Re: [PATCH] drm/xen-front: Remove CMA support

Oleksandr Andrushchenko
2018-04-18T07:27:24Z

On 04/17/2018 12:08 PM, Oleksandr Andrushchenko wrote:
> On 04/17/2018 12:04 PM, Daniel Vetter wrote:
>> On Tue, Apr 17, 2018 at 10:40:12AM +0300, Oleksandr Andrushchenko wrote:
>>> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>>>
>>> Even if xen-front allocates its buffers from contiguous memory
>>> those are still not contiguous in PA space, e.g. the buffer is only
>>> contiguous in IPA space.
>>> The only use-case for this mode was if xen-front is used to allocate
>>> dumb buffers which later be used by some other driver requiring
>>> contiguous memory, but there is no currently such a use-case or
>>> it can be worked around with xen-front.
>> Please also mention the nents confusion here, and the patch that
>> fixes it.
>> Or just outright take the commit message from my patch with all the
>> details:
> ok, if you don't mind then I'll use your commit message entirely
>>      drm/xen: Dissable CMA support
>>           It turns out this was only needed to paper over a bug in
>> the CMA
>>      helpers, which was addressed in
>>           commit 998fb1a0f478b83492220ff79583bf9ad538bdd8
>>      Author: Liviu Dudau <Liviu.Dudau@arm.com>
>>      Date:   Fri Nov 10 13:33:10 2017 +0000
>>               drm: gem_cma_helper.c: Allow importing of contiguous
>> scatterlists with nents > 1
>>           Without this the following pipeline didn't work:
>>           domU:
>>      1. xen-front allocates a non-contig buffer
>>      2. creates grants out of it
>>           dom0:
>>      3. converts the grants into a dma-buf. Since they're non-contig,
>> the
>>      scatter-list is huge.
>>      4. imports it into rcar-du, which requires dma-contig memory for
>>      scanout.
>>           -> On this given platform there's an IOMMU, so in theory
>> this should
>>      work. But in practice this failed, because of the huge number of sg
>>      entries, even though the IOMMU driver mapped it all into a
>> dma-contig
>>      range.
>>           With a guest-contig buffer allocated in step 1, this
>> problem doesn't
>>      exist. But there's technically no reason to require guest-contig
>>      memory for xen buffer sharing using grants.
>>
>> With the commit message improved:
>>
>> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> Thank you,
> I'll wait for a day and apply to drm-misc-next if this is ok
applied to drm-misc-next
>>
>>> Signed-off-by: Oleksandr Andrushchenko
>>> <oleksandr_andrushchenko@epam.com>
>>> Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
>>> ---
>>>   Documentation/gpu/xen-front.rst             | 12 ----
>>>   drivers/gpu/drm/xen/Kconfig                 | 13 ----
>>>   drivers/gpu/drm/xen/Makefile                |  9 +--
>>>   drivers/gpu/drm/xen/xen_drm_front.c         | 62 +++-------------
>>>   drivers/gpu/drm/xen/xen_drm_front.h         | 42 ++---------
>>>   drivers/gpu/drm/xen/xen_drm_front_gem.c     | 12 +---
>>>   drivers/gpu/drm/xen/xen_drm_front_gem.h     |  3 -
>>>   drivers/gpu/drm/xen/xen_drm_front_gem_cma.c | 79
>>> ---------------------
>>>   drivers/gpu/drm/xen/xen_drm_front_shbuf.c   | 22 ------
>>>   drivers/gpu/drm/xen/xen_drm_front_shbuf.h   |  8 ---
>>>   10 files changed, 21 insertions(+), 241 deletions(-)
>>>   delete mode 100644 drivers/gpu/drm/xen/xen_drm_front_gem_cma.c
>>>
>>> diff --git a/Documentation/gpu/xen-front.rst
>>> b/Documentation/gpu/xen-front.rst
>>> index 009d942386c5..d988da7d1983 100644
>>> --- a/Documentation/gpu/xen-front.rst
>>> +++ b/Documentation/gpu/xen-front.rst
>>> @@ -18,18 +18,6 @@ Buffers allocated by the frontend driver
>>>   .. kernel-doc:: drivers/gpu/drm/xen/xen_drm_front.h
>>>      :doc: Buffers allocated by the frontend driver
>>>   -With GEM CMA helpers
>>> -~~~~~~~~~~~~~~~~~~~~
>>> -
>>> -.. kernel-doc:: drivers/gpu/drm/xen/xen_drm_front.h
>>> -   :doc: With GEM CMA helpers
>>> -
>>> -Without GEM CMA helpers
>>> -~~~~~~~~~~~~~~~~~~~~~~~
>>> -
>>> -.. kernel-doc:: drivers/gpu/drm/xen/xen_drm_front.h
>>> -   :doc: Without GEM CMA helpers
>>> -
>>>   Buffers allocated by the backend
>>>   --------------------------------
>>>   diff --git a/drivers/gpu/drm/xen/Kconfig
>>> b/drivers/gpu/drm/xen/Kconfig
>>> index 4f4abc91f3b6..4cca160782ab 100644
>>> --- a/drivers/gpu/drm/xen/Kconfig
>>> +++ b/drivers/gpu/drm/xen/Kconfig
>>> @@ -15,16 +15,3 @@ config DRM_XEN_FRONTEND
>>>       help
>>>         Choose this option if you want to enable a para-virtualized
>>>         frontend DRM/KMS driver for Xen guest OSes.
>>> -
>>> -config DRM_XEN_FRONTEND_CMA
>>> -    bool "Use DRM CMA to allocate dumb buffers"
>>> -    depends on DRM_XEN_FRONTEND
>>> -    select DRM_KMS_CMA_HELPER
>>> -    select DRM_GEM_CMA_HELPER
>>> -    help
>>> -      Use DRM CMA helpers to allocate display buffers.
>>> -      This is useful for the use-cases when guest driver needs to
>>> -      share or export buffers to other drivers which only expect
>>> -      contiguous buffers.
>>> -      Note: in this mode driver cannot use buffers allocated
>>> -      by the backend.
>>> diff --git a/drivers/gpu/drm/xen/Makefile
>>> b/drivers/gpu/drm/xen/Makefile
>>> index 352730dc6c13..712afff5ffc3 100644
>>> --- a/drivers/gpu/drm/xen/Makefile
>>> +++ b/drivers/gpu/drm/xen/Makefile
>>> @@ -5,12 +5,7 @@ drm_xen_front-objs := xen_drm_front.o \
>>>                 xen_drm_front_conn.o \
>>>                 xen_drm_front_evtchnl.o \
>>>                 xen_drm_front_shbuf.o \
>>> -              xen_drm_front_cfg.o
>>> -
>>> -ifeq ($(CONFIG_DRM_XEN_FRONTEND_CMA),y)
>>> -    drm_xen_front-objs += xen_drm_front_gem_cma.o
>>> -else
>>> -    drm_xen_front-objs += xen_drm_front_gem.o
>>> -endif
>>> +              xen_drm_front_cfg.o \
>>> +              xen_drm_front_gem.o
>>>     obj-$(CONFIG_DRM_XEN_FRONTEND) += drm_xen_front.o
>>> diff --git a/drivers/gpu/drm/xen/xen_drm_front.c
>>> b/drivers/gpu/drm/xen/xen_drm_front.c
>>> index 4a08b77f1c9e..1b0ea9ac330e 100644
>>> --- a/drivers/gpu/drm/xen/xen_drm_front.c
>>> +++ b/drivers/gpu/drm/xen/xen_drm_front.c
>>> @@ -12,7 +12,6 @@
>>>   #include <drm/drm_atomic_helper.h>
>>>   #include <drm/drm_crtc_helper.h>
>>>   #include <drm/drm_gem.h>
>>> -#include <drm/drm_gem_cma_helper.h>
>>>     #include <linux/of_device.h>
>>>   @@ -167,10 +166,9 @@ int xen_drm_front_mode_set(struct
>>> xen_drm_front_drm_pipeline *pipeline,
>>>       return ret;
>>>   }
>>>   -static int be_dbuf_create_int(struct xen_drm_front_info *front_info,
>>> +int xen_drm_front_dbuf_create(struct xen_drm_front_info *front_info,
>>>                     u64 dbuf_cookie, u32 width, u32 height,
>>> -                  u32 bpp, u64 size, struct page **pages,
>>> -                  struct sg_table *sgt)
>>> +                  u32 bpp, u64 size, struct page **pages)
>>>   {
>>>       struct xen_drm_front_evtchnl *evtchnl;
>>>       struct xen_drm_front_shbuf *shbuf;
>>> @@ -187,7 +185,6 @@ static int be_dbuf_create_int(struct
>>> xen_drm_front_info *front_info,
>>>       buf_cfg.xb_dev = front_info->xb_dev;
>>>       buf_cfg.pages = pages;
>>>       buf_cfg.size = size;
>>> -    buf_cfg.sgt = sgt;
>>>       buf_cfg.be_alloc = front_info->cfg.be_alloc;
>>>         shbuf = xen_drm_front_shbuf_alloc(&buf_cfg);
>>> @@ -237,22 +234,6 @@ static int be_dbuf_create_int(struct
>>> xen_drm_front_info *front_info,
>>>       return ret;
>>>   }
>>>   -int xen_drm_front_dbuf_create_from_sgt(struct xen_drm_front_info
>>> *front_info,
>>> -                       u64 dbuf_cookie, u32 width, u32 height,
>>> -                       u32 bpp, u64 size, struct sg_table *sgt)
>>> -{
>>> -    return be_dbuf_create_int(front_info, dbuf_cookie, width, height,
>>> -                  bpp, size, NULL, sgt);
>>> -}
>>> -
>>> -int xen_drm_front_dbuf_create_from_pages(struct xen_drm_front_info
>>> *front_info,
>>> -                     u64 dbuf_cookie, u32 width, u32 height,
>>> -                     u32 bpp, u64 size, struct page **pages)
>>> -{
>>> -    return be_dbuf_create_int(front_info, dbuf_cookie, width, height,
>>> -                  bpp, size, pages, NULL);
>>> -}
>>> -
>>>   static int xen_drm_front_dbuf_destroy(struct xen_drm_front_info
>>> *front_info,
>>>                         u64 dbuf_cookie)
>>>   {
>>> @@ -434,24 +415,11 @@ static int xen_drm_drv_dumb_create(struct
>>> drm_file *filp,
>>>           goto fail;
>>>       }
>>>   -    /*
>>> -     * In case of CONFIG_DRM_XEN_FRONTEND_CMA gem_obj is constructed
>>> -     * via DRM CMA helpers and doesn't have ->pages allocated
>>> -     * (xendrm_gem_get_pages will return NULL), but instead can
>>> provide
>>> -     * sg table
>>> -     */
>>> -    if (xen_drm_front_gem_get_pages(obj))
>>> -        ret =
>>> xen_drm_front_dbuf_create_from_pages(drm_info->front_info,
>>> -                xen_drm_front_dbuf_to_cookie(obj),
>>> -                args->width, args->height, args->bpp,
>>> -                args->size,
>>> -                xen_drm_front_gem_get_pages(obj));
>>> -    else
>>> -        ret = xen_drm_front_dbuf_create_from_sgt(drm_info->front_info,
>>> -                xen_drm_front_dbuf_to_cookie(obj),
>>> -                args->width, args->height, args->bpp,
>>> -                args->size,
>>> -                xen_drm_front_gem_get_sg_table(obj));
>>> +    ret = xen_drm_front_dbuf_create(drm_info->front_info,
>>> +                    xen_drm_front_dbuf_to_cookie(obj),
>>> +                    args->width, args->height, args->bpp,
>>> +                    args->size,
>>> +                    xen_drm_front_gem_get_pages(obj));
>>>       if (ret)
>>>           goto fail_backend;
>>>   @@ -523,11 +491,7 @@ static const struct file_operations
>>> xen_drm_dev_fops = {
>>>       .poll           = drm_poll,
>>>       .read           = drm_read,
>>>       .llseek         = no_llseek,
>>> -#ifdef CONFIG_DRM_XEN_FRONTEND_CMA
>>> -    .mmap           = drm_gem_cma_mmap,
>>> -#else
>>>       .mmap           = xen_drm_front_gem_mmap,
>>> -#endif
>>>   };
>>>     static const struct vm_operations_struct xen_drm_drv_vm_ops = {
>>> @@ -547,6 +511,9 @@ static struct drm_driver xen_drm_driver = {
>>>       .gem_prime_export          = drm_gem_prime_export,
>>>       .gem_prime_import_sg_table = xen_drm_front_gem_import_sg_table,
>>>       .gem_prime_get_sg_table    = xen_drm_front_gem_get_sg_table,
>>> +    .gem_prime_vmap            = xen_drm_front_gem_prime_vmap,
>>> +    .gem_prime_vunmap          = xen_drm_front_gem_prime_vunmap,
>>> +    .gem_prime_mmap            = xen_drm_front_gem_prime_mmap,
>>>       .dumb_create               = xen_drm_drv_dumb_create,
>>>       .fops                      = &xen_drm_dev_fops,
>>>       .name                      = "xendrm-du",
>>> @@ -555,15 +522,6 @@ static struct drm_driver xen_drm_driver = {
>>>       .major                     = 1,
>>>       .minor                     = 0,
>>>   -#ifdef CONFIG_DRM_XEN_FRONTEND_CMA
>>> -    .gem_prime_vmap            = drm_gem_cma_prime_vmap,
>>> -    .gem_prime_vunmap          = drm_gem_cma_prime_vunmap,
>>> -    .gem_prime_mmap            = drm_gem_cma_prime_mmap,
>>> -#else
>>> -    .gem_prime_vmap            = xen_drm_front_gem_prime_vmap,
>>> -    .gem_prime_vunmap          = xen_drm_front_gem_prime_vunmap,
>>> -    .gem_prime_mmap            = xen_drm_front_gem_prime_mmap,
>>> -#endif
>>>   };
>>>     static int xen_drm_drv_init(struct xen_drm_front_info *front_info)
>>> diff --git a/drivers/gpu/drm/xen/xen_drm_front.h
>>> b/drivers/gpu/drm/xen/xen_drm_front.h
>>> index 16554b2463d8..2c2479b571ae 100644
>>> --- a/drivers/gpu/drm/xen/xen_drm_front.h
>>> +++ b/drivers/gpu/drm/xen/xen_drm_front.h
>>> @@ -23,40 +23,14 @@
>>>    *
>>>    * Depending on the requirements for the para-virtualized
>>> environment, namely
>>>    * requirements dictated by the accompanying DRM/(v)GPU drivers
>>> running in both
>>> - * host and guest environments, number of operating modes of
>>> para-virtualized
>>> - * display driver are supported:
>>> - *
>>> - * - display buffers can be allocated by either frontend driver or
>>> backend
>>> - * - display buffers can be allocated to be contiguous in memory or
>>> not
>>> - *
>>> - * Note! Frontend driver itself has no dependency on contiguous
>>> memory for
>>> - * its operation.
>>> + * host and guest environments, display buffers can be allocated by
>>> either
>>> + * frontend driver or backend.
>>>    */
>>>     /**
>>>    * DOC: Buffers allocated by the frontend driver
>>>    *
>>> - * The below modes of operation are configured at compile-time via
>>> - * frontend driver's kernel configuration:
>>> - */
>>> -
>>> -/**
>>> - * DOC: With GEM CMA helpers
>>> - *
>>> - * This use-case is useful when used with accompanying DRM/vGPU
>>> driver in
>>> - * guest domain which was designed to only work with contiguous
>>> buffers,
>>> - * e.g. DRM driver based on GEM CMA helpers: such drivers can only
>>> import
>>> - * contiguous PRIME buffers, thus requiring frontend driver to provide
>>> - * such. In order to implement this mode of operation para-virtualized
>>> - * frontend driver can be configured to use GEM CMA helpers.
>>> - */
>>> -
>>> -/**
>>> - * DOC: Without GEM CMA helpers
>>> - *
>>> - * If accompanying drivers can cope with non-contiguous memory
>>> then, to
>>> - * lower pressure on CMA subsystem of the kernel, driver can allocate
>>> - * buffers from system memory.
>>> + * In this mode of operation driver allocates buffers from system
>>> memory.
>>>    *
>>>    * Note! If used with accompanying DRM/(v)GPU drivers this mode of
>>> operation
>>>    * may require IOMMU support on the platform, so accompanying
>>> DRM/vGPU
>>> @@ -164,13 +138,9 @@ int xen_drm_front_mode_set(struct
>>> xen_drm_front_drm_pipeline *pipeline,
>>>                  u32 x, u32 y, u32 width, u32 height,
>>>                  u32 bpp, u64 fb_cookie);
>>>   -int xen_drm_front_dbuf_create_from_sgt(struct xen_drm_front_info
>>> *front_info,
>>> -                       u64 dbuf_cookie, u32 width, u32 height,
>>> -                       u32 bpp, u64 size, struct sg_table *sgt);
>>> -
>>> -int xen_drm_front_dbuf_create_from_pages(struct xen_drm_front_info
>>> *front_info,
>>> -                     u64 dbuf_cookie, u32 width, u32 height,
>>> -                     u32 bpp, u64 size, struct page **pages);
>>> +int xen_drm_front_dbuf_create(struct xen_drm_front_info *front_info,
>>> +                  u64 dbuf_cookie, u32 width, u32 height,
>>> +                  u32 bpp, u64 size, struct page **pages);
>>>     int xen_drm_front_fb_attach(struct xen_drm_front_info *front_info,
>>>                   u64 dbuf_cookie, u64 fb_cookie, u32 width,
>>> diff --git a/drivers/gpu/drm/xen/xen_drm_front_gem.c
>>> b/drivers/gpu/drm/xen/xen_drm_front_gem.c
>>> index 3b04a2269d7a..c85bfe7571cb 100644
>>> --- a/drivers/gpu/drm/xen/xen_drm_front_gem.c
>>> +++ b/drivers/gpu/drm/xen/xen_drm_front_gem.c
>>> @@ -210,15 +210,9 @@ xen_drm_front_gem_import_sg_table(struct
>>> drm_device *dev,
>>>       if (ret < 0)
>>>           return ERR_PTR(ret);
>>>   -    /*
>>> -     * N.B. Although we have an API to create display buffer from sgt
>>> -     * we use pages API, because we still need those for GEM handling,
>>> -     * e.g. for mapping etc.
>>> -     */
>>> -    ret = xen_drm_front_dbuf_create_from_pages(drm_info->front_info,
>>> - xen_drm_front_dbuf_to_cookie(&xen_obj->base),
>>> -                           0, 0, 0, size,
>>> -                           xen_obj->pages);
>>> +    ret = xen_drm_front_dbuf_create(drm_info->front_info,
>>> + xen_drm_front_dbuf_to_cookie(&xen_obj->base),
>>> +                    0, 0, 0, size, xen_obj->pages);
>>>       if (ret < 0)
>>>           return ERR_PTR(ret);
>>>   diff --git a/drivers/gpu/drm/xen/xen_drm_front_gem.h
>>> b/drivers/gpu/drm/xen/xen_drm_front_gem.h
>>> index 55e531f5a763..d5ab734fdafe 100644
>>> --- a/drivers/gpu/drm/xen/xen_drm_front_gem.h
>>> +++ b/drivers/gpu/drm/xen/xen_drm_front_gem.h
>>> @@ -27,8 +27,6 @@ struct page **xen_drm_front_gem_get_pages(struct
>>> drm_gem_object *obj);
>>>     void xen_drm_front_gem_free_object_unlocked(struct
>>> drm_gem_object *gem_obj);
>>>   -#ifndef CONFIG_DRM_XEN_FRONTEND_CMA
>>> -
>>>   int xen_drm_front_gem_mmap(struct file *filp, struct
>>> vm_area_struct *vma);
>>>     void *xen_drm_front_gem_prime_vmap(struct drm_gem_object *gem_obj);
>>> @@ -38,6 +36,5 @@ void xen_drm_front_gem_prime_vunmap(struct
>>> drm_gem_object *gem_obj,
>>>     int xen_drm_front_gem_prime_mmap(struct drm_gem_object *gem_obj,
>>>                    struct vm_area_struct *vma);
>>> -#endif
>>>     #endif /* __XEN_DRM_FRONT_GEM_H */
>>> diff --git a/drivers/gpu/drm/xen/xen_drm_front_gem_cma.c
>>> b/drivers/gpu/drm/xen/xen_drm_front_gem_cma.c
>>> deleted file mode 100644
>>> index ba30a4bc2a39..000000000000
>>> --- a/drivers/gpu/drm/xen/xen_drm_front_gem_cma.c
>>> +++ /dev/null
>>> @@ -1,79 +0,0 @@
>>> -// SPDX-License-Identifier: GPL-2.0 OR MIT
>>> -
>>> -/*
>>> - *  Xen para-virtual DRM device
>>> - *
>>> - * Copyright (C) 2016-2018 EPAM Systems Inc.
>>> - *
>>> - * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>>> - */
>>> -
>>> -#include <drm/drmP.h>
>>> -#include <drm/drm_gem.h>
>>> -#include <drm/drm_fb_cma_helper.h>
>>> -#include <drm/drm_gem_cma_helper.h>
>>> -
>>> -#include "xen_drm_front.h"
>>> -#include "xen_drm_front_gem.h"
>>> -
>>> -struct drm_gem_object *
>>> -xen_drm_front_gem_import_sg_table(struct drm_device *dev,
>>> -                  struct dma_buf_attachment *attach,
>>> -                  struct sg_table *sgt)
>>> -{
>>> -    struct xen_drm_front_drm_info *drm_info = dev->dev_private;
>>> -    struct drm_gem_object *gem_obj;
>>> -    struct drm_gem_cma_object *cma_obj;
>>> -    int ret;
>>> -
>>> -    gem_obj = drm_gem_cma_prime_import_sg_table(dev, attach, sgt);
>>> -    if (IS_ERR_OR_NULL(gem_obj))
>>> -        return gem_obj;
>>> -
>>> -    cma_obj = to_drm_gem_cma_obj(gem_obj);
>>> -
>>> -    ret = xen_drm_front_dbuf_create_from_sgt(drm_info->front_info,
>>> - xen_drm_front_dbuf_to_cookie(gem_obj),
>>> -                         0, 0, 0, gem_obj->size,
>>> - drm_gem_cma_prime_get_sg_table(gem_obj));
>>> -    if (ret < 0)
>>> -        return ERR_PTR(ret);
>>> -
>>> -    DRM_DEBUG("Imported CMA buffer of size %zu\n", gem_obj->size);
>>> -
>>> -    return gem_obj;
>>> -}
>>> -
>>> -struct sg_table *xen_drm_front_gem_get_sg_table(struct
>>> drm_gem_object *gem_obj)
>>> -{
>>> -    return drm_gem_cma_prime_get_sg_table(gem_obj);
>>> -}
>>> -
>>> -struct drm_gem_object *xen_drm_front_gem_create(struct drm_device
>>> *dev,
>>> -                        size_t size)
>>> -{
>>> -    struct xen_drm_front_drm_info *drm_info = dev->dev_private;
>>> -    struct drm_gem_cma_object *cma_obj;
>>> -
>>> -    if (drm_info->front_info->cfg.be_alloc) {
>>> -        /* This use-case is not yet supported and probably won't be */
>>> -        DRM_ERROR("Backend allocated buffers and CMA helpers are
>>> not supported at the same time\n");
>>> -        return ERR_PTR(-EINVAL);
>>> -    }
>>> -
>>> -    cma_obj = drm_gem_cma_create(dev, size);
>>> -    if (IS_ERR_OR_NULL(cma_obj))
>>> -        return ERR_CAST(cma_obj);
>>> -
>>> -    return &cma_obj->base;
>>> -}
>>> -
>>> -void xen_drm_front_gem_free_object_unlocked(struct drm_gem_object
>>> *gem_obj)
>>> -{
>>> -    drm_gem_cma_free_object(gem_obj);
>>> -}
>>> -
>>> -struct page **xen_drm_front_gem_get_pages(struct drm_gem_object
>>> *gem_obj)
>>> -{
>>> -    return NULL;
>>> -}
>>> diff --git a/drivers/gpu/drm/xen/xen_drm_front_shbuf.c
>>> b/drivers/gpu/drm/xen/xen_drm_front_shbuf.c
>>> index 19914dde4b3d..d5705251a0d6 100644
>>> --- a/drivers/gpu/drm/xen/xen_drm_front_shbuf.c
>>> +++ b/drivers/gpu/drm/xen/xen_drm_front_shbuf.c
>>> @@ -89,10 +89,6 @@ void xen_drm_front_shbuf_free(struct
>>> xen_drm_front_shbuf *buf)
>>>       }
>>>       kfree(buf->grefs);
>>>       kfree(buf->directory);
>>> -    if (buf->sgt) {
>>> -        sg_free_table(buf->sgt);
>>> -        kvfree(buf->pages);
>>> -    }
>>>       kfree(buf);
>>>   }
>>>   @@ -350,17 +346,6 @@ static int grant_references(struct
>>> xen_drm_front_shbuf *buf)
>>>     static int alloc_storage(struct xen_drm_front_shbuf *buf)
>>>   {
>>> -    if (buf->sgt) {
>>> -        buf->pages = kvmalloc_array(buf->num_pages,
>>> -                        sizeof(struct page *), GFP_KERNEL);
>>> -        if (!buf->pages)
>>> -            return -ENOMEM;
>>> -
>>> -        if (drm_prime_sg_to_page_addr_arrays(buf->sgt, buf->pages,
>>> -                             NULL, buf->num_pages) < 0)
>>> -            return -EINVAL;
>>> -    }
>>> -
>>>       buf->grefs = kcalloc(buf->num_grefs, sizeof(*buf->grefs),
>>> GFP_KERNEL);
>>>       if (!buf->grefs)
>>>           return -ENOMEM;
>>> @@ -396,12 +381,6 @@ xen_drm_front_shbuf_alloc(struct
>>> xen_drm_front_shbuf_cfg *cfg)
>>>       struct xen_drm_front_shbuf *buf;
>>>       int ret;
>>>   -    /* either pages or sgt, not both */
>>> -    if (unlikely(cfg->pages && cfg->sgt)) {
>>> -        DRM_ERROR("Cannot handle buffer allocation with both pages
>>> and sg table provided\n");
>>> -        return NULL;
>>> -    }
>>> -
>>>       buf = kzalloc(sizeof(*buf), GFP_KERNEL);
>>>       if (!buf)
>>>           return NULL;
>>> @@ -413,7 +392,6 @@ xen_drm_front_shbuf_alloc(struct
>>> xen_drm_front_shbuf_cfg *cfg)
>>>         buf->xb_dev = cfg->xb_dev;
>>>       buf->num_pages = DIV_ROUND_UP(cfg->size, PAGE_SIZE);
>>> -    buf->sgt = cfg->sgt;
>>>       buf->pages = cfg->pages;
>>>         buf->ops->calc_num_grefs(buf);
>>> diff --git a/drivers/gpu/drm/xen/xen_drm_front_shbuf.h
>>> b/drivers/gpu/drm/xen/xen_drm_front_shbuf.h
>>> index 8c037fd7608b..7545c692539e 100644
>>> --- a/drivers/gpu/drm/xen/xen_drm_front_shbuf.h
>>> +++ b/drivers/gpu/drm/xen/xen_drm_front_shbuf.h
>>> @@ -29,16 +29,9 @@ struct xen_drm_front_shbuf {
>>>       grant_ref_t *grefs;
>>>       unsigned char *directory;
>>>   -    /*
>>> -     * there are 2 ways to provide backing storage for this shared
>>> buffer:
>>> -     * either pages or sgt. if buffer created from sgt then we own
>>> -     * the pages and must free those ourselves on closure
>>> -     */
>>>       int num_pages;
>>>       struct page **pages;
>>>   -    struct sg_table *sgt;
>>> -
>>>       struct xenbus_device *xb_dev;
>>>         /* these are the ops used internally depending on be_alloc
>>> mode */
>>> @@ -52,7 +45,6 @@ struct xen_drm_front_shbuf_cfg {
>>>       struct xenbus_device *xb_dev;
>>>       size_t size;
>>>       struct page **pages;
>>> -    struct sg_table *sgt;
>>>       bool be_alloc;
>>>   };
>>>   --
>>> 2.17.0
>>>
>>> _______________________________________________
>>> dri-devel mailing list
>>> dri-devel@lists.freedesktop.org
>>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
>