In order to reduce excessive memory mapping cost in live migration and
VM reboot, it is desirable to decouple the vhost-vdpa IOTLB abstraction
from the virtio device life cycle, i.e. mappings can be kept intact
across virtio device reset. Leverage the .reset_map callback, which is
meant to destroy the iotlb on the given ASID and recreate the 1:1
passthrough/identity mapping. To be consistent, the mapping on device
creation is initiailized to passthrough/identity with PA 1:1 mapped
as IOVA. With this the device .reset op doesn't have to maintain and
clean up memory mappings by itself.
Add a module paramemter, iotlb_persist, to cater for older userspace
which may wish to see mapping to be cleared during reset.
Signed-off-by: Si-Wei Liu <si-wei....@oracle.com>
Tested-by: Stefano Garzarella <sgarz...@redhat.com>
---
drivers/vdpa/vdpa_sim/vdpa_sim.c | 58 ++++++++++++++++++++++++++------
1 file changed, 47 insertions(+), 11 deletions(-)
diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
index 76d41058add9..74506636375f 100644
--- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
@@ -40,6 +40,10 @@ static bool use_va = true;
module_param(use_va, bool, 0444);
MODULE_PARM_DESC(use_va, "Enable/disable the device's ability to use VA");
+static bool iotlb_persist = true;
+module_param(iotlb_persist, bool, 0444);
+MODULE_PARM_DESC(iotlb_persist, "Enable/disable persistent iotlb across reset:
1 to keep maps, 0 to clear");
+
#define VDPASIM_QUEUE_ALIGN PAGE_SIZE
#define VDPASIM_QUEUE_MAX 256
#define VDPASIM_VENDOR_ID 0
@@ -151,11 +155,13 @@ static void vdpasim_do_reset(struct vdpasim *vdpasim)
&vdpasim->iommu_lock);
}
- for (i = 0; i < vdpasim->dev_attr.nas; i++) {
- vhost_iotlb_reset(&vdpasim->iommu[i]);
- vhost_iotlb_add_range(&vdpasim->iommu[i], 0, ULONG_MAX,
- 0, VHOST_MAP_RW);
- vdpasim->iommu_pt[i] = true;
+ if (unlikely(!iotlb_persist)) {
+ for (i = 0; i < vdpasim->dev_attr.nas; i++) {
+ vhost_iotlb_reset(&vdpasim->iommu[i]);
+ vhost_iotlb_add_range(&vdpasim->iommu[i], 0, ULONG_MAX,
+ 0, VHOST_MAP_RW);
+ vdpasim->iommu_pt[i] = true;
+ }
}
vdpasim->running = true;
@@ -166,8 +172,8 @@ static void vdpasim_do_reset(struct vdpasim *vdpasim)
++vdpasim->generation;
}
-static const struct vdpa_config_ops vdpasim_config_ops;
-static const struct vdpa_config_ops vdpasim_batch_config_ops;
+static struct vdpa_config_ops vdpasim_config_ops;
+static struct vdpa_config_ops vdpasim_batch_config_ops;
static void vdpasim_work_fn(struct kthread_work *work)
{
@@ -191,7 +197,7 @@ static void vdpasim_work_fn(struct kthread_work *work)
struct vdpasim *vdpasim_create(struct vdpasim_dev_attr *dev_attr,
const struct vdpa_dev_set_config *config)
{
- const struct vdpa_config_ops *ops;
+ struct vdpa_config_ops *ops;
struct vdpa_device *vdpa;
struct vdpasim *vdpasim;
struct device *dev;
@@ -213,6 +219,9 @@ struct vdpasim *vdpasim_create(struct vdpasim_dev_attr
*dev_attr,
else
ops = &vdpasim_config_ops;
+ if (unlikely(!iotlb_persist))
+ ops->reset_map = NULL;
+
vdpa = __vdpa_alloc_device(NULL, ops,
dev_attr->ngroups, dev_attr->nas,
dev_attr->alloc_size,
@@ -259,8 +268,14 @@ struct vdpasim *vdpasim_create(struct vdpasim_dev_attr
*dev_attr,
if (!vdpasim->iommu_pt)
goto err_iommu;
- for (i = 0; i < vdpasim->dev_attr.nas; i++)
+ for (i = 0; i < vdpasim->dev_attr.nas; i++) {
vhost_iotlb_init(&vdpasim->iommu[i], max_iotlb_entries, 0);
+ if (likely(iotlb_persist)) {
+ vhost_iotlb_add_range(&vdpasim->iommu[i], 0, ULONG_MAX,
0,
+ VHOST_MAP_RW);
+ vdpasim->iommu_pt[i] = true;
+ }
+ }
for (i = 0; i < dev_attr->nvqs; i++)
vringh_set_iotlb(&vdpasim->vqs[i].vring, &vdpasim->iommu[0],
@@ -637,6 +652,25 @@ static int vdpasim_set_map(struct vdpa_device *vdpa,
unsigned int asid,
return ret;
}
+static int vdpasim_reset_map(struct vdpa_device *vdpa, unsigned int asid)
+{
+ struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
+
+ if (asid >= vdpasim->dev_attr.nas)
+ return -EINVAL;
+
+ spin_lock(&vdpasim->iommu_lock);
+ if (vdpasim->iommu_pt[asid])
+ goto out;
+ vhost_iotlb_reset(&vdpasim->iommu[asid]);
+ vhost_iotlb_add_range(&vdpasim->iommu[asid], 0, ULONG_MAX,
+ 0, VHOST_MAP_RW);
+ vdpasim->iommu_pt[asid] = true;
+out:
+ spin_unlock(&vdpasim->iommu_lock);
+ return 0;
+}
+
static int vdpasim_bind_mm(struct vdpa_device *vdpa, struct mm_struct *mm)
{
struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
@@ -726,7 +760,7 @@ static void vdpasim_free(struct vdpa_device *vdpa)
kfree(vdpasim->config);
}
-static const struct vdpa_config_ops vdpasim_config_ops = {
+static struct vdpa_config_ops vdpasim_config_ops = {
.set_vq_address = vdpasim_set_vq_address,
.set_vq_num = vdpasim_set_vq_num,
.kick_vq = vdpasim_kick_vq,
@@ -759,12 +793,13 @@ static const struct vdpa_config_ops vdpasim_config_ops = {
.set_group_asid = vdpasim_set_group_asid,
.dma_map = vdpasim_dma_map,
.dma_unmap = vdpasim_dma_unmap,
+ .reset_map = vdpasim_reset_map,
.bind_mm = vdpasim_bind_mm,
.unbind_mm = vdpasim_unbind_mm,
.free = vdpasim_free,
};
-static const struct vdpa_config_ops vdpasim_batch_config_ops = {
+static struct vdpa_config_ops vdpasim_batch_config_ops = {
.set_vq_address = vdpasim_set_vq_address,
.set_vq_num = vdpasim_set_vq_num,
.kick_vq = vdpasim_kick_vq,
@@ -796,6 +831,7 @@ static const struct vdpa_config_ops
vdpasim_batch_config_ops = {
.get_iova_range = vdpasim_get_iova_range,
.set_group_asid = vdpasim_set_group_asid,
.set_map = vdpasim_set_map,
+ .reset_map = vdpasim_reset_map,
.bind_mm = vdpasim_bind_mm,
.unbind_mm = vdpasim_unbind_mm,
.free = vdpasim_free,
--
2.39.3
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