Intel MIC Host Driver Changes for Virtio Devices.

This patch introduces the host "Virtio over PCIe" interface for
Intel MIC. It allows creating user space backends on the host and instantiating
virtio devices for them on the Intel MIC card. It uses the existing VRINGH
infrastructure in the kernel to access virtio rings from the host. A character
device per MIC is exposed with IOCTL, mmap and poll callbacks. This allows the
user space backend to:
(a) add/remove a virtio device via a device page.
(b) map (R/O) virtio rings and device page to user space.
(c) poll for availability of data.
(d) copy a descriptor or entire descriptor chain to/from the card.
(e) modify virtio configuration.
(f) handle virtio device reset.
The buffers are copied over using CPU copies for this initial patch
and host initiated MIC DMA support is planned for future patches.
The avail and desc virtio rings are in host memory and the used ring
is in card memory to maximize writes across PCIe for performance.

Co-author: Sudeep Dutt <sudeep.dutt@intel.com>
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Signed-off-by: Caz Yokoyama <Caz.Yokoyama@intel.com>
Signed-off-by: Dasaratharaman Chandramouli <dasaratharaman.chandramouli@intel.com>
Signed-off-by: Nikhil Rao <nikhil.rao@intel.com>
Signed-off-by: Harshavardhan R Kharche <harshavardhan.r.kharche@intel.com>
Signed-off-by: Sudeep Dutt <sudeep.dutt@intel.com>
Acked-by: Yaozu (Eddie) Dong <eddie.dong@intel.com>
Reviewed-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 703 insertions, 0 deletions

diff --git a/drivers/misc/mic/host/mic_virtio.c b/drivers/misc/mic/host/mic_virtio.c
new file mode 100644
index 000000000000..be2a1f06c4ca
--- /dev/null
+++ b/drivers/misc/mic/host/mic_virtio.c
@@ -0,0 +1,703 @@
+/*
+ * Intel MIC Platform Software Stack (MPSS)
+ *
+ * Copyright(c) 2013 Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 2, as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * The full GNU General Public License is included in this distribution in
+ * the file called "COPYING".
+ *
+ * Intel MIC Host driver.
+ *
+ */
+#include <linux/pci.h>
+#include <linux/sched.h>
+#include <linux/uaccess.h>
+
+#include <linux/mic_common.h>
+#include "../common/mic_device.h"
+#include "mic_device.h"
+#include "mic_smpt.h"
+#include "mic_virtio.h"
+
+/*
+ * Initiates the copies across the PCIe bus from card memory to
+ * a user space buffer.
+ */
+static int mic_virtio_copy_to_user(struct mic_vdev *mvdev,
+		void __user *ubuf, size_t len, u64 addr)
+{
+	int err;
+	void __iomem *dbuf = mvdev->mdev->aper.va + addr;
+	/*
+	 * We are copying from IO below an should ideally use something
+	 * like copy_to_user_fromio(..) if it existed.
+	 */
+	if (copy_to_user(ubuf, dbuf, len)) {
+		err = -EFAULT;
+		dev_err(mic_dev(mvdev), "%s %d err %d\n",
+			__func__, __LINE__, err);
+		goto err;
+	}
+	mvdev->in_bytes += len;
+	err = 0;
+err:
+	return err;
+}
+
+/*
+ * Initiates copies across the PCIe bus from a user space
+ * buffer to card memory.
+ */
+static int mic_virtio_copy_from_user(struct mic_vdev *mvdev,
+		void __user *ubuf, size_t len, u64 addr)
+{
+	int err;
+	void __iomem *dbuf = mvdev->mdev->aper.va + addr;
+	/*
+	 * We are copying to IO below and should ideally use something
+	 * like copy_from_user_toio(..) if it existed.
+	 */
+	if (copy_from_user(dbuf, ubuf, len)) {
+		err = -EFAULT;
+		dev_err(mic_dev(mvdev), "%s %d err %d\n",
+			__func__, __LINE__, err);
+		goto err;
+	}
+	mvdev->out_bytes += len;
+	err = 0;
+err:
+	return err;
+}
+
+#define MIC_VRINGH_READ true
+
+/* The function to call to notify the card about added buffers */
+static void mic_notify(struct vringh *vrh)
+{
+	struct mic_vringh *mvrh = container_of(vrh, struct mic_vringh, vrh);
+	struct mic_vdev *mvdev = mvrh->mvdev;
+	s8 db = mvdev->dc->h2c_vdev_db;
+
+	if (db != -1)
+		mvdev->mdev->ops->send_intr(mvdev->mdev, db);
+}
+
+/* Determine the total number of bytes consumed in a VRINGH KIOV */
+static inline u32 mic_vringh_iov_consumed(struct vringh_kiov *iov)
+{
+	int i;
+	u32 total = iov->consumed;
+
+	for (i = 0; i < iov->i; i++)
+		total += iov->iov[i].iov_len;
+	return total;
+}
+
+/*
+ * Traverse the VRINGH KIOV and issue the APIs to trigger the copies.
+ * This API is heavily based on the vringh_iov_xfer(..) implementation
+ * in vringh.c. The reason we cannot reuse vringh_iov_pull_kern(..)
+ * and vringh_iov_push_kern(..) directly is because there is no
+ * way to override the VRINGH xfer(..) routines as of v3.10.
+ */
+static int mic_vringh_copy(struct mic_vdev *mvdev, struct vringh_kiov *iov,
+	void __user *ubuf, size_t len, bool read, size_t *out_len)
+{
+	int ret = 0;
+	size_t partlen, tot_len = 0;
+
+	while (len && iov->i < iov->used) {
+		partlen = min(iov->iov[iov->i].iov_len, len);
+		if (read)
+			ret = mic_virtio_copy_to_user(mvdev,
+				ubuf, partlen,
+				(u64)iov->iov[iov->i].iov_base);
+		else
+			ret = mic_virtio_copy_from_user(mvdev,
+				ubuf, partlen,
+				(u64)iov->iov[iov->i].iov_base);
+		if (ret) {
+			dev_err(mic_dev(mvdev), "%s %d err %d\n",
+				__func__, __LINE__, ret);
+			break;
+		}
+		len -= partlen;
+		ubuf += partlen;
+		tot_len += partlen;
+		iov->consumed += partlen;
+		iov->iov[iov->i].iov_len -= partlen;
+		iov->iov[iov->i].iov_base += partlen;
+		if (!iov->iov[iov->i].iov_len) {
+			/* Fix up old iov element then increment. */
+			iov->iov[iov->i].iov_len = iov->consumed;
+			iov->iov[iov->i].iov_base -= iov->consumed;
+
+			iov->consumed = 0;
+			iov->i++;
+		}
+	}
+	*out_len = tot_len;
+	return ret;
+}
+
+/*
+ * Use the standard VRINGH infrastructure in the kernel to fetch new
+ * descriptors, initiate the copies and update the used ring.
+ */
+static int _mic_virtio_copy(struct mic_vdev *mvdev,
+	struct mic_copy_desc *copy)
+{
+	int ret = 0, iovcnt = copy->iovcnt;
+	struct iovec iov;
+	struct iovec __user *u_iov = copy->iov;
+	void __user *ubuf = NULL;
+	struct mic_vringh *mvr = &mvdev->mvr[copy->vr_idx];
+	struct vringh_kiov *riov = &mvr->riov;
+	struct vringh_kiov *wiov = &mvr->wiov;
+	struct vringh *vrh = &mvr->vrh;
+	u16 *head = &mvr->head;
+	struct mic_vring *vr = &mvr->vring;
+	size_t len = 0, out_len;
+
+	copy->out_len = 0;
+	/* Fetch a new IOVEC if all previous elements have been processed */
+	if (riov->i == riov->used && wiov->i == wiov->used) {
+		ret = vringh_getdesc_kern(vrh, riov, wiov,
+				head, GFP_KERNEL);
+		/* Check if there are available descriptors */
+		if (ret <= 0)
+			return ret;
+	}
+	while (iovcnt) {
+		if (!len) {
+			/* Copy over a new iovec from user space. */
+			ret = copy_from_user(&iov, u_iov, sizeof(*u_iov));
+			if (ret) {
+				ret = -EINVAL;
+				dev_err(mic_dev(mvdev), "%s %d err %d\n",
+					__func__, __LINE__, ret);
+				break;
+			}
+			len = iov.iov_len;
+			ubuf = iov.iov_base;
+		}
+		/* Issue all the read descriptors first */
+		ret = mic_vringh_copy(mvdev, riov, ubuf, len,
+			MIC_VRINGH_READ, &out_len);
+		if (ret) {
+			dev_err(mic_dev(mvdev), "%s %d err %d\n",
+					__func__, __LINE__, ret);
+			break;
+		}
+		len -= out_len;
+		ubuf += out_len;
+		copy->out_len += out_len;
+		/* Issue the write descriptors next */
+		ret = mic_vringh_copy(mvdev, wiov, ubuf, len,
+			!MIC_VRINGH_READ, &out_len);
+		if (ret) {
+			dev_err(mic_dev(mvdev), "%s %d err %d\n",
+					__func__, __LINE__, ret);
+			break;
+		}
+		len -= out_len;
+		ubuf += out_len;
+		copy->out_len += out_len;
+		if (!len) {
+			/* One user space iovec is now completed */
+			iovcnt--;
+			u_iov++;
+		}
+		/* Exit loop if all elements in KIOVs have been processed. */
+		if (riov->i == riov->used && wiov->i == wiov->used)
+			break;
+	}
+	/*
+	 * Update the used ring if a descriptor was available and some data was
+	 * copied in/out and the user asked for a used ring update.
+	 */
+	if (*head != USHRT_MAX && copy->out_len &&
+		copy->update_used) {
+		u32 total = 0;
+
+		/* Determine the total data consumed */
+		total += mic_vringh_iov_consumed(riov);
+		total += mic_vringh_iov_consumed(wiov);
+		vringh_complete_kern(vrh, *head, total);
+		*head = USHRT_MAX;
+		if (vringh_need_notify_kern(vrh) > 0)
+			vringh_notify(vrh);
+		vringh_kiov_cleanup(riov);
+		vringh_kiov_cleanup(wiov);
+		/* Update avail idx for user space */
+		vr->info->avail_idx = vrh->last_avail_idx;
+	}
+	return ret;
+}
+
+static inline int mic_verify_copy_args(struct mic_vdev *mvdev,
+		struct mic_copy_desc *copy)
+{
+	if (copy->vr_idx >= mvdev->dd->num_vq) {
+		dev_err(mic_dev(mvdev), "%s %d err %d\n",
+			__func__, __LINE__, -EINVAL);
+		return -EINVAL;
+	}
+	return 0;
+}
+
+/* Copy a specified number of virtio descriptors in a chain */
+int mic_virtio_copy_desc(struct mic_vdev *mvdev,
+		struct mic_copy_desc *copy)
+{
+	int err;
+	struct mic_vringh *mvr = &mvdev->mvr[copy->vr_idx];
+
+	err = mic_verify_copy_args(mvdev, copy);
+	if (err)
+		return err;
+
+	mutex_lock(&mvr->vr_mutex);
+	if (!mic_vdevup(mvdev)) {
+		err = -ENODEV;
+		dev_err(mic_dev(mvdev), "%s %d err %d\n",
+			__func__, __LINE__, err);
+		goto err;
+	}
+	err = _mic_virtio_copy(mvdev, copy);
+	if (err) {
+		dev_err(mic_dev(mvdev), "%s %d err %d\n",
+			__func__, __LINE__, err);
+	}
+err:
+	mutex_unlock(&mvr->vr_mutex);
+	return err;
+}
+
+static void mic_virtio_init_post(struct mic_vdev *mvdev)
+{
+	struct mic_vqconfig *vqconfig = mic_vq_config(mvdev->dd);
+	int i;
+
+	for (i = 0; i < mvdev->dd->num_vq; i++) {
+		if (!le64_to_cpu(vqconfig[i].used_address)) {
+			dev_warn(mic_dev(mvdev), "used_address zero??\n");
+			continue;
+		}
+		mvdev->mvr[i].vrh.vring.used =
+			mvdev->mdev->aper.va +
+			le64_to_cpu(vqconfig[i].used_address);
+	}
+
+	mvdev->dc->used_address_updated = 0;
+
+	dev_dbg(mic_dev(mvdev), "%s: device type %d LINKUP\n",
+		__func__, mvdev->virtio_id);
+}
+
+static inline void mic_virtio_device_reset(struct mic_vdev *mvdev)
+{
+	int i;
+
+	dev_dbg(mic_dev(mvdev), "%s: status %d device type %d RESET\n",
+		__func__, mvdev->dd->status, mvdev->virtio_id);
+
+	for (i = 0; i < mvdev->dd->num_vq; i++)
+		/*
+		 * Avoid lockdep false positive. The + 1 is for the mic
+		 * mutex which is held in the reset devices code path.
+		 */
+		mutex_lock_nested(&mvdev->mvr[i].vr_mutex, i + 1);
+
+	/* 0 status means "reset" */
+	mvdev->dd->status = 0;
+	mvdev->dc->vdev_reset = 0;
+	mvdev->dc->host_ack = 1;
+
+	for (i = 0; i < mvdev->dd->num_vq; i++) {
+		struct vringh *vrh = &mvdev->mvr[i].vrh;
+		mvdev->mvr[i].vring.info->avail_idx = 0;
+		vrh->completed = 0;
+		vrh->last_avail_idx = 0;
+		vrh->last_used_idx = 0;
+	}
+
+	for (i = 0; i < mvdev->dd->num_vq; i++)
+		mutex_unlock(&mvdev->mvr[i].vr_mutex);
+}
+
+void mic_virtio_reset_devices(struct mic_device *mdev)
+{
+	struct list_head *pos, *tmp;
+	struct mic_vdev *mvdev;
+
+	dev_dbg(mdev->sdev->parent, "%s\n",  __func__);
+
+	list_for_each_safe(pos, tmp, &mdev->vdev_list) {
+		mvdev = list_entry(pos, struct mic_vdev, list);
+		mic_virtio_device_reset(mvdev);
+		mvdev->poll_wake = 1;
+		wake_up(&mvdev->waitq);
+	}
+}
+
+void mic_bh_handler(struct work_struct *work)
+{
+	struct mic_vdev *mvdev = container_of(work, struct mic_vdev,
+			virtio_bh_work);
+
+	if (mvdev->dc->used_address_updated)
+		mic_virtio_init_post(mvdev);
+
+	if (mvdev->dc->vdev_reset)
+		mic_virtio_device_reset(mvdev);
+
+	mvdev->poll_wake = 1;
+	wake_up(&mvdev->waitq);
+}
+
+static irqreturn_t mic_virtio_intr_handler(int irq, void *data)
+{
+
+	struct mic_vdev *mvdev = data;
+	struct mic_device *mdev = mvdev->mdev;
+
+	mdev->ops->ack_interrupt(mdev);
+	schedule_work(&mvdev->virtio_bh_work);
+	return IRQ_HANDLED;
+}
+
+int mic_virtio_config_change(struct mic_vdev *mvdev,
+			void __user *argp)
+{
+	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wake);
+	int ret = 0, retry = 100, i;
+	struct mic_bootparam *bootparam = mvdev->mdev->dp;
+	s8 db = bootparam->h2c_config_db;
+
+	mutex_lock(&mvdev->mdev->mic_mutex);
+	for (i = 0; i < mvdev->dd->num_vq; i++)
+		mutex_lock_nested(&mvdev->mvr[i].vr_mutex, i + 1);
+
+	if (db == -1 || mvdev->dd->type == -1) {
+		ret = -EIO;
+		goto exit;
+	}
+
+	if (copy_from_user(mic_vq_configspace(mvdev->dd),
+				argp, mvdev->dd->config_len)) {
+		dev_err(mic_dev(mvdev), "%s %d err %d\n",
+			__func__, __LINE__, -EFAULT);
+		ret = -EFAULT;
+		goto exit;
+	}
+	mvdev->dc->config_change = MIC_VIRTIO_PARAM_CONFIG_CHANGED;
+	mvdev->mdev->ops->send_intr(mvdev->mdev, db);
+
+	for (i = retry; i--;) {
+		ret = wait_event_timeout(wake,
+			mvdev->dc->guest_ack, msecs_to_jiffies(100));
+		if (ret)
+			break;
+	}
+
+	dev_dbg(mic_dev(mvdev),
+		"%s %d retry: %d\n", __func__, __LINE__, retry);
+	mvdev->dc->config_change = 0;
+	mvdev->dc->guest_ack = 0;
+exit:
+	for (i = 0; i < mvdev->dd->num_vq; i++)
+		mutex_unlock(&mvdev->mvr[i].vr_mutex);
+	mutex_unlock(&mvdev->mdev->mic_mutex);
+	return ret;
+}
+
+static int mic_copy_dp_entry(struct mic_vdev *mvdev,
+					void __user *argp,
+					__u8 *type,
+					struct mic_device_desc **devpage)
+{
+	struct mic_device *mdev = mvdev->mdev;
+	struct mic_device_desc dd, *dd_config, *devp;
+	struct mic_vqconfig *vqconfig;
+	int ret = 0, i;
+	bool slot_found = false;
+
+	if (copy_from_user(&dd, argp, sizeof(dd))) {
+		dev_err(mic_dev(mvdev), "%s %d err %d\n",
+			__func__, __LINE__, -EFAULT);
+		return -EFAULT;
+	}
+
+	if (mic_aligned_desc_size(&dd) > MIC_MAX_DESC_BLK_SIZE
+		|| dd.num_vq > MIC_MAX_VRINGS) {
+		dev_err(mic_dev(mvdev), "%s %d err %d\n",
+			__func__, __LINE__, -EINVAL);
+		return -EINVAL;
+	}
+
+	dd_config = kmalloc(mic_desc_size(&dd), GFP_KERNEL);
+	if (dd_config == NULL) {
+		dev_err(mic_dev(mvdev), "%s %d err %d\n",
+			__func__, __LINE__, -ENOMEM);
+		return -ENOMEM;
+	}
+	if (copy_from_user(dd_config, argp, mic_desc_size(&dd))) {
+		ret = -EFAULT;
+		dev_err(mic_dev(mvdev), "%s %d err %d\n",
+			__func__, __LINE__, ret);
+		goto exit;
+	}
+
+	vqconfig = mic_vq_config(dd_config);
+	for (i = 0; i < dd.num_vq; i++) {
+		if (le16_to_cpu(vqconfig[i].num) > MIC_MAX_VRING_ENTRIES) {
+			ret =  -EINVAL;
+			dev_err(mic_dev(mvdev), "%s %d err %d\n",
+				__func__, __LINE__, ret);
+			goto exit;
+		}
+	}
+
+	/* Find the first free device page entry */
+	for (i = mic_aligned_size(struct mic_bootparam);
+		i < MIC_DP_SIZE - mic_total_desc_size(dd_config);
+		i += mic_total_desc_size(devp)) {
+		devp = mdev->dp + i;
+		if (devp->type == 0 || devp->type == -1) {
+			slot_found = true;
+			break;
+		}
+	}
+	if (!slot_found) {
+		ret =  -EINVAL;
+		dev_err(mic_dev(mvdev), "%s %d err %d\n",
+			__func__, __LINE__, ret);
+		goto exit;
+	}
+	/*
+	 * Save off the type before doing the memcpy. Type will be set in the
+	 * end after completing all initialization for the new device.
+	 */
+	*type = dd_config->type;
+	dd_config->type = 0;
+	memcpy(devp, dd_config, mic_desc_size(dd_config));
+
+	*devpage = devp;
+exit:
+	kfree(dd_config);
+	return ret;
+}
+
+static void mic_init_device_ctrl(struct mic_vdev *mvdev,
+				struct mic_device_desc *devpage)
+{
+	struct mic_device_ctrl *dc;
+
+	dc = mvdev->dc = (void *)devpage + mic_aligned_desc_size(devpage);
+
+	dc->config_change = 0;
+	dc->guest_ack = 0;
+	dc->vdev_reset = 0;
+	dc->host_ack = 0;
+	dc->used_address_updated = 0;
+	dc->c2h_vdev_db = -1;
+	dc->h2c_vdev_db = -1;
+}
+
+int mic_virtio_add_device(struct mic_vdev *mvdev,
+			void __user *argp)
+{
+	struct mic_device *mdev = mvdev->mdev;
+	struct mic_device_desc *dd;
+	struct mic_vqconfig *vqconfig;
+	int vr_size, i, j, ret;
+	u8 type;
+	s8 db;
+	char irqname[10];
+	struct mic_bootparam *bootparam = mdev->dp;
+	u16 num;
+
+	mutex_lock(&mdev->mic_mutex);
+
+	ret = mic_copy_dp_entry(mvdev, argp, &type, &dd);
+	if (ret) {
+		mutex_unlock(&mdev->mic_mutex);
+		return ret;
+	}
+
+	mic_init_device_ctrl(mvdev, dd);
+
+	mvdev->dd = dd;
+	mvdev->virtio_id = type;
+	vqconfig = mic_vq_config(dd);
+	INIT_WORK(&mvdev->virtio_bh_work, mic_bh_handler);
+
+	for (i = 0; i < dd->num_vq; i++) {
+		struct mic_vringh *mvr = &mvdev->mvr[i];
+		struct mic_vring *vr = &mvdev->mvr[i].vring;
+		num = le16_to_cpu(vqconfig[i].num);
+		mutex_init(&mvr->vr_mutex);
+		vr_size = PAGE_ALIGN(vring_size(num, MIC_VIRTIO_RING_ALIGN) +
+			sizeof(struct _mic_vring_info));
+		vr->va = (void *)
+			__get_free_pages(GFP_KERNEL | __GFP_ZERO,
+			get_order(vr_size));
+		if (!vr->va) {
+			ret = -ENOMEM;
+			dev_err(mic_dev(mvdev), "%s %d err %d\n",
+				__func__, __LINE__, ret);
+			goto err;
+		}
+		vr->len = vr_size;
+		vr->info = vr->va + vring_size(num, MIC_VIRTIO_RING_ALIGN);
+		vr->info->magic = MIC_MAGIC + mvdev->virtio_id + i;
+		vqconfig[i].address = mic_map_single(mdev,
+			vr->va, vr_size);
+		if (mic_map_error(vqconfig[i].address)) {
+			free_pages((unsigned long)vr->va,
+				get_order(vr_size));
+			ret = -ENOMEM;
+			dev_err(mic_dev(mvdev), "%s %d err %d\n",
+				__func__, __LINE__, ret);
+			goto err;
+		}
+		vqconfig[i].address = cpu_to_le64(vqconfig[i].address);
+
+		vring_init(&vr->vr, num,
+			vr->va, MIC_VIRTIO_RING_ALIGN);
+		ret = vringh_init_kern(&mvr->vrh,
+			*(u32 *)mic_vq_features(mvdev->dd), num, false,
+			vr->vr.desc, vr->vr.avail, vr->vr.used);
+		if (ret) {
+			dev_err(mic_dev(mvdev), "%s %d err %d\n",
+				__func__, __LINE__, ret);
+			goto err;
+		}
+		vringh_kiov_init(&mvr->riov, NULL, 0);
+		vringh_kiov_init(&mvr->wiov, NULL, 0);
+		mvr->head = USHRT_MAX;
+		mvr->mvdev = mvdev;
+		mvr->vrh.notify = mic_notify;
+		dev_dbg(mdev->sdev->parent,
+			"%s %d index %d va %p info %p vr_size 0x%x\n",
+			__func__, __LINE__, i, vr->va, vr->info, vr_size);
+	}
+
+	snprintf(irqname, sizeof(irqname),
+		"mic%dvirtio%d", mdev->id, mvdev->virtio_id);
+	mvdev->virtio_db = mic_next_db(mdev);
+	mvdev->virtio_cookie = mic_request_irq(mdev, mic_virtio_intr_handler,
+			irqname, mvdev, mvdev->virtio_db, MIC_INTR_DB);
+	if (IS_ERR(mvdev->virtio_cookie)) {
+		ret = PTR_ERR(mvdev->virtio_cookie);
+		dev_dbg(mdev->sdev->parent, "request irq failed\n");
+		goto err;
+	}
+
+	mvdev->dc->c2h_vdev_db = mvdev->virtio_db;
+
+	list_add_tail(&mvdev->list, &mdev->vdev_list);
+	/*
+	 * Order the type update with previous stores. This write barrier
+	 * is paired with the corresponding read barrier before the uncached
+	 * system memory read of the type, on the card while scanning the
+	 * device page.
+	 */
+	smp_wmb();
+	dd->type = type;
+
+	dev_dbg(mdev->sdev->parent, "Added virtio device id %d\n", dd->type);
+
+	db = bootparam->h2c_config_db;
+	if (db != -1)
+		mdev->ops->send_intr(mdev, db);
+	mutex_unlock(&mdev->mic_mutex);
+	return 0;
+err:
+	vqconfig = mic_vq_config(dd);
+	for (j = 0; j < i; j++) {
+		struct mic_vringh *mvr = &mvdev->mvr[j];
+		mic_unmap_single(mdev, le64_to_cpu(vqconfig[j].address),
+				mvr->vring.len);
+		free_pages((unsigned long)mvr->vring.va,
+			get_order(mvr->vring.len));
+	}
+	mutex_unlock(&mdev->mic_mutex);
+	return ret;
+}
+
+void mic_virtio_del_device(struct mic_vdev *mvdev)
+{
+	struct list_head *pos, *tmp;
+	struct mic_vdev *tmp_mvdev;
+	struct mic_device *mdev = mvdev->mdev;
+	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wake);
+	int i, ret, retry = 100;
+	struct mic_vqconfig *vqconfig;
+	struct mic_bootparam *bootparam = mdev->dp;
+	s8 db;
+
+	mutex_lock(&mdev->mic_mutex);
+	db = bootparam->h2c_config_db;
+	if (db == -1)
+		goto skip_hot_remove;
+	dev_dbg(mdev->sdev->parent,
+		"Requesting hot remove id %d\n", mvdev->virtio_id);
+	mvdev->dc->config_change = MIC_VIRTIO_PARAM_DEV_REMOVE;
+	mdev->ops->send_intr(mdev, db);
+	for (i = retry; i--;) {
+		ret = wait_event_timeout(wake,
+			mvdev->dc->guest_ack, msecs_to_jiffies(100));
+		if (ret)
+			break;
+	}
+	dev_dbg(mdev->sdev->parent,
+		"Device id %d config_change %d guest_ack %d\n",
+		mvdev->virtio_id, mvdev->dc->config_change,
+		mvdev->dc->guest_ack);
+	mvdev->dc->config_change = 0;
+	mvdev->dc->guest_ack = 0;
+skip_hot_remove:
+	mic_free_irq(mdev, mvdev->virtio_cookie, mvdev);
+	flush_work(&mvdev->virtio_bh_work);
+	vqconfig = mic_vq_config(mvdev->dd);
+	for (i = 0; i < mvdev->dd->num_vq; i++) {
+		struct mic_vringh *mvr = &mvdev->mvr[i];
+		vringh_kiov_cleanup(&mvr->riov);
+		vringh_kiov_cleanup(&mvr->wiov);
+		mic_unmap_single(mdev, le64_to_cpu(vqconfig[i].address),
+				mvr->vring.len);
+		free_pages((unsigned long)mvr->vring.va,
+			get_order(mvr->vring.len));
+	}
+
+	list_for_each_safe(pos, tmp, &mdev->vdev_list) {
+		tmp_mvdev = list_entry(pos, struct mic_vdev, list);
+		if (tmp_mvdev == mvdev) {
+			list_del(pos);
+			dev_dbg(mdev->sdev->parent,
+				"Removing virtio device id %d\n",
+				mvdev->virtio_id);
+			break;
+		}
+	}
+	/*
+	 * Order the type update with previous stores. This write barrier
+	 * is paired with the corresponding read barrier before the uncached
+	 * system memory read of the type, on the card while scanning the
+	 * device page.
+	 */
+	smp_wmb();
+	mvdev->dd->type = -1;
+	mutex_unlock(&mdev->mic_mutex);
+}