linux-kernel - Re: [PATCH] arch/powerpc/kvm: kvmppc_core_vcpu_create

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Message-ID: <ZCJu2WN9W5wQm1x2@li-a450e7cc-27df-11b2-a85c-b5a9ac31e8ef.ibm.com>
Date:   Tue, 28 Mar 2023 10:06:41 +0530
From:   Kautuk Consul <kconsul@...ux.vnet.ibm.com>
To:     Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Fabiano Rosas <farosas@...ux.ibm.com>
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arch/powerpc/kvm: kvmppc_core_vcpu_create_hv: check for
 kzalloc failure

Hi,
On 2023-03-23 03:47:18, Kautuk Consul wrote:
> kvmppc_vcore_create() might not be able to allocate memory through
> kzalloc. In that case the kvm->arch.online_vcores shouldn't be
> incremented.
> Add a check for kzalloc failure and return with -ENOMEM from
> kvmppc_core_vcpu_create_hv().
Anyone wants to review this ?
Its been a few days of silence.
By the way, I anyway have to post a v2 as I now know that
the commit description needs to be different. But I'll wait
for review comments on the code before I do so.
> 
> Signed-off-by: Kautuk Consul <kconsul@...ux.vnet.ibm.com>
> ---
>  arch/powerpc/kvm/book3s_hv.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> index 6ba68dd6190b..e29ee755c920 100644
> --- a/arch/powerpc/kvm/book3s_hv.c
> +++ b/arch/powerpc/kvm/book3s_hv.c
> @@ -2968,13 +2968,17 @@ static int kvmppc_core_vcpu_create_hv(struct kvm_vcpu *vcpu)
>  			pr_devel("KVM: collision on id %u", id);
>  			vcore = NULL;
>  		} else if (!vcore) {
> +			vcore = kvmppc_vcore_create(kvm,
> +					id & ~(kvm->arch.smt_mode - 1));
> +			if (unlikely(!vcore)) {
> +				mutex_unlock(&kvm->lock);
> +				return -ENOMEM;
> +			}
> +
>  			/*
>  			 * Take mmu_setup_lock for mutual exclusion
>  			 * with kvmppc_update_lpcr().
>  			 */
> -			err = -ENOMEM;
> -			vcore = kvmppc_vcore_create(kvm,
> -					id & ~(kvm->arch.smt_mode - 1));
>  			mutex_lock(&kvm->arch.mmu_setup_lock);
>  			kvm->arch.vcores[core] = vcore;
>  			kvm->arch.online_vcores++;
> -- 
> 2.39.2
>