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

[Bharat Bhushan]

Hi Eric,

> -----Original Message-----
> From: Auger Eric <address@hidden>
> Sent: Monday, May 11, 2020 12:26 PM
> To: Bharat Bhushan <address@hidden>; address@hidden;
> address@hidden; address@hidden; address@hidden;
> address@hidden; address@hidden; address@hidden;
> address@hidden; address@hidden
> 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 <address@hidden>
> >> Sent: Friday, May 8, 2020 11:01 PM
> >> To: address@hidden; address@hidden;
> >> address@hidden; address@hidden; address@hidden;
> >> address@hidden; jean- address@hidden; Bharat Bhushan
> >> <address@hidden>; address@hidden; address@hidden;
> >> address@hidden
> >> 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 <address@hidden>
> >>
> >> ---
> >>
> >> 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?

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
> >
> >