xen/gntdev: Add initial support for dma-buf UAPI
Add UAPI and IOCTLs for dma-buf grant device driver extension: the extension allows userspace processes and kernel modules to use Xen backed dma-buf implementation. With this extension grant references to the pages of an imported dma-buf can be exported for other domain use and grant references coming from a foreign domain can be converted into a local dma-buf for local export. Implement basic initialization and stubs for Xen DMA buffers' support. Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
This commit is contained in:
Oleksandr Andrushchenko
Boris Ostrovsky
Родитель
1d31456755
Коммит
932d656217
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@ -152,6 +152,16 @@ config XEN_GNTDEV
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help
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Allows userspace processes to use grants.
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config XEN_GNTDEV_DMABUF
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bool "Add support for dma-buf grant access device driver extension"
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depends on XEN_GNTDEV && XEN_GRANT_DMA_ALLOC && DMA_SHARED_BUFFER
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help
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Allows userspace processes and kernel modules to use Xen backed
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dma-buf implementation. With this extension grant references to
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the pages of an imported dma-buf can be exported for other domain
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use and grant references coming from a foreign domain can be
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converted into a local dma-buf for local export.
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config XEN_GRANT_DEV_ALLOC
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tristate "User-space grant reference allocator driver"
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depends on XEN
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@ -41,5 +41,6 @@ obj-$(CONFIG_XEN_PVCALLS_BACKEND) += pvcalls-back.o
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obj-$(CONFIG_XEN_PVCALLS_FRONTEND) += pvcalls-front.o
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xen-evtchn-y := evtchn.o
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xen-gntdev-y := gntdev.o
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xen-gntdev-$(CONFIG_XEN_GNTDEV_DMABUF) += gntdev-dmabuf.o
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xen-gntalloc-y := gntalloc.o
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xen-privcmd-y := privcmd.o privcmd-buf.o
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@ -16,6 +16,8 @@
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#include <linux/mmu_notifier.h>
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#include <linux/types.h>
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struct gntdev_dmabuf_priv;
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struct gntdev_priv {
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/* Maps with visible offsets in the file descriptor. */
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struct list_head maps;
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@ -33,6 +35,10 @@ struct gntdev_priv {
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/* Device for which DMA memory is allocated. */
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struct device *dma_dev;
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#endif
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#ifdef CONFIG_XEN_GNTDEV_DMABUF
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struct gntdev_dmabuf_priv *dmabuf_priv;
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#endif
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};
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struct gntdev_unmap_notify {
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@ -0,0 +1,177 @@
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Xen dma-buf functionality for gntdev.
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*
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* Copyright (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
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*/
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/slab.h>
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#include <linux/types.h>
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#include <linux/uaccess.h>
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#include <xen/xen.h>
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#include <xen/grant_table.h>
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#include "gntdev-common.h"
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#include "gntdev-dmabuf.h"
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struct gntdev_dmabuf_priv {
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/* List of exported DMA buffers. */
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struct list_head exp_list;
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/* List of wait objects. */
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struct list_head exp_wait_list;
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/* This is the lock which protects dma_buf_xxx lists. */
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struct mutex lock;
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};
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/* DMA buffer export support. */
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/* Implementation of wait for exported DMA buffer to be released. */
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static int dmabuf_exp_wait_released(struct gntdev_dmabuf_priv *priv, int fd,
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int wait_to_ms)
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{
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return -EINVAL;
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}
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static int dmabuf_exp_from_refs(struct gntdev_priv *priv, int flags,
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int count, u32 domid, u32 *refs, u32 *fd)
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{
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*fd = -1;
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return -EINVAL;
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}
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/* DMA buffer import support. */
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static struct gntdev_dmabuf *
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dmabuf_imp_to_refs(struct gntdev_dmabuf_priv *priv, struct device *dev,
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int fd, int count, int domid)
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{
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return ERR_PTR(-ENOMEM);
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}
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static u32 *dmabuf_imp_get_refs(struct gntdev_dmabuf *gntdev_dmabuf)
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{
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return NULL;
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}
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static int dmabuf_imp_release(struct gntdev_dmabuf_priv *priv, u32 fd)
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{
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return -EINVAL;
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}
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/* DMA buffer IOCTL support. */
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long gntdev_ioctl_dmabuf_exp_from_refs(struct gntdev_priv *priv, int use_ptemod,
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struct ioctl_gntdev_dmabuf_exp_from_refs __user *u)
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{
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struct ioctl_gntdev_dmabuf_exp_from_refs op;
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u32 *refs;
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long ret;
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if (use_ptemod) {
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pr_debug("Cannot provide dma-buf: use_ptemode %d\n",
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use_ptemod);
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return -EINVAL;
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}
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if (copy_from_user(&op, u, sizeof(op)) != 0)
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return -EFAULT;
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if (unlikely(op.count <= 0))
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return -EINVAL;
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refs = kcalloc(op.count, sizeof(*refs), GFP_KERNEL);
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if (!refs)
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return -ENOMEM;
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if (copy_from_user(refs, u->refs, sizeof(*refs) * op.count) != 0) {
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ret = -EFAULT;
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goto out;
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}
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ret = dmabuf_exp_from_refs(priv, op.flags, op.count,
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op.domid, refs, &op.fd);
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if (ret)
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goto out;
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if (copy_to_user(u, &op, sizeof(op)) != 0)
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ret = -EFAULT;
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out:
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kfree(refs);
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return ret;
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}
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long gntdev_ioctl_dmabuf_exp_wait_released(struct gntdev_priv *priv,
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struct ioctl_gntdev_dmabuf_exp_wait_released __user *u)
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{
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struct ioctl_gntdev_dmabuf_exp_wait_released op;
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if (copy_from_user(&op, u, sizeof(op)) != 0)
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return -EFAULT;
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return dmabuf_exp_wait_released(priv->dmabuf_priv, op.fd,
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op.wait_to_ms);
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}
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long gntdev_ioctl_dmabuf_imp_to_refs(struct gntdev_priv *priv,
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struct ioctl_gntdev_dmabuf_imp_to_refs __user *u)
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{
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struct ioctl_gntdev_dmabuf_imp_to_refs op;
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struct gntdev_dmabuf *gntdev_dmabuf;
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long ret;
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if (copy_from_user(&op, u, sizeof(op)) != 0)
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return -EFAULT;
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if (unlikely(op.count <= 0))
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return -EINVAL;
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gntdev_dmabuf = dmabuf_imp_to_refs(priv->dmabuf_priv,
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priv->dma_dev, op.fd,
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op.count, op.domid);
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if (IS_ERR(gntdev_dmabuf))
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return PTR_ERR(gntdev_dmabuf);
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if (copy_to_user(u->refs, dmabuf_imp_get_refs(gntdev_dmabuf),
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sizeof(*u->refs) * op.count) != 0) {
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ret = -EFAULT;
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goto out_release;
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}
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return 0;
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out_release:
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dmabuf_imp_release(priv->dmabuf_priv, op.fd);
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return ret;
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}
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long gntdev_ioctl_dmabuf_imp_release(struct gntdev_priv *priv,
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struct ioctl_gntdev_dmabuf_imp_release __user *u)
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{
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struct ioctl_gntdev_dmabuf_imp_release op;
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if (copy_from_user(&op, u, sizeof(op)) != 0)
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return -EFAULT;
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return dmabuf_imp_release(priv->dmabuf_priv, op.fd);
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}
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struct gntdev_dmabuf_priv *gntdev_dmabuf_init(void)
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{
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struct gntdev_dmabuf_priv *priv;
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priv = kzalloc(sizeof(*priv), GFP_KERNEL);
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if (!priv)
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return ERR_PTR(-ENOMEM);
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return priv;
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}
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void gntdev_dmabuf_fini(struct gntdev_dmabuf_priv *priv)
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{
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kfree(priv);
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}
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@ -0,0 +1,33 @@
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/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Xen dma-buf functionality for gntdev.
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*
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* Copyright (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
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*/
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#ifndef _GNTDEV_DMABUF_H
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#define _GNTDEV_DMABUF_H
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#include <xen/gntdev.h>
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struct gntdev_dmabuf_priv;
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struct gntdev_priv;
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struct gntdev_dmabuf_priv *gntdev_dmabuf_init(void);
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void gntdev_dmabuf_fini(struct gntdev_dmabuf_priv *priv);
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long gntdev_ioctl_dmabuf_exp_from_refs(struct gntdev_priv *priv, int use_ptemod,
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struct ioctl_gntdev_dmabuf_exp_from_refs __user *u);
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long gntdev_ioctl_dmabuf_exp_wait_released(struct gntdev_priv *priv,
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struct ioctl_gntdev_dmabuf_exp_wait_released __user *u);
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long gntdev_ioctl_dmabuf_imp_to_refs(struct gntdev_priv *priv,
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struct ioctl_gntdev_dmabuf_imp_to_refs __user *u);
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long gntdev_ioctl_dmabuf_imp_release(struct gntdev_priv *priv,
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struct ioctl_gntdev_dmabuf_imp_release __user *u);
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#endif
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@ -48,6 +48,9 @@
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#include <asm/xen/hypercall.h>
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#include "gntdev-common.h"
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#ifdef CONFIG_XEN_GNTDEV_DMABUF
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#include "gntdev-dmabuf.h"
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#endif
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Derek G. Murray <Derek.Murray@cl.cam.ac.uk>, "
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@ -566,6 +569,15 @@ static int gntdev_open(struct inode *inode, struct file *flip)
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INIT_LIST_HEAD(&priv->freeable_maps);
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mutex_init(&priv->lock);
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#ifdef CONFIG_XEN_GNTDEV_DMABUF
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priv->dmabuf_priv = gntdev_dmabuf_init();
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if (IS_ERR(priv->dmabuf_priv)) {
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ret = PTR_ERR(priv->dmabuf_priv);
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kfree(priv);
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return ret;
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}
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#endif
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if (use_ptemod) {
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priv->mm = get_task_mm(current);
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if (!priv->mm) {
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@ -616,8 +628,13 @@ static int gntdev_release(struct inode *inode, struct file *flip)
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WARN_ON(!list_empty(&priv->freeable_maps));
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mutex_unlock(&priv->lock);
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#ifdef CONFIG_XEN_GNTDEV_DMABUF
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gntdev_dmabuf_fini(priv->dmabuf_priv);
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#endif
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if (use_ptemod)
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mmu_notifier_unregister(&priv->mn, priv->mm);
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kfree(priv);
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return 0;
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}
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@ -1009,6 +1026,20 @@ static long gntdev_ioctl(struct file *flip,
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case IOCTL_GNTDEV_GRANT_COPY:
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return gntdev_ioctl_grant_copy(priv, ptr);
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#ifdef CONFIG_XEN_GNTDEV_DMABUF
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case IOCTL_GNTDEV_DMABUF_EXP_FROM_REFS:
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return gntdev_ioctl_dmabuf_exp_from_refs(priv, use_ptemod, ptr);
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case IOCTL_GNTDEV_DMABUF_EXP_WAIT_RELEASED:
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return gntdev_ioctl_dmabuf_exp_wait_released(priv, ptr);
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case IOCTL_GNTDEV_DMABUF_IMP_TO_REFS:
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return gntdev_ioctl_dmabuf_imp_to_refs(priv, ptr);
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case IOCTL_GNTDEV_DMABUF_IMP_RELEASE:
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return gntdev_ioctl_dmabuf_imp_release(priv, ptr);
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#endif
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default:
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pr_debug("priv %p, unknown cmd %x\n", priv, cmd);
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return -ENOIOCTLCMD;
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@ -5,6 +5,7 @@
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* Interface to /dev/xen/gntdev.
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*
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* Copyright (c) 2007, D G Murray
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* Copyright (c) 2018, Oleksandr Andrushchenko, EPAM Systems Inc.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License version 2
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@ -215,4 +216,94 @@ struct ioctl_gntdev_grant_copy {
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*/
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#define GNTDEV_DMA_FLAG_COHERENT (1 << 1)
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/*
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* Create a dma-buf [1] from grant references @refs of count @count provided
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* by the foreign domain @domid with flags @flags.
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*
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* By default dma-buf is backed by system memory pages, but by providing
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* one of the GNTDEV_DMA_FLAG_XXX flags it can also be created as
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* a DMA write-combine or coherent buffer, e.g. allocated with dma_alloc_wc/
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* dma_alloc_coherent.
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*
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* Returns 0 if dma-buf was successfully created and the corresponding
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* dma-buf's file descriptor is returned in @fd.
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*
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* [1] Documentation/driver-api/dma-buf.rst
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*/
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#define IOCTL_GNTDEV_DMABUF_EXP_FROM_REFS \
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_IOC(_IOC_NONE, 'G', 9, \
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sizeof(struct ioctl_gntdev_dmabuf_exp_from_refs))
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struct ioctl_gntdev_dmabuf_exp_from_refs {
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/* IN parameters. */
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/* Specific options for this dma-buf: see GNTDEV_DMA_FLAG_XXX. */
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__u32 flags;
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/* Number of grant references in @refs array. */
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__u32 count;
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/* OUT parameters. */
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/* File descriptor of the dma-buf. */
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__u32 fd;
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/* The domain ID of the grant references to be mapped. */
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__u32 domid;
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/* Variable IN parameter. */
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/* Array of grant references of size @count. */
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__u32 refs[1];
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};
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/*
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* This will block until the dma-buf with the file descriptor @fd is
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* released. This is only valid for buffers created with
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* IOCTL_GNTDEV_DMABUF_EXP_FROM_REFS.
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*
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* If within @wait_to_ms milliseconds the buffer is not released
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* then -ETIMEDOUT error is returned.
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* If the buffer with the file descriptor @fd does not exist or has already
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* been released, then -ENOENT is returned. For valid file descriptors
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* this must not be treated as error.
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*/
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#define IOCTL_GNTDEV_DMABUF_EXP_WAIT_RELEASED \
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_IOC(_IOC_NONE, 'G', 10, \
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sizeof(struct ioctl_gntdev_dmabuf_exp_wait_released))
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struct ioctl_gntdev_dmabuf_exp_wait_released {
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/* IN parameters */
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__u32 fd;
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__u32 wait_to_ms;
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};
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/*
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* Import a dma-buf with file descriptor @fd and export granted references
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* to the pages of that dma-buf into array @refs of size @count.
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*/
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#define IOCTL_GNTDEV_DMABUF_IMP_TO_REFS \
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_IOC(_IOC_NONE, 'G', 11, \
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sizeof(struct ioctl_gntdev_dmabuf_imp_to_refs))
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struct ioctl_gntdev_dmabuf_imp_to_refs {
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/* IN parameters. */
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/* File descriptor of the dma-buf. */
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__u32 fd;
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/* Number of grant references in @refs array. */
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__u32 count;
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/* The domain ID for which references to be granted. */
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__u32 domid;
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/* Reserved - must be zero. */
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__u32 reserved;
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/* OUT parameters. */
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/* Array of grant references of size @count. */
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__u32 refs[1];
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};
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/*
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* This will close all references to the imported buffer with file descriptor
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* @fd, so it can be released by the owner. This is only valid for buffers
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* created with IOCTL_GNTDEV_DMABUF_IMP_TO_REFS.
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*/
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#define IOCTL_GNTDEV_DMABUF_IMP_RELEASE \
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_IOC(_IOC_NONE, 'G', 12, \
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sizeof(struct ioctl_gntdev_dmabuf_imp_release))
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struct ioctl_gntdev_dmabuf_imp_release {
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/* IN parameters */
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__u32 fd;
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__u32 reserved;
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};
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#endif /* __LINUX_PUBLIC_GNTDEV_H__ */
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