Re: [PATCH v5 1/4] KVM: stats: Separate common stats from architecture specific ones

[David Matlack <dmatlack@google.com>]

On Mon, May 17, 2021 at 5:10 PM Jing Zhang <jingzhangos@google.com> wrote:
<snip>
> Actually the definition of kvm_{vcpu,vm}_stat are arch specific. There is
> no real structure for arch agnostic stats. Most of the stats in common
> structures are arch agnostic, but not all of them.
> There are some benefits to put all common stats in a separate structure.
> e.g. if we want to add a stat in kvm_main.c, we only need to add this stat
> in the common structure, don't have to update all kvm_{vcpu,vm}_stat
> definition for all architectures.

I meant rename the existing arch-specific struct kvm_{vcpu,vm}_stat to
kvm_{vcpu,vm}_stat_arch and rename struct kvm_{vcpu,vm}_stat_common to
kvm_{vcpu,vm}_stat.

So in  include/linux/kvm_types.h you'd have:

struct kvm_vm_stat {
  ulong remote_tlb_flush;
  struct kvm_vm_stat_arch arch;
};

struct kvm_vcpu_stat {
  u64 halt_successful_poll;
  u64 halt_attempted_poll;
  u64 halt_poll_invalid;
  u64 halt_wakeup;
  u64 halt_poll_success_ns;
  u64 halt_poll_fail_ns;
  struct kvm_vcpu_stat_arch arch;
};

And in arch/x86/include/asm/kvm_host.h you'd have:

struct kvm_vm_stat_arch {
  ulong mmu_shadow_zapped;
  ...
};

struct kvm_vcpu_stat_arch {
  u64 pf_fixed;
  u64 pf_guest;
  u64 tlb_flush;
  ...
};

You still have the same benefits of having an arch-neutral place to
store stats but the struct layout more closely resembles struct
kvm_vcpu and struct kvm.