Re: [PATCH for-5.0 v11 08/20] virtio-iommu: Implement translate

[Auger Eric <eric.auger@redhat.com>]

Hi Peter,
On 12/10/19 8:33 PM, Peter Xu wrote:
> On Fri, Nov 22, 2019 at 07:29:31PM +0100, Eric Auger wrote:
>> This patch implements the translate callback
>>
>> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>>
>> ---
>>
>> v10 -> v11:
>> - take into account the new value struct and use
>>   g_tree_lookup_extended
>> - switched to error_report_once
>>
>> v6 -> v7:
>> - implemented bypass-mode
>>
>> v5 -> v6:
>> - replace error_report by qemu_log_mask
>>
>> v4 -> v5:
>> - check the device domain is not NULL
>> - s/printf/error_report
>> - set flags to IOMMU_NONE in case of all translation faults
>> ---
>>  hw/virtio/trace-events   |  1 +
>>  hw/virtio/virtio-iommu.c | 63 +++++++++++++++++++++++++++++++++++++++-
>>  2 files changed, 63 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/virtio/trace-events b/hw/virtio/trace-events
>> index f25359cee2..de7cbb3c8f 100644
>> --- a/hw/virtio/trace-events
>> +++ b/hw/virtio/trace-events
>> @@ -72,3 +72,4 @@ virtio_iommu_get_endpoint(uint32_t ep_id) "Alloc endpoint=%d"
>>  virtio_iommu_put_endpoint(uint32_t ep_id) "Free endpoint=%d"
>>  virtio_iommu_get_domain(uint32_t domain_id) "Alloc domain=%d"
>>  virtio_iommu_put_domain(uint32_t domain_id) "Free domain=%d"
>> +virtio_iommu_translate_out(uint64_t virt_addr, uint64_t phys_addr, uint32_t sid) "0x%"PRIx64" -> 0x%"PRIx64 " for sid=%d"
>> diff --git a/hw/virtio/virtio-iommu.c b/hw/virtio/virtio-iommu.c
>> index f0a56833a2..a83666557b 100644
>> --- a/hw/virtio/virtio-iommu.c
>> +++ b/hw/virtio/virtio-iommu.c
>> @@ -412,19 +412,80 @@ static IOMMUTLBEntry virtio_iommu_translate(IOMMUMemoryRegion *mr, hwaddr addr,
>>                                              int iommu_idx)
>>  {
>>      IOMMUDevice *sdev = container_of(mr, IOMMUDevice, iommu_mr);
>> +    viommu_interval interval, *mapping_key;
>> +    viommu_mapping *mapping_value;
>> +    VirtIOIOMMU *s = sdev->viommu;
>> +    viommu_endpoint *ep;
>> +    bool bypass_allowed;
>>      uint32_t sid;
>> +    bool found;
>> +
>> +    interval.low = addr;
>> +    interval.high = addr + 1;
>>  
>>      IOMMUTLBEntry entry = {
>>          .target_as = &address_space_memory,
>>          .iova = addr,
>>          .translated_addr = addr,
>> -        .addr_mask = ~(hwaddr)0,
>> +        .addr_mask = (1 << ctz32(s->config.page_size_mask)) - 1,
>>          .perm = IOMMU_NONE,
>>      };
>>  
>> +    bypass_allowed = virtio_has_feature(s->acked_features,
>> +                                        VIRTIO_IOMMU_F_BYPASS);
>> +
> 
> Would it be easier to check bypass_allowed here once and then drop the
> latter [1] and [2] check?
bypass_allowed does not mean you systematically bypass. You bypass if
the SID is unknown or if the device is not attached to any domain.
Otherwise you translate. But maybe I miss your point.
> 
>>      sid = virtio_iommu_get_sid(sdev);
>>  
>>      trace_virtio_iommu_translate(mr->parent_obj.name, sid, addr, flag);
>> +    qemu_mutex_lock(&s->mutex);
>> +
>> +    ep = g_tree_lookup(s->endpoints, GUINT_TO_POINTER(sid));
>> +    if (!ep) {
>> +        if (!bypass_allowed) {
> 
> [1]
> 
>> +            error_report_once("%s sid=%d is not known!!", __func__, sid);
>> +        } else {
>> +            entry.perm = flag;
>> +        }
>> +        goto unlock;
>> +    }
>> +
>> +    if (!ep->domain) {
>> +        if (!bypass_allowed) {
> 
> [2]
> 
>> +            qemu_log_mask(LOG_GUEST_ERROR,
>> +                          "%s %02x:%02x.%01x not attached to any domain\n",
>> +                          __func__, PCI_BUS_NUM(sid),
>> +                          PCI_SLOT(sid), PCI_FUNC(sid));
>> +        } else {
>> +            entry.perm = flag;
>> +        }
>> +        goto unlock;
>> +    }
>> +
>> +    found = g_tree_lookup_extended(ep->domain->mappings, (gpointer)(&interval),
>> +                                   (void **)&mapping_key,
>> +                                   (void **)&mapping_value);
>> +    if (!found) {
>> +        qemu_log_mask(LOG_GUEST_ERROR,
>> +                      "%s no mapping for 0x%"PRIx64" for sid=%d\n",
>> +                      __func__, addr, sid);
> 
> I would still suggest that we use the same logging interface (either
> error_report_once() or qemu_log_mask(), not use them randomly).
OK I will switch to error_report_once() then
> 
>> +        goto unlock;
>> +    }
>> +
>> +    if (((flag & IOMMU_RO) &&
>> +            !(mapping_value->flags & VIRTIO_IOMMU_MAP_F_READ)) ||
>> +        ((flag & IOMMU_WO) &&
>> +            !(mapping_value->flags & VIRTIO_IOMMU_MAP_F_WRITE))) {
>> +        qemu_log_mask(LOG_GUEST_ERROR,
>> +                      "Permission error on 0x%"PRIx64"(%d): allowed=%d\n",
>> +                      addr, flag, mapping_value->flags);
> 
> (Btw, IIUC this may not be a guest error. Say, what if the device is
>  simply broken?)
> 
>> +        goto unlock;
>> +    }
>> +    entry.translated_addr = addr - mapping_key->low + mapping_value->phys_addr;
>> +    entry.perm = flag;
>> +    trace_virtio_iommu_translate_out(addr, entry.translated_addr, sid);
>> +
>> +unlock:
>> +    qemu_mutex_unlock(&s->mutex);
>>      return entry;
>>  }
>>  
>> -- 
>> 2.20.1
>>
> 
Thanks

Eric