* [PATCH] RISC-V: KVM: remove a redundant condition in kvm_arch_vcpu_ioctl_run()
@ 2023-12-11 9:40 ` Chao Du
0 siblings, 0 replies; 8+ messages in thread
From: Chao Du @ 2023-12-11 9:40 UTC (permalink / raw)
To: kvm-riscv
The latest ret value is updated by kvm_riscv_vcpu_aia_update(),
the loop will continue if the ret is less than or equal to zero.
So the later condition will never hit. Thus remove it.
Signed-off-by: Chao Du <duchao@eswincomputing.com>
---
arch/riscv/kvm/vcpu.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index e087c809073c..bf3952d1a621 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -757,8 +757,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
/* Update HVIP CSR for current CPU */
kvm_riscv_update_hvip(vcpu);
- if (ret <= 0 ||
- kvm_riscv_gstage_vmid_ver_changed(&vcpu->kvm->arch.vmid) ||
+ if (kvm_riscv_gstage_vmid_ver_changed(&vcpu->kvm->arch.vmid) ||
kvm_request_pending(vcpu) ||
xfer_to_guest_mode_work_pending()) {
vcpu->mode = OUTSIDE_GUEST_MODE;
--
2.17.1
^ permalink raw reply related [flat|nested] 8+ messages in thread* [PATCH] RISC-V: KVM: remove a redundant condition in kvm_arch_vcpu_ioctl_run()
@ 2023-12-11 9:40 ` Chao Du
0 siblings, 0 replies; 8+ messages in thread
From: Chao Du @ 2023-12-11 9:40 UTC (permalink / raw)
To: kvm, kvm-riscv, anup, atishp, dbarboza
The latest ret value is updated by kvm_riscv_vcpu_aia_update(),
the loop will continue if the ret is less than or equal to zero.
So the later condition will never hit. Thus remove it.
Signed-off-by: Chao Du <duchao@eswincomputing.com>
---
arch/riscv/kvm/vcpu.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index e087c809073c..bf3952d1a621 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -757,8 +757,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
/* Update HVIP CSR for current CPU */
kvm_riscv_update_hvip(vcpu);
- if (ret <= 0 ||
- kvm_riscv_gstage_vmid_ver_changed(&vcpu->kvm->arch.vmid) ||
+ if (kvm_riscv_gstage_vmid_ver_changed(&vcpu->kvm->arch.vmid) ||
kvm_request_pending(vcpu) ||
xfer_to_guest_mode_work_pending()) {
vcpu->mode = OUTSIDE_GUEST_MODE;
--
2.17.1
^ permalink raw reply related [flat|nested] 8+ messages in thread* [PATCH] RISC-V: KVM: remove a redundant condition in kvm_arch_vcpu_ioctl_run()
2023-12-11 9:40 ` Chao Du
@ 2023-12-11 12:06 ` Daniel Henrique Barboza
-1 siblings, 0 replies; 8+ messages in thread
From: Daniel Henrique Barboza @ 2023-12-11 12:06 UTC (permalink / raw)
To: kvm-riscv
On 12/11/23 06:40, Chao Du wrote:
> The latest ret value is updated by kvm_riscv_vcpu_aia_update(),
> the loop will continue if the ret is less than or equal to zero.
> So the later condition will never hit. Thus remove it.
Good catch. There's another potential optimization to be done a little above
this change:
while (ret > 0) {
(...)
/* Update AIA HW state before entering guest */
ret = kvm_riscv_vcpu_aia_update(vcpu);
if (ret <= 0) {
preempt_enable();
continue; <------------------
}
(...)
Note that this 'continue' isn't doing much - we'll restart the loop with ret <= 0
while requiring ret > 0 to do another iteration. I.e. this 'continue' can be
replaced for 'break' without compromising the logic.
(of course, testing it to be sure is always advised :D )
>
> Signed-off-by: Chao Du <duchao@eswincomputing.com>
> ---
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
> arch/riscv/kvm/vcpu.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> index e087c809073c..bf3952d1a621 100644
> --- a/arch/riscv/kvm/vcpu.c
> +++ b/arch/riscv/kvm/vcpu.c
> @@ -757,8 +757,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
> /* Update HVIP CSR for current CPU */
> kvm_riscv_update_hvip(vcpu);
>
> - if (ret <= 0 ||
> - kvm_riscv_gstage_vmid_ver_changed(&vcpu->kvm->arch.vmid) ||
> + if (kvm_riscv_gstage_vmid_ver_changed(&vcpu->kvm->arch.vmid) ||
> kvm_request_pending(vcpu) ||
> xfer_to_guest_mode_work_pending()) {
> vcpu->mode = OUTSIDE_GUEST_MODE;
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH] RISC-V: KVM: remove a redundant condition in kvm_arch_vcpu_ioctl_run()
@ 2023-12-11 12:06 ` Daniel Henrique Barboza
0 siblings, 0 replies; 8+ messages in thread
From: Daniel Henrique Barboza @ 2023-12-11 12:06 UTC (permalink / raw)
To: Chao Du, kvm, kvm-riscv, anup, atishp
On 12/11/23 06:40, Chao Du wrote:
> The latest ret value is updated by kvm_riscv_vcpu_aia_update(),
> the loop will continue if the ret is less than or equal to zero.
> So the later condition will never hit. Thus remove it.
Good catch. There's another potential optimization to be done a little above
this change:
while (ret > 0) {
(...)
/* Update AIA HW state before entering guest */
ret = kvm_riscv_vcpu_aia_update(vcpu);
if (ret <= 0) {
preempt_enable();
continue; <------------------
}
(...)
Note that this 'continue' isn't doing much - we'll restart the loop with ret <= 0
while requiring ret > 0 to do another iteration. I.e. this 'continue' can be
replaced for 'break' without compromising the logic.
(of course, testing it to be sure is always advised :D )
>
> Signed-off-by: Chao Du <duchao@eswincomputing.com>
> ---
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
> arch/riscv/kvm/vcpu.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> index e087c809073c..bf3952d1a621 100644
> --- a/arch/riscv/kvm/vcpu.c
> +++ b/arch/riscv/kvm/vcpu.c
> @@ -757,8 +757,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
> /* Update HVIP CSR for current CPU */
> kvm_riscv_update_hvip(vcpu);
>
> - if (ret <= 0 ||
> - kvm_riscv_gstage_vmid_ver_changed(&vcpu->kvm->arch.vmid) ||
> + if (kvm_riscv_gstage_vmid_ver_changed(&vcpu->kvm->arch.vmid) ||
> kvm_request_pending(vcpu) ||
> xfer_to_guest_mode_work_pending()) {
> vcpu->mode = OUTSIDE_GUEST_MODE;
^ permalink raw reply [flat|nested] 8+ messages in thread* [PATCH] RISC-V: KVM: remove a redundant condition in kvm_arch_vcpu_ioctl_run()
2023-12-11 12:06 ` Daniel Henrique Barboza
@ 2023-12-12 7:12 ` Chao Du
-1 siblings, 0 replies; 8+ messages in thread
From: Chao Du @ 2023-12-12 7:12 UTC (permalink / raw)
To: kvm-riscv
> -----Original Messages-----From:"Daniel Henrique Barboza" <dbarboza@ventanamicro.com>Sent Time:2023-12-11 20:06:33 (Monday)To:"Chao Du" <duchao@eswincomputing.com>, kvm at vger.kernel.org, kvm-riscv at lists.infradead.org, anup at brainfault.org, atishp at atishpatra.orgCc:Subject:Re: [PATCH] RISC-V: KVM: remove a redundant condition in kvm_arch_vcpu_ioctl_run()
>
>
>
> On 12/11/23 06:40, Chao Du wrote:
> > The latest ret value is updated by kvm_riscv_vcpu_aia_update(),
> > the loop will continue if the ret is less than or equal to zero.
> > So the later condition will never hit. Thus remove it.
>
> Good catch. There's another potential optimization to be done a little above
> this change:
>
>
> while (ret > 0) {
> (...)
>
> /* Update AIA HW state before entering guest */
> ret = kvm_riscv_vcpu_aia_update(vcpu);
> if (ret <= 0) {
> preempt_enable();
> continue; <------------------
> }
> (...)
>
> Note that this 'continue' isn't doing much - we'll restart the loop with ret <= 0
> while requiring ret > 0 to do another iteration. I.e. this 'continue' can be
> replaced for 'break' without compromising the logic.
Yes, you are right. The 'continue' could be replaced by a 'break'.
I also find another small point:
ret = 1;
(...)
/* Update AIA HW state before entering guest */
ret = kvm_riscv_vcpu_aia_update(vcpu);
the assignment 'ret = 1' is somehow redundant, since it will be
overwritten before any reference.
>
> (of course, testing it to be sure is always advised :D )
>
> >
> > Signed-off-by: Chao Du <duchao@eswincomputing.com>
> > ---
>
>
> Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
>
>
> > arch/riscv/kvm/vcpu.c | 3 +--
> > 1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> > index e087c809073c..bf3952d1a621 100644
> > --- a/arch/riscv/kvm/vcpu.c
> > +++ b/arch/riscv/kvm/vcpu.c
> > @@ -757,8 +757,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
> > /* Update HVIP CSR for current CPU */
> > kvm_riscv_update_hvip(vcpu);
> >
> > - if (ret <= 0 ||
> > - kvm_riscv_gstage_vmid_ver_changed(&vcpu->kvm->arch.vmid) ||
> > + if (kvm_riscv_gstage_vmid_ver_changed(&vcpu->kvm->arch.vmid) ||
> > kvm_request_pending(vcpu) ||
> > xfer_to_guest_mode_work_pending()) {
> > vcpu->mode = OUTSIDE_GUEST_MODE;
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH] RISC-V: KVM: remove a redundant condition in kvm_arch_vcpu_ioctl_run()
@ 2023-12-12 7:12 ` Chao Du
0 siblings, 0 replies; 8+ messages in thread
From: Chao Du @ 2023-12-12 7:12 UTC (permalink / raw)
To: Daniel Henrique Barboza; +Cc: kvm, kvm-riscv, anup, atishp
> -----Original Messages-----From:"Daniel Henrique Barboza" <dbarboza@ventanamicro.com>Sent Time:2023-12-11 20:06:33 (Monday)To:"Chao Du" <duchao@eswincomputing.com>, kvm@vger.kernel.org, kvm-riscv@lists.infradead.org, anup@brainfault.org, atishp@atishpatra.orgCc:Subject:Re: [PATCH] RISC-V: KVM: remove a redundant condition in kvm_arch_vcpu_ioctl_run()
>
>
>
> On 12/11/23 06:40, Chao Du wrote:
> > The latest ret value is updated by kvm_riscv_vcpu_aia_update(),
> > the loop will continue if the ret is less than or equal to zero.
> > So the later condition will never hit. Thus remove it.
>
> Good catch. There's another potential optimization to be done a little above
> this change:
>
>
> while (ret > 0) {
> (...)
>
> /* Update AIA HW state before entering guest */
> ret = kvm_riscv_vcpu_aia_update(vcpu);
> if (ret <= 0) {
> preempt_enable();
> continue; <------------------
> }
> (...)
>
> Note that this 'continue' isn't doing much - we'll restart the loop with ret <= 0
> while requiring ret > 0 to do another iteration. I.e. this 'continue' can be
> replaced for 'break' without compromising the logic.
Yes, you are right. The 'continue' could be replaced by a 'break'.
I also find another small point:
ret = 1;
(...)
/* Update AIA HW state before entering guest */
ret = kvm_riscv_vcpu_aia_update(vcpu);
the assignment 'ret = 1' is somehow redundant, since it will be
overwritten before any reference.
>
> (of course, testing it to be sure is always advised :D )
>
> >
> > Signed-off-by: Chao Du <duchao@eswincomputing.com>
> > ---
>
>
> Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
>
>
> > arch/riscv/kvm/vcpu.c | 3 +--
> > 1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> > index e087c809073c..bf3952d1a621 100644
> > --- a/arch/riscv/kvm/vcpu.c
> > +++ b/arch/riscv/kvm/vcpu.c
> > @@ -757,8 +757,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
> > /* Update HVIP CSR for current CPU */
> > kvm_riscv_update_hvip(vcpu);
> >
> > - if (ret <= 0 ||
> > - kvm_riscv_gstage_vmid_ver_changed(&vcpu->kvm->arch.vmid) ||
> > + if (kvm_riscv_gstage_vmid_ver_changed(&vcpu->kvm->arch.vmid) ||
> > kvm_request_pending(vcpu) ||
> > xfer_to_guest_mode_work_pending()) {
> > vcpu->mode = OUTSIDE_GUEST_MODE;
^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH] RISC-V: KVM: remove a redundant condition in kvm_arch_vcpu_ioctl_run()
2023-12-11 9:40 ` Chao Du
@ 2023-12-13 12:22 ` Anup Patel
-1 siblings, 0 replies; 8+ messages in thread
From: Anup Patel @ 2023-12-13 12:22 UTC (permalink / raw)
To: kvm-riscv
On Mon, Dec 11, 2023 at 3:11?PM Chao Du <duchao@eswincomputing.com> wrote:
>
> The latest ret value is updated by kvm_riscv_vcpu_aia_update(),
> the loop will continue if the ret is less than or equal to zero.
> So the later condition will never hit. Thus remove it.
>
> Signed-off-by: Chao Du <duchao@eswincomputing.com>
Queued this patch for Linux-6.8
Thanks,
Anup
> ---
> arch/riscv/kvm/vcpu.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> index e087c809073c..bf3952d1a621 100644
> --- a/arch/riscv/kvm/vcpu.c
> +++ b/arch/riscv/kvm/vcpu.c
> @@ -757,8 +757,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
> /* Update HVIP CSR for current CPU */
> kvm_riscv_update_hvip(vcpu);
>
> - if (ret <= 0 ||
> - kvm_riscv_gstage_vmid_ver_changed(&vcpu->kvm->arch.vmid) ||
> + if (kvm_riscv_gstage_vmid_ver_changed(&vcpu->kvm->arch.vmid) ||
> kvm_request_pending(vcpu) ||
> xfer_to_guest_mode_work_pending()) {
> vcpu->mode = OUTSIDE_GUEST_MODE;
> --
> 2.17.1
>
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH] RISC-V: KVM: remove a redundant condition in kvm_arch_vcpu_ioctl_run()
@ 2023-12-13 12:22 ` Anup Patel
0 siblings, 0 replies; 8+ messages in thread
From: Anup Patel @ 2023-12-13 12:22 UTC (permalink / raw)
To: Chao Du; +Cc: kvm, kvm-riscv, atishp, dbarboza
On Mon, Dec 11, 2023 at 3:11 PM Chao Du <duchao@eswincomputing.com> wrote:
>
> The latest ret value is updated by kvm_riscv_vcpu_aia_update(),
> the loop will continue if the ret is less than or equal to zero.
> So the later condition will never hit. Thus remove it.
>
> Signed-off-by: Chao Du <duchao@eswincomputing.com>
Queued this patch for Linux-6.8
Thanks,
Anup
> ---
> arch/riscv/kvm/vcpu.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> index e087c809073c..bf3952d1a621 100644
> --- a/arch/riscv/kvm/vcpu.c
> +++ b/arch/riscv/kvm/vcpu.c
> @@ -757,8 +757,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
> /* Update HVIP CSR for current CPU */
> kvm_riscv_update_hvip(vcpu);
>
> - if (ret <= 0 ||
> - kvm_riscv_gstage_vmid_ver_changed(&vcpu->kvm->arch.vmid) ||
> + if (kvm_riscv_gstage_vmid_ver_changed(&vcpu->kvm->arch.vmid) ||
> kvm_request_pending(vcpu) ||
> xfer_to_guest_mode_work_pending()) {
> vcpu->mode = OUTSIDE_GUEST_MODE;
> --
> 2.17.1
>
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2023-12-13 12:22 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2023-12-11 9:40 [PATCH] RISC-V: KVM: remove a redundant condition in kvm_arch_vcpu_ioctl_run() Chao Du
2023-12-11 9:40 ` Chao Du
2023-12-11 12:06 ` Daniel Henrique Barboza
2023-12-11 12:06 ` Daniel Henrique Barboza
2023-12-12 7:12 ` Chao Du
2023-12-12 7:12 ` Chao Du
2023-12-13 12:22 ` Anup Patel
2023-12-13 12:22 ` Anup Patel
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