Re: [RFC PATCH] riscv: kvm: return SBI_ERR_FAILURE for PMU shmem OOM

From: Osama Abdelkader <osama.abdelkader@gmail.com>
To: Anup Patel <anup@brainfault.org>,
	Atish Patra <atish.patra@linux.dev>,
	Paul Walmsley <pjw@kernel.org>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Alexandre Ghiti <alex@ghiti.fr>,
	kvm@vger.kernel.org, kvm-riscv@lists.infradead.org,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH] riscv: kvm: return SBI_ERR_FAILURE for PMU shmem OOM
Date: Wed, 6 May 2026 15:21:43 +0200	[thread overview]
Message-ID: <aftAZ6U93qCXLcSc@osama> (raw)
In-Reply-To: <20260415220930.287592-1-osama.abdelkader@gmail.com>

On Thu, Apr 16, 2026 at 12:09:30AM +0200, Osama Abdelkader wrote:
> kvm_riscv_vcpu_pmu_snapshot_set_shmem() and kvm_riscv_vcpu_pmu_event_info()
> returned -ENOMEM from the SBI extension handler, which caused 
> kvm_riscv_vcpu_sbi_ecall() to abort KVM_RUN and surface the error to 
> userspace instead of completing the ECALL with a negative SBI error in a0.
> Use SBI_ERR_FAILURE and the normal retdata path, matching other PMU
> handlers and kvm_sbi_ext_pmu_handler comment.
> 
> Signed-off-by: Osama Abdelkader <osama.abdelkader@gmail.com>
> ---
>  arch/riscv/kvm/vcpu_pmu.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/riscv/kvm/vcpu_pmu.c b/arch/riscv/kvm/vcpu_pmu.c
> index e873430e596b..f36b099f447c 100644
> --- a/arch/riscv/kvm/vcpu_pmu.c
> +++ b/arch/riscv/kvm/vcpu_pmu.c
> @@ -435,8 +435,10 @@ int kvm_riscv_vcpu_pmu_snapshot_set_shmem(struct kvm_vcpu *vcpu, unsigned long s
>  	}
>  
>  	kvpmu->sdata = kzalloc(snapshot_area_size, GFP_ATOMIC);
> -	if (!kvpmu->sdata)
> -		return -ENOMEM;
> +	if (!kvpmu->sdata) {
> +		sbiret = SBI_ERR_FAILURE;
> +		goto out;
> +	}
>  
>  	/* No need to check writable slot explicitly as kvm_vcpu_write_guest does it internally */
>  	if (kvm_vcpu_write_guest(vcpu, saddr, kvpmu->sdata, snapshot_area_size)) {
> @@ -480,8 +482,10 @@ int kvm_riscv_vcpu_pmu_event_info(struct kvm_vcpu *vcpu, unsigned long saddr_low
>  	}
>  
>  	einfo = kzalloc(shmem_size, GFP_KERNEL);
> -	if (!einfo)
> -		return -ENOMEM;
> +	if (!einfo) {
> +		ret = SBI_ERR_FAILURE;
> +		goto out;
> +	}
>  
>  	ret = kvm_vcpu_read_guest(vcpu, shmem, einfo, shmem_size);
>  	if (ret) {
> -- 
> 2.43.0
> 
ping.

-- 
kvm-riscv mailing list
kvm-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kvm-riscv