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

From: Oleksandr Andrushchenko
Date: Tue Apr 17 2018 - 03:40:29 EST

From: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>

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.

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
Suggested-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
---
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@xxxxxxxx>
- */
-
-#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