LoongArch: KVM: Remove redundant assignment in kvm_map_page_fast

[PATCH] LoongArch: KVM: Remove redundant assignment in kvm_map_page_fast

Posted by tangbin 1 year, 6 months ago

In the function kvm_map_page_fast, the assignment of 'ret' is
redundant, so remove it.

Signed-off-by: tangbin <tangbin@cmss.chinamobile.com>
---
 arch/loongarch/kvm/mmu.c | 17 +++++------------
 1 file changed, 5 insertions(+), 12 deletions(-)

diff --git a/arch/loongarch/kvm/mmu.c b/arch/loongarch/kvm/mmu.c
index 2634a9e8d..d6c922a4a 100644
--- a/arch/loongarch/kvm/mmu.c
+++ b/arch/loongarch/kvm/mmu.c
@@ -551,7 +551,6 @@ bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
  */
 static int kvm_map_page_fast(struct kvm_vcpu *vcpu, unsigned long gpa, bool write)
 {
-	int ret = 0;
 	kvm_pfn_t pfn = 0;
 	kvm_pte_t *ptep, changed, new;
 	gfn_t gfn = gpa >> PAGE_SHIFT;
@@ -563,20 +562,16 @@ static int kvm_map_page_fast(struct kvm_vcpu *vcpu, unsigned long gpa, bool writ
 
 	/* Fast path - just check GPA page table for an existing entry */
 	ptep = kvm_populate_gpa(kvm, NULL, gpa, 0);
-	if (!ptep || !kvm_pte_present(NULL, ptep)) {
-		ret = -EFAULT;
+	if (!ptep || !kvm_pte_present(NULL, ptep))
 		goto out;
-	}
 
 	/* Track access to pages marked old */
 	new = kvm_pte_mkyoung(*ptep);
 	/* call kvm_set_pfn_accessed() after unlock */
 
 	if (write && !kvm_pte_dirty(new)) {
-		if (!kvm_pte_write(new)) {
-			ret = -EFAULT;
+		if (!kvm_pte_write(new))
 			goto out;
-		}
 
 		if (kvm_pte_huge(new)) {
 			/*
@@ -584,10 +579,8 @@ static int kvm_map_page_fast(struct kvm_vcpu *vcpu, unsigned long gpa, bool writ
 			 * enabled for HugePages
 			 */
 			slot = gfn_to_memslot(kvm, gfn);
-			if (kvm_slot_dirty_track_enabled(slot)) {
-				ret = -EFAULT;
+			if (kvm_slot_dirty_track_enabled(slot))
 				goto out;
-			}
 		}
 
 		/* Track dirtying of writeable pages */
@@ -615,10 +608,10 @@ static int kvm_map_page_fast(struct kvm_vcpu *vcpu, unsigned long gpa, bool writ
 		if (page)
 			put_page(page);
 	}
-	return ret;
+	return 0;
 out:
 	spin_unlock(&kvm->mmu_lock);
-	return ret;
+	return -EFAULT;
 }
 
 static bool fault_supports_huge_mapping(struct kvm_memory_slot *memslot,
-- 
2.18.4

Re: [PATCH] LoongArch: KVM: Remove redundant assignment in kvm_map_page_fast

Posted by maobibo 1 year, 6 months ago

Hi Tangbin,

There is only return value with -EFAULT or 0 in function 
kvm_map_page_fast(), if there is better error code or different error 
for new code, the situation will be different :)

I would like to keep existing code unchanged, however thanks for your patch.

Regards
Bibo Mao

On 2024/7/13 下午11:59, tangbin wrote:
> In the function kvm_map_page_fast, the assignment of 'ret' is
> redundant, so remove it.
> 
> Signed-off-by: tangbin <tangbin@cmss.chinamobile.com>
> ---
>   arch/loongarch/kvm/mmu.c | 17 +++++------------
>   1 file changed, 5 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/loongarch/kvm/mmu.c b/arch/loongarch/kvm/mmu.c
> index 2634a9e8d..d6c922a4a 100644
> --- a/arch/loongarch/kvm/mmu.c
> +++ b/arch/loongarch/kvm/mmu.c
> @@ -551,7 +551,6 @@ bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
>    */
>   static int kvm_map_page_fast(struct kvm_vcpu *vcpu, unsigned long gpa, bool write)
>   {
> -	int ret = 0;
>   	kvm_pfn_t pfn = 0;
>   	kvm_pte_t *ptep, changed, new;
>   	gfn_t gfn = gpa >> PAGE_SHIFT;
> @@ -563,20 +562,16 @@ static int kvm_map_page_fast(struct kvm_vcpu *vcpu, unsigned long gpa, bool writ
>   
>   	/* Fast path - just check GPA page table for an existing entry */
>   	ptep = kvm_populate_gpa(kvm, NULL, gpa, 0);
> -	if (!ptep || !kvm_pte_present(NULL, ptep)) {
> -		ret = -EFAULT;
> +	if (!ptep || !kvm_pte_present(NULL, ptep))
>   		goto out;
> -	}
>   
>   	/* Track access to pages marked old */
>   	new = kvm_pte_mkyoung(*ptep);
>   	/* call kvm_set_pfn_accessed() after unlock */
>   
>   	if (write && !kvm_pte_dirty(new)) {
> -		if (!kvm_pte_write(new)) {
> -			ret = -EFAULT;
> +		if (!kvm_pte_write(new))
>   			goto out;
> -		}
>   
>   		if (kvm_pte_huge(new)) {
>   			/*
> @@ -584,10 +579,8 @@ static int kvm_map_page_fast(struct kvm_vcpu *vcpu, unsigned long gpa, bool writ
>   			 * enabled for HugePages
>   			 */
>   			slot = gfn_to_memslot(kvm, gfn);
> -			if (kvm_slot_dirty_track_enabled(slot)) {
> -				ret = -EFAULT;
> +			if (kvm_slot_dirty_track_enabled(slot))
>   				goto out;
> -			}
>   		}
>   
>   		/* Track dirtying of writeable pages */
> @@ -615,10 +608,10 @@ static int kvm_map_page_fast(struct kvm_vcpu *vcpu, unsigned long gpa, bool writ
>   		if (page)
>   			put_page(page);
>   	}
> -	return ret;
> +	return 0;
>   out:
>   	spin_unlock(&kvm->mmu_lock);
> -	return ret;
> +	return -EFAULT;
>   }
>   
>   static bool fault_supports_huge_mapping(struct kvm_memory_slot *memslot,
>