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

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

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:
>> +        {
>> +            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
> 
>