On 6/18/20 11:22 AM, Andrew Jones wrote:
> On Wed, Jun 17, 2020 at 03:08:00PM +0200, Philippe Mathieu-Daudé wrote:
>> Since commit d70c996df23f, when enabling the PMU we get:
>>
>> $ qemu-system-aarch64 -cpu host,pmu=on -M virt,accel=kvm,gic-version=3
>> Segmentation fault (core dumped)
>>
>> Thread 1 "qemu-system-aar" received signal SIGSEGV, Segmentation fault.
>> 0x0000aaaaaae356d0 in kvm_ioctl (s=0x0, type=44547) at accel/kvm/kvm-all.c:2588
>> 2588 ret = ioctl(s->fd, type, arg);
>> (gdb) bt
>> #0 0x0000aaaaaae356d0 in kvm_ioctl (s=0x0, type=44547) at accel/kvm/kvm-all.c:2588
>> #1 0x0000aaaaaae31568 in kvm_check_extension (s=0x0, extension=126) at accel/kvm/kvm-all.c:916
>> #2 0x0000aaaaaafce254 in kvm_arm_pmu_supported (cpu=0xaaaaac214ab0) at target/arm/kvm.c:213
>> #3 0x0000aaaaaafc0f94 in arm_set_pmu (obj=0xaaaaac214ab0, value=true, errp=0xffffffffe438) at target/arm/cpu.c:1111
>> #4 0x0000aaaaab5533ac in property_set_bool (obj=0xaaaaac214ab0, v=0xaaaaac223a80, name=0xaaaaac11a970 "pmu", opaque=0xaaaaac222730, errp=0xffffffffe438) at qom/object.c:2170
>> #5 0x0000aaaaab5512f0 in object_property_set (obj=0xaaaaac214ab0, v=0xaaaaac223a80, name=0xaaaaac11a970 "pmu", errp=0xffffffffe438) at qom/object.c:1328
>> #6 0x0000aaaaab551e10 in object_property_parse (obj=0xaaaaac214ab0, string=0xaaaaac11b4c0 "on", name=0xaaaaac11a970 "pmu", errp=0xffffffffe438) at qom/object.c:1561
>> #7 0x0000aaaaab54ee8c in object_apply_global_props (obj=0xaaaaac214ab0, props=0xaaaaac018e20, errp=0xaaaaabd6fd88 <error_fatal>) at qom/object.c:407
>> #8 0x0000aaaaab1dd5a4 in qdev_prop_set_globals (dev=0xaaaaac214ab0) at hw/core/qdev-properties.c:1218
>> #9 0x0000aaaaab1d9fac in device_post_init (obj=0xaaaaac214ab0) at hw/core/qdev.c:1050
>> ...
>> #15 0x0000aaaaab54f310 in object_initialize_with_type (obj=0xaaaaac214ab0, size=52208, type=0xaaaaabe237f0) at qom/object.c:512
>> #16 0x0000aaaaab54fa24 in object_new_with_type (type=0xaaaaabe237f0) at qom/object.c:687
>> #17 0x0000aaaaab54fa80 in object_new (typename=0xaaaaabe23970 "host-arm-cpu") at qom/object.c:702
>> #18 0x0000aaaaaaf04a74 in machvirt_init (machine=0xaaaaac0a8550) at hw/arm/virt.c:1770
>> #19 0x0000aaaaab1e8720 in machine_run_board_init (machine=0xaaaaac0a8550) at hw/core/machine.c:1138
>> #20 0x0000aaaaaaf95394 in qemu_init (argc=5, argv=0xffffffffea58, envp=0xffffffffea88) at softmmu/vl.c:4348
>> #21 0x0000aaaaaada3f74 in main (argc=<optimized out>, argv=<optimized out>, envp=<optimized out>) at softmmu/main.c:48
>>
>> This is because in frame #2, cpu->kvm_state is still NULL
>> (the vCPU is not yet realized).
>>
>> KVM has a hard requirement of all cores supporting the same
>> feature set. We only need to check if the accelerator supports
>> a feature, not each vCPU individually.
>>
>> Fix by kvm_arm_<FEATURE>_supported() functions take a AccelState
>> argument (already realized/valid at this point) instead of a
>> CPUState argument.
>>
>> Reported-by: Haibo Xu <haibo.xu@xxxxxxxxxx>
>> Signed-off-by: Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>
>> ---
>> target/arm/kvm_arm.h | 25 +++++++++++++------------
>> target/arm/cpu.c | 2 +-
>> target/arm/cpu64.c | 10 +++++-----
>> target/arm/kvm.c | 4 ++--
>> target/arm/kvm64.c | 14 +++++---------
>> 5 files changed, 26 insertions(+), 29 deletions(-)
>>
>> diff --git a/target/arm/kvm_arm.h b/target/arm/kvm_arm.h
>> index 48bf5e16d5..8209525f20 100644
>> --- a/target/arm/kvm_arm.h
>> +++ b/target/arm/kvm_arm.h
>> @@ -12,6 +12,7 @@
>> #define QEMU_KVM_ARM_H
>>
>> #include "sysemu/kvm.h"
>> +#include "sysemu/accel.h"
>> #include "exec/memory.h"
>> #include "qemu/error-report.h"
>>
>> @@ -269,29 +270,29 @@ void kvm_arm_add_vcpu_properties(Object *obj);
>>
>> /**
>> * kvm_arm_aarch32_supported:
>> - * @cs: CPUState
>> + * @as: AccelState
>> *
>> - * Returns: true if the KVM VCPU can enable AArch32 mode
>> + * Returns: true if the KVM accelerator can enable AArch32 mode
>> * and false otherwise.
>> */
>> -bool kvm_arm_aarch32_supported(CPUState *cs);
>> +bool kvm_arm_aarch32_supported(AccelState *as);
>>
>> /**
>> * kvm_arm_pmu_supported:
>> - * @cs: CPUState
>> + * @as: AccelState
>> *
>> - * Returns: true if the KVM VCPU can enable its PMU
>> + * Returns: true if the KVM accelerator can enable its PMU
>> * and false otherwise.
>> */
>> -bool kvm_arm_pmu_supported(CPUState *cs);
>> +bool kvm_arm_pmu_supported(AccelState *as);
>>
>> /**
>> * kvm_arm_sve_supported:
>> - * @cs: CPUState
>> + * @as: AccelState
>> *
>> - * Returns true if the KVM VCPU can enable SVE and false otherwise.
>> + * Returns true if the KVM accelerator can enable SVE and false otherwise.
>> */
>> -bool kvm_arm_sve_supported(CPUState *cs);
>> +bool kvm_arm_sve_supported(AccelState *as);
>>
>> /**
>> * kvm_arm_get_max_vm_ipa_size:
>> @@ -359,17 +360,17 @@ static inline void kvm_arm_set_cpu_features_from_host(ARMCPU *cpu)
>>
>> static inline void kvm_arm_add_vcpu_properties(Object *obj) {}
>>
>> -static inline bool kvm_arm_aarch32_supported(CPUState *cs)
>> +static inline bool kvm_arm_aarch32_supported(AccelState *as)
>> {
>> return false;
>> }
>>
>> -static inline bool kvm_arm_pmu_supported(CPUState *cs)
>> +static inline bool kvm_arm_pmu_supported(AccelState *as)
>> {
>> return false;
>> }
>>
>> -static inline bool kvm_arm_sve_supported(CPUState *cs)
>> +static inline bool kvm_arm_sve_supported(AccelState *as)
>> {
>> return false;
>> }
>> diff --git a/target/arm/cpu.c b/target/arm/cpu.c
>> index 5b7a36b5d7..29b314427c 100644
>> --- a/target/arm/cpu.c
>> +++ b/target/arm/cpu.c
>> @@ -1108,7 +1108,7 @@ static void arm_set_pmu(Object *obj, bool value, Error **errp)
>> ARMCPU *cpu = ARM_CPU(obj);
>>
>> if (value) {
>> - if (kvm_enabled() && !kvm_arm_pmu_supported(CPU(cpu))) {
>> + if (kvm_enabled() && !kvm_arm_pmu_supported(current_accel())) {
>> error_setg(errp, "'pmu' feature not supported by KVM on this host");
>> return;
>> }
>> diff --git a/target/arm/cpu64.c b/target/arm/cpu64.c
>> index 778cecc2e6..13835768ab 100644
>> --- a/target/arm/cpu64.c
>> +++ b/target/arm/cpu64.c
>> @@ -266,7 +266,7 @@ void arm_cpu_sve_finalize(ARMCPU *cpu, Error **errp)
>>
>> /* Collect the set of vector lengths supported by KVM. */
>> bitmap_zero(kvm_supported, ARM_MAX_VQ);
>> - if (kvm_enabled() && kvm_arm_sve_supported(CPU(cpu))) {
>> + if (kvm_enabled() && kvm_arm_sve_supported(current_accel())) {
>> kvm_arm_sve_get_vls(CPU(cpu), kvm_supported);
>> } else if (kvm_enabled()) {
>> assert(!cpu_isar_feature(aa64_sve, cpu));
>> @@ -473,7 +473,7 @@ static void cpu_max_set_sve_max_vq(Object *obj, Visitor *v, const char *name,
>> return;
>> }
>>
>> - if (kvm_enabled() && !kvm_arm_sve_supported(CPU(cpu))) {
>> + if (kvm_enabled() && !kvm_arm_sve_supported(current_accel())) {
>> error_setg(errp, "cannot set sve-max-vq");
>> error_append_hint(errp, "SVE not supported by KVM on this host\n");
>> return;
>> @@ -519,7 +519,7 @@ static void cpu_arm_set_sve_vq(Object *obj, Visitor *v, const char *name,
>> return;
>> }
>>
>> - if (value && kvm_enabled() && !kvm_arm_sve_supported(CPU(cpu))) {
>> + if (value && kvm_enabled() && !kvm_arm_sve_supported(current_accel())) {
>> error_setg(errp, "cannot enable %s", name);
>> error_append_hint(errp, "SVE not supported by KVM on this host\n");
>> return;
>> @@ -556,7 +556,7 @@ static void cpu_arm_set_sve(Object *obj, Visitor *v, const char *name,
>> return;
>> }
>>
>> - if (value && kvm_enabled() && !kvm_arm_sve_supported(CPU(cpu))) {
>> + if (value && kvm_enabled() && !kvm_arm_sve_supported(current_accel())) {
>> error_setg(errp, "'sve' feature not supported by KVM on this host");
>> return;
>> }
>> @@ -751,7 +751,7 @@ static void aarch64_cpu_set_aarch64(Object *obj, bool value, Error **errp)
>> * uniform execution state like do_interrupt.
>> */
>> if (value == false) {
>> - if (!kvm_enabled() || !kvm_arm_aarch32_supported(CPU(cpu))) {
>> + if (!kvm_enabled() || !kvm_arm_aarch32_supported(current_accel())) {
>> error_setg(errp, "'aarch64' feature cannot be disabled "
>> "unless KVM is enabled and 32-bit EL1 "
>> "is supported");
>> diff --git a/target/arm/kvm.c b/target/arm/kvm.c
>> index eef3bbd1cc..2247a96757 100644
>> --- a/target/arm/kvm.c
>> +++ b/target/arm/kvm.c
>> @@ -208,9 +208,9 @@ void kvm_arm_add_vcpu_properties(Object *obj)
>> }
>> }
>>
>> -bool kvm_arm_pmu_supported(CPUState *cpu)
>> +bool kvm_arm_pmu_supported(AccelState *as)
>> {
>> - return kvm_check_extension(cpu->kvm_state, KVM_CAP_ARM_PMU_V3);
>> + return kvm_check_extension(KVM_STATE(as), KVM_CAP_ARM_PMU_V3);
>> }
>>
>> int kvm_arm_get_max_vm_ipa_size(MachineState *ms)
>> diff --git a/target/arm/kvm64.c b/target/arm/kvm64.c
>> index f09ed9f4df..ae4e37ce78 100644
>> --- a/target/arm/kvm64.c
>> +++ b/target/arm/kvm64.c
>> @@ -652,18 +652,14 @@ bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)
>> return true;
>> }
>>
>> -bool kvm_arm_aarch32_supported(CPUState *cpu)
>> +bool kvm_arm_aarch32_supported(AccelState *as)
>> {
>> - KVMState *s = KVM_STATE(current_accel());
>> -
>> - return kvm_check_extension(s, KVM_CAP_ARM_EL1_32BIT);
>> + return kvm_check_extension(KVM_STATE(as), KVM_CAP_ARM_EL1_32BIT);
>> }
>>
>> -bool kvm_arm_sve_supported(CPUState *cpu)
>> +bool kvm_arm_sve_supported(AccelState *as)
>> {
>> - KVMState *s = KVM_STATE(current_accel());
>> -
>> - return kvm_check_extension(s, KVM_CAP_ARM_SVE);
>> + return kvm_check_extension(KVM_STATE(as), KVM_CAP_ARM_SVE);
>> }
>>
>> QEMU_BUILD_BUG_ON(KVM_ARM64_SVE_VQ_MIN != 1);
>> @@ -798,7 +794,7 @@ int kvm_arch_init_vcpu(CPUState *cs)
>> env->features &= ~(1ULL << ARM_FEATURE_PMU);
>> }
>> if (cpu_isar_feature(aa64_sve, cpu)) {
>> - assert(kvm_arm_sve_supported(cs));
>> + assert(kvm_arm_sve_supported(ACCEL(cs->kvm_state)));
>
> Might as well use current_accel() here too, right?
I was not sure, I used kvm_state since at this point we are
sure it is initialized.
>
>> cpu->kvm_init_features[0] |= 1 << KVM_ARM_VCPU_SVE;
>> }
>>
>> --
>> 2.21.3
>>
>>
>
> At all callsites we pass current_accel() to the kvm_arm_<feat>_supported()
> functions. Is there any reason not to drop their input parameter and just
> use current_accel() internally?
Clever idea :)
>
> Thanks,
> drew
>
