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Date: Mon, 18 Jan 2010 15:52:35 +0200
From: "Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [Qemu-devel] [PATCHv2 1/3] qemu: memory notifiers
Message-ID: <20100118135234.GC8317@redhat.com>
References: <cover.1262634464.git.mst@redhat.com>
	<20100104194904.GB21299@redhat.com> <4B545C03.40807@redhat.com>
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To: Avi Kivity <avi@redhat.com>
Cc: gleb@redhat.com, qemu-devel@nongnu.org

On Mon, Jan 18, 2010 at 03:02:59PM +0200, Avi Kivity wrote:
> On 01/04/2010 09:49 PM, Michael S. Tsirkin wrote:
>> This adds notifiers for phys memory changes: a set of callbacks that
>> vhost can register and update kernel accordingly.  Down the road, kvm
>> code can be switched to use these as well, instead of calling kvm code
>> directly from exec.c as is done now.
>>
>>
>> +
>> +static void phys_page_for_each_in_l1_map(PhysPageDesc **phys_map,
>> +                                         CPUPhysMemoryClient *client)
>> +{
>> +    PhysPageDesc *pd;
>> +    int l1, l2;
>> +
>> +    for (l1 = 0; l1<  L1_SIZE; ++l1) {
>> +        pd = phys_map[l1];
>> +        if (!pd) {
>> +            continue;
>> +        }
>> +        for (l2 = 0; l2<  L2_SIZE; ++l2) {
>> +            if (pd[l2].phys_offset == IO_MEM_UNASSIGNED) {
>> +                continue;
>> +            }
>> +            client->set_memory(client, pd[l2].region_offset,
>> +                               TARGET_PAGE_SIZE, pd[l2].phys_offset);
>> +        }
>> +    }
>> +}
>> +
>> +static void phys_page_for_each(CPUPhysMemoryClient *client)
>> +{
>> +#if TARGET_PHYS_ADDR_SPACE_BITS>  32
>> +
>> +#if TARGET_PHYS_ADDR_SPACE_BITS>  (32 + L1_BITS)
>> +#error unsupported TARGET_PHYS_ADDR_SPACE_BITS
>> +#endif
>> +    void **phys_map = (void **)l1_phys_map;
>> +    int l1;
>> +    if (!l1_phys_map) {
>> +        return;
>> +    }
>> +    for (l1 = 0; l1<  L1_SIZE; ++l1) {
>> +        if (phys_map[l1]) {
>> +            phys_page_for_each_in_l1_map(phys_map[l1], client);
>> +        }
>> +    }
>> +#else
>> +    if (!l1_phys_map) {
>> +        return;
>> +    }
>> +    phys_page_for_each_in_l1_map(l1_phys_map, client);
>> +#endif
>> +}
>>    
>
> This looks pretty frightening.  What is it needed for?

The point is that clients can be registered at any point.

A client that registered when memory is present needs to
be notified about it.

>
> I think we should stick with range operations, but maybe I misunderstood  
> something here.
> Otherwise, I like this patchset.
>
> -- 
> error compiling committee.c: too many arguments to function