On Wed, May 19, 2021, Krish Sadhukhan wrote:
> 'struct kvm' already has a member for counting the number of VCPUs created
> for a given VM. Add this as a new VM statistic to KVM debugfs.
Huh!?? Why? Userspace is the one creating the vCPUs, it darn well should know
how many it's created.
> Signed-off-by: Krish Sadhukhan <Krish.Sadhukhan@xxxxxxxxxx>
> ---
> arch/x86/include/asm/kvm_host.h | 1 +
> arch/x86/kvm/svm/svm.c | 3 +--
> arch/x86/kvm/x86.c | 1 +
> virt/kvm/kvm_main.c | 2 ++
> 4 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index a19fe2cfaa93..69ca1d6f6557 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1139,6 +1139,7 @@ struct kvm_vm_stat {
> ulong nx_lpage_splits;
> ulong max_mmu_page_hash_collisions;
> ulong vcpus_ran_nested;
> + u64 created_vcpus;
> };
>
> struct kvm_vcpu_stat {
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index d1871c51411f..fef0baba043b 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -3875,8 +3875,7 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
>
> /* Track VMRUNs that have made past consistency checking */
> if (svm->nested.nested_run_pending &&
> - svm->vmcb->control.exit_code != SVM_EXIT_ERR &&
> - svm->vmcb->control.exit_code != SVM_EXIT_NPF) {
> + svm->vmcb->control.exit_code != SVM_EXIT_ERR) {
???
> if (!vcpu->stat.nested_runs)
> ++vcpu->kvm->stat.vcpus_ran_nested;
> ++vcpu->stat.nested_runs;
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index cbca3609a152..a9d27ce4cc93 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -258,6 +258,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
> VM_STAT("nx_largepages_splitted", nx_lpage_splits, .mode = 0444),
> VM_STAT("max_mmu_page_hash_collisions", max_mmu_page_hash_collisions),
> VM_STAT("vcpus_ran_nested", vcpus_ran_nested),
> + VM_STAT("created_vcpus", created_vcpus),
> { NULL }
> };
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 6b4feb92dc79..ac8f02d8a051 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -3318,6 +3318,7 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
> }
>
> kvm->created_vcpus++;
> + kvm->stat.created_vcpus++;
> mutex_unlock(&kvm->lock);
>
> r = kvm_arch_vcpu_precreate(kvm, id);
> @@ -3394,6 +3395,7 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
> vcpu_decrement:
> mutex_lock(&kvm->lock);
> kvm->created_vcpus--;
> + kvm->stat.created_vcpus--;
> mutex_unlock(&kvm->lock);
> return r;
> }
> --
> 2.27.0
>
