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iommu/virtio: Add probe request
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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>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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Jean-Philippe Brucker authored and Michael S. Tsirkin committed Jun 6, 2019
1 parent edcd69a commit 2a5a314
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Showing 2 changed files with 187 additions and 6 deletions.
157 changes: 151 additions & 6 deletions drivers/iommu/virtio-iommu.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -46,6 +46,7 @@ struct viommu_dev {
struct iommu_domain_geometry geometry;
u64 pgsize_bitmap;
u8 domain_bits;
u32 probe_size;
};

struct viommu_mapping {
Expand All @@ -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 {
Expand Down Expand Up @@ -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;
}

Expand Down Expand Up @@ -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)
Expand Down Expand Up @@ -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);
}

Expand Down Expand Up @@ -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;
Expand All @@ -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;
Expand All @@ -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);
}

Expand Down Expand Up @@ -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,
Expand Down Expand Up @@ -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[] = {
Expand Down
36 changes: 36 additions & 0 deletions include/uapi/linux/virtio_iommu.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand All @@ -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
Expand Down Expand Up @@ -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

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