Messages in this thread | | | Date | Thu, 9 Dec 2021 14:31:41 +0100 | Subject | Re: [PATCH v5 1/1] s390x: KVM: accept STSI for CPU topology information | From | Pierre Morel <> |
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On 12/9/21 13:36, Claudio Imbrenda wrote: > On Mon, 22 Nov 2021 14:14:43 +0100 > Pierre Morel <pmorel@linux.ibm.com> wrote: > >> We let the userland hypervisor know if the machine support the CPU >> topology facility using a new KVM capability: KVM_CAP_S390_CPU_TOPOLOGY. >> >> The PTF instruction will report a topology change if there is any change >> with a previous STSI_15_1_2 SYSIB. >> Changes inside a STSI_15_1_2 SYSIB occur if CPU bits are set or clear >> inside the CPU Topology List Entry CPU mask field, which happens with >> changes in CPU polarization, dedication, CPU types and adding or >> removing CPUs in a socket. >> >> The reporting to the guest is done using the Multiprocessor >> Topology-Change-Report (MTCR) bit of the utility entry of the guest's >> SCA which will be cleared during the interpretation of PTF. >> >> To check if the topology has been modified we use a new field of the >> arch vCPU to save the previous real CPU ID at the end of a schedule >> and verify on next schedule that the CPU used is in the same socket. >> >> We assume in this patch: >> - no polarization change: only horizontal polarization is currently >> used in linux. >> - no CPU Type change: only IFL Type are supported in Linux >> - Dedication: with this patch, only a complete dedicated CPU stack can >> take benefit of the CPU Topology. >> >> STSI(15.1.x) gives information on the CPU configuration topology. >> Let's accept the interception of STSI with the function code 15 and >> let the userland part of the hypervisor handle it when userland >> support the CPU Topology facility. >> >> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com> > > Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com> > > Although the title of the patch is not very correct, you are doing more > than just accepting STSI. > > Maybe call it "guest PTF support", or "guest support for topology > function"?
Right, thanks will do.
Thanks for the review. Pierre
> >> --- >> Documentation/virt/kvm/api.rst | 16 ++++++++++ >> arch/s390/include/asm/kvm_host.h | 14 ++++++--- >> arch/s390/kvm/kvm-s390.c | 52 +++++++++++++++++++++++++++++++- >> arch/s390/kvm/priv.c | 7 ++++- >> arch/s390/kvm/vsie.c | 3 ++ >> include/uapi/linux/kvm.h | 1 + >> 6 files changed, 87 insertions(+), 6 deletions(-) >> >> diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst >> index aeeb071c7688..e5c9da0782a6 100644 >> --- a/Documentation/virt/kvm/api.rst >> +++ b/Documentation/virt/kvm/api.rst >> @@ -7484,3 +7484,19 @@ The argument to KVM_ENABLE_CAP is also a bitmask, and must be a subset >> of the result of KVM_CHECK_EXTENSION. KVM will forward to userspace >> the hypercalls whose corresponding bit is in the argument, and return >> ENOSYS for the others. >> + >> +8.17 KVM_CAP_S390_CPU_TOPOLOGY >> +------------------------------ >> + >> +:Capability: KVM_CAP_S390_CPU_TOPOLOGY >> +:Architectures: s390 >> +:Type: vm >> + >> +This capability indicates that kvm will provide the S390 CPU Topology facility >> +which consist of the interpretation of the PTF instruction for the Function >> +Code 2 along with interception and forwarding of both the PTF instruction >> +with function Codes 0 or 1 and the STSI(15,1,x) instruction to the userland >> +hypervisor. >> + >> +The stfle facility 11, CPU Topology facility, should not be provided to the >> +guest without this capability. >> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h >> index a604d51acfc8..cccc09a8fdab 100644 >> --- a/arch/s390/include/asm/kvm_host.h >> +++ b/arch/s390/include/asm/kvm_host.h >> @@ -95,15 +95,19 @@ struct bsca_block { >> union ipte_control ipte_control; >> __u64 reserved[5]; >> __u64 mcn; >> - __u64 reserved2; >> +#define ESCA_UTILITY_MTCR 0x8000 >> + __u16 utility; >> + __u8 reserved2[6]; >> struct bsca_entry cpu[KVM_S390_BSCA_CPU_SLOTS]; >> }; >> >> struct esca_block { >> union ipte_control ipte_control; >> - __u64 reserved1[7]; >> + __u64 reserved1[6]; >> + __u16 utility; >> + __u8 reserved2[6]; >> __u64 mcn[4]; >> - __u64 reserved2[20]; >> + __u64 reserved3[20]; >> struct esca_entry cpu[KVM_S390_ESCA_CPU_SLOTS]; >> }; >> >> @@ -228,7 +232,7 @@ struct kvm_s390_sie_block { >> __u8 icptcode; /* 0x0050 */ >> __u8 icptstatus; /* 0x0051 */ >> __u16 ihcpu; /* 0x0052 */ >> - __u8 reserved54; /* 0x0054 */ >> + __u8 mtcr; /* 0x0054 */ >> #define IICTL_CODE_NONE 0x00 >> #define IICTL_CODE_MCHK 0x01 >> #define IICTL_CODE_EXT 0x02 >> @@ -247,6 +251,7 @@ struct kvm_s390_sie_block { >> #define ECB_SPECI 0x08 >> #define ECB_SRSI 0x04 >> #define ECB_HOSTPROTINT 0x02 >> +#define ECB_PTF 0x01 >> __u8 ecb; /* 0x0061 */ >> #define ECB2_CMMA 0x80 >> #define ECB2_IEP 0x20 >> @@ -748,6 +753,7 @@ struct kvm_vcpu_arch { >> bool skey_enabled; >> struct kvm_s390_pv_vcpu pv; >> union diag318_info diag318_info; >> + int prev_cpu; >> }; >> >> struct kvm_vm_stat { >> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c >> index 14a18ba5ff2c..b40d2a20bce0 100644 >> --- a/arch/s390/kvm/kvm-s390.c >> +++ b/arch/s390/kvm/kvm-s390.c >> @@ -606,6 +606,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) >> case KVM_CAP_S390_PROTECTED: >> r = is_prot_virt_host(); >> break; >> + case KVM_CAP_S390_CPU_TOPOLOGY: >> + r = test_facility(11); >> + break; >> default: >> r = 0; >> } >> @@ -817,6 +820,20 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap) >> icpt_operexc_on_all_vcpus(kvm); >> r = 0; >> break; >> + case KVM_CAP_S390_CPU_TOPOLOGY: >> + r = -EINVAL; >> + mutex_lock(&kvm->lock); >> + if (kvm->created_vcpus) { >> + r = -EBUSY; >> + } else if (test_facility(11)) { >> + set_kvm_facility(kvm->arch.model.fac_mask, 11); >> + set_kvm_facility(kvm->arch.model.fac_list, 11); >> + r = 0; >> + } >> + mutex_unlock(&kvm->lock); >> + VM_EVENT(kvm, 3, "ENABLE: CPU TOPOLOGY %s", >> + r ? "(not available)" : "(success)"); >> + break; >> default: >> r = -EINVAL; >> break; >> @@ -3089,18 +3106,44 @@ __u64 kvm_s390_get_cpu_timer(struct kvm_vcpu *vcpu) >> return value; >> } >> >> -void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) >> +static void kvm_s390_set_mtcr(struct kvm_vcpu *vcpu) >> { >> + struct esca_block *esca = vcpu->kvm->arch.sca; >> >> + if (vcpu->arch.sie_block->ecb & ECB_PTF) { >> + ipte_lock(vcpu); >> + WRITE_ONCE(esca->utility, ESCA_UTILITY_MTCR); >> + ipte_unlock(vcpu); >> + } >> +} >> + >> +void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) >> +{ >> gmap_enable(vcpu->arch.enabled_gmap); >> kvm_s390_set_cpuflags(vcpu, CPUSTAT_RUNNING); >> if (vcpu->arch.cputm_enabled && !is_vcpu_idle(vcpu)) >> __start_cpu_timer_accounting(vcpu); >> vcpu->cpu = cpu; >> + >> + /* >> + * With PTF interpretation the guest will be aware of topology >> + * change when the Multiprocessor Topology-Change-Report is pending. >> + * We check for events modifying the result of STSI_15_2: >> + * - A new vCPU has been hotplugged (prev_cpu == -1) >> + * - The real CPU backing up the vCPU moved to another socket >> + */ >> + if (vcpu->arch.sie_block->ecb & ECB_PTF) { >> + if (vcpu->arch.prev_cpu == -1 || >> + (topology_physical_package_id(cpu) != >> + topology_physical_package_id(vcpu->arch.prev_cpu))) >> + kvm_s390_set_mtcr(vcpu); >> + } >> } >> >> void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) >> { >> + /* Remember which CPU was backing the vCPU */ >> + vcpu->arch.prev_cpu = vcpu->cpu; >> vcpu->cpu = -1; >> if (vcpu->arch.cputm_enabled && !is_vcpu_idle(vcpu)) >> __stop_cpu_timer_accounting(vcpu); >> @@ -3220,6 +3263,13 @@ static int kvm_s390_vcpu_setup(struct kvm_vcpu *vcpu) >> vcpu->arch.sie_block->ecb |= ECB_HOSTPROTINT; >> if (test_kvm_facility(vcpu->kvm, 9)) >> vcpu->arch.sie_block->ecb |= ECB_SRSI; >> + >> + /* PTF needs guest facilities to enable interpretation */ >> + if (test_kvm_facility(vcpu->kvm, 11)) >> + vcpu->arch.sie_block->ecb |= ECB_PTF; >> + /* Set the prev_cpu value to an impossible value to detect a new vcpu */ >> + vcpu->arch.prev_cpu = -1; >> + >> if (test_kvm_facility(vcpu->kvm, 73)) >> vcpu->arch.sie_block->ecb |= ECB_TE; >> if (!kvm_is_ucontrol(vcpu->kvm)) >> diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c >> index 417154b314a6..26d165733496 100644 >> --- a/arch/s390/kvm/priv.c >> +++ b/arch/s390/kvm/priv.c >> @@ -861,7 +861,8 @@ static int handle_stsi(struct kvm_vcpu *vcpu) >> if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE) >> return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP); >> >> - if (fc > 3) { >> + if ((fc > 3 && fc != 15) || >> + (fc == 15 && !test_kvm_facility(vcpu->kvm, 11))) { >> kvm_s390_set_psw_cc(vcpu, 3); >> return 0; >> } >> @@ -898,6 +899,10 @@ static int handle_stsi(struct kvm_vcpu *vcpu) >> goto out_no_data; >> handle_stsi_3_2_2(vcpu, (void *) mem); >> break; >> + case 15: >> + trace_kvm_s390_handle_stsi(vcpu, fc, sel1, sel2, operand2); >> + insert_stsi_usr_data(vcpu, operand2, ar, fc, sel1, sel2); >> + return -EREMOTE; >> } >> if (kvm_s390_pv_cpu_is_protected(vcpu)) { >> memcpy((void *)sida_origin(vcpu->arch.sie_block), (void *)mem, >> diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c >> index acda4b6fc851..da0397cf2cc7 100644 >> --- a/arch/s390/kvm/vsie.c >> +++ b/arch/s390/kvm/vsie.c >> @@ -503,6 +503,9 @@ static int shadow_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page) >> /* Host-protection-interruption introduced with ESOP */ >> if (test_kvm_cpu_feat(vcpu->kvm, KVM_S390_VM_CPU_FEAT_ESOP)) >> scb_s->ecb |= scb_o->ecb & ECB_HOSTPROTINT; >> + /* CPU Topology */ >> + if (test_kvm_facility(vcpu->kvm, 11)) >> + scb_s->ecb |= scb_o->ecb & ECB_PTF; >> /* transactional execution */ >> if (test_kvm_facility(vcpu->kvm, 73) && wants_tx) { >> /* remap the prefix is tx is toggled on */ >> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h >> index 1daa45268de2..273c62dfbe9a 100644 >> --- a/include/uapi/linux/kvm.h >> +++ b/include/uapi/linux/kvm.h >> @@ -1131,6 +1131,7 @@ struct kvm_ppc_resize_hpt { >> #define KVM_CAP_EXIT_ON_EMULATION_FAILURE 204 >> #define KVM_CAP_ARM_MTE 205 >> #define KVM_CAP_VM_MOVE_ENC_CONTEXT_FROM 206 >> +#define KVM_CAP_S390_CPU_TOPOLOGY 207 >> >> #ifdef KVM_CAP_IRQ_ROUTING >> >
-- Pierre Morel IBM Lab Boeblingen
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