Re: [PATCH v2 10/28] KVM: x86/mmu: Fix TDP MMU zap collapsible SPTEs

[Paolo Bonzini]

On 02/02/21 19:57, Ben Gardon wrote:
> There is a bug in the TDP MMU function to zap SPTEs which could be
> replaced with a larger mapping which prevents the function from doing
> anything. Fix this by correctly zapping the last level SPTEs.
>
> Fixes: 14881998566d ("kvm: x86/mmu: Support disabling dirty logging for the tdp MMU")
> Signed-off-by: Ben Gardon <bgardon@xxxxxxxxxx>
> ---
>   arch/x86/kvm/mmu/tdp_mmu.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
> index c3075fb568eb..e3066d08c1dc 100644
> --- a/arch/x86/kvm/mmu/tdp_mmu.c
> +++ b/arch/x86/kvm/mmu/tdp_mmu.c
> @@ -1098,8 +1098,8 @@ bool kvm_tdp_mmu_slot_set_dirty(struct kvm *kvm, struct kvm_memory_slot *slot)
>   }
>   
>   /*
> - * Clear non-leaf entries (and free associated page tables) which could
> - * be replaced by large mappings, for GFNs within the slot.
> + * Clear leaf entries which could be replaced by large mappings, for
> + * GFNs within the slot.
>    */
>   static void zap_collapsible_spte_range(struct kvm *kvm,
>   				       struct kvm_mmu_page *root,
> @@ -1111,7 +1111,7 @@ static void zap_collapsible_spte_range(struct kvm *kvm,
>   
>   	tdp_root_for_each_pte(iter, root, start, end) {
>   		if (!is_shadow_present_pte(iter.old_spte) ||
> -		    is_last_spte(iter.old_spte, iter.level))
> +		    !is_last_spte(iter.old_spte, iter.level))
>   			continue;
>   
>   		pfn = spte_to_pfn(iter.old_spte);

Queued for 5.11-rc, thanks.

Paolo