Re: [RFC PATCH 04/37] KVM: x86/mmu: Invert sp->tdp_mmu_page to sp->shadow_mmu_page

[Paolo Bonzini <pbonzini@xxxxxxxxxx>]

On 12/8/22 20:38, David Matlack wrote:
> Invert the meaning of sp->tdp_mmu_page and rename it accordingly. This
> allows the TDP MMU code to not care about this field, which will be used
> in a subsequent commit to move the TDP MMU to common code.
>
> No functional change intended.

Let's use a bit of the role instead.

Paolo

> Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx>
> ---
>   arch/x86/kvm/mmu/mmu.c          | 1 +
>   arch/x86/kvm/mmu/mmu_internal.h | 2 +-
>   arch/x86/kvm/mmu/tdp_mmu.c      | 3 ---
>   arch/x86/kvm/mmu/tdp_mmu.h      | 5 ++++-
>   4 files changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 355548603960..f7668a32721d 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -2180,6 +2180,7 @@ static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm *kvm,
>   
>   	sp->gfn = gfn;
>   	sp->role = role;
> +	sp->shadow_mmu_page = true;
>   	hlist_add_head(&sp->hash_link, sp_list);
>   	if (sp_has_gptes(sp))
>   		account_shadowed(kvm, sp);
> diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
> index e32379c5b1ad..c1a379fba24d 100644
> --- a/arch/x86/kvm/mmu/mmu_internal.h
> +++ b/arch/x86/kvm/mmu/mmu_internal.h
> @@ -52,7 +52,7 @@ struct kvm_mmu_page {
>   	struct list_head link;
>   	struct hlist_node hash_link;
>   
> -	bool tdp_mmu_page;
> +	bool shadow_mmu_page;
>   	bool unsync;
>   	u8 mmu_valid_gen;
>   
> diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
> index 7ccac1aa8df6..fc0b87ceb1ea 100644
> --- a/arch/x86/kvm/mmu/tdp_mmu.c
> +++ b/arch/x86/kvm/mmu/tdp_mmu.c
> @@ -133,8 +133,6 @@ void kvm_tdp_mmu_put_root(struct kvm *kvm, struct kvm_mmu_page *root,
>   	if (!refcount_dec_and_test(&root->tdp_mmu_root_count))
>   		return;
>   
> -	WARN_ON(!is_tdp_mmu_page(root));
> -
>   	/*
>   	 * The root now has refcount=0.  It is valid, but readers already
>   	 * cannot acquire a reference to it because kvm_tdp_mmu_get_root()
> @@ -279,7 +277,6 @@ static void tdp_mmu_init_sp(struct kvm_mmu_page *sp, tdp_ptep_t sptep,
>   	sp->role = role;
>   	sp->gfn = gfn;
>   	sp->ptep = sptep;
> -	sp->tdp_mmu_page = true;
>   
>   	trace_kvm_mmu_get_page(sp, true);
>   }
> diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h
> index 0a63b1afabd3..18d3719f14ea 100644
> --- a/arch/x86/kvm/mmu/tdp_mmu.h
> +++ b/arch/x86/kvm/mmu/tdp_mmu.h
> @@ -71,7 +71,10 @@ u64 *kvm_tdp_mmu_fast_pf_get_last_sptep(struct kvm_vcpu *vcpu, u64 addr,
>   					u64 *spte);
>   
>   #ifdef CONFIG_X86_64
> -static inline bool is_tdp_mmu_page(struct kvm_mmu_page *sp) { return sp->tdp_mmu_page; }
> +static inline bool is_tdp_mmu_page(struct kvm_mmu_page *sp)
> +{
> +	return !sp->shadow_mmu_page;
> +}
>   #else
>   static inline bool is_tdp_mmu_page(struct kvm_mmu_page *sp) { return false; }
>   #endif