diff mbox series

[v4,18/20] KVM: x86/mmu: Refactor drop_large_spte()

Message ID 20220422210546.458943-19-dmatlack@google.com (mailing list archive)
State New, archived
Headers show
Series KVM: Extend Eager Page Splitting to the shadow MMU | expand

Commit Message

David Matlack April 22, 2022, 9:05 p.m. UTC 
drop_large_spte() drops a large SPTE if it exists and then flushes TLBs.
Its helper function, __drop_large_spte(), does the drop without the
flush.

In preparation for eager page splitting, which will need to sometimes
flush when dropping large SPTEs (and sometimes not), push the flushing
logic down into __drop_large_spte() and add a bool parameter to control
it.

No functional change intended.

Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
---
 arch/x86/kvm/mmu/mmu.c | 29 +++++++++++++++--------------
 1 file changed, 15 insertions(+), 14 deletions(-)

Comments

Sean Christopherson May 9, 2022, 4:36 p.m. UTC | #1 
On Fri, Apr 22, 2022, David Matlack wrote:
> drop_large_spte() drops a large SPTE if it exists and then flushes TLBs.
> Its helper function, __drop_large_spte(), does the drop without the
> flush.
> 
> In preparation for eager page splitting, which will need to sometimes
> flush when dropping large SPTEs (and sometimes not), push the flushing
> logic down into __drop_large_spte() and add a bool parameter to control
> it.
> 
> No functional change intended.
> 
> Reviewed-by: Peter Xu <peterx@redhat.com>
> Signed-off-by: David Matlack <dmatlack@google.com>
> ---
>  arch/x86/kvm/mmu/mmu.c | 29 +++++++++++++++--------------
>  1 file changed, 15 insertions(+), 14 deletions(-)
> 
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 479c581e8a96..a5961c17eb36 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -1183,28 +1183,29 @@ static void drop_spte(struct kvm *kvm, u64 *sptep)
>  		rmap_remove(kvm, sptep);
>  }
>  
> -
> -static bool __drop_large_spte(struct kvm *kvm, u64 *sptep)
> +static void __drop_large_spte(struct kvm *kvm, u64 *sptep, bool flush)
>  {
> -	if (is_large_pte(*sptep)) {
> -		WARN_ON(sptep_to_sp(sptep)->role.level == PG_LEVEL_4K);
> -		drop_spte(kvm, sptep);
> -		return true;
> -	}
> +	struct kvm_mmu_page *sp;
>  
> -	return false;
> -}
> +	if (!is_large_pte(*sptep))
> +		return;
>  
> -static void drop_large_spte(struct kvm_vcpu *vcpu, u64 *sptep)
> -{
> -	if (__drop_large_spte(vcpu->kvm, sptep)) {
> -		struct kvm_mmu_page *sp = sptep_to_sp(sptep);
> +	sp = sptep_to_sp(sptep);
> +	WARN_ON(sp->role.level == PG_LEVEL_4K);
>  
> -		kvm_flush_remote_tlbs_with_address(vcpu->kvm, sp->gfn,
> +	drop_spte(kvm, sptep);
> +
> +	if (flush) {

Unnecessary curly braces.

> +		kvm_flush_remote_tlbs_with_address(kvm, sp->gfn,
>  			KVM_PAGES_PER_HPAGE(sp->role.level));
>  	}
>  }
>  
> +static void drop_large_spte(struct kvm_vcpu *vcpu, u64 *sptep)
> +{
> +	return __drop_large_spte(vcpu->kvm, sptep, true);
> +}
> +
>  /*
>   * Write-protect on the specified @sptep, @pt_protect indicates whether
>   * spte write-protection is caused by protecting shadow page table.
> -- 
> 2.36.0.rc2.479.g8af0fa9b8e-goog
>
diff mbox series

Patch

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 479c581e8a96..a5961c17eb36 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1183,28 +1183,29 @@  static void drop_spte(struct kvm *kvm, u64 *sptep)
 		rmap_remove(kvm, sptep);
 }
 
-
-static bool __drop_large_spte(struct kvm *kvm, u64 *sptep)
+static void __drop_large_spte(struct kvm *kvm, u64 *sptep, bool flush)
 {
-	if (is_large_pte(*sptep)) {
-		WARN_ON(sptep_to_sp(sptep)->role.level == PG_LEVEL_4K);
-		drop_spte(kvm, sptep);
-		return true;
-	}
+	struct kvm_mmu_page *sp;
 
-	return false;
-}
+	if (!is_large_pte(*sptep))
+		return;
 
-static void drop_large_spte(struct kvm_vcpu *vcpu, u64 *sptep)
-{
-	if (__drop_large_spte(vcpu->kvm, sptep)) {
-		struct kvm_mmu_page *sp = sptep_to_sp(sptep);
+	sp = sptep_to_sp(sptep);
+	WARN_ON(sp->role.level == PG_LEVEL_4K);
 
-		kvm_flush_remote_tlbs_with_address(vcpu->kvm, sp->gfn,
+	drop_spte(kvm, sptep);
+
+	if (flush) {
+		kvm_flush_remote_tlbs_with_address(kvm, sp->gfn,
 			KVM_PAGES_PER_HPAGE(sp->role.level));
 	}
 }
 
+static void drop_large_spte(struct kvm_vcpu *vcpu, u64 *sptep)
+{
+	return __drop_large_spte(vcpu->kvm, sptep, true);
+}
+
 /*
  * Write-protect on the specified @sptep, @pt_protect indicates whether
  * spte write-protection is caused by protecting shadow page table.