[PATCH v7 6/7] iommu/virtio: Add probe request

Jean-Philippe Brucker
2019-01-15T12:19:58Z

When the device offers the probe feature, send a probe request for each
device managed by the IOMMU. Extract RESV_MEM information. When we
encounter a MSI doorbell region, set it up as a IOMMU_RESV_MSI region.
This will tell other subsystems that there is no need to map the MSI
doorbell in the virtio-iommu, because MSIs bypass it.

Tested-by: Bharat Bhushan <bharat.bhushan@nxp.com>
Tested-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
---
drivers/iommu/virtio-iommu.c | 157 ++++++++++++++++++++++++++++--
include/uapi/linux/virtio_iommu.h | 36 +++++++
2 files changed, 187 insertions(+), 6 deletions(-)

diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c
index 6fa012cd727e..5e194493a531 100644
--- a/drivers/iommu/virtio-iommu.c
+++ b/drivers/iommu/virtio-iommu.c
@@ -46,6 +46,7 @@ struct viommu_dev {
struct iommu_domain_geometry geometry;
u64 pgsize_bitmap;
u8 domain_bits;
+ u32 probe_size;
};

struct viommu_mapping {
@@ -67,8 +68,10 @@ struct viommu_domain {
};

struct viommu_endpoint {
+ struct device *dev;
struct viommu_dev *viommu;
struct viommu_domain *vdomain;
+ struct list_head resv_regions;
};

struct viommu_request {
@@ -119,6 +122,9 @@ static off_t viommu_get_write_desc_offset(struct viommu_dev *viommu,
{
size_t tail_size = sizeof(struct virtio_iommu_req_tail);

+ if (req->type == VIRTIO_IOMMU_T_PROBE)
+ return len - viommu->probe_size - tail_size;
+
return len - tail_size;
}

@@ -393,6 +399,110 @@ static int viommu_replay_mappings(struct viommu_domain *vdomain)
return ret;
}

+static int viommu_add_resv_mem(struct viommu_endpoint *vdev,
+ struct virtio_iommu_probe_resv_mem *mem,
+ size_t len)
+{
+ size_t size;
+ u64 start64, end64;
+ phys_addr_t start, end;
+ struct iommu_resv_region *region = NULL;
+ unsigned long prot = IOMMU_WRITE | IOMMU_NOEXEC | IOMMU_MMIO;
+
+ start = start64 = le64_to_cpu(mem->start);
+ end = end64 = le64_to_cpu(mem->end);
+ size = end64 - start64 + 1;
+
+ /* Catch any overflow, including the unlikely end64 - start64 + 1 = 0 */
+ if (start != start64 || end != end64 || size < end64 - start64)
+ return -EOVERFLOW;
+
+ if (len < sizeof(*mem))
+ return -EINVAL;
+
+ switch (mem->subtype) {
+ default:
+ dev_warn(vdev->dev, "unknown resv mem subtype 0x%x\n",
+ mem->subtype);
+ /* Fall-through */
+ case VIRTIO_IOMMU_RESV_MEM_T_RESERVED:
+ region = iommu_alloc_resv_region(start, size, 0,
+ IOMMU_RESV_RESERVED);
+ break;
+ case VIRTIO_IOMMU_RESV_MEM_T_MSI:
+ region = iommu_alloc_resv_region(start, size, prot,
+ IOMMU_RESV_MSI);
+ break;
+ }
+ if (!region)
+ return -ENOMEM;
+
+ list_add(&vdev->resv_regions, &region->list);
+ return 0;
+}
+
+static int viommu_probe_endpoint(struct viommu_dev *viommu, struct device *dev)
+{
+ int ret;
+ u16 type, len;
+ size_t cur = 0;
+ size_t probe_len;
+ struct virtio_iommu_req_probe *probe;
+ struct virtio_iommu_probe_property *prop;
+ struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
+ struct viommu_endpoint *vdev = fwspec->iommu_priv;
+
+ if (!fwspec->num_ids)
+ return -EINVAL;
+
+ probe_len = sizeof(*probe) + viommu->probe_size +
+ sizeof(struct virtio_iommu_req_tail);
+ probe = kzalloc(probe_len, GFP_KERNEL);
+ if (!probe)
+ return -ENOMEM;
+
+ probe->head.type = VIRTIO_IOMMU_T_PROBE;
+ /*
+ * For now, assume that properties of an endpoint that outputs multiple
+ * IDs are consistent. Only probe the first one.
+ */
+ probe->endpoint = cpu_to_le32(fwspec->ids[0]);
+
+ ret = viommu_send_req_sync(viommu, probe, probe_len);
+ if (ret)
+ goto out_free;
+
+ prop = (void *)probe->properties;
+ type = le16_to_cpu(prop->type) & VIRTIO_IOMMU_PROBE_T_MASK;
+
+ while (type != VIRTIO_IOMMU_PROBE_T_NONE &&
+ cur < viommu->probe_size) {
+ len = le16_to_cpu(prop->length) + sizeof(*prop);
+
+ switch (type) {
+ case VIRTIO_IOMMU_PROBE_T_RESV_MEM:
+ ret = viommu_add_resv_mem(vdev, (void *)prop, len);
+ break;
+ default:
+ dev_err(dev, "unknown viommu prop 0x%x\n", type);
+ }
+
+ if (ret)
+ dev_err(dev, "failed to parse viommu prop 0x%x\n", type);
+
+ cur += len;
+ if (cur >= viommu->probe_size)
+ break;
+
+ prop = (void *)probe->properties + cur;
+ type = le16_to_cpu(prop->type) & VIRTIO_IOMMU_PROBE_T_MASK;
+ }
+
+out_free:
+ kfree(probe);
+ return ret;
+}
+
/* IOMMU API */

static struct iommu_domain *viommu_domain_alloc(unsigned type)
@@ -614,15 +724,34 @@ static void viommu_iotlb_sync(struct iommu_domain *domain)

static void viommu_get_resv_regions(struct device *dev, struct list_head *head)
{
- struct iommu_resv_region *region;
+ struct iommu_resv_region *entry, *new_entry, *msi = NULL;
+ struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
+ struct viommu_endpoint *vdev = fwspec->iommu_priv;
int prot = IOMMU_WRITE | IOMMU_NOEXEC | IOMMU_MMIO;

- region = iommu_alloc_resv_region(MSI_IOVA_BASE, MSI_IOVA_LENGTH, prot,
- IOMMU_RESV_SW_MSI);
- if (!region)
- return;
+ list_for_each_entry(entry, &vdev->resv_regions, list) {
+ if (entry->type == IOMMU_RESV_MSI)
+ msi = entry;
+
+ new_entry = kmemdup(entry, sizeof(*entry), GFP_KERNEL);
+ if (!new_entry)
+ return;
+ list_add_tail(&new_entry->list, head);
+ }
+
+ /*
+ * If the device didn't register any bypass MSI window, add a
+ * software-mapped region.
+ */
+ if (!msi) {
+ msi = iommu_alloc_resv_region(MSI_IOVA_BASE, MSI_IOVA_LENGTH,
+ prot, IOMMU_RESV_SW_MSI);
+ if (!msi)
+ return;
+
+ list_add_tail(&msi->list, head);
+ }

- list_add_tail(&region->list, head);
iommu_dma_get_resv_regions(dev, head);
}

@@ -670,9 +799,18 @@ static int viommu_add_device(struct device *dev)
if (!vdev)
return -ENOMEM;

+ vdev->dev = dev;
vdev->viommu = viommu;
+ INIT_LIST_HEAD(&vdev->resv_regions);
fwspec->iommu_priv = vdev;

+ if (viommu->probe_size) {
+ /* Get additional information for this endpoint */
+ ret = viommu_probe_endpoint(viommu, dev);
+ if (ret)
+ goto err_free_dev;
+ }
+
ret = iommu_device_link(&viommu->iommu, dev);
if (ret)
goto err_free_dev;
@@ -694,6 +832,7 @@ static int viommu_add_device(struct device *dev)
err_unlink_dev:
iommu_device_unlink(&viommu->iommu, dev);
err_free_dev:
+ viommu_put_resv_regions(dev, &vdev->resv_regions);
kfree(vdev);

return ret;
@@ -711,6 +850,7 @@ static void viommu_remove_device(struct device *dev)

iommu_group_remove_device(dev);
iommu_device_unlink(&vdev->viommu->iommu, dev);
+ viommu_put_resv_regions(dev, &vdev->resv_regions);
kfree(vdev);
}

@@ -810,6 +950,10 @@ static int viommu_probe(struct virtio_device *vdev)
struct virtio_iommu_config, domain_bits,
&viommu->domain_bits);

+ virtio_cread_feature(vdev, VIRTIO_IOMMU_F_PROBE,
+ struct virtio_iommu_config, probe_size,
+ &viommu->probe_size);
+
viommu->geometry = (struct iommu_domain_geometry) {
.aperture_start = input_start,
.aperture_end = input_end,
@@ -891,6 +1035,7 @@ static unsigned int features[] = {
VIRTIO_IOMMU_F_MAP_UNMAP,
VIRTIO_IOMMU_F_DOMAIN_BITS,
VIRTIO_IOMMU_F_INPUT_RANGE,
+ VIRTIO_IOMMU_F_PROBE,
};

static struct virtio_device_id id_table[] = {
diff --git a/include/uapi/linux/virtio_iommu.h b/include/uapi/linux/virtio_iommu.h
index 5e5fd62689fb..ae6145cf5928 100644
--- a/include/uapi/linux/virtio_iommu.h
+++ b/include/uapi/linux/virtio_iommu.h
@@ -14,6 +14,7 @@
#define VIRTIO_IOMMU_F_DOMAIN_BITS 1
#define VIRTIO_IOMMU_F_MAP_UNMAP 2
#define VIRTIO_IOMMU_F_BYPASS 3
+#define VIRTIO_IOMMU_F_PROBE 4

struct virtio_iommu_range {
__u64 start;
@@ -37,6 +38,7 @@ struct virtio_iommu_config {
#define VIRTIO_IOMMU_T_DETACH 0x02
#define VIRTIO_IOMMU_T_MAP 0x03
#define VIRTIO_IOMMU_T_UNMAP 0x04
+#define VIRTIO_IOMMU_T_PROBE 0x05

/* Status types */
#define VIRTIO_IOMMU_S_OK 0x00
@@ -103,4 +105,38 @@ struct virtio_iommu_req_unmap {
struct virtio_iommu_req_tail tail;
};

+#define VIRTIO_IOMMU_PROBE_T_NONE 0
+#define VIRTIO_IOMMU_PROBE_T_RESV_MEM 1
+
+#define VIRTIO_IOMMU_PROBE_T_MASK 0xfff
+
+struct virtio_iommu_probe_property {
+ __le16 type;
+ __le16 length;
+};
+
+#define VIRTIO_IOMMU_RESV_MEM_T_RESERVED 0
+#define VIRTIO_IOMMU_RESV_MEM_T_MSI 1
+
+struct virtio_iommu_probe_resv_mem {
+ struct virtio_iommu_probe_property head;
+ __u8 subtype;
+ __u8 reserved[3];
+ __le64 start;
+ __le64 end;
+};
+
+struct virtio_iommu_req_probe {
+ struct virtio_iommu_req_head head;
+ __le32 endpoint;
+ __u8 reserved[64];
+
+ __u8 properties[];
+
+ /*
+ * Tail follows the variable-length properties array. No padding,
+ * property lengths are all aligned on 8 bytes.
+ */
+};
+
#endif
--
2.19.1