* [PATCH] RISC-V: KVM: Exit run-loop immediately if xfer_to_guest fails
@ 2022-11-08 11:55 Anup Patel
2022-11-08 12:18 ` Andreas Schwab
0 siblings, 1 reply; 3+ messages in thread
From: Anup Patel @ 2022-11-08 11:55 UTC (permalink / raw)
To: Paolo Bonzini, Atish Patra
Cc: Palmer Dabbelt, Paul Walmsley, Andrew Jones, Anup Patel, kvm,
kvm-riscv, linux-riscv, linux-kernel, Anup Patel
If xfer_to_guest_mode_handle_work() fails in the run-loop then exit
the run-loop immediately instead of doing it after some more work.
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
---
arch/riscv/kvm/vcpu.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index 71ebbc4821f0..17d5b3f8c2ee 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -984,8 +984,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
while (ret > 0) {
/* Check conditions before entering the guest */
ret = xfer_to_guest_mode_handle_work(vcpu);
- if (!ret)
- ret = 1;
+ if (ret)
+ continue;
+ ret = 1;
kvm_riscv_gstage_vmid_update(vcpu);
--
2.34.1
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^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] RISC-V: KVM: Exit run-loop immediately if xfer_to_guest fails
2022-11-08 11:55 [PATCH] RISC-V: KVM: Exit run-loop immediately if xfer_to_guest fails Anup Patel
@ 2022-11-08 12:18 ` Andreas Schwab
2022-11-27 12:19 ` Anup Patel
0 siblings, 1 reply; 3+ messages in thread
From: Andreas Schwab @ 2022-11-08 12:18 UTC (permalink / raw)
To: Anup Patel
Cc: Paolo Bonzini, Atish Patra, Palmer Dabbelt, Paul Walmsley,
Andrew Jones, Anup Patel, kvm, kvm-riscv, linux-riscv,
linux-kernel
On Nov 08 2022, Anup Patel wrote:
> If xfer_to_guest_mode_handle_work() fails in the run-loop then exit
> the run-loop immediately instead of doing it after some more work.
>
> Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
> ---
> arch/riscv/kvm/vcpu.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> index 71ebbc4821f0..17d5b3f8c2ee 100644
> --- a/arch/riscv/kvm/vcpu.c
> +++ b/arch/riscv/kvm/vcpu.c
> @@ -984,8 +984,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
> while (ret > 0) {
> /* Check conditions before entering the guest */
> ret = xfer_to_guest_mode_handle_work(vcpu);
> - if (!ret)
> - ret = 1;
> + if (ret)
> + continue;
If that is supposed to exit the loop, it would be clearer to just use
break.
> + ret = 1;
There is a condition on ret <= 0 later in the loop that no longer can be
true.
--
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] RISC-V: KVM: Exit run-loop immediately if xfer_to_guest fails
2022-11-08 12:18 ` Andreas Schwab
@ 2022-11-27 12:19 ` Anup Patel
0 siblings, 0 replies; 3+ messages in thread
From: Anup Patel @ 2022-11-27 12:19 UTC (permalink / raw)
To: Andreas Schwab
Cc: Anup Patel, Paolo Bonzini, Atish Patra, Palmer Dabbelt,
Paul Walmsley, Andrew Jones, kvm, kvm-riscv, linux-riscv,
linux-kernel
On Tue, Nov 8, 2022 at 5:48 PM Andreas Schwab <schwab@suse.de> wrote:
>
> On Nov 08 2022, Anup Patel wrote:
>
> > If xfer_to_guest_mode_handle_work() fails in the run-loop then exit
> > the run-loop immediately instead of doing it after some more work.
> >
> > Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> > Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
> > ---
> > arch/riscv/kvm/vcpu.c | 5 +++--
> > 1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> > index 71ebbc4821f0..17d5b3f8c2ee 100644
> > --- a/arch/riscv/kvm/vcpu.c
> > +++ b/arch/riscv/kvm/vcpu.c
> > @@ -984,8 +984,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
> > while (ret > 0) {
> > /* Check conditions before entering the guest */
> > ret = xfer_to_guest_mode_handle_work(vcpu);
> > - if (!ret)
> > - ret = 1;
> > + if (ret)
> > + continue;
>
> If that is supposed to exit the loop, it would be clearer to just use
> break.
This is a convention within the run-loop that we continue whenever
whenever "ret" is no longer suitable to continue. I don't see any
particular advantage in breaking this convention over here.
>
> > + ret = 1;
>
> There is a condition on ret <= 0 later in the loop that no longer can be
> true.
Yes, for now the "ret <= 0" check is useless and the compiler will
optimize this comparison. We will be soon having more stuff added
to run-loop (such as AIA update) which will make "ret <= 0" check
useful again.
>
> --
> Andreas Schwab, SUSE Labs, schwab@suse.de
> GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7
> "And now for something completely different."
Queued this patch for Linux-6.2
Thanks,
Anup
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2022-11-08 11:55 [PATCH] RISC-V: KVM: Exit run-loop immediately if xfer_to_guest fails Anup Patel
2022-11-08 12:18 ` Andreas Schwab
2022-11-27 12:19 ` Anup Patel
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