Userspace needs this feature flag to distinguish if vhost-vdpa
iotlb in the kernel supports persistent IOTLB mapping across
device reset. There are two cases that backend may claim
this feature bit on:
- parent device that has to work with platform IOMMU
- parent device with on-chip IOMMU that has the expected
.reset_map support in driver
Signed-off-by: Si-Wei Liu <si-wei....@oracle.com>
---
drivers/vhost/vdpa.c | 15 ++++++++++++++-
include/uapi/linux/vhost_types.h | 2 ++
2 files changed, 16 insertions(+), 1 deletion(-)
diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 71fbd559..bbb1092 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -414,6 +414,14 @@ static bool vhost_vdpa_has_desc_group(const struct
vhost_vdpa *v)
return ops->get_vq_desc_group;
}
+static bool vhost_vdpa_has_persistent_map(const struct vhost_vdpa *v)
+{
+ struct vdpa_device *vdpa = v->vdpa;
+ const struct vdpa_config_ops *ops = vdpa->config;
+
+ return (!ops->set_map && !ops->dma_map) || ops->reset_map;
+}
+
static long vhost_vdpa_get_features(struct vhost_vdpa *v, u64 __user *featurep)
{
struct vdpa_device *vdpa = v->vdpa;
@@ -716,7 +724,8 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
if (features & ~(VHOST_VDPA_BACKEND_FEATURES |
BIT_ULL(VHOST_BACKEND_F_DESC_ASID) |
BIT_ULL(VHOST_BACKEND_F_SUSPEND) |
- BIT_ULL(VHOST_BACKEND_F_RESUME)))
+ BIT_ULL(VHOST_BACKEND_F_RESUME) |
+ BIT_ULL(VHOST_BACKEND_F_IOTLB_PERSIST)))
return -EOPNOTSUPP;
if ((features & BIT_ULL(VHOST_BACKEND_F_SUSPEND)) &&
!vhost_vdpa_can_suspend(v))
@@ -729,6 +738,8 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
return -EINVAL;
if ((features & BIT_ULL(VHOST_BACKEND_F_DESC_ASID)) &&
!vhost_vdpa_has_desc_group(v))
+ if ((features & BIT_ULL(VHOST_BACKEND_F_IOTLB_PERSIST)) &&
+ !vhost_vdpa_has_persistent_map(v))
return -EOPNOTSUPP;
vhost_set_backend_features(&v->vdev, features);
return 0;
@@ -785,6 +796,8 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
features |= BIT_ULL(VHOST_BACKEND_F_RESUME);
if (vhost_vdpa_has_desc_group(v))
features |= BIT_ULL(VHOST_BACKEND_F_DESC_ASID);
+ if (vhost_vdpa_has_persistent_map(v))
+ features |= BIT_ULL(VHOST_BACKEND_F_IOTLB_PERSIST);
if (copy_to_user(featurep, &features, sizeof(features)))
r = -EFAULT;
break;
diff --git a/include/uapi/linux/vhost_types.h b/include/uapi/linux/vhost_types.h
index 6acc604..0fdb6f0 100644
--- a/include/uapi/linux/vhost_types.h
+++ b/include/uapi/linux/vhost_types.h
@@ -186,5 +186,7 @@ struct vhost_vdpa_iova_range {
* buffers may reside. Requires VHOST_BACKEND_F_IOTLB_ASID.
*/
#define VHOST_BACKEND_F_DESC_ASID 0x6
+/* IOTLB don't flush memory mapping across device reset */
+#define VHOST_BACKEND_F_IOTLB_PERSIST 0x7
#endif
--
1.8.3.1
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