linux-kernel - Re: [PATCH] RISC-V: KVM: Exit run-loop immediately if xfer_to

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Message-ID: <mvmiljpd4ht.fsf@suse.de>
Date:   Tue, 08 Nov 2022 13:18:06 +0100
From:   Andreas Schwab <schwab@...e.de>
To:     Anup Patel <apatel@...tanamicro.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Atish Patra <atishp@...shpatra.org>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Andrew Jones <ajones@...tanamicro.com>,
        Anup Patel <anup@...infault.org>, kvm@...r.kernel.org,
        kvm-riscv@...ts.infradead.org, linux-riscv@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] RISC-V: KVM: Exit run-loop immediately if xfer_to_guest
 fails

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@...tanamicro.com>
> Reviewed-by: Andrew Jones <ajones@...tanamicro.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@...e.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."