[PATCH 21/21] vdpasim: control virtqueue support

From: Jason Wang
Date: Wed Dec 16 2020 - 01:53:35 EST

This patch introduces the control virtqueue support for vDPA
simulator. This is a requirement for supporting advanced features like
multiqueue.

A requirement for control virtqueue is to isolate its memory access
from the rx/tx virtqueues. This is because when using vDPA device
for VM, the control virqueue is not directly assigned to VM. Userspace
(Qemu) will present a shadow control virtqueue to control for
recording the device states.

The isolation is done via the virtqueue groups and ASID support in
vDPA through vhost-vdpa. The simulator is extended to have:

1) three virtqueues: RXVQ, TXVQ and CVQ (control virtqueue)
2) two virtqueue groups: group 0 contains RXVQ and TXVQ; group 1
contains CVQ
3) two address spaces and the simulator simply implements the address
spaces by mapping it 1:1 to IOTLB.

For the VM use cases, userspace(Qemu) may set AS 0 to group 0 and AS 1
to group 1. So we have:

1) The IOTLB for virtqueue group 0 contains the mappings of guest, so
RX and TX can be assigned to guest directly.
2) The IOTLB for virtqueue group 1 contains the mappings of CVQ which
is the buffers that allocated and managed by VMM only. So CVQ of
vhost-vdpa is visible to VMM only. And Guest can not access the CVQ
of vhost-vdpa.

For the other use cases, since AS 0 is associated to all virtqueue
groups by default. All virtqueues share the same mapping by default.

To demonstrate the function, VIRITO_NET_F_CTRL_MACADDR is
implemented in the simulator for the driver to set mac address.

Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
---
drivers/vdpa/vdpa_sim/vdpa_sim.c | 189 +++++++++++++++++++++++++++----
1 file changed, 166 insertions(+), 23 deletions(-)

diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
index fe90a783bde4..0fd06ac491cd 100644
--- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
@@ -60,14 +60,18 @@ struct vdpasim_virtqueue {
#define VDPASIM_QUEUE_MAX 256
#define VDPASIM_DEVICE_ID 0x1
#define VDPASIM_VENDOR_ID 0
-#define VDPASIM_VQ_NUM 0x2
+#define VDPASIM_VQ_NUM 0x3
+#define VDPASIM_AS_NUM 0x2
+#define VDPASIM_GROUP_NUM 0x2
#define VDPASIM_NAME "vdpasim-netdev"

static u64 vdpasim_features = (1ULL << VIRTIO_F_ANY_LAYOUT) |
(1ULL << VIRTIO_F_VERSION_1) |
(1ULL << VIRTIO_F_ACCESS_PLATFORM) |
+ (1ULL << VIRTIO_NET_F_MTU) |
(1ULL << VIRTIO_NET_F_MAC) |
- (1ULL << VIRTIO_NET_F_MTU);
+ (1ULL << VIRTIO_NET_F_CTRL_VQ) |
+ (1ULL << VIRTIO_NET_F_CTRL_MAC_ADDR);

/* State of each vdpasim device */
struct vdpasim {
@@ -147,11 +151,17 @@ static void vdpasim_reset(struct vdpasim *vdpasim)
{
int i;

- for (i = 0; i < VDPASIM_VQ_NUM; i++)
+ spin_lock(&vdpasim->iommu_lock);
+
+ for (i = 0; i < VDPASIM_VQ_NUM; i++) {
vdpasim_vq_reset(&vdpasim->vqs[i]);
+ vringh_set_iotlb(&vdpasim->vqs[i].vring,
+ &vdpasim->iommu[0]);
+ }

- spin_lock(&vdpasim->iommu_lock);
- vhost_iotlb_reset(vdpasim->iommu);
+ for (i = 0; i < VDPASIM_AS_NUM; i++) {
+ vhost_iotlb_reset(&vdpasim->iommu[i]);
+ }
spin_unlock(&vdpasim->iommu_lock);

vdpasim->features = 0;
@@ -191,6 +201,81 @@ static bool receive_filter(struct vdpasim *vdpasim, size_t len)
return false;
}

+virtio_net_ctrl_ack vdpasim_handle_ctrl_mac(struct vdpasim *vdpasim,
+ u8 cmd)
+{
+ struct vdpasim_virtqueue *cvq = &vdpasim->vqs[2];
+ virtio_net_ctrl_ack status = VIRTIO_NET_ERR;
+ size_t read;
+
+ switch (cmd) {
+ case VIRTIO_NET_CTRL_MAC_ADDR_SET:
+ read = vringh_iov_pull_iotlb(&cvq->vring, &cvq->in_iov,
+ (void *)vdpasim->config.mac,
+ ETH_ALEN);
+ if (read == ETH_ALEN)
+ status = VIRTIO_NET_OK;
+ break;
+ default:
+ break;
+ }
+
+ return status;
+}
+
+static void vdpasim_handle_cvq(struct vdpasim *vdpasim)
+{
+ struct vdpasim_virtqueue *cvq = &vdpasim->vqs[2];
+ virtio_net_ctrl_ack status = VIRTIO_NET_ERR;
+ struct virtio_net_ctrl_hdr ctrl;
+ size_t read, write;
+ int err;
+
+ if (!(vdpasim->features & (1ULL << VIRTIO_NET_F_CTRL_VQ)))
+ return;
+
+ if (!cvq->ready)
+ return;
+
+ while (true) {
+ err = vringh_getdesc_iotlb(&cvq->vring, &cvq->in_iov,
+ &cvq->out_iov,
+ &cvq->head, GFP_ATOMIC);
+ if (err <= 0)
+ break;
+
+ read = vringh_iov_pull_iotlb(&cvq->vring, &cvq->in_iov, &ctrl,
+ sizeof(ctrl));
+ if (read != sizeof(ctrl))
+ break;
+
+ switch (ctrl.class) {
+ case VIRTIO_NET_CTRL_MAC:
+ status = vdpasim_handle_ctrl_mac(vdpasim, ctrl.cmd);
+ break;
+ default:
+ break;
+ }
+
+ /* Make sure data is wrote before advancing index */
+ smp_wmb();
+
+ write = vringh_iov_push_iotlb(&cvq->vring, &cvq->out_iov,
+ &status, sizeof (status));
+ vringh_complete_iotlb(&cvq->vring, cvq->head, write);
+ vringh_kiov_cleanup(&cvq->in_iov);
+ vringh_kiov_cleanup(&cvq->out_iov);
+
+ /* Make sure used is visible before rasing the interrupt. */
+ smp_wmb();
+
+ local_bh_disable();
+ if (cvq->cb)
+ cvq->cb(cvq->private);
+ local_bh_enable();
+ }
+}
+
static void vdpasim_work(struct work_struct *work)
{
struct vdpasim *vdpasim = container_of(work, struct
@@ -276,7 +361,7 @@ static dma_addr_t vdpasim_map_page(struct device *dev, struct page *page,
unsigned long attrs)
{
struct vdpasim *vdpasim = dev_to_sim(dev);
- struct vhost_iotlb *iommu = vdpasim->iommu;
+ struct vhost_iotlb *iommu = &vdpasim->iommu[0];
u64 pa = (page_to_pfn(page) << PAGE_SHIFT) + offset;
int ret, perm = dir_to_perm(dir);

@@ -301,7 +386,7 @@ static void vdpasim_unmap_page(struct device *dev, dma_addr_t dma_addr,
unsigned long attrs)
{
struct vdpasim *vdpasim = dev_to_sim(dev);
- struct vhost_iotlb *iommu = vdpasim->iommu;
+ struct vhost_iotlb *iommu = &vdpasim->iommu[0];

spin_lock(&vdpasim->iommu_lock);
vhost_iotlb_del_range(iommu, (u64)dma_addr,
@@ -314,7 +399,7 @@ static void *vdpasim_alloc_coherent(struct device *dev, size_t size,
unsigned long attrs)
{
struct vdpasim *vdpasim = dev_to_sim(dev);
- struct vhost_iotlb *iommu = vdpasim->iommu;
+ struct vhost_iotlb *iommu = &vdpasim->iommu[0];
void *addr = kmalloc(size, flag);
int ret;

@@ -344,7 +429,7 @@ static void vdpasim_free_coherent(struct device *dev, size_t size,
unsigned long attrs)
{
struct vdpasim *vdpasim = dev_to_sim(dev);
- struct vhost_iotlb *iommu = vdpasim->iommu;
+ struct vhost_iotlb *iommu = &vdpasim->iommu[0];

spin_lock(&vdpasim->iommu_lock);
vhost_iotlb_del_range(iommu, (u64)dma_addr,
@@ -370,14 +455,17 @@ static struct vdpasim *vdpasim_create(void)
struct vdpasim *vdpasim;
struct device *dev;
int ret = -ENOMEM;
+ int i;

if (batch_mapping)
ops = &vdpasim_net_batch_config_ops;
else
ops = &vdpasim_net_config_ops;

+ /* 3 virtqueues, 2 address spaces, 2 virtqueue groups */
vdpasim = vdpa_alloc_device(struct vdpasim, vdpa, NULL, ops,
- VDPASIM_VQ_NUM, 1, 1);
+ VDPASIM_VQ_NUM, VDPASIM_AS_NUM,
+ VDPASIM_GROUP_NUM);
if (!vdpasim)
goto err_alloc;

@@ -391,10 +479,14 @@ static struct vdpasim *vdpasim_create(void)
goto err_iommu;
set_dma_ops(dev, &vdpasim_dma_ops);

- vdpasim->iommu = vhost_iotlb_alloc(2048, 0);
+ vdpasim->iommu = kmalloc_array(VDPASIM_AS_NUM,
+ sizeof(*vdpasim->iommu), GFP_KERNEL);
if (!vdpasim->iommu)
goto err_iommu;

+ for (i = 0; i < VDPASIM_AS_NUM; i++)
+ vhost_iotlb_init(&vdpasim->iommu[i], 0, 0);
+
vdpasim->buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (!vdpasim->buffer)
goto err_iommu;
@@ -409,8 +501,9 @@ static struct vdpasim *vdpasim_create(void)
eth_random_addr(vdpasim->config.mac);
}

- vringh_set_iotlb(&vdpasim->vqs[0].vring, vdpasim->iommu);
- vringh_set_iotlb(&vdpasim->vqs[1].vring, vdpasim->iommu);
+ /* Make sure that default ASID is zero */
+ for (i = 0; i < VDPASIM_VQ_NUM; i++)
+ vringh_set_iotlb(&vdpasim->vqs[i].vring, &vdpasim->iommu[0]);

vdpasim->vdpa.dma_dev = dev;
ret = vdpa_register_device(&vdpasim->vdpa);
@@ -452,7 +545,14 @@ static void vdpasim_kick_vq(struct vdpa_device *vdpa, u16 idx)
struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
struct vdpasim_virtqueue *vq = &vdpasim->vqs[idx];

- if (vq->ready)
+ if (idx == 2) {
+ /* Kernel virtio driver will do busy waiting for the
+ * result, so we can't handle cvq in the workqueue.
+ */
+ spin_lock(&vdpasim->lock);
+ vdpasim_handle_cvq(vdpasim);
+ spin_unlock(&vdpasim->lock);
+ } else if (vq->ready)
schedule_work(&vdpasim->work);
}

@@ -518,7 +618,11 @@ static u32 vdpasim_get_vq_align(struct vdpa_device *vdpa)

static u32 vdpasim_get_vq_group(struct vdpa_device *vdpa, u16 idx)
{
- return 0;
+ /* RX and TX belongs to group 0, CVQ belongs to group 1 */
+ if (idx == 2)
+ return 1;
+ else
+ return 0;
}

static u64 vdpasim_get_features(struct vdpa_device *vdpa)
@@ -624,20 +728,52 @@ static struct vdpa_iova_range vdpasim_get_iova_range(struct vdpa_device *vdpa)
return range;
}

+int vdpasim_set_group_asid(struct vdpa_device *vdpa, unsigned int group,
+ unsigned int asid)
+{
+ struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
+ struct vhost_iotlb *iommu;
+ int i;
+
+ if (group > VDPASIM_GROUP_NUM)
+ return -EINVAL;
+
+ if (asid > VDPASIM_AS_NUM)
+ return -EINVAL;
+
+ iommu = &vdpasim->iommu[asid];
+
+ spin_lock(&vdpasim->lock);
+
+ for (i = 0; i < VDPASIM_VQ_NUM; i++)
+ if (vdpasim_get_vq_group(vdpa, i) == group)
+ vringh_set_iotlb(&vdpasim->vqs[i].vring, iommu);
+
+ spin_unlock(&vdpasim->lock);
+
+ return 0;
+}
+
static int vdpasim_set_map(struct vdpa_device *vdpa, unsigned int asid,
struct vhost_iotlb *iotlb)
{
struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
struct vhost_iotlb_map *map;
+ struct vhost_iotlb *iommu;
u64 start = 0ULL, last = 0ULL - 1;
int ret;

+ if (asid >= VDPASIM_AS_NUM)
+ return -EINVAL;
+
spin_lock(&vdpasim->iommu_lock);
- vhost_iotlb_reset(vdpasim->iommu);
+
+ iommu = &vdpasim->iommu[asid];
+ vhost_iotlb_reset(iommu);

for (map = vhost_iotlb_itree_first(iotlb, start, last); map;
map = vhost_iotlb_itree_next(map, start, last)) {
- ret = vhost_iotlb_add_range(vdpasim->iommu, map->start,
+ ret = vhost_iotlb_add_range(iommu, map->start,
map->last, map->addr, map->perm);
if (ret)
goto err;
@@ -646,7 +782,7 @@ static int vdpasim_set_map(struct vdpa_device *vdpa, unsigned int asid,
return 0;

err:
- vhost_iotlb_reset(vdpasim->iommu);
+ vhost_iotlb_reset(iommu);
spin_unlock(&vdpasim->iommu_lock);
return ret;
}
@@ -658,9 +794,12 @@ static int vdpasim_dma_map(struct vdpa_device *vdpa, unsigned int asid,
struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
int ret;

+ if (asid >= VDPASIM_AS_NUM)
+ return -EINVAL;
+
spin_lock(&vdpasim->iommu_lock);
- ret = vhost_iotlb_add_range(vdpasim->iommu, iova, iova + size - 1, pa,
- perm);
+ ret = vhost_iotlb_add_range(&vdpasim->iommu[asid], iova,
+ iova + size - 1, pa, perm);
spin_unlock(&vdpasim->iommu_lock);

return ret;
@@ -671,8 +810,11 @@ static int vdpasim_dma_unmap(struct vdpa_device *vdpa, unsigned int asid,
{
struct vdpasim *vdpasim = vdpa_to_sim(vdpa);

+ if (asid >= VDPASIM_AS_NUM)
+ return -EINVAL;
+
spin_lock(&vdpasim->iommu_lock);
- vhost_iotlb_del_range(vdpasim->iommu, iova, iova + size - 1);
+ vhost_iotlb_del_range(&vdpasim->iommu[asid], iova, iova + size - 1);
spin_unlock(&vdpasim->iommu_lock);

return 0;
@@ -684,8 +826,7 @@ static void vdpasim_free(struct vdpa_device *vdpa)

cancel_work_sync(&vdpasim->work);
kfree(vdpasim->buffer);
- if (vdpasim->iommu)
- vhost_iotlb_free(vdpasim->iommu);
+ vhost_iotlb_free(vdpasim->iommu);
}

static const struct vdpa_config_ops vdpasim_net_config_ops = {
@@ -711,6 +852,7 @@ static const struct vdpa_config_ops vdpasim_net_config_ops = {
.set_config = vdpasim_set_config,
.get_generation = vdpasim_get_generation,
.get_iova_range = vdpasim_get_iova_range,
+ .set_group_asid = vdpasim_set_group_asid,
.dma_map = vdpasim_dma_map,
.dma_unmap = vdpasim_dma_unmap,
.free = vdpasim_free,
@@ -739,6 +881,7 @@ static const struct vdpa_config_ops vdpasim_net_batch_config_ops = {
.set_config = vdpasim_set_config,
.get_generation = vdpasim_get_generation,
.get_iova_range = vdpasim_get_iova_range,
+ .set_group_asid = vdpasim_set_group_asid,
.set_map = vdpasim_set_map,
.free = vdpasim_free,
};
--
2.25.1