linux-kernel - Re: [PATCH] KVM: Check the allocation of pv cpu mask

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Message-ID: <0617b9ae-8ddb-dcb7-a345-9d629916d20d@redhat.com>
Date:   Fri, 11 Sep 2020 17:42:57 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Haiwei Li <lihaiwei.kernel@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>
Cc:     "hpa@...or.com" <hpa@...or.com>, "bp@...en8.de" <bp@...en8.de>,
        "mingo@...hat.com" <mingo@...hat.com>, tglx@...utronix.de,
        joro@...tes.org, jmattson@...gle.com,
        "wanpengli@...cent.com" <wanpengli@...cent.com>,
        vkuznets@...hat.com,
        Sean Christopherson <sean.j.christopherson@...el.com>
Subject: Re: [PATCH] KVM: Check the allocation of pv cpu mask

On 01/09/20 13:41, Haiwei Li wrote:
> From: Haiwei Li <lihaiwei@...cent.com>
> 
> check the allocation of per-cpu __pv_cpu_mask. Initialize ops only when
> successful.
> 
> Signed-off-by: Haiwei Li <lihaiwei@...cent.com>
> ---
>  arch/x86/kernel/kvm.c | 23 +++++++++++++++++++----
>  1 file changed, 19 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> index 08320b0b2b27..a64b894eaac0 100644
> --- a/arch/x86/kernel/kvm.c
> +++ b/arch/x86/kernel/kvm.c
> @@ -555,7 +555,6 @@ static void kvm_send_ipi_mask_allbutself(const
> struct cpumask *mask, int vector)
>  static void kvm_setup_pv_ipi(void)
>  {
>      apic->send_IPI_mask = kvm_send_ipi_mask;
> -    apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself;
>      pr_info("setup PV IPIs\n");
>  }
> 
> @@ -654,7 +653,6 @@ static void __init kvm_guest_init(void)
>      }
> 
>      if (pv_tlb_flush_supported()) {
> -        pv_ops.mmu.flush_tlb_others = kvm_flush_tlb_others;
>          pv_ops.mmu.tlb_remove_table = tlb_remove_table;
>          pr_info("KVM setup pv remote TLB flush\n");
>      }
> @@ -767,6 +765,14 @@ static __init int activate_jump_labels(void)
>  }
>  arch_initcall(activate_jump_labels);
> 
> +static void kvm_free_pv_cpu_mask(void)
> +{
> +    unsigned int cpu;
> +
> +    for_each_possible_cpu(cpu)
> +        free_cpumask_var(per_cpu(__pv_cpu_mask, cpu));
> +}
> +
>  static __init int kvm_alloc_cpumask(void)
>  {
>      int cpu;
> @@ -785,11 +791,20 @@ static __init int kvm_alloc_cpumask(void)
> 
>      if (alloc)
>          for_each_possible_cpu(cpu) {
> -            zalloc_cpumask_var_node(per_cpu_ptr(&__pv_cpu_mask, cpu),
> -                GFP_KERNEL, cpu_to_node(cpu));
> +            if (!zalloc_cpumask_var_node(
> +                per_cpu_ptr(&__pv_cpu_mask, cpu),
> +                GFP_KERNEL, cpu_to_node(cpu))) {
> +                goto zalloc_cpumask_fail;
> +            }
>          }
> 
> +    apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself;
> +    pv_ops.mmu.flush_tlb_others = kvm_flush_tlb_others;
>      return 0;
> +
> +zalloc_cpumask_fail:
> +    kvm_free_pv_cpu_mask();
> +    return -ENOMEM;
>  }
>  arch_initcall(kvm_alloc_cpumask);
> 
> -- 
> 2.18.4
> 

Queued, thanks.

I am currently on leave so I am going through the patches and queuing
them, but I will only push kvm/next and kvm/queue next week.  kvm/master
patches will be sent to Linus for the next -rc though.

Paolo