Re: [PATCH v7 3/5] virtio-iommu: Call iommu notifier for attach/detach

[Auger Eric]

Hi Bharat,

On 3/16/20 9:58 AM, Bharat Bhushan wrote:
> Hi Eric,
> 
> On Mon, Mar 16, 2020 at 1:15 PM Bharat Bhushan <address@hidden> wrote:
>>
>> Hi Eric,
>>
>> On Mon, Mar 16, 2020 at 1:02 PM Auger Eric <address@hidden> wrote:
>>>
>>> Hi Bharat,
>>>
>>> On 3/16/20 7:41 AM, Bharat Bhushan wrote:
>>>> Hi Eric,
>>>>
>>>> On Fri, Mar 13, 2020 at 8:11 PM Auger Eric <address@hidden> wrote:
>>>>>
>>>>> Hi Bharat
>>>>>
>>>>> On 3/13/20 8:48 AM, Bharat Bhushan wrote:
>>>>>> iommu-notifier are called when a device is attached
>>>>> IOMMU notifiers
>>>>>> or detached to as address-space.
>>>>>> This is needed for VFIO.
>>>>> and vhost for detach
>>>>>>
>>>>>> Signed-off-by: Bharat Bhushan <address@hidden>
>>>>>> ---
>>>>>>  hw/virtio/virtio-iommu.c | 47 ++++++++++++++++++++++++++++++++++++++++
>>>>>>  1 file changed, 47 insertions(+)
>>>>>>
>>>>>> diff --git a/hw/virtio/virtio-iommu.c b/hw/virtio/virtio-iommu.c
>>>>>> index e51344a53e..2006f72901 100644
>>>>>> --- a/hw/virtio/virtio-iommu.c
>>>>>> +++ b/hw/virtio/virtio-iommu.c
>>>>>> @@ -49,6 +49,7 @@ typedef struct VirtIOIOMMUEndpoint {
>>>>>>      uint32_t id;
>>>>>>      VirtIOIOMMUDomain *domain;
>>>>>>      QLIST_ENTRY(VirtIOIOMMUEndpoint) next;
>>>>>> +    VirtIOIOMMU *viommu;
>>>>> This needs specal care on post-load. When migrating the EPs, only the id
>>>>> is migrated. On post-load you need to set viommu as it is done for
>>>>> domain. migration is allowed with vhost.
>>>>
>>>> ok, I have not tried vhost/migration. Below change set viommu when
>>>> reconstructing endpoint.
>>>
>>>
>>> Yes I think this should be OK.
>>>
>>> By the end I did the series a try with vhost/vfio. with vhost it works
>>> (not with recent kernel though, but the issue may be related to kernel).
>>> With VFIO however it does not for me.
>>>
>>> First issue is: your guest can use 4K page and your host can use 64KB
>>> pages. In that case VFIO_DMA_MAP will fail with -EINVAL. We must devise
>>> a way to pass the host settings to the VIRTIO-IOMMU device.
>>>
>>> Even with 64KB pages, it did not work for me. I have obviously not the
>>> storm of VFIO_DMA_MAP failures but I have some, most probably due to
>>> some wrong notifications somewhere. I will try to investigate on my side.
>>>
>>> Did you test with VFIO on your side?
>>
>> I did not tried with different page sizes, only tested with 4K page size.
>>
>> Yes it works, I tested with two n/w device assigned to VM, both interfaces 
>> works
>>
>> First I will try with 64k page size.
> 
> 64K page size does not work for me as well,
> 
> I think we are not passing correct page_size_mask here
> (config.page_size_mask is set to TARGET_PAGE_MASK ( which is
> 0xfffffffffffff000))
I guess you mean with guest using 4K and host using 64K.
> 
> We need to set this correctly as per host page size, correct?
Yes that's correct. We need to put in place a control path to retrieve
the page settings on host through VFIO to inform the virtio-iommu device.

Besides this issue, did you try with 64kB on host and guest?

Thanks

Eric
> 
> Thanks
> -Bharat
> 
>>
>> Thanks
>> -Bharat
>>
>>>
>>> Thanks
>>>
>>> Eric
>>>>
>>>> @@ -984,6 +973,7 @@ static gboolean reconstruct_endpoints(gpointer
>>>> key, gpointer value,
>>>>
>>>>      QLIST_FOREACH(iter, &d->endpoint_list, next) {
>>>>          iter->domain = d;
>>>> +       iter->viommu = s;
>>>>          g_tree_insert(s->endpoints, GUINT_TO_POINTER(iter->id), iter);
>>>>      }
>>>>      return false; /* continue the domain traversal */
>>>>
>>>>>>  } VirtIOIOMMUEndpoint;
>>>>>>
>>>>>>  typedef struct VirtIOIOMMUInterval {
>>>>>> @@ -155,8 +156,44 @@ static void 
>>>>>> virtio_iommu_notify_unmap(IOMMUMemoryRegion *mr, hwaddr iova,
>>>>>>      memory_region_notify_iommu(mr, 0, entry);
>>>>>>  }
>>>>>>
>>>>>> +static gboolean virtio_iommu_mapping_unmap(gpointer key, gpointer value,
>>>>>> +                                           gpointer data)
>>>>>> +{
>>>>>> +    VirtIOIOMMUInterval *interval = (VirtIOIOMMUInterval *) key;
>>>>>> +    IOMMUMemoryRegion *mr = (IOMMUMemoryRegion *) data;
>>>>>> +
>>>>>> +    virtio_iommu_notify_unmap(mr, interval->low,
>>>>>> +                              interval->high - interval->low + 1);
>>>>>> +
>>>>>> +    return false;
>>>>>> +}
>>>>>> +
>>>>>> +static gboolean virtio_iommu_mapping_map(gpointer key, gpointer value,
>>>>>> +                                         gpointer data)
>>>>>> +{
>>>>>> +    VirtIOIOMMUMapping *mapping = (VirtIOIOMMUMapping *) value;
>>>>>> +    VirtIOIOMMUInterval *interval = (VirtIOIOMMUInterval *) key;
>>>>>> +    IOMMUMemoryRegion *mr = (IOMMUMemoryRegion *) data;
>>>>>> +
>>>>>> +    virtio_iommu_notify_map(mr, interval->low, mapping->phys_addr,
>>>>>> +                            interval->high - interval->low + 1);
>>>>>> +
>>>>>> +    return false;
>>>>>> +}
>>>>>> +
>>>>>>  static void 
>>>>>> virtio_iommu_detach_endpoint_from_domain(VirtIOIOMMUEndpoint *ep)
>>>>>>  {
>>>>>> +    VirtioIOMMUNotifierNode *node;
>>>>>> +    VirtIOIOMMU *s = ep->viommu;
>>>>>> +    VirtIOIOMMUDomain *domain = ep->domain;
>>>>>> +
>>>>>> +    QLIST_FOREACH(node, &s->notifiers_list, next) {
>>>>>> +        if (ep->id == node->iommu_dev->devfn) {
>>>>>> +            g_tree_foreach(domain->mappings, virtio_iommu_mapping_unmap,
>>>>>> +                           &node->iommu_dev->iommu_mr);
>>>>> I understand this should fo the job for domain removal
>>>>
>>>> did not get the comment, are you saying we should do this on domain 
>>>> removal?
>>> see my reply on 2/5
>>>
>>> Note the above code should be moved after the check of !ep->domain below
>>
>> ohh yes, will move
>>
>> Thanks
>> -Bharat
>>
>>>>
>>>>>> +        }
>>>>>> +    }
>>>>>> +
>>>>>>      if (!ep->domain) {
>>>>>>          return;
>>>>>>      }
>>>>>> @@ -178,6 +215,7 @@ static VirtIOIOMMUEndpoint 
>>>>>> *virtio_iommu_get_endpoint(VirtIOIOMMU *s,
>>>>>>      }
>>>>>>      ep = g_malloc0(sizeof(*ep));
>>>>>>      ep->id = ep_id;
>>>>>> +    ep->viommu = s;
>>>>>>      trace_virtio_iommu_get_endpoint(ep_id);
>>>>>>      g_tree_insert(s->endpoints, GUINT_TO_POINTER(ep_id), ep);
>>>>>>      return ep;
>>>>>> @@ -272,6 +310,7 @@ static int virtio_iommu_attach(VirtIOIOMMU *s,
>>>>>>  {
>>>>>>      uint32_t domain_id = le32_to_cpu(req->domain);
>>>>>>      uint32_t ep_id = le32_to_cpu(req->endpoint);
>>>>>> +    VirtioIOMMUNotifierNode *node;
>>>>>>      VirtIOIOMMUDomain *domain;
>>>>>>      VirtIOIOMMUEndpoint *ep;
>>>>>>
>>>>>> @@ -299,6 +338,14 @@ static int virtio_iommu_attach(VirtIOIOMMU *s,
>>>>>>
>>>>>>      ep->domain = domain;
>>>>>>
>>>>>> +    /* Replay existing address space mappings on the associated memory 
>>>>>> region */
>>>>> maybe use the "domain" terminology here.
>>>>
>>>> ok,
>>>>
>>>> Thanks
>>>> -Bharat
>>>>
>>>>>> +    QLIST_FOREACH(node, &s->notifiers_list, next) {
>>>>>> +        if (ep_id == node->iommu_dev->devfn) {
>>>>>> +            g_tree_foreach(domain->mappings, virtio_iommu_mapping_map,
>>>>>> +                           &node->iommu_dev->iommu_mr);
>>>>>> +        }
>>>>>> +    }
>>>>>> +
>>>>>>      return VIRTIO_IOMMU_S_OK;
>>>>>>  }
>>>>>>
>>>>>>
>>>>> Thanks
>>>>>
>>>>> Eric
>>>>>
>>>>
>>>
>