Re: [PATCH] libgnttab: Add support for Linux dma-buf

[Oleksandr Andrushchenko <andr2000@gmail.com>]

ping

On 07/23/2018 03:27 PM, Oleksandr Andrushchenko wrote:
> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>
> Add support for Linux grant device driver extension which allows
> converting existing dma-buf's into an array of grant references
> and vise versa. This is only implemented for Linux as other OSes
> have no Linux dma-buf support.
>
> Bump gnttab library minor version to 3.
>
> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
> ---
>   tools/include/xen-sys/Linux/gntdev.h  | 106 ++++++++++++++++++++++++
>   tools/libs/gnttab/Makefile            |   2 +-
>   tools/libs/gnttab/gnttab_core.c       |  26 ++++++
>   tools/libs/gnttab/gnttab_unimp.c      |  26 ++++++
>   tools/libs/gnttab/include/xengnttab.h |  61 ++++++++++++++
>   tools/libs/gnttab/libxengnttab.map    |   8 ++
>   tools/libs/gnttab/linux.c             | 113 ++++++++++++++++++++++++++
>   tools/libs/gnttab/minios.c            |  26 ++++++
>   tools/libs/gnttab/private.h           |  13 +++
>   9 files changed, 380 insertions(+), 1 deletion(-)
>
> diff --git a/tools/include/xen-sys/Linux/gntdev.h b/tools/include/xen-sys/Linux/gntdev.h
> index 0ca07c92b21c..d16076044c71 100644
> --- a/tools/include/xen-sys/Linux/gntdev.h
> +++ b/tools/include/xen-sys/Linux/gntdev.h
> @@ -4,6 +4,7 @@
>    * Interface to /dev/xen/gntdev.
>    *
>    * Copyright (c) 2007, D G Murray
> + * Copyright (c) 2018, Oleksandr Andrushchenko, EPAM Systems Inc.
>    *
>    * This program is free software; you can redistribute it and/or
>    * modify it under the terms of the GNU General Public License version 2
> @@ -168,4 +169,109 @@ struct ioctl_gntdev_grant_copy {
>       struct ioctl_gntdev_grant_copy_segment *segments;
>   };
>   
> +/*
> + * Flags to be used while requesting memory mapping's backing storage
> + * to be allocated with DMA API.
> + */
> +
> +/*
> + * The buffer is backed with memory allocated with dma_alloc_wc.
> + */
> +#define GNTDEV_DMA_FLAG_WC		(1 << 0)
> +
> +/*
> + * The buffer is backed with memory allocated with dma_alloc_coherent.
> + */
> +#define GNTDEV_DMA_FLAG_COHERENT	(1 << 1)
> +
> +/*
> + * Create a dma-buf [1] from grant references @refs of count @count provided
> + * by the foreign domain @domid with flags @flags.
> + *
> + * By default dma-buf is backed by system memory pages, but by providing
> + * one of the GNTDEV_DMA_FLAG_XXX flags it can also be created as
> + * a DMA write-combine or coherent buffer, e.g. allocated with dma_alloc_wc/
> + * dma_alloc_coherent.
> + *
> + * Returns 0 if dma-buf was successfully created and the corresponding
> + * dma-buf's file descriptor is returned in @fd.
> + *
> + * [1] https://elixir.bootlin.com/linux/latest/source/Documentation/driver-api/dma-buf.rst
> + */
> +
> +#define IOCTL_GNTDEV_DMABUF_EXP_FROM_REFS \
> +    _IOC(_IOC_NONE, 'G', 9, \
> +         sizeof(struct ioctl_gntdev_dmabuf_exp_from_refs))
> +struct ioctl_gntdev_dmabuf_exp_from_refs {
> +    /* IN parameters. */
> +    /* Specific options for this dma-buf: see GNTDEV_DMABUF_FLAG_XXX. */
> +    uint32_t flags;
> +    /* Number of grant references in @refs array. */
> +    uint32_t count;
> +    /* OUT parameters. */
> +    /* File descriptor of the dma-buf. */
> +    uint32_t fd;
> +    /* The domain ID of the grant references to be mapped. */
> +    uint32_t domid;
> +    /* Variable IN parameter. */
> +    /* Array of grant references of size @count. */
> +    uint32_t refs[1];
> +};
> +
> +/*
> + * This will block until the dma-buf with the file descriptor @fd is
> + * released. This is only valid for buffers created with
> + * IOCTL_GNTDEV_DMABUF_EXP_FROM_REFS.
> + *
> + * If withing @wait_to_ms milliseconds the buffer is not released
> + * then -ETIMEDOUT error is returned.
> + * If the buffer with file descriptor @fd does not exist or has already
> + * been released, then -ENOENT is returned. For valid file descriptors
> + * this must not be treated as error.
> + */
> +#define IOCTL_GNTDEV_DMABUF_EXP_WAIT_RELEASED \
> +    _IOC(_IOC_NONE, 'G', 10, \
> +         sizeof(struct ioctl_gntdev_dmabuf_exp_wait_released))
> +struct ioctl_gntdev_dmabuf_exp_wait_released {
> +    /* IN parameters */
> +    uint32_t fd;
> +    uint32_t wait_to_ms;
> +};
> +
> +/*
> + * Import a dma-buf with file descriptor @fd and export granted references
> + * to the pages of that dma-buf into array @refs of size @count.
> + */
> +#define IOCTL_GNTDEV_DMABUF_IMP_TO_REFS \
> +    _IOC(_IOC_NONE, 'G', 11, \
> +         sizeof(struct ioctl_gntdev_dmabuf_imp_to_refs))
> +struct ioctl_gntdev_dmabuf_imp_to_refs {
> +    /* IN parameters. */
> +    /* File descriptor of the dma-buf. */
> +    uint32_t fd;
> +    /* Number of grant references in @refs array. */
> +    uint32_t count;
> +    /* The domain ID for which references to be granted. */
> +    uint32_t domid;
> +    /* Reserved - must be zero. */
> +    uint32_t reserved;
> +    /* OUT parameters. */
> +    /* Array of grant references of size @count. */
> +    uint32_t refs[1];
> +};
> +
> +/*
> + * This will close all references to an imported buffer, so it can be
> + * released by the owner. This is only valid for buffers created with
> + * IOCTL_GNTDEV_DMABUF_IMP_TO_REFS.
> + */
> +#define IOCTL_GNTDEV_DMABUF_IMP_RELEASE \
> +    _IOC(_IOC_NONE, 'G', 12, \
> +         sizeof(struct ioctl_gntdev_dmabuf_imp_release))
> +struct ioctl_gntdev_dmabuf_imp_release {
> +    /* IN parameters */
> +    uint32_t fd;
> +    uint32_t reserved;
> +};
> +
>   #endif /* __LINUX_PUBLIC_GNTDEV_H__ */
> diff --git a/tools/libs/gnttab/Makefile b/tools/libs/gnttab/Makefile
> index 6c2e7e36a2c3..0befbd18f1af 100644
> --- a/tools/libs/gnttab/Makefile
> +++ b/tools/libs/gnttab/Makefile
> @@ -2,7 +2,7 @@ XEN_ROOT = $(CURDIR)/../../..
>   include $(XEN_ROOT)/tools/Rules.mk
>   
>   MAJOR    = 1
> -MINOR    = 2
> +MINOR    = 3
>   SHLIB_LDFLAGS += -Wl,--version-script=libxengnttab.map
>   
>   CFLAGS   += -Werror -Wmissing-prototypes
> diff --git a/tools/libs/gnttab/gnttab_core.c b/tools/libs/gnttab/gnttab_core.c
> index bd075f818aa6..92e7228a2671 100644
> --- a/tools/libs/gnttab/gnttab_core.c
> +++ b/tools/libs/gnttab/gnttab_core.c
> @@ -1,6 +1,7 @@
>   /******************************************************************************
>    *
>    * Copyright (c) 2007-2008, D G Murray <Derek.Murray@cl.cam.ac.uk>
> + * Copyright (c) 2018, Oleksandr Andrushchenko, EPAM Systems Inc.
>    *
>    * This library is free software; you can redistribute it and/or
>    * modify it under the terms of the GNU Lesser General Public
> @@ -134,6 +135,31 @@ int xengnttab_grant_copy(xengnttab_handle *xgt,
>   {
>       return osdep_gnttab_grant_copy(xgt, count, segs);
>   }
> +
> +int xengnttab_dmabuf_exp_from_refs(xengnttab_handle *xgt, uint32_t domid,
> +                                   uint32_t flags, uint32_t count,
> +                                   const uint32_t *refs, uint32_t *fd)
> +{
> +    return osdep_gnttab_dmabuf_exp_from_refs(xgt, domid, flags, count,
> +                                             refs, fd);
> +}
> +
> +int xengnttab_dmabuf_exp_wait_released(xengnttab_handle *xgt, uint32_t fd,
> +                                       uint32_t wait_to_ms)
> +{
> +    return osdep_gnttab_dmabuf_exp_wait_released(xgt, fd, wait_to_ms);
> +}
> +
> +int xengnttab_dmabuf_imp_to_refs(xengnttab_handle *xgt, uint32_t domid,
> +                                 uint32_t fd, uint32_t count, uint32_t *refs)
> +{
> +    return osdep_gnttab_dmabuf_imp_to_refs(xgt, domid, fd, count, refs);
> +}
> +
> +int xengnttab_dmabuf_imp_release(xengnttab_handle *xgt, uint32_t fd)
> +{
> +    return osdep_gnttab_dmabuf_imp_release(xgt, fd);
> +}
>   /*
>    * Local variables:
>    * mode: C
> diff --git a/tools/libs/gnttab/gnttab_unimp.c b/tools/libs/gnttab/gnttab_unimp.c
> index 26e4ee129d03..dee1afd2647f 100644
> --- a/tools/libs/gnttab/gnttab_unimp.c
> +++ b/tools/libs/gnttab/gnttab_unimp.c
> @@ -1,6 +1,7 @@
>   /******************************************************************************
>    *
>    * Copyright (c) 2007-2008, D G Murray <Derek.Murray@cl.cam.ac.uk>
> + * Copyright (c) 2018, Oleksandr Andrushchenko, EPAM Systems Inc.
>    *
>    * This library is free software; you can redistribute it and/or
>    * modify it under the terms of the GNU Lesser General Public
> @@ -84,6 +85,31 @@ int xengnttab_grant_copy(xengnttab_handle *xgt,
>   {
>       abort();
>   }
> +
> +int xengnttab_dmabuf_exp_from_refs(xengnttab_handle *xgt, uint32_t domid,
> +                                   uint32_t flags, uint32_t count,
> +                                   const uint32_t *refs, uint32_t *fd)
> +{
> +    abort();
> +}
> +
> +int xengnttab_dmabuf_exp_wait_released(xengnttab_handle *xgt, uint32_t fd,
> +                                       uint32_t wait_to_ms)
> +{
> +    abort();
> +}
> +
> +int xengnttab_dmabuf_imp_to_refs(xengnttab_handle *xgt, uint32_t domid,
> +                                 uint32_t fd, uint32_t count, uint32_t *refs)
> +{
> +    abort();
> +}
> +
> +int xengnttab_dmabuf_imp_release(xengnttab_handle *xgt, uint32_t fd)
> +{
> +    abort();
> +}
> +
>   /*
>    * Local variables:
>    * mode: C
> diff --git a/tools/libs/gnttab/include/xengnttab.h b/tools/libs/gnttab/include/xengnttab.h
> index 91d4cd5bdd88..111fc88caeb3 100644
> --- a/tools/libs/gnttab/include/xengnttab.h
> +++ b/tools/libs/gnttab/include/xengnttab.h
> @@ -18,6 +18,7 @@
>    * A library for low-level access to the Xen control interfaces.
>    *
>    * Copyright (c) 2007-2008, D G Murray <Derek.Murray@cl.cam.ac.uk>
> + * Copyright (c) 2018, Oleksandr Andrushchenko, EPAM Systems Inc.
>    */
>   #ifndef XENGNTTAB_H
>   #define XENGNTTAB_H
> @@ -295,6 +296,66 @@ int xengnttab_grant_copy(xengnttab_handle *xgt,
>                            uint32_t count,
>                            xengnttab_grant_copy_segment_t *segs);
>   
> +/*
> + * Flags to be used while requesting memory mapping's backing storage
> + * to be allocated with DMA API.
> + */
> +
> +/*
> + * The buffer is backed with memory allocated with dma_alloc_wc.
> + */
> +#define GNTDEV_DMA_FLAG_WC		(1 << 0)
> +
> +/*
> + * The buffer is backed with memory allocated with dma_alloc_coherent.
> + */
> +#define GNTDEV_DMA_FLAG_COHERENT	(1 << 1)
> +
> +/**
> + * Create a dma-buf [1] from grant references @refs of count @count provided
> + * by the foreign domain @domid with flags @flags.
> + *
> + * By default dma-buf is backed by system memory pages, but by providing
> + * one of the GNTDEV_DMA_FLAG_XXX flags it can also be created as
> + * a DMA write-combine or coherent buffer.
> + *
> + * Returns 0 if dma-buf was successfully created and the corresponding
> + * dma-buf's file descriptor is returned in @fd.
> + *
> + * [1] https://elixir.bootlin.com/linux/latest/source/Documentation/driver-api/dma-buf.rst
> + */
> +int xengnttab_dmabuf_exp_from_refs(xengnttab_handle *xgt, uint32_t domid,
> +                                   uint32_t flags, uint32_t count,
> +                                   const uint32_t *refs, uint32_t *fd);
> +
> +/*
> + * This will block until the dma-buf with the file descriptor @fd is
> + * released. This is only valid for buffers created with
> + * IOCTL_GNTDEV_DMABUF_EXP_FROM_REFS.
> + *
> + * If withing @wait_to_ms milliseconds the buffer is not released
> + * then -ETIMEDOUT error is returned.
> + * If the buffer with file descriptor @fd does not exist or has already
> + * been released, then -ENOENT is returned. For valid file descriptors
> + * this must not be treated as error.
> + */
> +int xengnttab_dmabuf_exp_wait_released(xengnttab_handle *xgt, uint32_t fd,
> +                                       uint32_t wait_to_ms);
> +
> +/*
> + * Import a dma-buf with file descriptor @fd and export granted references
> + * to the pages of that dma-buf into array @refs of size @count.
> + */
> +int xengnttab_dmabuf_imp_to_refs(xengnttab_handle *xgt, uint32_t domid,
> +                                 uint32_t fd, uint32_t count, uint32_t *refs);
> +
> +/*
> + * This will close all references to an imported buffer, so it can be
> + * released by the owner. This is only valid for buffers created with
> + * IOCTL_GNTDEV_DMABUF_IMP_TO_REFS.
> + */
> +int xengnttab_dmabuf_imp_release(xengnttab_handle *xgt, uint32_t fd);
> +
>   /*
>    * Grant Sharing Interface (allocating and granting pages to others)
>    */
> diff --git a/tools/libs/gnttab/libxengnttab.map b/tools/libs/gnttab/libxengnttab.map
> index d5da388a0d8d..9de2183810a9 100644
> --- a/tools/libs/gnttab/libxengnttab.map
> +++ b/tools/libs/gnttab/libxengnttab.map
> @@ -32,3 +32,11 @@ VERS_1.2 {
>   		xengnttab_fd;
>   		xengntshr_fd;
>   } VERS_1.1;
> +
> +VERS_1.3 {
> +	global:
> +		xengnttab_dmabuf_exp_from_refs;
> +		xengnttab_dmabuf_exp_wait_released;
> +		xengnttab_dmabuf_imp_to_refs;
> +		xengnttab_dmabuf_imp_release;
> +} VERS_1.2;
> diff --git a/tools/libs/gnttab/linux.c b/tools/libs/gnttab/linux.c
> index 8347ddd3d9cf..9765146f7eb6 100644
> --- a/tools/libs/gnttab/linux.c
> +++ b/tools/libs/gnttab/linux.c
> @@ -1,5 +1,6 @@
>   /*
>    * Copyright (c) 2007-2008, D G Murray <Derek.Murray@cl.cam.ac.uk>
> + * Copyright (c) 2018, Oleksandr Andrushchenko, EPAM Systems Inc.
>    *
>    * This library is free software; you can redistribute it and/or
>    * modify it under the terms of the GNU Lesser General Public
> @@ -309,6 +310,118 @@ int osdep_gnttab_grant_copy(xengnttab_handle *xgt,
>       return rc;
>   }
>   
> +int osdep_gnttab_dmabuf_exp_from_refs(xengnttab_handle *xgt, uint32_t domid,
> +                                      uint32_t flags, uint32_t count,
> +                                      const uint32_t *refs,
> +                                      uint32_t *dmabuf_fd)
> +{
> +    struct ioctl_gntdev_dmabuf_exp_from_refs *from_refs;
> +    int rc = 0;
> +
> +    if ( !count )
> +    {
> +        errno = EINVAL;
> +        return -1;
> +    }
> +
> +    from_refs = malloc(sizeof(*from_refs) +
> +                       (count - 1) * sizeof(from_refs->refs[0]));
> +    if ( !from_refs )
> +    {
> +        errno = ENOMEM;
> +        return -1;
> +    }
> +
> +    from_refs->flags = flags;
> +    from_refs->count = count;
> +    from_refs->domid = domid;
> +
> +    memcpy(from_refs->refs, refs, count * sizeof(from_refs->refs[0]));
> +
> +    if ( (rc = ioctl(xgt->fd, IOCTL_GNTDEV_DMABUF_EXP_FROM_REFS, from_refs)) )
> +    {
> +        GTERROR(xgt->logger, "ioctl DMABUF_EXP_FROM_REFS failed");
> +        goto out;
> +    }
> +
> +    *dmabuf_fd = from_refs->fd;
> +
> +out:
> +    free(from_refs);
> +    return rc;
> +}
> +
> +int osdep_gnttab_dmabuf_exp_wait_released(xengnttab_handle *xgt,
> +                                          uint32_t fd, uint32_t wait_to_ms)
> +{
> +    struct ioctl_gntdev_dmabuf_exp_wait_released wait;
> +    int rc;
> +
> +    wait.fd = fd;
> +    wait.wait_to_ms = wait_to_ms;
> +
> +    if ( (rc = ioctl(xgt->fd, IOCTL_GNTDEV_DMABUF_EXP_WAIT_RELEASED, &wait)) ) {
> +        if ( errno == ENOENT ) {
> +            /* The buffer may have already been released. */
> +            errno = 0;
> +            rc = 0;
> +        } else
> +            GTERROR(xgt->logger, "ioctl DMABUF_EXP_WAIT_RELEASED failed");
> +    }
> +
> +    return rc;
> +}
> +
> +int osdep_gnttab_dmabuf_imp_to_refs(xengnttab_handle *xgt, uint32_t domid,
> +                                    uint32_t fd, uint32_t count, uint32_t *refs)
> +{
> +    struct ioctl_gntdev_dmabuf_imp_to_refs *to_refs;
> +    int rc = 0;
> +
> +    if ( !count )
> +    {
> +        errno = EINVAL;
> +        return -1;
> +    }
> +
> +    to_refs = malloc(sizeof(*to_refs) +
> +                     (count - 1) * sizeof(to_refs->refs[0]));
> +    if ( !to_refs )
> +    {
> +        errno = ENOMEM;
> +        return -1;
> +    }
> +
> +    to_refs->fd = fd;
> +    to_refs->count = count;
> +    to_refs->domid = domid;
> +
> +    if ( (rc = ioctl(xgt->fd, IOCTL_GNTDEV_DMABUF_IMP_TO_REFS, to_refs)) )
> +    {
> +        GTERROR(xgt->logger, "ioctl DMABUF_IMP_TO_REFS failed");
> +        goto out;
> +    }
> +
> +    memcpy(refs, to_refs->refs, count * sizeof(*refs));
> +
> +out:
> +    free(to_refs);
> +    return rc;
> +}
> +
> +int osdep_gnttab_dmabuf_imp_release(xengnttab_handle *xgt, uint32_t fd)
> +{
> +    struct ioctl_gntdev_dmabuf_imp_release release;
> +    int rc;
> +
> +    release.fd = fd;
> +
> +    if ( (rc = ioctl(xgt->fd, IOCTL_GNTDEV_DMABUF_IMP_RELEASE, &release)) )
> +        GTERROR(xgt->logger, "ioctl DMABUF_IMP_RELEASE failed");
> +
> +    return rc;
> +}
> +
>   int osdep_gntshr_open(xengntshr_handle *xgs)
>   {
>       int fd = open(DEVXEN "gntalloc", O_RDWR);
> diff --git a/tools/libs/gnttab/minios.c b/tools/libs/gnttab/minios.c
> index 0951bc9bac5b..f78caadd3043 100644
> --- a/tools/libs/gnttab/minios.c
> +++ b/tools/libs/gnttab/minios.c
> @@ -112,6 +112,32 @@ int osdep_gnttab_grant_copy(xengnttab_handle *xgt,
>   {
>       return -1;
>   }
> +
> +int osdep_gnttab_dmabuf_exp_from_refs(xengnttab_handle *xgt, uint32_t domid,
> +                                      uint32_t flags, uint32_t count,
> +                                      const uint32_t *refs, uint32_t *fd)
> +{
> +    return -1;
> +}
> +
> +int osdep_gnttab_dmabuf_exp_wait_released(xengnttab_handle *xgt,
> +                                          uint32_t fd, uint32_t wait_to_ms)
> +{
> +    return -1;
> +}
> +
> +int osdep_gnttab_dmabuf_imp_to_refs(xengnttab_handle *xgt, uint32_t domid,
> +                                    uint32_t fd, uint32_t count,
> +                                    uint32_t *refs)
> +{
> +    return -1;
> +}
> +
> +int osdep_gnttab_dmabuf_imp_release(xengnttab_handle *xgt, uint32_t fd)
> +{
> +    return -1;
> +}
> +
>   /*
>    * Local variables:
>    * mode: C
> diff --git a/tools/libs/gnttab/private.h b/tools/libs/gnttab/private.h
> index ed8df40def0d..c5e23639b141 100644
> --- a/tools/libs/gnttab/private.h
> +++ b/tools/libs/gnttab/private.h
> @@ -35,6 +35,19 @@ int osdep_gnttab_grant_copy(xengnttab_handle *xgt,
>                               uint32_t count,
>                               xengnttab_grant_copy_segment_t *segs);
>   
> +int osdep_gnttab_dmabuf_exp_from_refs(xengnttab_handle *xgt, uint32_t domid,
> +                                      uint32_t flags, uint32_t count,
> +                                      const uint32_t *refs, uint32_t *fd);
> +
> +int osdep_gnttab_dmabuf_exp_wait_released(xengnttab_handle *xgt,
> +                                          uint32_t fd, uint32_t wait_to_ms);
> +
> +int osdep_gnttab_dmabuf_imp_to_refs(xengnttab_handle *xgt, uint32_t domid,
> +                                    uint32_t fd, uint32_t count,
> +                                    uint32_t *refs);
> +
> +int osdep_gnttab_dmabuf_imp_release(xengnttab_handle *xgt, uint32_t fd);
> +
>   int osdep_gntshr_open(xengntshr_handle *xgs);
>   int osdep_gntshr_close(xengntshr_handle *xgs);
>   


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