Re: [PATCH v7 2/5] virtio-iommu: Implement RESV_MEM probe request

[Michael S. Tsirkin]

On Mon, Jun 29, 2020 at 09:04:01AM +0200, Eric Auger wrote:
> 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>
> Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> 
> ---
> 
> v6 -> v7:
> - put the assert again to make it clear there is no risk
>   of truncation
> 
> v5 -> v6:
> - removed validation of s->reserved_regions[i].type in the
>   probe request as it should rather happen in the realize()
> 
> v4 -> v5:
> - assert if reserved region type is different from RESERVED or
>   MSI
> 
> v3 -> v4:
> - removed any reference to the NONE property that does not
>   exist anymore.
> 
> v2 -> v3:
> - on probe, do not fill the reminder of the buffer with zeroes
>   as the buffer was already zero initialized (Bharat)
> 
> 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 483883ec1d..2cdaa1969b 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++) {
> +        unsigned subtype = s->reserved_regions[i].type;
> +
> +        assert(subtype == VIRTIO_IOMMU_RESV_MEM_T_RESERVED ||
> +               subtype == VIRTIO_IOMMU_RESV_MEM_T_MSI);
> +        prop.head.type = cpu_to_le16(VIRTIO_IOMMU_PROBE_T_RESV_MEM);
> +        prop.head.length = cpu_to_le16(length);
> +        prop.subtype = subtype;
> +        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
> + */
> +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;
> +
> +    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);
>

Don't we need to disable this for existing machine types?

  
>      qemu_mutex_init(&s->mutex);
>  
> diff --git a/hw/virtio/trace-events b/hw/virtio/trace-events
> index 6427a0047d..23109f69bb 100644
> --- a/hw/virtio/trace-events
> +++ b/hw/virtio/trace-events
> @@ -74,3 +74,4 @@ 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