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Mon, 22 Jun 2020 16:05:04 -0700 (PDT) Subject: Re: [PATCH v2] target/arm: Check supported KVM features globally (not per vCPU) To: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , qemu-devel@nongnu.org References: <20200619095542.2095-1-philmd@redhat.com> From: Paolo Bonzini Message-ID: <51efbadc-8061-47f6-ed0b-9b846ace36d7@redhat.com> Date: Tue, 23 Jun 2020 01:05:04 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20200619095542.2095-1-philmd@redhat.com> Content-Language: en-US Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=205.139.110.120; envelope-from=pbonzini@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/22 01:27:42 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Andrew Jones , kvm@vger.kernel.org, "Dr . David Alan Gilbert" , qemu-arm@nongnu.org, Haibo Xu Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 19/06/20 11:55, 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 ) 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=, argv=, envp=) 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__supported() functions take a AccelState > argument (already realized/valid at this point) instead of a > CPUState argument. > > Reported-by: Haibo Xu > Suggested-by: Paolo Bonzini > Signed-off-by: Philippe Mathieu-Daudé > --- > v2: Use global kvm_state (bonzini) > > Paolo, does this break migration of encrypted memory assumptions? > > Cc: Dr. David Alan Gilbert > Supersedes: <20200617130800.26355-1-philmd@redhat.com> > --- > target/arm/kvm_arm.h | 21 +++++++++------------ > target/arm/cpu.c | 2 +- > target/arm/cpu64.c | 10 +++++----- > target/arm/kvm.c | 4 ++-- > target/arm/kvm64.c | 14 +++++--------- > 5 files changed, 22 insertions(+), 29 deletions(-) > > diff --git a/target/arm/kvm_arm.h b/target/arm/kvm_arm.h > index 48bf5e16d5..a4ce4fd93d 100644 > --- a/target/arm/kvm_arm.h > +++ b/target/arm/kvm_arm.h > @@ -269,29 +269,26 @@ void kvm_arm_add_vcpu_properties(Object *obj); > > /** > * kvm_arm_aarch32_supported: > - * @cs: CPUState > * > - * Returns: true if the KVM VCPU can enable AArch32 mode > + * Returns: true if KVM can enable AArch32 mode > * and false otherwise. > */ > -bool kvm_arm_aarch32_supported(CPUState *cs); > +bool kvm_arm_aarch32_supported(void); > > /** > * kvm_arm_pmu_supported: > - * @cs: CPUState > * > - * Returns: true if the KVM VCPU can enable its PMU > + * Returns: true if KVM can enable the PMU > * and false otherwise. > */ > -bool kvm_arm_pmu_supported(CPUState *cs); > +bool kvm_arm_pmu_supported(void); > > /** > * kvm_arm_sve_supported: > - * @cs: CPUState > * > - * Returns true if the KVM VCPU can enable SVE and false otherwise. > + * Returns true if KVM can enable SVE and false otherwise. > */ > -bool kvm_arm_sve_supported(CPUState *cs); > +bool kvm_arm_sve_supported(void); > > /** > * kvm_arm_get_max_vm_ipa_size: > @@ -359,17 +356,17 @@ 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(void) > { > return false; > } > > -static inline bool kvm_arm_pmu_supported(CPUState *cs) > +static inline bool kvm_arm_pmu_supported(void) > { > return false; > } > > -static inline bool kvm_arm_sve_supported(CPUState *cs) > +static inline bool kvm_arm_sve_supported(void) > { > return false; > } > diff --git a/target/arm/cpu.c b/target/arm/cpu.c > index 5b7a36b5d7..e44e18062c 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()) { > 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..a0c1d8894b 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()) { > 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()) { > 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()) { > 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()) { > 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()) { > 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..7c672c78b8 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(void) > { > - return kvm_check_extension(cpu->kvm_state, KVM_CAP_ARM_PMU_V3); > + return kvm_check_extension(kvm_state, 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..3dc494aaa7 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(void) > { > - KVMState *s = KVM_STATE(current_accel()); > - > - return kvm_check_extension(s, KVM_CAP_ARM_EL1_32BIT); > + return kvm_check_extension(kvm_state, KVM_CAP_ARM_EL1_32BIT); > } > > -bool kvm_arm_sve_supported(CPUState *cpu) > +bool kvm_arm_sve_supported(void) > { > - KVMState *s = KVM_STATE(current_accel()); > - > - return kvm_check_extension(s, KVM_CAP_ARM_SVE); > + return kvm_check_extension(kvm_state, 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()); > cpu->kvm_init_features[0] |= 1 << KVM_ARM_VCPU_SVE; > } > > Acked-by: Paolo Bonzini I think the patch and the test can go through the ARM tree. Thanks, Paolo