vdpa_sim: implement .reset_map support

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.

Additionally, implement .compat_reset to cater for older userspace,
which may wish to see mapping to be cleared during reset.

Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com>
Tested-by: Stefano Garzarella <sgarzare@redhat.com>
Message-Id: <1697880319-4937-8-git-send-email-si-wei.liu@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>

diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
index 76d41058add9a8a5f45edb405ed822efba6de67f..be2925d0d28368e8959a9696f2d1c92ba4eb7fd8 100644 (file)
--- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
@@ -139,7 +139,7 @@ static void vdpasim_vq_reset(struct vdpasim *vdpasim,
        vq->vring.notify = NULL;
 }
 
-static void vdpasim_do_reset(struct vdpasim *vdpasim)
+static void vdpasim_do_reset(struct vdpasim *vdpasim, u32 flags)
 {
        int i;
 
@@ -151,11 +151,13 @@ 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 (flags & VDPA_RESET_F_CLEAN_MAP) {
+               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;
@@ -259,8 +261,12 @@ 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);
+               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],
@@ -480,18 +486,23 @@ static void vdpasim_set_status(struct vdpa_device *vdpa, u8 status)
        mutex_unlock(&vdpasim->mutex);
 }
 
-static int vdpasim_reset(struct vdpa_device *vdpa)
+static int vdpasim_compat_reset(struct vdpa_device *vdpa, u32 flags)
 {
        struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
 
        mutex_lock(&vdpasim->mutex);
        vdpasim->status = 0;
-       vdpasim_do_reset(vdpasim);
+       vdpasim_do_reset(vdpasim, flags);
        mutex_unlock(&vdpasim->mutex);
 
        return 0;
 }
 
+static int vdpasim_reset(struct vdpa_device *vdpa)
+{
+       return vdpasim_compat_reset(vdpa, 0);
+}
+
 static int vdpasim_suspend(struct vdpa_device *vdpa)
 {
        struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
@@ -637,6 +648,25 @@ err:
        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);
@@ -749,6 +779,7 @@ static const struct vdpa_config_ops vdpasim_config_ops = {
        .get_status             = vdpasim_get_status,
        .set_status             = vdpasim_set_status,
        .reset                  = vdpasim_reset,
+       .compat_reset           = vdpasim_compat_reset,
        .suspend                = vdpasim_suspend,
        .resume                 = vdpasim_resume,
        .get_config_size        = vdpasim_get_config_size,
@@ -759,6 +790,7 @@ 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,
@@ -787,6 +819,7 @@ static const struct vdpa_config_ops vdpasim_batch_config_ops = {
        .get_status             = vdpasim_get_status,
        .set_status             = vdpasim_set_status,
        .reset                  = vdpasim_reset,
+       .compat_reset           = vdpasim_compat_reset,
        .suspend                = vdpasim_suspend,
        .resume                 = vdpasim_resume,
        .get_config_size        = vdpasim_get_config_size,
@@ -796,6 +829,7 @@ 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,