linux-kernel - Re: [PATCH 5/6] kvm: allocate vcpu pointer array separately

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Message-ID: <2aed0475-3df0-5ac6-f393-042b5e798ebc@suse.com>
Date:   Mon, 26 Jul 2021 15:46:50 +0200
From:   Juergen Gross <jgross@...e.com>
To:     Paolo Bonzini <pbonzini@...hat.com>, linux-kernel@...r.kernel.org,
        x86@...nel.org, linux-arm-kernel@...ts.infradead.org,
        kvm@...r.kernel.org
Cc:     Marc Zyngier <maz@...nel.org>, James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, kvmarm@...ts.cs.columbia.edu
Subject: Re: [PATCH 5/6] kvm: allocate vcpu pointer array separately

On 26.07.21 15:40, Paolo Bonzini wrote:
> On 01/07/21 17:41, Juergen Gross wrote:
>>   {
>> -    if (!has_vhe())
>> +    if (!has_vhe()) {
>> +        kfree(kvm->vcpus);
>>           kfree(kvm);
>> -    else
>> +    } else {
>> +        vfree(kvm->vcpus);
>>           vfree(kvm);
>> +    }
>>   }
>>   int kvm_arch_vcpu_precreate(struct kvm *kvm, unsigned int id)
>> diff --git a/arch/x86/include/asm/kvm_host.h 
>> b/arch/x86/include/asm/kvm_host.h
>> index 79138c91f83d..39cbc4b6bffb 100644
>> --- a/arch/x86/include/asm/kvm_host.h
>> +++ b/arch/x86/include/asm/kvm_host.h
>> @@ -1440,10 +1440,7 @@ static inline void 
>> kvm_ops_static_call_update(void)
>>   }
>>   #define __KVM_HAVE_ARCH_VM_ALLOC
>> -static inline struct kvm *kvm_arch_alloc_vm(void)
>> -{
>> -    return __vmalloc(kvm_x86_ops.vm_size, GFP_KERNEL_ACCOUNT | 
>> __GFP_ZERO);
>> -}
>> +struct kvm *kvm_arch_alloc_vm(void);
>>   void kvm_arch_free_vm(struct kvm *kvm);
>>   #define __KVM_HAVE_ARCH_FLUSH_REMOTE_TLB
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index 3af398ef1fc9..a9b0bb2221ea 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -10741,9 +10741,28 @@ void kvm_arch_sched_in(struct kvm_vcpu *vcpu, 
>> int cpu)
>>       static_call(kvm_x86_sched_in)(vcpu, cpu);
>>   }
>> +struct kvm *kvm_arch_alloc_vm(void)
>> +{
>> +    struct kvm *kvm;
>> +
>> +    kvm = __vmalloc(kvm_x86_ops.vm_size, GFP_KERNEL_ACCOUNT | 
>> __GFP_ZERO);
>> +    if (!kvm)
>> +        return NULL;
>> +
>> +    kvm->vcpus = __vmalloc(KVM_MAX_VCPUS * sizeof(void *),
>> +                   GFP_KERNEL_ACCOUNT | __GFP_ZERO);
>> +    if (!kvm->vcpus) {
>> +        vfree(kvm);
>> +        kvm = NULL;
>> +    }
>> +
> 
> Let's keep this cleaner:
> 
> 1) use kvfree in the common version of kvm_arch_free_vm
> 
> 2) split __KVM_HAVE_ARCH_VM_ALLOC and __KVM_HAVE_ARCH_VM_FREE (ARM does 
> not need it once kvfree is used)
> 
> 3) define a __kvm_arch_free_vm version that is defined even if 
> !__KVM_HAVE_ARCH_VM_FREE, and which can be used on x86.

Okay, will do so.


Juergen

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