Subject: Re: [PART1 RFC v3 02/12] KVM: x86: Introducing kvm_x86_ops VM
 init/uninit hooks
To: Paolo Bonzini <pbonzini@redhat.com>, <rkrcmar@redhat.com>,
        <joro@8bytes.org>, <bp@alien8.de>, <gleb@kernel.org>,
        <alex.williamson@redhat.com>
References: <1458281388-14452-1-git-send-email-Suravee.Suthikulpanit@amd.com>
 <1458281388-14452-3-git-send-email-Suravee.Suthikulpanit@amd.com>
 <56EBD438.5000702@redhat.com> <56FA1240.2000600@amd.com>
 <56FA5737.2090406@redhat.com> <56FA6B36.4030607@amd.com>
CC: <kvm@vger.kernel.org>, <linux-kernel@vger.kernel.org>, <wei@redhat.com>,
        <sherry.hurwitz@amd.com>
From: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
Message-ID: <56FBA3A3.1060907@amd.com>
Date: Wed, 30 Mar 2016 17:00:03 +0700
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:38.0)
 Gecko/20100101 Thunderbird/38.6.0
MIME-Version: 1.0
In-Reply-To: <56FA6B36.4030607@amd.com>
Content-Type: text/plain; charset="windows-1252"; format=flowed
Content-Transfer-Encoding: 7bit
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 30 Mar 2016 10:00:13.4191
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY1PR12MB0440
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 2134
Lines: 67

Hi Paolo,

On 3/29/16 18:47, Suravee Suthikulpanit wrote:
> Hi,
>
> On 03/29/2016 05:21 PM, Paolo Bonzini wrote:
>>
>>
>> On 29/03/2016 07:27, Suravee Suthikulpanit wrote:
>>>>
>>>>>> Adding function pointers in struct kvm_x86_ops for processor-specific
>>>>>> layer to provide hooks for when KVM initialize and un-initialize VM.
>>>> This is not the only thing your patch is doing, and the "other" change
>>>> definitely needs a lot more explanation about why you did it and how
>>>> you
>>>> audited the code to ensure that it is safe.
>>>>
>>>> Paolo
>>>>
>>>
>>> Sorry, for not mentioning this earlier. I am moving the
>>> kvm_arch_init_vm() call mainly to go after mutex_init(&kvm->slots_lock)
>>> since I am calling the x86_set_memory_region() (which uses slots_lock)
>>> in the vm_init() hooks (for AVIC initialization).
>>>
>>> Lemme re-check if this would be safe for other code.
>>
>> No problem.  In the meanwhile a patch got in ("KVM: fix spin_lock_init
>> order on x86") that should help you.
>>
>> Thanks,
>>
>> Paolo
>>
>
> Right.... that's just what I need :) I'll re-base to the latest tip then.

Actually, in the file virt/kvm/kvm_main.c, I still need to move the 
kvm_arch_init_vm() to some place after the call to kvm_alloc_memslots() 
since I am calling x86_set_memory_region() in the vm_init hook.

         r = -ENOMEM;
         for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
                 kvm->memslots[i] = kvm_alloc_memslots();
                 if (!kvm->memslots[i])
                         goto out_err_no_srcu;
         }

         if (init_srcu_struct(&kvm->srcu))
                 goto out_err_no_srcu;
         if (init_srcu_struct(&kvm->irq_srcu))
                 goto out_err_no_irq_srcu;
         for (i = 0; i < KVM_NR_BUSES; i++) {
                 kvm->buses[i] = kzalloc(sizeof(struct kvm_io_bus),
                                         GFP_KERNEL);
                 if (!kvm->buses[i])
                         goto out_err;
         }
//HERE
         r = kvm_arch_init_vm(kvm, type);
         if (r)
                 goto out_err;

Do you think that would be a problem?

Thanks,
Suravee