From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: Haiwei Li <lihaiwei.kernel@gmail.com>
Cc: "pbonzini\@redhat.com" <pbonzini@redhat.com>,
Sean Christopherson <sean.j.christopherson@intel.com>,
"wanpengli\@tencent.com" <wanpengli@tencent.com>,
"jmattson\@google.com" <jmattson@google.com>,
"joro\@8bytes.org" <joro@8bytes.org>,
tglx@linutronix.de, mingo@redhat.com,
"bp\@alien8.de" <bp@alien8.de>, "hpa\@zytor.com" <hpa@zytor.com>,
"linux-kernel\@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"kvm\@vger.kernel.org" <kvm@vger.kernel.org>,
"x86\@kernel.org" <x86@kernel.org>
Subject: Re: [PATCH v2] KVM: Check the allocation of pv cpu mask
Date: Thu, 03 Sep 2020 12:39:52 +0200 [thread overview]
Message-ID: <87y2lrnnyf.fsf@vitty.brq.redhat.com> (raw)
In-Reply-To: <654d8c60-49f0-e398-be25-24aed352360d@gmail.com>
Haiwei Li <lihaiwei.kernel@gmail.com> writes:
> From: Haiwei Li <lihaiwei@tencent.com>
>
> check the allocation of per-cpu __pv_cpu_mask. Initialize ops only when
> successful.
>
> Signed-off-by: Haiwei Li <lihaiwei@tencent.com>
> ---
> arch/x86/kernel/kvm.c | 24 ++++++++++++++++++++----
> 1 file changed, 20 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> index 08320b0b2b27..d3c062e551d7 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 +791,21 @@ 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;
> }
>
> +#if defined(CONFIG_SMP)
> + apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself;
> +#endif
> + pv_ops.mmu.flush_tlb_others = kvm_flush_tlb_others;
This is too late I'm afraid. If I'm not mistaken PV patching happens
earlier, so .init.guest_late_init (kvm_guest_init()) is good and
arch_initcall() is bad.
Have you checked that with this patch kvm_flush_tlb_others() is still
being called?
Actually, there is no need to assign kvm_flush_tlb_others() so late. We
can always check if __pv_cpu_mask was allocated and revert back to the
architectural path if not.
> return 0;
> +
> +zalloc_cpumask_fail:
> + kvm_free_pv_cpu_mask();
> + return -ENOMEM;
> }
> arch_initcall(kvm_alloc_cpumask);
>
> --
> 2.18.4
>
--
Vitaly
next prev parent reply other threads:[~2020-09-03 10:40 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-03 1:59 [PATCH v2] KVM: Check the allocation of pv cpu mask Haiwei Li
2020-09-03 10:39 ` Vitaly Kuznetsov [this message]
2020-09-04 1:01 ` Haiwei Li
2020-09-04 9:53 ` Vitaly Kuznetsov
2020-09-04 12:21 ` Haiwei Li
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