Re: [Qemu-devel] [PATCH for-4.2 v10 08/15] virtio-iommu: Implement map/unmap

[Auger Eric]

Hi Peter,

On 8/19/19 10:11 AM, Peter Xu wrote:
> On Tue, Jul 30, 2019 at 07:21:30PM +0200, Eric Auger wrote:
> 
> [...]
> 
>> +    mapping = g_tree_lookup(domain->mappings, (gpointer)(&interval));
>> +
>> +    while (mapping) {
>> +        viommu_interval current;
>> +        uint64_t low  = mapping->virt_addr;
>> +        uint64_t high = mapping->virt_addr + mapping->size - 1;
>> +
>> +        current.low = low;
>> +        current.high = high;
>> +
>> +        if (low == interval.low && size >= mapping->size) {
>> +            g_tree_remove(domain->mappings, (gpointer)(&current));
>> +            interval.low = high + 1;
>> +            trace_virtio_iommu_unmap_left_interval(current.low, 
>> current.high,
>> +                interval.low, interval.high);
>> +        } else if (high == interval.high && size >= mapping->size) {
>> +            trace_virtio_iommu_unmap_right_interval(current.low, 
>> current.high,
>> +                interval.low, interval.high);
>> +            g_tree_remove(domain->mappings, (gpointer)(&current));
>> +            interval.high = low - 1;
>> +        } else if (low > interval.low && high < interval.high) {
>> +            trace_virtio_iommu_unmap_inc_interval(current.low, 
>> current.high);
>> +            g_tree_remove(domain->mappings, (gpointer)(&current));
>> +        } else {
>> +            break;
>> +        }
>> +        if (interval.low >= interval.high) {
>> +            return VIRTIO_IOMMU_S_OK;
>> +        } else {
>> +            mapping = g_tree_lookup(domain->mappings, 
>> (gpointer)(&interval));
>> +        }
>> +    }
>> +
>> +    if (mapping) {
>> +        qemu_log_mask(LOG_GUEST_ERROR,
>> +                      "****** %s: Unmap 0x%"PRIx64" size=0x%"PRIx64
>> +                     " from 0x%"PRIx64" size=0x%"PRIx64" is not 
>> supported\n",
>> +                     __func__, interval.low, size,
>> +                     mapping->virt_addr, mapping->size);
>> +    } else {
>> +        return VIRTIO_IOMMU_S_OK;
>> +    }
>> +
>> +    return VIRTIO_IOMMU_S_INVAL;
> 
> Could the above chunk be simplified as something like below?
> 
>   while ((mapping = g_tree_lookup(domain->mappings, &interval))) {
>     g_tree_remove(domain->mappings, mapping);
>   }
Indeed the code could be simplified. I only need to make sure I don't
split an existing mapping.

Also I needed to use g_tree_lookup_extended to retrieve the actual key
to remove. The usage of g_tree_lookup_extended() allows me to remove the
virt_addr and size fields from the mapping value value struct as those
info can be retrieved from the key.

Thanks!

Eric
> 
> Thanks,
>