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vhost/vsock: add IOTLB API support

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This patch enables the IOTLB API support for vhost-vsock devices,
allowing the userspace to emulate an IOMMU for the guest.

These changes were made following vhost-net, in details this patch:
- exposes VIRTIO_F_ACCESS_PLATFORM feature and inits the iotlb
  device if the feature is acked
- implements VHOST_GET_BACKEND_FEATURES and
  VHOST_SET_BACKEND_FEATURES ioctls
- calls vq_meta_prefetch() before vq processing to prefetch vq
  metadata address in IOTLB
- provides .read_iter, .write_iter, and .poll callbacks for the
  chardev; they are used by the userspace to exchange IOTLB messages

This patch was tested specifying "intel_iommu=strict" in the guest
kernel command line. I used QEMU with a patch applied [1] to fix a
simple issue (that patch was merged in QEMU v5.2.0):
    $ qemu -M q35,accel=kvm,kernel-irqchip=split \
           -drive file=fedora.qcow2,format=qcow2,if=virtio \
           -device intel-iommu,intremap=on,device-iotlb=on \
           -device vhost-vsock-pci,guest-cid=3,iommu_platform=on,ats=on

[1] https://lists.gnu.org/archive/html/qemu-devel/2020-10/msg09077.html

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://lore.kernel.org/r/20201223143638.123417-1-sgarzare@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
This commit is contained in:
Stefano Garzarella 2020-12-23 15:36:38 +01:00 committed by Michael S. Tsirkin
parent 418eddef05
commit e13a6915a0
1 changed files with 65 additions and 3 deletions
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68
drivers/vhost/vsock.c
View File

@ -30,7 +30,12 @@
#define VHOST_VSOCK_PKT_WEIGHT 256
enum {
VHOST_VSOCK_FEATURES = VHOST_FEATURES,
VHOST_VSOCK_FEATURES = VHOST_FEATURES |
(1ULL << VIRTIO_F_ACCESS_PLATFORM)
};
enum {
VHOST_VSOCK_BACKEND_FEATURES = (1ULL << VHOST_BACKEND_F_IOTLB_MSG_V2)
};
/* Used to track all the vhost_vsock instances on the system. */
@ -94,6 +99,9 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
if (!vhost_vq_get_backend(vq))
goto out;
if (!vq_meta_prefetch(vq))
goto out;
/* Avoid further vmexits, we're already processing the virtqueue */
vhost_disable_notify(&vsock->dev, vq);
@ -449,6 +457,9 @@ static void vhost_vsock_handle_tx_kick(struct vhost_work *work)
if (!vhost_vq_get_backend(vq))
goto out;
if (!vq_meta_prefetch(vq))
goto out;
vhost_disable_notify(&vsock->dev, vq);
do {
u32 len;
@ -766,8 +777,12 @@ static int vhost_vsock_set_features(struct vhost_vsock *vsock, u64 features)
mutex_lock(&vsock->dev.mutex);
if ((features & (1 << VHOST_F_LOG_ALL)) &&
!vhost_log_access_ok(&vsock->dev)) {
mutex_unlock(&vsock->dev.mutex);
return -EFAULT;
goto err;
}
if ((features & (1ULL << VIRTIO_F_ACCESS_PLATFORM))) {
if (vhost_init_device_iotlb(&vsock->dev, true))
goto err;
}
for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) {
@ -778,6 +793,10 @@ static int vhost_vsock_set_features(struct vhost_vsock *vsock, u64 features)
}
mutex_unlock(&vsock->dev.mutex);
return 0;
err:
mutex_unlock(&vsock->dev.mutex);
return -EFAULT;
}
static long vhost_vsock_dev_ioctl(struct file *f, unsigned int ioctl,
@ -811,6 +830,18 @@ static long vhost_vsock_dev_ioctl(struct file *f, unsigned int ioctl,
if (copy_from_user(&features, argp, sizeof(features)))
return -EFAULT;
return vhost_vsock_set_features(vsock, features);
case VHOST_GET_BACKEND_FEATURES:
features = VHOST_VSOCK_BACKEND_FEATURES;
if (copy_to_user(argp, &features, sizeof(features)))
return -EFAULT;
return 0;
case VHOST_SET_BACKEND_FEATURES:
if (copy_from_user(&features, argp, sizeof(features)))
return -EFAULT;
if (features & ~VHOST_VSOCK_BACKEND_FEATURES)
return -EOPNOTSUPP;
vhost_set_backend_features(&vsock->dev, features);
return 0;
default:
mutex_lock(&vsock->dev.mutex);
r = vhost_dev_ioctl(&vsock->dev, ioctl, argp);
@ -823,6 +854,34 @@ static long vhost_vsock_dev_ioctl(struct file *f, unsigned int ioctl,
}
}
static ssize_t vhost_vsock_chr_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
struct file *file = iocb->ki_filp;
struct vhost_vsock *vsock = file->private_data;
struct vhost_dev *dev = &vsock->dev;
int noblock = file->f_flags & O_NONBLOCK;
return vhost_chr_read_iter(dev, to, noblock);
}
static ssize_t vhost_vsock_chr_write_iter(struct kiocb *iocb,
struct iov_iter *from)
{
struct file *file = iocb->ki_filp;
struct vhost_vsock *vsock = file->private_data;
struct vhost_dev *dev = &vsock->dev;
return vhost_chr_write_iter(dev, from);
}
static __poll_t vhost_vsock_chr_poll(struct file *file, poll_table *wait)
{
struct vhost_vsock *vsock = file->private_data;
struct vhost_dev *dev = &vsock->dev;
return vhost_chr_poll(file, dev, wait);
}
static const struct file_operations vhost_vsock_fops = {
.owner = THIS_MODULE,
.open = vhost_vsock_dev_open,
@ -830,6 +889,9 @@ static const struct file_operations vhost_vsock_fops = {
.llseek = noop_llseek,
.unlocked_ioctl = vhost_vsock_dev_ioctl,
.compat_ioctl = compat_ptr_ioctl,
.read_iter = vhost_vsock_chr_read_iter,
.write_iter = vhost_vsock_chr_write_iter,
.poll = vhost_vsock_chr_poll,
};
static struct miscdevice vhost_vsock_misc = {