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From: Si-Wei Liu <si-wei.liu@oracle.com>
To: eperezma@redhat.com, jasowang@redhat.com, mst@redhat.com,
	xuanzhuo@linux.alibaba.com, dtatulea@nvidia.com
Cc: virtualization@lists.linux-foundation.org
Subject: [PATCH RFC v3 4/4] vhost-vdpa: introduce IOTLB_PERSIST backend feature bit
Date: Sat,  9 Sep 2023 06:43:59 -0700	[thread overview]
Message-ID: <1694267039-718-5-git-send-email-si-wei.liu@oracle.com> (raw)
In-Reply-To: <1694267039-718-1-git-send-email-si-wei.liu@oracle.com>

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.liu@oracle.com>
---
RFC v2 -> v3:
  - fix missing return due to merge error

---
 drivers/vhost/vdpa.c             | 16 +++++++++++++++-
 include/uapi/linux/vhost_types.h |  2 ++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 71fbd559..b404504 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))
@@ -730,6 +739,9 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
 		if ((features & BIT_ULL(VHOST_BACKEND_F_DESC_ASID)) &&
 		     !vhost_vdpa_has_desc_group(v))
 			return -EOPNOTSUPP;
+		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 +797,8 @@ 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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  parent reply	other threads:[~2023-09-09 13:46 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-09 13:43 [PATCH RFC v3 0/4] vdpa: decouple reset of iotlb mapping from device reset Si-Wei Liu
2023-09-09 13:43 ` [PATCH RFC v3 1/4] vdpa: introduce .reset_map operation callback Si-Wei Liu
2023-09-09 13:43 ` [PATCH RFC v3 2/4] vdpa/mlx5: implement .reset_map driver op Si-Wei Liu
2023-09-11  3:48   ` Jason Wang
2023-09-12  0:01     ` Si-Wei Liu
2023-09-12  6:53       ` Jason Wang
2023-09-15  5:45         ` Si-Wei Liu
2023-09-09 13:43 ` [PATCH RFC v3 3/4] vhost-vdpa: should restore 1:1 dma mapping before detaching driver Si-Wei Liu
2023-09-09 13:43 ` Si-Wei Liu [this message]
2023-09-11  3:52   ` [PATCH RFC v3 4/4] vhost-vdpa: introduce IOTLB_PERSIST backend feature bit Jason Wang
2023-09-12  0:28     ` Si-Wei Liu
2023-09-12  7:01       ` Jason Wang
2023-09-15  5:55         ` Si-Wei Liu

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