Re: [PATCH 3/3] migration dirtybitmap support ARMv7

[Marc Zyngier <marc.zyngier@arm.com>]

Hi Mario,

On 16/04/14 02:24, Mario Smarduch wrote:
> Hi Eric, Mark -
>    what repository should I use to pick up Eric patches?

The initial posting was there:

https://lists.cs.columbia.edu/pipermail/kvmarm/2014-April/008791.html

Reading Eric's patch again, it is not doing exactly the same thing, but
actually dealing with a slightly different (but connected) case.

I suggest you both work together on a common patch (or patch series)
that deals with the various memory region change thingy.

> For kvm_vm_ioctl_get_dirty_log() not sure what to make generic
> it appears generic enough and it does what it needs to do?

What I'm saying is that it should be put in a common location
(virt/kvm/kvm_main.c?), possibly as a weak symbol so it can be
overridden by other architectures.

As much as possible, try to share code with other arches rather than
duplicating it.

Thanks,

	M.

> Thanks,
>   Mario
> 
> On 04/15/2014 02:06 AM, Marc Zyngier wrote:
>> On 15/04/14 02:24, Mario Smarduch wrote:
>>>
>>> - support QEMU interface for initial VM Write Protect
>>> - QEMU Dirty bit map log retrieval
>>>
>>>
>>> Signed-off-by: Mario Smarduch <m.smarduch@samsung.com>
>>> ---
>>>  arch/arm/kvm/arm.c |   62 +++++++++++++++++++++++++++++++++++++++++++++++++++-
>>>  1 file changed, 61 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
>>> index bd18bb8..9076e3d 100644
>>> --- a/arch/arm/kvm/arm.c
>>> +++ b/arch/arm/kvm/arm.c
>>> @@ -241,6 +241,8 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
>>>  				   const struct kvm_memory_slot *old,
>>>  				   enum kvm_mr_change change)
>>>  {
>>> +	if ((change != KVM_MR_DELETE) && (mem->flags & KVM_MEM_LOG_DIRTY_PAGES))
>>> +		kvm_mmu_slot_remove_write_access(kvm, mem->slot);
>>>  }
>>
>> There is a patch by Eric Auger doing the same thing. Please use it as a
>> dependency.
>>
>>>  void kvm_arch_flush_shadow_all(struct kvm *kvm)
>>> @@ -773,9 +775,67 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
>>>  	}
>>>  }
>>>  
>>> +/*
>>> + * Walks the memslot dirty bitmap, write protects dirty pages for next rount,
>>> + * and stores the dirty bitmap fo QEMU retrieval.
>>> + *
>>> + */
>>>  int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log)
>>>  {
>>> -	return -EINVAL;
>>> +	int r;
>>> +	struct kvm_memory_slot *memslot;
>>> +	unsigned long n, i;
>>> +	unsigned long *dirty_bitmap;
>>> +	unsigned long *dirty_bitmap_buffer;
>>> +	bool is_dirty = false;
>>> +	gfn_t offset;
>>> +
>>> +	mutex_lock(&kvm->slots_lock);
>>> +	r = -EINVAL;
>>> +
>>> +	if (log->slot >= KVM_USER_MEM_SLOTS)
>>> +		goto out;
>>> +
>>> +	memslot = id_to_memslot(kvm->memslots, log->slot);
>>> +	dirty_bitmap = memslot->dirty_bitmap;
>>> +
>>> +	r = -ENOENT;
>>> +	if (!dirty_bitmap)
>>> +		goto out;
>>> +
>>> +	n = kvm_dirty_bitmap_bytes(memslot);
>>> +	dirty_bitmap_buffer = dirty_bitmap + n / sizeof(long);
>>> +	memset(dirty_bitmap_buffer, 0, n);
>>> +
>>> +	spin_lock(&kvm->mmu_lock);
>>> +	for (i = 0; i < n / sizeof(long); i++) {
>>> +		unsigned long mask;
>>> +
>>> +		if (!dirty_bitmap[i])
>>> +			continue;
>>> +
>>> +		is_dirty = true;
>>> +		offset = i * BITS_PER_LONG;
>>> +		kvm_mmu_write_protect_pt_masked(kvm, memslot, offset,
>>> +							dirty_bitmap[i]);
>>> +		mask = dirty_bitmap[i];
>>> +		dirty_bitmap_buffer[i] = mask;
>>> +		dirty_bitmap[i] = 0;
>>> +	}
>>> +
>>> +	if (is_dirty)
>>> +		kvm_tlb_flush_vmid(kvm);
>>> +
>>> +	spin_unlock(&kvm->mmu_lock);
>>> +	r = -EFAULT;
>>> +
>>> +	if (copy_to_user(log->dirty_bitmap, dirty_bitmap_buffer, n))
>>> +		goto out;
>>> +
>>> +	r = 0;
>>> +out:
>>> +	mutex_unlock(&kvm->slots_lock);
>>> +	return r;
>>>  }
>>
>> This is a direct copy of the x86 code. Please make it generic.
>>
>>>  static int kvm_vm_ioctl_set_device_addr(struct kvm *kvm,
>>>
>>
>> Thanks,
>>
>> 	M.
>>
> 
> 


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