Messages in this thread | | | Date | Mon, 16 May 2022 12:36:01 +0200 | Subject | Re: [PATCH v9 3/3] s390x: KVM: resetting the Topology-Change-Report | From | Pierre Morel <> |
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On 5/12/22 11:31, David Hildenbrand wrote: > On 06.05.22 11:24, Pierre Morel wrote: >> During a subsystem reset the Topology-Change-Report is cleared. >> Let's give userland the possibility to clear the MTCR in the case >> of a subsystem reset. >> >> To migrate the MTCR, let's give userland the possibility to >> query the MTCR state. >> >> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com> >> --- >> arch/s390/include/uapi/asm/kvm.h | 5 ++ >> arch/s390/kvm/kvm-s390.c | 79 ++++++++++++++++++++++++++++++++ >> 2 files changed, 84 insertions(+) >> >> diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h >> index 7a6b14874d65..abdcf4069343 100644 >> --- a/arch/s390/include/uapi/asm/kvm.h >> +++ b/arch/s390/include/uapi/asm/kvm.h >> @@ -74,6 +74,7 @@ struct kvm_s390_io_adapter_req { >> #define KVM_S390_VM_CRYPTO 2 >> #define KVM_S390_VM_CPU_MODEL 3 >> #define KVM_S390_VM_MIGRATION 4 >> +#define KVM_S390_VM_CPU_TOPOLOGY 5 >> >> /* kvm attributes for mem_ctrl */ >> #define KVM_S390_VM_MEM_ENABLE_CMMA 0 >> @@ -171,6 +172,10 @@ struct kvm_s390_vm_cpu_subfunc { >> #define KVM_S390_VM_MIGRATION_START 1 >> #define KVM_S390_VM_MIGRATION_STATUS 2 >> >> +/* kvm attributes for cpu topology */ >> +#define KVM_S390_VM_CPU_TOPO_MTR_CLEAR 0 >> +#define KVM_S390_VM_CPU_TOPO_MTR_SET 1 >> + >> /* for KVM_GET_REGS and KVM_SET_REGS */ >> struct kvm_regs { >> /* general purpose regs for s390 */ >> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c >> index c8bdce31464f..80a1244f0ead 100644 >> --- a/arch/s390/kvm/kvm-s390.c >> +++ b/arch/s390/kvm/kvm-s390.c >> @@ -1731,6 +1731,76 @@ static void kvm_s390_sca_set_mtcr(struct kvm *kvm) >> ipte_unlock(kvm); >> } >> >> +/** >> + * kvm_s390_sca_clear_mtcr >> + * @kvm: guest KVM description >> + * >> + * Is only relevant if the topology facility is present, >> + * the caller should check KVM facility 11 >> + * >> + * Updates the Multiprocessor Topology-Change-Report to signal >> + * the guest with a topology change. >> + */ >> +static void kvm_s390_sca_clear_mtcr(struct kvm *kvm) >> +{ >> + struct bsca_block *sca = kvm->arch.sca; /* SCA version doesn't matter */ >> + >> + ipte_lock(kvm); >> + sca->utility &= ~SCA_UTILITY_MTCR; > > > One space too much. > > sca->utility &= ~SCA_UTILITY_MTCR; > >> + ipte_unlock(kvm); >> +} >> + >> +static int kvm_s390_set_topology(struct kvm *kvm, struct kvm_device_attr *attr) >> +{ >> + if (!test_kvm_facility(kvm, 11)) >> + return -ENXIO; >> + >> + switch (attr->attr) { >> + case KVM_S390_VM_CPU_TOPO_MTR_SET: >> + kvm_s390_sca_set_mtcr(kvm); >> + break; >> + case KVM_S390_VM_CPU_TOPO_MTR_CLEAR: >> + kvm_s390_sca_clear_mtcr(kvm); >> + break; >> + } >> + return 0; >> +} >> + >> +/** >> + * kvm_s390_sca_get_mtcr >> + * @kvm: guest KVM description >> + * >> + * Is only relevant if the topology facility is present, >> + * the caller should check KVM facility 11 >> + * >> + * reports to QEMU the Multiprocessor Topology-Change-Report. >> + */ >> +static int kvm_s390_sca_get_mtcr(struct kvm *kvm) >> +{ >> + struct bsca_block *sca = kvm->arch.sca; /* SCA version doesn't matter */ >> + int val; >> + >> + ipte_lock(kvm); >> + val = !!(sca->utility & SCA_UTILITY_MTCR); >> + ipte_unlock(kvm); >> + >> + return val; >> +} >> + >> +static int kvm_s390_get_topology(struct kvm *kvm, struct kvm_device_attr *attr) >> +{ >> + int mtcr; > > I think we prefer something like u16 when copying to user space.
If you prefer. The original idea was to have something like a bool but then I should have change get_mtcr to has_mtcr.
> >> + >> + if (!test_kvm_facility(kvm, 11)) >> + return -ENXIO; >> + >> + mtcr = kvm_s390_sca_get_mtcr(kvm); >> + if (copy_to_user((void __user *)attr->addr, &mtcr, sizeof(mtcr))) >> + return -EFAULT; >> + >> + return 0; >> +} > > You should probably add documentation, and document that only the last > bit (0x1) has a meaning. > > Apart from that LGTM. >
-- Pierre Morel IBM Lab Boeblingen
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