linux-kernel - Re: [PATCH] vfio-pci/zdev: require KVM to be built-in

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Date:   Tue, 16 Aug 2022 15:47:53 +0200
From:   Pierre Morel <pmorel@...ux.ibm.com>
To:     Randy Dunlap <rdunlap@...radead.org>, linux-kernel@...r.kernel.org
Cc:     kernel test robot <lkp@...el.com>,
        Matthew Rosato <mjrosato@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Eric Farman <farman@...ux.ibm.com>, linux-s390@...r.kernel.org,
        kvm@...r.kernel.org
Subject: Re: [PATCH] vfio-pci/zdev: require KVM to be built-in

Randy,

I need to provide the correction patch rapidly.
Without answer I will propose the patch.

Regards,
Pierre

On 8/16/22 09:55, Pierre Morel wrote:
> 
> 
> On 8/16/22 08:04, Randy Dunlap wrote:
>> Hi--
>>
>> On 8/15/22 02:43, Pierre Morel wrote:
>>> Thank you Randy for this good catch.
>>> However forcing KVM to be include statically in the kernel when using 
>>> VFIO_PCI extensions is not a good solution for us I think.
>>>
>>> I suggest we better do something like:
>>>
>>> ----
>>>
>>> diff --git a/arch/s390/include/asm/kvm_host.h 
>>> b/arch/s390/include/asm/kvm_host.h
>>> index 6287a843e8bc..1733339cc4eb 100644
>>> --- a/arch/s390/include/asm/kvm_host.h
>>> +++ b/arch/s390/include/asm/kvm_host.h
>>> @@ -1038,7 +1038,7 @@ static inline void 
>>> kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu) {}
>>>   #define __KVM_HAVE_ARCH_VM_FREE
>>>   void kvm_arch_free_vm(struct kvm *kvm);
>>>
>>> -#ifdef CONFIG_VFIO_PCI_ZDEV_KVM
>>> +#if defined(CONFIG_VFIO_PCI_ZDEV_KVM) || 
>>> defined(CONFIG_VFIO_PCI_ZDEV_KVM_MODULE)
>>
>> This all looks good except for the line above.
>> It should be:
>>
>> #if IS_ENABLED(CONFIG_VFIO_PCI_ZDEV_KVM)
>>
>> Thanks.
> 
> Yes, better, thanks.
> How do we do? Should I repost it with reported-by you or do you want to 
> post it?
> 
> Pierre
> 
> 
>>
>>
>>>   int kvm_s390_pci_register_kvm(struct zpci_dev *zdev, struct kvm *kvm);
>>>   void kvm_s390_pci_unregister_kvm(struct zpci_dev *zdev);
>>>   #else
>>> diff --git a/drivers/vfio/pci/Kconfig b/drivers/vfio/pci/Kconfig
>>> index f9d0c908e738..bbc375b028ef 100644
>>> --- a/drivers/vfio/pci/Kconfig
>>> +++ b/drivers/vfio/pci/Kconfig
>>> @@ -45,9 +45,9 @@ config VFIO_PCI_IGD
>>>   endif
>>>
>>>   config VFIO_PCI_ZDEV_KVM
>>> -       bool "VFIO PCI extensions for s390x KVM passthrough"
>>> +       def_tristate y
>>> +       prompt "VFIO PCI extensions for s390x KVM passthrough"
>>>          depends on S390 && KVM
>>> -       default y
>>>          help
>>>            Support s390x-specific extensions to enable support for 
>>> enhancements
>>>            to KVM passthrough capabilities, such as interpretive 
>>> execution of
>>>
>>> ----
>>>
>>> What do you think? It seems to me it solves the problem, what do you 
>>> think?
>>>
>>> Regards,
>>> Pierre
>>
>>
> 

-- 
Pierre Morel
IBM Lab Boeblingen