Re: [EXT] [PATCH v2 2/5] virtio-iommu: Implement RESV_MEM probe request

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

Hi Bharat,
On 5/12/20 5:03 AM, Bharat Bhushan wrote:
> Hi Eric,
> 
>> -----Original Message-----
>> From: Auger Eric <eric.auger@redhat.com>
>> Sent: Monday, May 11, 2020 2:19 PM
>> To: Bharat Bhushan <bbhushan2@marvell.com>; eric.auger.pro@gmail.com;
>> qemu-devel@nongnu.org; qemu-arm@nongnu.org; peter.maydell@linaro.org;
>> mst@redhat.com; jean-philippe@linaro.org; peterx@redhat.com;
>> armbru@redhat.com; pbonzini@redhat.com
>> Subject: Re: [EXT] [PATCH v2 2/5] virtio-iommu: Implement RESV_MEM probe
>> request
>>
>> Hi Bharat,
>>
>> On 5/11/20 10:42 AM, Bharat Bhushan wrote:
>>> Hi Eric,
>>>
>>>> -----Original Message-----
>>>> From: Auger Eric <eric.auger@redhat.com>
>>>> Sent: Monday, May 11, 2020 12:26 PM
>>>> To: Bharat Bhushan <bbhushan2@marvell.com>; eric.auger.pro@gmail.com;
>>>> qemu-devel@nongnu.org; qemu-arm@nongnu.org; peter.maydell@linaro.org;
>>>> mst@redhat.com; jean-philippe@linaro.org; peterx@redhat.com;
>>>> armbru@redhat.com; pbonzini@redhat.com
>>>> Subject: Re: [EXT] [PATCH v2 2/5] virtio-iommu: Implement RESV_MEM
>>>> probe request
>>>>
>>>> Hi Bharat,
>>>> On 5/11/20 8:38 AM, Bharat Bhushan wrote:
>>>>> Hi Eric,
>>>>>
>>>>>> -----Original Message-----
>>>>>> From: Eric Auger <eric.auger@redhat.com>
>>>>>> Sent: Friday, May 8, 2020 11:01 PM
>>>>>> To: eric.auger.pro@gmail.com; eric.auger@redhat.com;
>>>>>> qemu-devel@nongnu.org; qemu-arm@nongnu.org;
>>>>>> peter.maydell@linaro.org; mst@redhat.com; jean-
>>>>>> philippe@linaro.org; Bharat Bhushan <bbhushan2@marvell.com>;
>>>>>> peterx@redhat.com; armbru@redhat.com; pbonzini@redhat.com
>>>>>> Subject: [EXT] [PATCH v2 2/5] virtio-iommu: Implement RESV_MEM
>>>>>> probe request
>>>>>>
>>>>>> External Email
>>>>>>
>>>>>> -------------------------------------------------------------------
>>>>>> --
>>>>>> - This patch implements the PROBE request. At the moment, only THE
>>>>>> RESV_MEM property is handled. The first goal is to report iommu
>>>>>> wide reserved regions such as the MSI regions set by the machine
>>>>>> code. On
>>>>>> x86 this will be the IOAPIC MSI region,
>>>>>> [0xFEE00000 - 0xFEEFFFFF], on ARM this may be the ITS doorbell.
>>>>>>
>>>>>> In the future we may introduce per device reserved regions.
>>>>>> This will be useful when protecting host assigned devices which may
>>>>>> expose their own reserved regions
>>>>>>
>>>>>> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>>>>>>
>>>>>> ---
>>>>>>
>>>>>> v1 -> v2:
>>>>>> - move the unlock back to the same place
>>>>>> - remove the push label and factorize the code after the out label
>>>>>> - fix a bunch of cpu_to_leX according to the latest spec revision
>>>>>> - do not remove sizeof(last) from free space
>>>>>> - check the ep exists
>>>>>> ---
>>>>>>  include/hw/virtio/virtio-iommu.h |  2 +
>>>>>>  hw/virtio/virtio-iommu.c         | 94 ++++++++++++++++++++++++++++++--
>>>>>>  hw/virtio/trace-events           |  1 +
>>>>>>  3 files changed, 93 insertions(+), 4 deletions(-)
>>>>>>
>>>>>> diff --git a/include/hw/virtio/virtio-iommu.h
>>>>>> b/include/hw/virtio/virtio-iommu.h
>>>>>> index e653004d7c..49eb105cd8 100644
>>>>>> --- a/include/hw/virtio/virtio-iommu.h
>>>>>> +++ b/include/hw/virtio/virtio-iommu.h
>>>>>> @@ -53,6 +53,8 @@ typedef struct VirtIOIOMMU {
>>>>>>      GHashTable *as_by_busptr;
>>>>>>      IOMMUPciBus *iommu_pcibus_by_bus_num[PCI_BUS_MAX];
>>>>>>      PCIBus *primary_bus;
>>>>>> +    ReservedRegion *reserved_regions;
>>>>>> +    uint32_t nb_reserved_regions;
>>>>>>      GTree *domains;
>>>>>>      QemuMutex mutex;
>>>>>>      GTree *endpoints;
>>>>>> diff --git a/hw/virtio/virtio-iommu.c b/hw/virtio/virtio-iommu.c
>>>>>> index
>>>>>> 22ba8848c2..35d772e021 100644
>>>>>> --- a/hw/virtio/virtio-iommu.c
>>>>>> +++ b/hw/virtio/virtio-iommu.c
>>>>>> @@ -38,6 +38,7 @@
>>>>>>
>>>>>>  /* Max size */
>>>>>>  #define VIOMMU_DEFAULT_QUEUE_SIZE 256
>>>>>> +#define VIOMMU_PROBE_SIZE 512
>>>>>>
>>>>>>  typedef struct VirtIOIOMMUDomain {
>>>>>>      uint32_t id;
>>>>>> @@ -378,6 +379,65 @@ static int virtio_iommu_unmap(VirtIOIOMMU *s,
>>>>>>      return ret;
>>>>>>  }
>>>>>>
>>>>>> +static ssize_t virtio_iommu_fill_resv_mem_prop(VirtIOIOMMU *s, uint32_t
>> ep,
>>>>>> +                                               uint8_t *buf,
>>>>>> +size_t
>>>>>> +free) {
>>>>>> +    struct virtio_iommu_probe_resv_mem prop = {};
>>>>>> +    size_t size = sizeof(prop), length = size - sizeof(prop.head), total;
>>>>>> +    int i;
>>>>>> +
>>>>>> +    total = size * s->nb_reserved_regions;
>>>>>> +
>>>>>> +    if (total > free) {
>>>>>> +        return -ENOSPC;
>>>>>> +    }
>>>>>> +
>>>>>> +    for (i = 0; i < s->nb_reserved_regions; i++) {
>>>>>> +        prop.head.type = cpu_to_le16(VIRTIO_IOMMU_PROBE_T_RESV_MEM);
>>>>>> +        prop.head.length = cpu_to_le16(length);
>>>>>> +        prop.subtype = s->reserved_regions[i].type;
>>>>>> +        prop.start = cpu_to_le64(s->reserved_regions[i].low);
>>>>>> +        prop.end = cpu_to_le64(s->reserved_regions[i].high);
>>>>>> +
>>>>>> +        memcpy(buf, &prop, size);
>>>>>> +
>>>>>> +        trace_virtio_iommu_fill_resv_property(ep, prop.subtype,
>>>>>> +                                              prop.start, prop.end);
>>>>>> +        buf += size;
>>>>>> +    }
>>>>>> +    return total;
>>>>>> +}
>>>>>> +
>>>>>> +/**
>>>>>> + * virtio_iommu_probe - Fill the probe request buffer with
>>>>>> + * the properties the device is able to return and add a NONE
>>>>>> + * property at the end.
>>>>>> + */
>>>>>> +static int virtio_iommu_probe(VirtIOIOMMU *s,
>>>>>> +                              struct virtio_iommu_req_probe *req,
>>>>>> +                              uint8_t *buf) {
>>>>>> +    uint32_t ep_id = le32_to_cpu(req->endpoint);
>>>>>> +    size_t free = VIOMMU_PROBE_SIZE;
>>>>>> +    ssize_t count;
>>>>>> +
>>>>>> +    if (!virtio_iommu_mr(s, ep_id)) {
>>>>>> +        return VIRTIO_IOMMU_S_NOENT;
>>>>>> +    }
>>>>>> +
>>>>>> +    count = virtio_iommu_fill_resv_mem_prop(s, ep_id, buf, free);
>>>>>> +    if (count < 0) {
>>>>>> +        return VIRTIO_IOMMU_S_INVAL;
>>>>>> +    }
>>>>>> +    buf += count;
>>>>>> +    free -= count;
>>>>>> +
>>>>>> +    /* Fill the rest with zeroes */
>>>>>> +    memset(buf, 0, free);
>>>>>
>>>>> No need to fill with zero here as "buf" is set to zero on allocation, no?
>>>>
>>>> You're right. I will remove this in the next version.
>>>>
>>>> Thanks
>>>>
>>>> Eric
>>>>>
>>>>> Thanks
>>>>> -Bharat
>>>>>
>>>>>> +
>>>>>> +    return VIRTIO_IOMMU_S_OK;
>>>>>> +}
>>>>>> +
>>>>>>  static int virtio_iommu_iov_to_req(struct iovec *iov,
>>>>>>                                     unsigned int iov_cnt,
>>>>>>                                     void *req, size_t req_sz) @@
>>>>>> -407,15 +467,27 @@
>>>>>> virtio_iommu_handle_req(detach)
>>>>>>  virtio_iommu_handle_req(map)
>>>>>>  virtio_iommu_handle_req(unmap)
>>>>>>
>>>>>> +static int virtio_iommu_handle_probe(VirtIOIOMMU *s,
>>>>>> +                                     struct iovec *iov,
>>>>>> +                                     unsigned int iov_cnt,
>>>>>> +                                     uint8_t *buf) {
>>>>>> +    struct virtio_iommu_req_probe req;
>>>>>> +    int ret = virtio_iommu_iov_to_req(iov, iov_cnt, &req,
>>>>>> +sizeof(req));
>>>>>> +
>>>>>> +    return ret ? ret : virtio_iommu_probe(s, &req, buf); }
>>>>>> +
>>>>>>  static void virtio_iommu_handle_command(VirtIODevice *vdev,
>>>>>> VirtQueue
>>>> *vq)  {
>>>>>>      VirtIOIOMMU *s = VIRTIO_IOMMU(vdev);
>>>>>>      struct virtio_iommu_req_head head;
>>>>>>      struct virtio_iommu_req_tail tail = {};
>>>>>> +    size_t output_size = sizeof(tail), sz;
>>>>>>      VirtQueueElement *elem;
>>>>>>      unsigned int iov_cnt;
>>>>>>      struct iovec *iov;
>>>>>> -    size_t sz;
>>>>>> +    void *buf = NULL;
>>>>>>
>>>>>>      for (;;) {
>>>>>>          elem = virtqueue_pop(vq, sizeof(VirtQueueElement)); @@
>>>>>> -452,6 +524,17 @@ static void
>>>>>> virtio_iommu_handle_command(VirtIODevice
>>>> *vdev, VirtQueue *vq)
>>>>>>          case VIRTIO_IOMMU_T_UNMAP:
>>>>>>              tail.status = virtio_iommu_handle_unmap(s, iov, iov_cnt);
>>>>>>              break;
>>>>>> +        case VIRTIO_IOMMU_T_PROBE:
>>>
>>> As per spec
>>>   "
>>>    If the device does not offer the VIRTIO_IOMMU_F_PROBE feature, and if the
>> driver sends a VIRTIO_-
>>>    IOMMU_T_PROBE request, then the device SHOULD NOT write the buffer and
>> SHOULD set the used
>>>    length to zero.
>>>   "
>>> So we should check if device supports "VIRTIO_IOMMU_F_PROBE" before
>> proceed?
>> But are the device and from that patch onwards we do support the
>> VIRTIO_IOMMU_F_PROBE feature, right?
> 
> Yes I agree, do you think if for debugging one wants to try out without this feature then he should just disable VIRTIO_IOMMU_F_PROBE.

You mean for debugging the driver? I don't think this is the purpose of
this device.

Thanks

Eric
> 
> Thanks
> -Bharat
> 
>>
>> Thanks
>>
>> Eric
>>>
>>> Thanks
>>> -Bharat
>>>
>>>>>> +        {
>>>>>> +            struct virtio_iommu_req_tail *ptail;
>>>>>> +
>>>>>> +            output_size = s->config.probe_size + sizeof(tail);
>>>>>> +            buf = g_malloc0(output_size);
>>>>>> +
>>>>>> +            ptail = (struct virtio_iommu_req_tail *)
>>>>>> +                        (buf + s->config.probe_size);
>>>>>> +            ptail->status = virtio_iommu_handle_probe(s, iov, iov_cnt, buf);
>>>>>> +        }
>>>>>>          default:
>>>>>>              tail.status = VIRTIO_IOMMU_S_UNSUPP;
>>>>>>          }
>>>>>> @@ -459,12 +542,13 @@ static void
>>>>>> virtio_iommu_handle_command(VirtIODevice *vdev, VirtQueue *vq)
>>>>>>
>>>>>>  out:
>>>>>>          sz = iov_from_buf(elem->in_sg, elem->in_num, 0,
>>>>>> -                          &tail, sizeof(tail));
>>>>>> -        assert(sz == sizeof(tail));
>>>>>> +                          buf ? buf : &tail, output_size);
>>>>>> +        assert(sz == output_size);
>>>>>>
>>>>>> -        virtqueue_push(vq, elem, sizeof(tail));
>>>>>> +        virtqueue_push(vq, elem, sz);
>>>>>>          virtio_notify(vdev, vq);
>>>>>>          g_free(elem);
>>>>>> +        g_free(buf);
>>>>>>      }
>>>>>>  }
>>>>>>
>>>>>> @@ -667,6 +751,7 @@ static void
>>>>>> virtio_iommu_device_realize(DeviceState *dev, Error **errp)
>>>>>>      s->config.page_size_mask = TARGET_PAGE_MASK;
>>>>>>      s->config.input_range.end = -1UL;
>>>>>>      s->config.domain_range.end = 32;
>>>>>> +    s->config.probe_size = VIOMMU_PROBE_SIZE;
>>>>>>
>>>>>>      virtio_add_feature(&s->features, VIRTIO_RING_F_EVENT_IDX);
>>>>>>      virtio_add_feature(&s->features, VIRTIO_RING_F_INDIRECT_DESC);
>>>>>> @@ -676,6
>>>>>> +761,7 @@ static void virtio_iommu_device_realize(DeviceState *dev,
>>>>>> +Error
>>>>>> **errp)
>>>>>>      virtio_add_feature(&s->features, VIRTIO_IOMMU_F_MAP_UNMAP);
>>>>>>      virtio_add_feature(&s->features, VIRTIO_IOMMU_F_BYPASS);
>>>>>>      virtio_add_feature(&s->features, VIRTIO_IOMMU_F_MMIO);
>>>>>> +    virtio_add_feature(&s->features, VIRTIO_IOMMU_F_PROBE);
>>>>>>
>>>>>>      qemu_mutex_init(&s->mutex);
>>>>>>
>>>>>> diff --git a/hw/virtio/trace-events b/hw/virtio/trace-events index
>>>>>> e83500bee9..5550475691 100644
>>>>>> --- a/hw/virtio/trace-events
>>>>>> +++ b/hw/virtio/trace-events
>>>>>> @@ -73,3 +73,4 @@ 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"
>>>>>>  virtio_iommu_report_fault(uint8_t reason, uint32_t flags, uint32_t
>>>>>> endpoint, uint64_t addr) "FAULT reason=%d flags=%d endpoint=%d
>>>>>> address =0x%"PRIx64
>>>>>> +virtio_iommu_fill_resv_property(uint32_t devid, uint8_t subtype,
>>>>>> +uint64_t start, uint64_t end) "dev= %d, type=%d start=0x%"PRIx64"
>>>>>> +end=0x%"PRIx64
>>>>>> --
>>>>>> 2.20.1
>>>>>
>>>>>
>>>
>