[PATCH 4/7] KVM: arm64: Add flush_all_cache_lines counter for kvm_stat

[Marc Zyngier]

On Fri, 19 Mar 2021 16:17:08 +0000,
Yoan Picchi <yoan.picchi at arm.com> wrote:
> 
> Add a counter that triggers when all the cache are flushed. This happens
> when toggling caching for instance.

Which cache?

> 
> Signed-off-by: Yoan Picchi <yoan.picchi at arm.com>
> ---
>  arch/arm64/include/asm/kvm_host.h | 1 +
>  arch/arm64/kvm/guest.c            | 1 +
>  arch/arm64/kvm/mmu.c              | 1 +
>  3 files changed, 3 insertions(+)
> 
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 3609aa89d..e6967951f 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -547,6 +547,7 @@ static inline bool __vcpu_write_sys_reg_to_cpu(u64 val, int reg)
>  
>  struct kvm_vm_stat {
>  	ulong remote_tlb_flush;
> +	ulong flush_all_cache_lines;
>  	ulong cached_page_invalidated;
>  };
>  
> diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
> index f6b1f0b63..d948c3bd2 100644
> --- a/arch/arm64/kvm/guest.c
> +++ b/arch/arm64/kvm/guest.c
> @@ -41,6 +41,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
>  	VCPU_STAT("regular_page_mapped", regular_page_mapped),
>  	VCPU_STAT("huge_page_mapped", huge_page_mapped),
>  	VM_STAT("remote_tlb_flush", remote_tlb_flush),
> +	VM_STAT("flush_all_cache_lines", flush_all_cache_lines),
>  	VM_STAT("cached_page_invalidated", cached_page_invalidated),
>  	VCPU_STAT("exits", exits),
>  	VCPU_STAT("halt_poll_success_ns", halt_poll_success_ns),
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index d6ddf5ab8..985b048df 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -181,6 +181,7 @@ static void stage2_flush_vm(struct kvm *kvm)
>  	kvm_for_each_memslot(memslot, slots)
>  		stage2_flush_memslot(kvm, memslot);
>  
> +	kvm->stat.flush_all_cache_lines++;

What additional information does this give over the other d-side flush
counter?

	M.

-- 
Without deviation from the norm, progress is not possible.