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[v2] vhost/vsock: add IOTLB API support

Message ID 20201223143638.123417-1-sgarzare@redhat.com (mailing list archive)
State Not Applicable
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Series [v2] vhost/vsock: add IOTLB API support | expand

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netdev/tree_selection success Not a local patch

Commit Message

Stefano Garzarella Dec. 23, 2020, 2:36 p.m. UTC 
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>
---

The patch is the same of v1, but I re-tested it with:
- QEMU v5.2.0-551-ga05f8ecd88
- Linux 5.9.15 (host)
- Linux 5.9.15 and 5.10.0 (guest)
Now, enabling 'ats' it works well, there are just a few simple changes.

v1: https://www.spinics.net/lists/kernel/msg3716022.html
v2:
- updated commit message about QEMU version and string used to test
- rebased on mst/vhost branch

Thanks,
Stefano
---
 drivers/vhost/vsock.c | 68 +++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 65 insertions(+), 3 deletions(-)

Comments

Jason Wang Dec. 24, 2020, 2:11 a.m. UTC | #1 
On 2020/12/23 下午10:36, Stefano Garzarella wrote:
> 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>


Acked-by: Jason Wang <jasowang@redhat.com>


> ---
>
> The patch is the same of v1, but I re-tested it with:
> - QEMU v5.2.0-551-ga05f8ecd88
> - Linux 5.9.15 (host)
> - Linux 5.9.15 and 5.10.0 (guest)
> Now, enabling 'ats' it works well, there are just a few simple changes.
>
> v1: https://www.spinics.net/lists/kernel/msg3716022.html
> v2:
> - updated commit message about QEMU version and string used to test
> - rebased on mst/vhost branch
>
> Thanks,
> Stefano
> ---
>   drivers/vhost/vsock.c | 68 +++++++++++++++++++++++++++++++++++++++++--
>   1 file changed, 65 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
> index a483cec31d5c..5e78fb719602 100644
> --- a/drivers/vhost/vsock.c
> +++ b/drivers/vhost/vsock.c
> @@ -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 = {
Stefan Hajnoczi Jan. 4, 2021, 10:19 a.m. UTC | #2 
On Wed, Dec 23, 2020 at 03:36:38PM +0100, Stefano Garzarella wrote:
> 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>
> ---
> 
> The patch is the same of v1, but I re-tested it with:
> - QEMU v5.2.0-551-ga05f8ecd88
> - Linux 5.9.15 (host)
> - Linux 5.9.15 and 5.10.0 (guest)
> Now, enabling 'ats' it works well, there are just a few simple changes.
> 
> v1: https://www.spinics.net/lists/kernel/msg3716022.html
> v2:
> - updated commit message about QEMU version and string used to test
> - rebased on mst/vhost branch
> 
> Thanks,
> Stefano
> ---
>  drivers/vhost/vsock.c | 68 +++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 65 insertions(+), 3 deletions(-)

Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
diff mbox series

Patch

diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index a483cec31d5c..5e78fb719602 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -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 = {