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vdpa: move iova tree to the shared struct
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Next patches will register the vhost_vdpa memory listener while the VM
is migrating at the destination, so we can map the memory to the device
before stopping the VM at the source.  The main goal is to reduce the
downtime.

However, the destination QEMU is unaware of which vhost_vdpa device will
register its memory_listener.  If the source guest has CVQ enabled, it
will be the CVQ device.  Otherwise, it  will be the first one.

Move the iova tree to VhostVDPAShared so all vhost_vdpa can use it,
rather than always in the first or last vhost_vdpa.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20231221174322.3130442-3-eperezma@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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@eugpermar @mstsirkin
eugpermar authored and mstsirkin committed Dec 26, 2023
1 parent 8c5e980 commit 5edb02e
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Showing 3 changed files with 35 additions and 42 deletions.
19 changes: 10 additions & 9 deletions hw/virtio/vhost-vdpa.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -358,7 +358,7 @@ static void vhost_vdpa_listener_region_add(MemoryListener *listener,
mem_region.size = int128_get64(llsize) - 1,
mem_region.perm = IOMMU_ACCESS_FLAG(true, section->readonly),

r = vhost_iova_tree_map_alloc(v->iova_tree, &mem_region);
r = vhost_iova_tree_map_alloc(v->shared->iova_tree, &mem_region);
if (unlikely(r != IOVA_OK)) {
error_report("Can't allocate a mapping (%d)", r);
goto fail;
Expand All @@ -379,7 +379,7 @@ static void vhost_vdpa_listener_region_add(MemoryListener *listener,

fail_map:
if (v->shadow_data) {
vhost_iova_tree_remove(v->iova_tree, mem_region);
vhost_iova_tree_remove(v->shared->iova_tree, mem_region);
}

fail:
Expand Down Expand Up @@ -441,13 +441,13 @@ static void vhost_vdpa_listener_region_del(MemoryListener *listener,
.size = int128_get64(llsize) - 1,
};

result = vhost_iova_tree_find_iova(v->iova_tree, &mem_region);
result = vhost_iova_tree_find_iova(v->shared->iova_tree, &mem_region);
if (!result) {
/* The memory listener map wasn't mapped */
return;
}
iova = result->iova;
vhost_iova_tree_remove(v->iova_tree, *result);
vhost_iova_tree_remove(v->shared->iova_tree, *result);
}
vhost_vdpa_iotlb_batch_begin_once(v);
/*
Expand Down Expand Up @@ -1063,7 +1063,8 @@ static void vhost_vdpa_svq_unmap_ring(struct vhost_vdpa *v, hwaddr addr)
const DMAMap needle = {
.translated_addr = addr,
};
const DMAMap *result = vhost_iova_tree_find_iova(v->iova_tree, &needle);
const DMAMap *result = vhost_iova_tree_find_iova(v->shared->iova_tree,
&needle);
hwaddr size;
int r;

Expand All @@ -1079,7 +1080,7 @@ static void vhost_vdpa_svq_unmap_ring(struct vhost_vdpa *v, hwaddr addr)
return;
}

vhost_iova_tree_remove(v->iova_tree, *result);
vhost_iova_tree_remove(v->shared->iova_tree, *result);
}

static void vhost_vdpa_svq_unmap_rings(struct vhost_dev *dev,
Expand Down Expand Up @@ -1107,7 +1108,7 @@ static bool vhost_vdpa_svq_map_ring(struct vhost_vdpa *v, DMAMap *needle,
{
int r;

r = vhost_iova_tree_map_alloc(v->iova_tree, needle);
r = vhost_iova_tree_map_alloc(v->shared->iova_tree, needle);
if (unlikely(r != IOVA_OK)) {
error_setg(errp, "Cannot allocate iova (%d)", r);
return false;
Expand All @@ -1119,7 +1120,7 @@ static bool vhost_vdpa_svq_map_ring(struct vhost_vdpa *v, DMAMap *needle,
needle->perm == IOMMU_RO);
if (unlikely(r != 0)) {
error_setg_errno(errp, -r, "Cannot map region to device");
vhost_iova_tree_remove(v->iova_tree, *needle);
vhost_iova_tree_remove(v->shared->iova_tree, *needle);
}

return r == 0;
Expand Down Expand Up @@ -1220,7 +1221,7 @@ static bool vhost_vdpa_svqs_start(struct vhost_dev *dev)
goto err;
}

vhost_svq_start(svq, dev->vdev, vq, v->iova_tree);
vhost_svq_start(svq, dev->vdev, vq, v->shared->iova_tree);
ok = vhost_vdpa_svq_map_rings(dev, svq, &addr, &err);
if (unlikely(!ok)) {
goto err_map;
Expand Down
4 changes: 2 additions & 2 deletions include/hw/virtio/vhost-vdpa.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,8 @@ typedef struct VhostVDPAHostNotifier {

/* Info shared by all vhost_vdpa device models */
typedef struct vhost_vdpa_shared {
/* IOVA mapping used by the Shadow Virtqueue */
VhostIOVATree *iova_tree;
} VhostVDPAShared;

typedef struct vhost_vdpa {
Expand All @@ -48,8 +50,6 @@ typedef struct vhost_vdpa {
bool shadow_data;
/* Device suspended successfully */
bool suspended;
/* IOVA mapping used by the Shadow Virtqueue */
VhostIOVATree *iova_tree;
VhostVDPAShared *shared;
GPtrArray *shadow_vqs;
const VhostShadowVirtqueueOps *shadow_vq_ops;
Expand Down
54 changes: 23 additions & 31 deletions net/vhost-vdpa.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -354,8 +354,8 @@ static void vhost_vdpa_net_data_start_first(VhostVDPAState *s)
migration_add_notifier(&s->migration_state,
vdpa_net_migration_state_notifier);
if (v->shadow_vqs_enabled) {
v->iova_tree = vhost_iova_tree_new(v->iova_range.first,
v->iova_range.last);
v->shared->iova_tree = vhost_iova_tree_new(v->iova_range.first,
v->iova_range.last);
}
}

Expand All @@ -380,11 +380,6 @@ static int vhost_vdpa_net_data_start(NetClientState *nc)
return 0;
}

if (v->shadow_vqs_enabled) {
VhostVDPAState *s0 = vhost_vdpa_net_first_nc_vdpa(s);
v->iova_tree = s0->vhost_vdpa.iova_tree;
}

return 0;
}

Expand Down Expand Up @@ -417,9 +412,8 @@ static void vhost_vdpa_net_client_stop(NetClientState *nc)

dev = s->vhost_vdpa.dev;
if (dev->vq_index + dev->nvqs == dev->vq_index_end) {
g_clear_pointer(&s->vhost_vdpa.iova_tree, vhost_iova_tree_delete);
} else {
s->vhost_vdpa.iova_tree = NULL;
g_clear_pointer(&s->vhost_vdpa.shared->iova_tree,
vhost_iova_tree_delete);
}
}

Expand Down Expand Up @@ -474,7 +468,7 @@ static int vhost_vdpa_set_address_space_id(struct vhost_vdpa *v,

static void vhost_vdpa_cvq_unmap_buf(struct vhost_vdpa *v, void *addr)
{
VhostIOVATree *tree = v->iova_tree;
VhostIOVATree *tree = v->shared->iova_tree;
DMAMap needle = {
/*
* No need to specify size or to look for more translations since
Expand Down Expand Up @@ -508,7 +502,7 @@ static int vhost_vdpa_cvq_map_buf(struct vhost_vdpa *v, void *buf, size_t size,
map.translated_addr = (hwaddr)(uintptr_t)buf;
map.size = size - 1;
map.perm = write ? IOMMU_RW : IOMMU_RO,
r = vhost_iova_tree_map_alloc(v->iova_tree, &map);
r = vhost_iova_tree_map_alloc(v->shared->iova_tree, &map);
if (unlikely(r != IOVA_OK)) {
error_report("Cannot map injected element");
return r;
Expand All @@ -523,7 +517,7 @@ static int vhost_vdpa_cvq_map_buf(struct vhost_vdpa *v, void *buf, size_t size,
return 0;

dma_map_err:
vhost_iova_tree_remove(v->iova_tree, map);
vhost_iova_tree_remove(v->shared->iova_tree, map);
return r;
}

Expand Down Expand Up @@ -583,24 +577,22 @@ static int vhost_vdpa_net_cvq_start(NetClientState *nc)
return 0;
}

if (s0->vhost_vdpa.iova_tree) {
/*
* SVQ is already configured for all virtqueues. Reuse IOVA tree for
* simplicity, whether CVQ shares ASID with guest or not, because:
* - Memory listener need access to guest's memory addresses allocated
* in the IOVA tree.
* - There should be plenty of IOVA address space for both ASID not to
* worry about collisions between them. Guest's translations are
* still validated with virtio virtqueue_pop so there is no risk for
* the guest to access memory that it shouldn't.
*
* To allocate a iova tree per ASID is doable but it complicates the
* code and it is not worth it for the moment.
*/
v->iova_tree = s0->vhost_vdpa.iova_tree;
} else {
v->iova_tree = vhost_iova_tree_new(v->iova_range.first,
v->iova_range.last);
/*
* If other vhost_vdpa already have an iova_tree, reuse it for simplicity,
* whether CVQ shares ASID with guest or not, because:
* - Memory listener need access to guest's memory addresses allocated in
* the IOVA tree.
* - There should be plenty of IOVA address space for both ASID not to
* worry about collisions between them. Guest's translations are still
* validated with virtio virtqueue_pop so there is no risk for the guest
* to access memory that it shouldn't.
*
* To allocate a iova tree per ASID is doable but it complicates the code
* and it is not worth it for the moment.
*/
if (!v->shared->iova_tree) {
v->shared->iova_tree = vhost_iova_tree_new(v->iova_range.first,
v->iova_range.last);
}

r = vhost_vdpa_cvq_map_buf(&s->vhost_vdpa, s->cvq_cmd_out_buffer,
Expand Down

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