* [PATCH] KVM: VMX: replace "fall through" with "return true" to indicate different case
@ 2020-02-18 3:39 linmiaohe
2020-02-18 3:42 ` Joe Perches
` (2 more replies)
0 siblings, 3 replies; 7+ messages in thread
From: linmiaohe @ 2020-02-18 3:39 UTC (permalink / raw)
To: pbonzini, rkrcmar, sean.j.christopherson, vkuznets, wanpengli,
jmattson, joro, tglx, mingo, bp, hpa
Cc: linmiaohe, kvm, linux-kernel, x86
From: Miaohe Lin <linmiaohe@huawei.com>
The second "/* fall through */" in rmode_exception() makes code harder to
read. Replace it with "return true" to indicate they are different cases
and also this improves the readability.
Suggested-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
arch/x86/kvm/vmx/vmx.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index a13368b2719c..c5bcbbada2db 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -4495,7 +4495,7 @@ static bool rmode_exception(struct kvm_vcpu *vcpu, int vec)
if (vcpu->guest_debug &
(KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP))
return false;
- /* fall through */
+ return true;
case DE_VECTOR:
case OF_VECTOR:
case BR_VECTOR:
--
2.19.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH] KVM: VMX: replace "fall through" with "return true" to indicate different case
2020-02-18 3:39 [PATCH] KVM: VMX: replace "fall through" with "return true" to indicate different case linmiaohe
@ 2020-02-18 3:42 ` Joe Perches
2020-02-18 16:25 ` Paolo Bonzini
2020-02-18 12:25 ` Vitaly Kuznetsov
2020-02-18 15:42 ` Sean Christopherson
2 siblings, 1 reply; 7+ messages in thread
From: Joe Perches @ 2020-02-18 3:42 UTC (permalink / raw)
To: linmiaohe, pbonzini, rkrcmar, sean.j.christopherson, vkuznets,
wanpengli, jmattson, joro, tglx, mingo, bp, hpa
Cc: kvm, linux-kernel, x86
On Tue, 2020-02-18 at 11:39 +0800, linmiaohe wrote:
> The second "/* fall through */" in rmode_exception() makes code harder to
> read. Replace it with "return true" to indicate they are different cases
> and also this improves the readability.
[]
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
[]
> @@ -4495,7 +4495,7 @@ static bool rmode_exception(struct kvm_vcpu *vcpu, int vec)
> if (vcpu->guest_debug &
> (KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP))
> return false;
> - /* fall through */
> + return true;
perhaps
return !(vcpu->guest_debug & (KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP));
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] KVM: VMX: replace "fall through" with "return true" to indicate different case
2020-02-18 3:39 [PATCH] KVM: VMX: replace "fall through" with "return true" to indicate different case linmiaohe
2020-02-18 3:42 ` Joe Perches
@ 2020-02-18 12:25 ` Vitaly Kuznetsov
2020-02-18 15:42 ` Sean Christopherson
2 siblings, 0 replies; 7+ messages in thread
From: Vitaly Kuznetsov @ 2020-02-18 12:25 UTC (permalink / raw)
To: linmiaohe
Cc: kvm, linux-kernel, x86, pbonzini, rkrcmar, sean.j.christopherson,
wanpengli, jmattson, joro, tglx, mingo, bp, hpa
linmiaohe <linmiaohe@huawei.com> writes:
> From: Miaohe Lin <linmiaohe@huawei.com>
>
> The second "/* fall through */" in rmode_exception() makes code harder to
> read. Replace it with "return true" to indicate they are different cases
> and also this improves the readability.
>
> Suggested-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> ---
> arch/x86/kvm/vmx/vmx.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index a13368b2719c..c5bcbbada2db 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -4495,7 +4495,7 @@ static bool rmode_exception(struct kvm_vcpu *vcpu, int vec)
> if (vcpu->guest_debug &
> (KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP))
> return false;
> - /* fall through */
> + return true;
> case DE_VECTOR:
> case OF_VECTOR:
> case BR_VECTOR:
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Thanks!
--
Vitaly
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] KVM: VMX: replace "fall through" with "return true" to indicate different case
2020-02-18 3:39 [PATCH] KVM: VMX: replace "fall through" with "return true" to indicate different case linmiaohe
2020-02-18 3:42 ` Joe Perches
2020-02-18 12:25 ` Vitaly Kuznetsov
@ 2020-02-18 15:42 ` Sean Christopherson
2 siblings, 0 replies; 7+ messages in thread
From: Sean Christopherson @ 2020-02-18 15:42 UTC (permalink / raw)
To: linmiaohe
Cc: pbonzini, rkrcmar, vkuznets, wanpengli, jmattson, joro, tglx,
mingo, bp, hpa, kvm, linux-kernel, x86
On Tue, Feb 18, 2020 at 11:39:28AM +0800, linmiaohe wrote:
> From: Miaohe Lin <linmiaohe@huawei.com>
>
> The second "/* fall through */" in rmode_exception() makes code harder to
> read. Replace it with "return true" to indicate they are different cases
> and also this improves the readability.
>
> Suggested-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> ---
> arch/x86/kvm/vmx/vmx.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index a13368b2719c..c5bcbbada2db 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -4495,7 +4495,7 @@ static bool rmode_exception(struct kvm_vcpu *vcpu, int vec)
> if (vcpu->guest_debug &
> (KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP))
> return false;
> - /* fall through */
> + return true;
I prefer the current code, i.e. the fall through. This code is already
burdened with a fall through, from #BP->#DB, and IMO the fall through makes
it more obvious that the vcpu->guest_debug checks are corner cases, while
everything else is handled by common logic.
> case DE_VECTOR:
> case OF_VECTOR:
> case BR_VECTOR:
> --
> 2.19.1
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] KVM: VMX: replace "fall through" with "return true" to indicate different case
2020-02-18 3:42 ` Joe Perches
@ 2020-02-18 16:25 ` Paolo Bonzini
0 siblings, 0 replies; 7+ messages in thread
From: Paolo Bonzini @ 2020-02-18 16:25 UTC (permalink / raw)
To: Joe Perches, linmiaohe, rkrcmar, sean.j.christopherson, vkuznets,
wanpengli, jmattson, joro, tglx, mingo, bp, hpa
Cc: kvm, linux-kernel, x86
On 18/02/20 04:42, Joe Perches wrote:
> On Tue, 2020-02-18 at 11:39 +0800, linmiaohe wrote:
>> The second "/* fall through */" in rmode_exception() makes code harder to
>> read. Replace it with "return true" to indicate they are different cases
>> and also this improves the readability.
> []
>> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> []
>> @@ -4495,7 +4495,7 @@ static bool rmode_exception(struct kvm_vcpu *vcpu, int vec)
>> if (vcpu->guest_debug &
>> (KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP))
>> return false;
>> - /* fall through */
>> + return true;
>
> perhaps
> return !(vcpu->guest_debug & (KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP));
Nice, thanks Joe.
Paolo
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] KVM: VMX: replace "fall through" with "return true" to indicate different case
@ 2020-02-19 1:59 linmiaohe
0 siblings, 0 replies; 7+ messages in thread
From: linmiaohe @ 2020-02-19 1:59 UTC (permalink / raw)
To: Sean Christopherson
Cc: pbonzini, rkrcmar, vkuznets, wanpengli, jmattson, joro, tglx,
mingo, bp, hpa, kvm, linux-kernel, x86
Sean Christopherson <sean.j.christopherson@intel.com> wrote:
>On Tue, Feb 18, 2020 at 11:39:28AM +0800, linmiaohe wrote:
>> From: Miaohe Lin <linmiaohe@huawei.com>
>>
>> @@ -4495,7 +4495,7 @@ static bool rmode_exception(struct kvm_vcpu *vcpu, int vec)
>> if (vcpu->guest_debug &
>> (KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP))
>> return false;
>> - /* fall through */
>> + return true;
>
>I prefer the current code, i.e. the fall through. This code is already burdened with a fall through, from #BP->#DB, and IMO the fall through makes it more obvious that the vcpu->guest_debug checks are corner cases, while everything else is handled by common logic.
Yeh, it looks better this way. But from a different perspective, "return turn" here indicates #BP and #DB need do vcpu->guest_debug checks, while others not.
Thanks. :)
>
>> case DE_VECTOR:
>> case OF_VECTOR:
>> case BR_VECTOR:
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] KVM: VMX: replace "fall through" with "return true" to indicate different case
@ 2020-02-19 1:40 linmiaohe
0 siblings, 0 replies; 7+ messages in thread
From: linmiaohe @ 2020-02-19 1:40 UTC (permalink / raw)
To: Joe Perches
Cc: pbonzini, rkrcmar, sean.j.christopherson, vkuznets, wanpengli,
jmattson, joro, tglx, mingo, bp, hpa, kvm, linux-kernel, x86
Joe Perches <joe@perches.com> wrote:
>On Tue, 2020-02-18 at 11:39 +0800, linmiaohe wrote:
>> The second "/* fall through */" in rmode_exception() makes code harder
>> to read. Replace it with "return true" to indicate they are different
>> cases and also this improves the readability.
>
>perhaps
> return !(vcpu->guest_debug & (KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP));
>
Will do. Thanks for your advice.
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2020-02-19 1:59 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
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2020-02-18 3:39 [PATCH] KVM: VMX: replace "fall through" with "return true" to indicate different case linmiaohe
2020-02-18 3:42 ` Joe Perches
2020-02-18 16:25 ` Paolo Bonzini
2020-02-18 12:25 ` Vitaly Kuznetsov
2020-02-18 15:42 ` Sean Christopherson
2020-02-19 1:40 linmiaohe
2020-02-19 1:59 linmiaohe
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