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Re: [PATCH] target/arm/kvm: Check supported feature per accelerator (not
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From: |
Andrew Jones |
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Subject: |
Re: [PATCH] target/arm/kvm: Check supported feature per accelerator (not per vCPU) |
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Date: |
Thu, 18 Jun 2020 11:22:08 +0200 |
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@linaro.org>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
> 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?
> 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?
Thanks,
drew