Re: [PATCH v2 03/12] vfio: Collect container iova range info

[Eric Auger]

Hi Cédric,

On 9/13/23 14:55, Cédric Le Goater wrote:
> On 9/13/23 10:01, Eric Auger wrote:
>> Collect iova range information if VFIO_IOMMU_TYPE1_INFO_CAP_IOVA_RANGE
>> capability is supported.
>>
>> This allows to propagate the information though the IOMMU MR
>> set_iova_ranges() callback so that virtual IOMMUs
>> get aware of those aperture constraints.
>>
>> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>> ---
>>   include/hw/vfio/vfio-common.h |  2 ++
>>   hw/vfio/common.c              | 45 +++++++++++++++++++++++++++++++++--
>>   2 files changed, 45 insertions(+), 2 deletions(-)
>>
>> diff --git a/include/hw/vfio/vfio-common.h
>> b/include/hw/vfio/vfio-common.h
>> index da43d27352..74b9b27270 100644
>> --- a/include/hw/vfio/vfio-common.h
>> +++ b/include/hw/vfio/vfio-common.h
>> @@ -98,6 +98,8 @@ typedef struct VFIOContainer {
>>       QLIST_HEAD(, VFIOGroup) group_list;
>>       QLIST_HEAD(, VFIORamDiscardListener) vrdl_list;
>>       QLIST_ENTRY(VFIOContainer) next;
>> +    unsigned nr_iovas;
>> +    struct  vfio_iova_range *iova_ranges;
>>   } VFIOContainer;
>>     typedef struct VFIOGuestIOMMU {
>> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
>> index 9aac21abb7..26da38de05 100644
>> --- a/hw/vfio/common.c
>> +++ b/hw/vfio/common.c
>> @@ -1157,6 +1157,14 @@ static void
>> vfio_listener_region_add(MemoryListener *listener,
>>               goto fail;
>>           }
>>   +        ret = memory_region_iommu_set_iova_ranges(giommu->iommu_mr,
>> +                container->nr_iovas, (struct Range
>> *)container->iova_ranges,
>> +                &err);
>> +        if (ret) {
>> +            g_free(giommu);
>> +            goto fail;
>> +        }
>> +
>>           ret = memory_region_register_iommu_notifier(section->mr,
>> &giommu->n,
>>                                                       &err);
>>           if (ret) {
>> @@ -1981,6 +1989,29 @@ bool vfio_get_info_dma_avail(struct
>> vfio_iommu_type1_info *info,
>>       return true;
>>   }
>>   +static void vfio_get_info_iova_range(struct vfio_iommu_type1_info
>> *info,
>> +                                     unsigned int *nr_iovas,
>> +                                     struct  vfio_iova_range
>> **iova_ranges)
>
> I guess there is no point in returning an error since we can not
> assign default values.
Actually this will return a boolean depending on the whether the
capability is supported,
as reported by Alex. I should have get inspired of
vfio_get_info_dma_avail()!
>
>> +{
>> +    struct vfio_info_cap_header *hdr;
>> +    struct vfio_iommu_type1_info_cap_iova_range *cap;
>> +
>> +    hdr = vfio_get_iommu_type1_info_cap(info,
>> +                                       
>> VFIO_IOMMU_TYPE1_INFO_CAP_IOVA_RANGE);
>> +    if (hdr == NULL) {
>
> May be :
>
>     if (!hdr) {
yep. I guess I copy/pasted the vfio_get_info_dma_avail() code here ;-)
>
>
>> +        return;
>> +    }
>> +
>> +    cap = (void *)hdr;
>> +    *nr_iovas = cap->nr_iovas;
>> +
>
> I would add a trace event with the #iovas.
I do agree tracing the resv regions is usefyl however I would be tempted
to have this trace point elsewhere, maybe at the place where
vfio_host_win_add is called to trace aperture min/max and in the
set_iova cb. Because here I would need to enumerate the regions to trace
them and usually trace points do not add any code.

Thanks

Eric
>
> Thanks,
>
> C.
>
>
>> +    if (*nr_iovas == 0) {
>> +        return;
>> +    }
>> +    *iova_ranges = g_memdup2(cap->iova_ranges,
>> +                             *nr_iovas * sizeof(struct 
>> vfio_iova_range));
>> +}
>> +
>>   static int vfio_setup_region_sparse_mmaps(VFIORegion *region,
>>                                             struct vfio_region_info
>> *info)
>>   {
>> @@ -2433,6 +2464,12 @@ static void
>> vfio_get_iommu_info_migration(VFIOContainer *container,
>>       }
>>   }
>>   +static void vfio_free_container(VFIOContainer *container)
>> +{
>> +    g_free(container->iova_ranges);
>> +    g_free(container);
>> +}
>> +
>>   static int vfio_connect_container(VFIOGroup *group, AddressSpace *as,
>>                                     Error **errp)
>>   {
>> @@ -2550,6 +2587,10 @@ static int vfio_connect_container(VFIOGroup
>> *group, AddressSpace *as,
>>           if (!vfio_get_info_dma_avail(info,
>> &container->dma_max_mappings)) {
>>               container->dma_max_mappings = 65535;
>>           }
>> +
>> +        vfio_get_info_iova_range(info, &container->nr_iovas,
>> +                                 &container->iova_ranges);
>> +
>>           vfio_get_iommu_info_migration(container, info);
>>           g_free(info);
>>   @@ -2663,7 +2704,7 @@ enable_discards_exit:
>>       vfio_ram_block_discard_disable(container, false);
>>     free_container_exit:
>> -    g_free(container);
>> +    vfio_free_container(container);
>>     close_fd_exit:
>>       close(fd);
>> @@ -2717,7 +2758,7 @@ static void vfio_disconnect_container(VFIOGroup
>> *group)
>>             trace_vfio_disconnect_container(container->fd);
>>           close(container->fd);
>> -        g_free(container);
>> +        vfio_free_container(container);
>>             vfio_put_address_space(space);
>>       }
>