Re: [PATCH v3 14/19] KVM: MMU: clean up spte updating and clearing

Marcelo Tosatti
2011-07-06T17:39:28Z

On Thu, Jun 30, 2011 at 04:25:34PM +0800, Xiao Guangrong wrote:
> Clean up the code between mmu_spte_clear_* and mmu_spte_update
>
> Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
> ---
> arch/x86/kvm/mmu.c | 75 +++++++++++++++++++++++++++-------------------------
> 1 files changed, 39 insertions(+), 36 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index 48c0a45..857d0d6 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -279,24 +279,51 @@ static u64 __xchg_spte(u64 *sptep, u64 new_spte)
> #endif
> }
>
> -static bool spte_has_volatile_bits(u64 spte)
> +static bool spte_is_bit_cleared(u64 old_spte, u64 new_spte, u64 bit_mask)
> +{
> + return (old_spte & bit_mask) && !(new_spte & bit_mask);
> +}
> +
> +static bool spte_has_volatile_bits(u64 spte, u64 keep_bits)
> {
> + bool access_nonvolatile = false, dirty_nonvolatile = false;
> +
> if (!shadow_accessed_mask)
> return false;
>
> - if (!is_shadow_present_pte(spte))
> - return false;
> + if ((spte | keep_bits) & shadow_accessed_mask)
> + access_nonvolatile = true;
> +
> + if (!is_writable_pte(spte) || ((spte | keep_bits) & shadow_dirty_mask))
> + dirty_nonvolatile = true;
>
> - if ((spte & shadow_accessed_mask) &&
> - (!is_writable_pte(spte) || (spte & shadow_dirty_mask)))
> + if (access_nonvolatile && dirty_nonvolatile)
> return false;
>
> return true;
> }
>
> -static bool spte_is_bit_cleared(u64 old_spte, u64 new_spte, u64 bit_mask)
> +static void track_spte_bits(u64 old_spte, u64 keep_bits, bool always_track)
> {
> - return (old_spte & bit_mask) && !(new_spte & bit_mask);
> + if (always_track ||
> + (spte_is_bit_cleared(old_spte, keep_bits, shadow_accessed_mask)))
> + kvm_set_pfn_accessed(spte_to_pfn(old_spte));
> +
> + if (always_track ||
> + (spte_is_bit_cleared(old_spte, keep_bits, shadow_dirty_mask)))
> + kvm_set_pfn_dirty(spte_to_pfn(old_spte));
> +}

This is much more confusing than previously, please drop it.