, MPAM, + "FEAT_MPAM (Memory Partitioning" + " and Monitoring Extension)"); /* FEAT_NV (Nested Virtualization) */ - cpu->isar.id_aa64mmfr2 = - FIELD_DP64(cpu->isar.id_aa64mmfr2, ID_AA64MMFR2, NV, 0); + DISABLE_UNIMP_CPU_FEATURE(64, cpu, id_aa64mmfr2, ID_AA64MMFR2, NV, + "FEAT_NV (Nested Virtualization)"); } /* MPU can be configured out of a PMSA CPU either by setting has-mpu -- 2.38.1
