From: Haiwei Li <lihaiwei.kernel@gmail.com>
To: Vitaly Kuznetsov <vkuznets@redhat.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: Fri, 4 Sep 2020 09:01:59 +0800 [thread overview]
Message-ID: <61e2fd6f-effd-64d7-148a-1b1f9fda1449@gmail.com> (raw)
In-Reply-To: <87y2lrnnyf.fsf@vitty.brq.redhat.com>
On 20/9/3 18:39, Vitaly Kuznetsov wrote:
> 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.
.init.guest_late_init (kvm_guest_init()) is called before
arch_initcall() and kvm_flush_tlb_others && kvm_send_ipi_mask_allbutself
rely on __pv_cpu_mask. So, i can not put this assign in kvm_guest_init().
>
> Have you checked that with this patch kvm_flush_tlb_others() is still
> being called?
yes. I add a printk and i get the log.
>
> 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.
I am sorry i don't really understand. Can you explain in more detail? Thx.
>
>> return 0;
>> +
>> +zalloc_cpumask_fail:
>> + kvm_free_pv_cpu_mask();
>> + return -ENOMEM;
>> }
>> arch_initcall(kvm_alloc_cpumask);
>>
>> --
>> 2.18.4
>>
>
next prev parent reply other threads:[~2020-09-04 1:02 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
2020-09-04 1:01 ` Haiwei Li [this message]
2020-09-04 9:53 ` Vitaly Kuznetsov
2020-09-04 12:21 ` Haiwei Li
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