[PATCH] KVM: riscv: SBI FWFT: Apply LOCK flag only on successful set

[PATCH] KVM: riscv: SBI FWFT: Apply LOCK flag only on successful set

[SeungJu Cheon]

kvm_sbi_fwft_set() applies the caller's flags to conf->flags before
invoking the set() callback. If the callback returns an error, the LOCK
bit persists and the feature becomes permanently locked without its value
ever being changed.

Move the flags assignment after the callback so LOCK takes effect only
on success.

Fixes: 6b72fd170592 ("RISC-V: KVM: add support for FWFT SBI extension")
Signed-off-by: SeungJu Cheon <suunj1331@gmail.com>
---
 arch/riscv/kvm/vcpu_sbi_fwft.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/kvm/vcpu_sbi_fwft.c b/arch/riscv/kvm/vcpu_sbi_fwft.c
index ab39ac464ffd..1342adb3180c 100644
--- a/arch/riscv/kvm/vcpu_sbi_fwft.c
+++ b/arch/riscv/kvm/vcpu_sbi_fwft.c
@@ -327,9 +327,11 @@ static int kvm_sbi_fwft_set(struct kvm_vcpu *vcpu, u32 feature,
 	if (conf->flags & SBI_FWFT_SET_FLAG_LOCK)
 		return SBI_ERR_DENIED_LOCKED;
 
-	conf->flags = flags;
+	ret = conf->feature->set(vcpu, conf, false, value);
+	if (ret == SBI_SUCCESS)
+		conf->flags = flags;
 
-	return conf->feature->set(vcpu, conf, false, value);
+	return ret;
 }
 
 static int kvm_sbi_fwft_get(struct kvm_vcpu *vcpu, unsigned long feature,
-- 
2.52.0

Re: [PATCH] KVM: riscv: SBI FWFT: Apply LOCK flag only on successful set

[Anup Patel]

On Wed, Jun 24, 2026 at 6:33 PM SeungJu Cheon <suunj1331@gmail.com> wrote:
>
> kvm_sbi_fwft_set() applies the caller's flags to conf->flags before
> invoking the set() callback. If the callback returns an error, the LOCK
> bit persists and the feature becomes permanently locked without its value
> ever being changed.
>
> Move the flags assignment after the callback so LOCK takes effect only
> on success.
>
> Fixes: 6b72fd170592 ("RISC-V: KVM: add support for FWFT SBI extension")
> Signed-off-by: SeungJu Cheon <suunj1331@gmail.com>

LGTM.

Reviewed-by: Anup Patel <anup@brainfault.org>

Queued this patch as a fix for Linux-7.2-rcX

Thanks,
Anup


> ---
>  arch/riscv/kvm/vcpu_sbi_fwft.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/arch/riscv/kvm/vcpu_sbi_fwft.c b/arch/riscv/kvm/vcpu_sbi_fwft.c
> index ab39ac464ffd..1342adb3180c 100644
> --- a/arch/riscv/kvm/vcpu_sbi_fwft.c
> +++ b/arch/riscv/kvm/vcpu_sbi_fwft.c
> @@ -327,9 +327,11 @@ static int kvm_sbi_fwft_set(struct kvm_vcpu *vcpu, u32 feature,
>         if (conf->flags & SBI_FWFT_SET_FLAG_LOCK)
>                 return SBI_ERR_DENIED_LOCKED;
>
> -       conf->flags = flags;
> +       ret = conf->feature->set(vcpu, conf, false, value);
> +       if (ret == SBI_SUCCESS)
> +               conf->flags = flags;
>
> -       return conf->feature->set(vcpu, conf, false, value);
> +       return ret;
>  }
>
>  static int kvm_sbi_fwft_get(struct kvm_vcpu *vcpu, unsigned long feature,
> --
> 2.52.0
>