Re: [PATCH v3 2/6] KVM: x86: Move declaration of kvm_cpu_dirty_log_size() to kvm_dirty_ring.h

From: Gavin Shan <gshan@redhat.com>
To: Marc Zyngier <maz@kernel.org>
Cc: kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
	catalin.marinas@arm.com, bgardon@google.com, shuah@kernel.org,
	andrew.jones@linux.dev, will@kernel.org, dmatlack@google.com,
	oliver.upton@linux.dev, peterx@redhat.com, pbonzini@redhat.com,
	zhenyzha@redhat.com, shan.gavin@gmail.com
Subject: Re: [PATCH v3 2/6] KVM: x86: Move declaration of kvm_cpu_dirty_log_size() to kvm_dirty_ring.h
Date: Mon, 26 Sep 2022 09:09:34 +1000	[thread overview]
Message-ID: <b226886c-3fc3-8f31-2e91-c4a6e1865097@redhat.com> (raw)
In-Reply-To: <877d1sio31.wl-maz@kernel.org>

Hi Marc,

On 9/25/22 5:12 AM, Marc Zyngier wrote:
> On Thu, 22 Sep 2022 01:32:10 +0100,
> Gavin Shan <gshan@redhat.com> wrote:
>>
>> Not all architectures like ARM64 need to override the function. Move
>> its declaration to kvm_dirty_ring.h to avoid the following compiling
>> warning on ARM64 when the feature is enabled.
>>
>>    arch/arm64/kvm/../../../virt/kvm/dirty_ring.c:14:12:        \
>>    warning: no previous prototype for 'kvm_cpu_dirty_log_size' \
>>    [-Wmissing-prototypes]                                      \
>>    int __weak kvm_cpu_dirty_log_size(void)
>>
>> Reported-by: kernel test robot <lkp@intel.com>
>> Signed-off-by: Gavin Shan <gshan@redhat.com>
>> ---
>>   arch/x86/include/asm/kvm_host.h | 2 --
>>   arch/x86/kvm/mmu/mmu.c          | 2 ++
>>   include/linux/kvm_dirty_ring.h  | 1 +
>>   3 files changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
>> index 2c96c43c313a..4c0fd517282b 100644
>> --- a/arch/x86/include/asm/kvm_host.h
>> +++ b/arch/x86/include/asm/kvm_host.h
>> @@ -2082,8 +2082,6 @@ static inline int kvm_cpu_get_apicid(int mps_cpu)
>>   #define GET_SMSTATE(type, buf, offset)		\
>>   	(*(type *)((buf) + (offset) - 0x7e00))
>>   
>> -int kvm_cpu_dirty_log_size(void);
>> -
>>   int memslot_rmap_alloc(struct kvm_memory_slot *slot, unsigned long npages);
>>   
>>   #define KVM_CLOCK_VALID_FLAGS						\
>> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
>> index e418ef3ecfcb..b3eb6a3627ec 100644
>> --- a/arch/x86/kvm/mmu/mmu.c
>> +++ b/arch/x86/kvm/mmu/mmu.c
>> @@ -1349,10 +1349,12 @@ void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
>>   		kvm_mmu_write_protect_pt_masked(kvm, slot, gfn_offset, mask);
>>   }
>>   
>> +#ifdef CONFIG_HAVE_KVM_DIRTY_RING
> 
> I think you can drop the ifdeffery, as HAVE_KVM_DIRTY_RING is
> unconditionally selected by the arch Kconfig.
> 

Yeah, I think so. Lets drop it in v4, which will be rebased on top
of your v2 series.

>>   int kvm_cpu_dirty_log_size(void)
>>   {
>>   	return kvm_x86_ops.cpu_dirty_log_size;
>>   }
>> +#endif
>>   
>>   bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm,
>>   				    struct kvm_memory_slot *slot, u64 gfn,
>> diff --git a/include/linux/kvm_dirty_ring.h b/include/linux/kvm_dirty_ring.h
>> index 906f899813dc..8c6755981c9b 100644
>> --- a/include/linux/kvm_dirty_ring.h
>> +++ b/include/linux/kvm_dirty_ring.h
>> @@ -71,6 +71,7 @@ static inline bool kvm_dirty_ring_soft_full(struct kvm_dirty_ring *ring)
>>   
>>   #else /* CONFIG_HAVE_KVM_DIRTY_RING */
>>   
>> +int kvm_cpu_dirty_log_size(void);
>>   u32 kvm_dirty_ring_get_rsvd_entries(void);
>>   int kvm_dirty_ring_alloc(struct kvm_dirty_ring *ring, int index, u32 size);
> 

Thanks,
Gavin