Messages in this thread | | | Date | Mon, 27 Jun 2022 15:30:39 +0200 | Subject | Re: [PATCH v10 2/3] KVM: s390: guest support for topology function | From | Pierre Morel <> |
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On 6/24/22 08:22, Janosch Frank wrote: > On 6/20/22 14:54, Pierre Morel wrote: >> We report a topology change to the guest for any CPU hotplug. >> >> The reporting to the guest is done using the Multiprocessor >> Topology-Change-Report (MTCR) bit of the utility entry in the guest's >> SCA which will be cleared during the interpretation of PTF. >> >> On every vCPU creation we set the MCTR bit to let the guest know the >> next time he uses the PTF with command 2 instruction that the >> topology changed and that he should use the STSI(15.1.x) instruction >> to get the topology details. >> >> 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> >> --- >> arch/s390/include/asm/kvm_host.h | 11 ++++++++--- >> arch/s390/kvm/kvm-s390.c | 27 ++++++++++++++++++++++++++- >> arch/s390/kvm/priv.c | 15 +++++++++++---- >> arch/s390/kvm/vsie.c | 3 +++ >> 4 files changed, 48 insertions(+), 8 deletions(-) >> >> diff --git a/arch/s390/include/asm/kvm_host.h >> b/arch/s390/include/asm/kvm_host.h >> index 766028d54a3e..bb54196d4ed6 100644 >> --- a/arch/s390/include/asm/kvm_host.h >> +++ b/arch/s390/include/asm/kvm_host.h >> @@ -97,15 +97,19 @@ struct bsca_block { >> union ipte_control ipte_control; >> __u64 reserved[5]; >> __u64 mcn; >> - __u64 reserved2; >> +#define SCA_UTILITY_MTCR 0x8000 > > I'm not too happy having this in the bsca but not in the esca. I'd > suggest putting it outside the structs or to go with my next suggestion: > > Just make it a bit field struct and make that a member in bsca/esca. > No messing about with ANDing, ORing etc. > > It's unfortunate that we only use one bit in that field but I'd still > find it easier to read.
OK
> >> + __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]; >> }; >> @@ -249,6 +253,7 @@ 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 >> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c >> index 8fcb56141689..95b96019ca8e 100644 >> --- a/arch/s390/kvm/kvm-s390.c >> +++ b/arch/s390/kvm/kvm-s390.c >> @@ -1691,6 +1691,25 @@ static int kvm_s390_get_cpu_model(struct kvm >> *kvm, struct kvm_device_attr *attr) >> return ret; >> } >> +/** >> + * kvm_s390_sca_set_mtcr >> + * @kvm: guest KVM description >> + * >> + * Is only relevant if the topology facility is present, >> + * the caller should check KVM facility 11 > > I'm not sure that this statement make sense since you set the mctr in > kvm_s390_vcpu_setup() unconditionally and don't check stfle 11. > > I think we can remove the second line from this. > >> + * >> + * Updates the Multiprocessor Topology-Change-Report to signal >> + * the guest with a topology change. > > Please swap those two comments > >> + */ >> +static void kvm_s390_sca_set_mtcr(struct kvm *kvm) >> +{ >> + struct bsca_block *sca = kvm->arch.sca; /* SCA version doesn't >> matter */ > > Please put the comment above the statement and maybe extend it a bit: > SCA version doesn't matter, the utility field always has the same offset. > >> + >> + ipte_lock(kvm); >> + sca->utility |= SCA_UTILITY_MTCR; >> + ipte_unlock(kvm); >> +} >> + >> static int kvm_s390_vm_set_attr(struct kvm *kvm, struct >> kvm_device_attr *attr) >> { >> int ret; >> @@ -3143,7 +3162,6 @@ __u64 kvm_s390_get_cpu_timer(struct kvm_vcpu *vcpu) >> void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) >> { >> - > > Please remove that change > >> gmap_enable(vcpu->arch.enabled_gmap); >> kvm_s390_set_cpuflags(vcpu, CPUSTAT_RUNNING); >> if (vcpu->arch.cputm_enabled && !is_vcpu_idle(vcpu)) >> @@ -3272,6 +3290,11 @@ 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; >> + >> if (test_kvm_facility(vcpu->kvm, 73)) >> vcpu->arch.sie_block->ecb |= ECB_TE; >> if (!kvm_is_ucontrol(vcpu->kvm)) >> @@ -3403,6 +3426,8 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu) >> rc = kvm_s390_vcpu_setup(vcpu); >> if (rc) >> goto out_ucontrol_uninit; >> + >> + kvm_s390_sca_set_mtcr(vcpu->kvm); >> return 0; >> out_ucontrol_uninit: >> diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c >> index 12c464c7cddf..77a692238585 100644 >> --- a/arch/s390/kvm/priv.c >> +++ b/arch/s390/kvm/priv.c >> @@ -873,10 +873,13 @@ 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) { >> - kvm_s390_set_psw_cc(vcpu, 3); >> - return 0; >> - } >> + /* Bailout forbidden function codes */ >> + if (fc > 3 && fc != 15) >> + goto out_no_data; >> + >> + /* fc 15 is provided with PTF/CPU topology support */ >> + if (fc == 15 && !test_kvm_facility(vcpu->kvm, 11)) >> + goto out_no_data; >> if (vcpu->run->s.regs.gprs[0] & 0x0fffff00 >> || vcpu->run->s.regs.gprs[1] & 0xffff0000) >> @@ -910,6 +913,10 @@ 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 dada78b92691..4f4fee697550 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 */ > > Maybe also add: > This facility only uses the utility field of the SCA and none of the cpu > entries that are problematic with the other interpretation facilities so > we can pass it through. > >> + 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 */ >
OK with all comments, I make the changes.
Thanks, Pierre
-- Pierre Morel IBM Lab Boeblingen
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