Message-Id: <20180417074012.21311-1-andr2000@gmail.com>
Date:   Tue, 17 Apr 2018 10:40:12 +0300
From:   Oleksandr Andrushchenko <andr2000@...il.com>
To:     xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, airlied@...ux.ie,
        daniel.vetter@...el.com, seanpaul@...omium.org,
        gustavo@...ovan.org, jgross@...e.com, boris.ostrovsky@...cle.com,
        konrad.wilk@...cle.com
Cc:     andr2000@...il.com,
        Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
Subject: [PATCH] drm/xen-front: Remove CMA support

From: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.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.

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
Suggested-by: Daniel Vetter <daniel.vetter@...ll.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@...m.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

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