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

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Date:   Mon, 26 Jul 2021 14:57:14 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Juergen Gross <jgross@...e.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>, linux-kernel@...r.kernel.org,
        x86@...nel.org, linux-arm-kernel@...ts.infradead.org,
        kvm@...r.kernel.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 2021-07-26 14:46, Juergen Gross wrote:
> 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.

I'd appreciate if you could Cc me on the whole series, and
not just the single arm64 patch.

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...