Messages in this thread | | | Date | Tue, 9 Apr 2024 21:54:37 +0700 | Subject | Re: [RFC 1/3] x86: KVM: stats: Add a stat to report status of APICv inhibition | From | "Suthikulpanit, Suravee" <> |
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Hi
On 2/15/2024 11:01 PM, Alejandro Jimenez wrote: > The inhibition status of APICv can currently be checked using the > 'kvm_apicv_inhibit_changed' tracepoint, but this is not accessible if > tracefs is not available (e.g. kernel lockdown, non-root user). Export > inhibition status as a binary stat that can be monitored from userspace > without elevated privileges. > > Signed-off-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com> > --- > arch/x86/include/asm/kvm_host.h | 1 + > arch/x86/kvm/x86.c | 10 +++++++++- > 2 files changed, 10 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index ad5319a503f0..9b960a523715 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -1524,6 +1524,7 @@ struct kvm_vm_stat { > u64 nx_lpage_splits; > u64 max_mmu_page_hash_collisions; > u64 max_mmu_rmap_size; > + u64 apicv_inhibited; > }; > > struct kvm_vcpu_stat { > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index b66c45e7f6f8..f7f598f066e7 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -255,7 +255,8 @@ const struct _kvm_stats_desc kvm_vm_stats_desc[] = { > STATS_DESC_ICOUNTER(VM, pages_1g), > STATS_DESC_ICOUNTER(VM, nx_lpage_splits), > STATS_DESC_PCOUNTER(VM, max_mmu_rmap_size), > - STATS_DESC_PCOUNTER(VM, max_mmu_page_hash_collisions) > + STATS_DESC_PCOUNTER(VM, max_mmu_page_hash_collisions), > + STATS_DESC_IBOOLEAN(VM, apicv_inhibited)
One use for this stats would be to help: 1. Determine if vm and/or vcpu is inhibited. 2. Determine the inhibit reason.
Therefore can we use STATS_DESC_ICOUNTER() instead of STATS_DESC_IBOOLEAN(), and show the inhibit flag from
vm_reason = struct kvm->arch.apicv_inhibit_reasons vcpu_reason = static_call(kvm_x86_vcpu_get_apicv_inhibit_reasons)(vcpu)
See kvm_vcpu_apicv_activated().
Thanks, Suravee
> }; > > const struct kvm_stats_header kvm_vm_stats_header = { > @@ -10588,6 +10589,13 @@ void __kvm_set_or_clear_apicv_inhibit(struct kvm *kvm, > */ > kvm_make_all_cpus_request(kvm, KVM_REQ_APICV_UPDATE); > kvm->arch.apicv_inhibit_reasons = new; > + > + /* > + * Update inhibition statistic only when toggling APICv > + * activation status. > + */ > + kvm->stat.apicv_inhibited = !!new; > + > if (new) { > unsigned long gfn = gpa_to_gfn(APIC_DEFAULT_PHYS_BASE); > int idx = srcu_read_lock(&kvm->srcu);
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