[PATCH v4 0/9] xen: dma-buf support for grant device

[PATCH v4 0/9] xen: dma-buf support for grant device

[Oleksandr Andrushchenko]

From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

This work is in response to my previous attempt to introduce Xen/DRM
zero-copy driver [1] to enable Linux dma-buf API [2] for Xen based
frontends/backends. There is also an existing hyper_dmabuf approach
available [3] which, if reworked to utilize the proposed solution,
can greatly benefit as well.

RFC for this series was published and discussed [9], comments addressed.

The original rationale behind this work was to enable zero-copying
use-cases while working with Xen para-virtual display driver [4]:
when using Xen PV DRM frontend driver then on backend side one will
need to do copying of display buffers' contents (filled by the
frontend's user-space) into buffers allocated at the backend side.
Taking into account the size of display buffers and frames per
second it may result in unneeded huge data bus occupation and
performance loss.

The helper driver [4] allows implementing zero-copying use-cases
when using Xen para-virtualized frontend display driver by implementing
a DRM/KMS helper driver running on backend's side.
It utilizes PRIME buffers API (implemented on top of Linux dma-buf)
to share frontend's buffers with physical device drivers on
backend's side:

 - a dumb buffer created on backend's side can be shared
   with the Xen PV frontend driver, so it directly writes
   into backend's domain memory (into the buffer exported from
   DRM/KMS driver of a physical display device)
 - a dumb buffer allocated by the frontend can be imported
   into physical device DRM/KMS driver, thus allowing to
   achieve no copying as well

Finally, it was discussed and decided ([1], [5]) that it is worth
implementing such use-cases via extension of the existing Xen gntdev
driver instead of introducing new DRM specific driver.
Please note, that the support of dma-buf is Linux only,
as dma-buf is a Linux only thing.

Now to the proposed solution. The changes  to the existing Xen drivers
in the Linux kernel fall into 2 categories:
1. DMA-able memory buffer allocation and increasing/decreasing memory
   reservation of the pages of such a buffer.
   This is required if we are about to share dma-buf with the hardware
   that does require those to be allocated with dma_alloc_xxx API.
   (It is still possible to allocate a dma-buf from any system memory,
   e.g. system pages).
2. Extension of the gntdev driver to enable it to import/export dma-buf’s.

The first six patches are in preparation for Xen dma-buf support,
but I consider those usable regardless of the dma-buf use-case,
e.g. other frontend/backend kernel modules may also benefit from these
for better code reuse:
    0001-xen-grant-table-Export-gnttab_-alloc-free-_pages-as-.patch
    0002-xen-grant-table-Make-set-clear-page-private-code-sha.patch
    0003-xen-balloon-Share-common-memory-reservation-routines.patch
    0004-xen-grant-table-Allow-allocating-buffers-suitable-fo.patch
    0005-xen-gntdev-Allow-mappings-for-DMA-buffers.patch
    0006-xen-gntdev-Make-private-routines-structures-accessib.patch

The next three patches are Xen implementation of dma-buf as part of
the grant device:
    0007-xen-gntdev-Add-initial-support-for-dma-buf-UAPI.patch
    0008-xen-gntdev-Implement-dma-buf-export-functionality.patch
    0009-xen-gntdev-Implement-dma-buf-import-functionality.patch

The corresponding libxengnttab changes are available at [6].

All the above was tested with display backend [7] and its accompanying
helper library [8] on Renesas ARM64 based board.
Basic balloon tests on x86.

*To all the communities*: I would like to ask you to review the proposed
solution and give feedback on it, so I can improve and send final
patches for review (this is still work in progress, but enough to start
discussing the implementation).

Thank you in advance,
Oleksandr Andrushchenko

[1] https://lists.freedesktop.org/archives/dri-devel/2018-April/173163.html
[2] https://elixir.bootlin.com/linux/v4.17-rc5/source/Documentation/driver-api/dma-buf.rst
[3] https://lists.xenproject.org/archives/html/xen-devel/2018-02/msg01202.html
[4] https://cgit.freedesktop.org/drm/drm-misc/tree/drivers/gpu/drm/xen
[5] https://patchwork.kernel.org/patch/10279681/
[6] https://github.com/andr2000/xen/tree/xen_dma_buf_v1
[7] https://github.com/andr2000/displ_be/tree/xen_dma_buf_v1
[8] https://github.com/andr2000/libxenbe/tree/xen_dma_buf_v1
[9] https://lkml.org/lkml/2018/5/17/215

Changes since v3:
*****************
- added r-b tags
- minor fixes
- removed gntdev_remove_map as it can be coded directly now
- moved IOCTL code to gntdev-dmabuf.c
- removed usless wait list walks and changed some walks to use
  normal version of list iterators instead of safe ones as
  we run under a lock anyways
- cleaned up comments, descriptions, pr_debug messages

Changes since v2:
*****************
- fixed missed break in dmabuf_exp_wait_obj_signal
- re-worked debug and error messages, be less verbose
- removed patch for making gntdev functions available to other drivers
- removed WARN_ON's in dma-buf code
- moved all dma-buf related code into gntdev-dmabuf
- introduced gntdev-common.h with common structures and function prototypes
- added additional checks for number of grants in IOCTLs
- gnttab patch cleanup
- made xenmem_reservation_scrub_page defined in the header as inline
- fixed __pfn_to_mfn use to pfn_to_bfn
- no changes to patches 1-2

Changes since v1:
*****************
- Define GNTDEV_DMA_FLAG_XXX starting from bit 0
- Rename mem_reservation.h to mem-reservation.h
- Remove usless comments
- Change licenses from GPLv2 OR MIT to GPLv2 only
- Make xenmem_reservation_va_mapping_{update|clear} inline
- Change EXPORT_SYMBOL to EXPORT_SYMBOL_GPL for new functions
- Make gnttab_dma_{alloc|free}_pages to request frames array
  be allocated outside
- Fixe gnttab_dma_alloc_pages fail path (added xenmem_reservation_increase)
- Move most of dma-buf from gntdev.c to gntdev-dmabuf.c
- Add required dependencies to Kconfig
- Rework "#ifdef CONFIG_XEN_XXX" for if/else
- Export gnttab_{alloc|free}_pages as GPL symbols (patch 1)

Oleksandr Andrushchenko (9):
  xen/grant-table: Export gnttab_{alloc|free}_pages as GPL
  xen/grant-table: Make set/clear page private code shared
  xen/balloon: Share common memory reservation routines
  xen/grant-table: Allow allocating buffers suitable for DMA
  xen/gntdev: Allow mappings for DMA buffers
  xen/gntdev: Make private routines/structures accessible
  xen/gntdev: Add initial support for dma-buf UAPI
  xen/gntdev: Implement dma-buf export functionality
  xen/gntdev: Implement dma-buf import functionality

 drivers/xen/Kconfig           |  24 +
 drivers/xen/Makefile          |   2 +
 drivers/xen/balloon.c         |  75 +--
 drivers/xen/gntdev-common.h   |  94 ++++
 drivers/xen/gntdev-dmabuf.c   | 870 ++++++++++++++++++++++++++++++++++
 drivers/xen/gntdev-dmabuf.h   |  33 ++
 drivers/xen/gntdev.c          | 220 ++++++---
 drivers/xen/grant-table.c     | 153 +++++-
 drivers/xen/mem-reservation.c | 118 +++++
 include/uapi/xen/gntdev.h     | 106 +++++
 include/xen/grant_table.h     |  21 +
 include/xen/mem-reservation.h |  59 +++
 12 files changed, 1615 insertions(+), 160 deletions(-)
 create mode 100644 drivers/xen/gntdev-common.h
 create mode 100644 drivers/xen/gntdev-dmabuf.c
 create mode 100644 drivers/xen/gntdev-dmabuf.h
 create mode 100644 drivers/xen/mem-reservation.c
 create mode 100644 include/xen/mem-reservation.h

-- 
2.17.1

[PATCH v4 1/9] xen/grant-table: Export gnttab_{alloc|free}_pages as GPL

[Oleksandr Andrushchenko]

From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

Only gnttab_{alloc|free}_pages are exported as EXPORT_SYMBOL
while all the rest are exported as EXPORT_SYMBOL_GPL, thus
effectively making it not possible for non-GPL driver modules
to use grant table module. Export gnttab_{alloc|free}_pages as
EXPORT_SYMBOL_GPL so all the exports are aligned.

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
---
 drivers/xen/grant-table.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index 27be107d6480..ba36ff3e4903 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -799,7 +799,7 @@ int gnttab_alloc_pages(int nr_pages, struct page **pages)
 
 	return 0;
 }
-EXPORT_SYMBOL(gnttab_alloc_pages);
+EXPORT_SYMBOL_GPL(gnttab_alloc_pages);
 
 /**
  * gnttab_free_pages - free pages allocated by gnttab_alloc_pages()
@@ -820,7 +820,7 @@ void gnttab_free_pages(int nr_pages, struct page **pages)
 	}
 	free_xenballooned_pages(nr_pages, pages);
 }
-EXPORT_SYMBOL(gnttab_free_pages);
+EXPORT_SYMBOL_GPL(gnttab_free_pages);
 
 /* Handling of paged out grant targets (GNTST_eagain) */
 #define MAX_DELAY 256
-- 
2.17.1

[PATCH v4 2/9] xen/grant-table: Make set/clear page private code shared

[Oleksandr Andrushchenko]

From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

Make set/clear page private code shared and accessible to
other kernel modules which can re-use these instead of open-coding.

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
---
 drivers/xen/grant-table.c | 54 +++++++++++++++++++++++++--------------
 include/xen/grant_table.h |  3 +++
 2 files changed, 38 insertions(+), 19 deletions(-)

diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index ba36ff3e4903..dbb48a89e987 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -769,29 +769,18 @@ void gnttab_free_auto_xlat_frames(void)
 }
 EXPORT_SYMBOL_GPL(gnttab_free_auto_xlat_frames);
 
-/**
- * gnttab_alloc_pages - alloc pages suitable for grant mapping into
- * @nr_pages: number of pages to alloc
- * @pages: returns the pages
- */
-int gnttab_alloc_pages(int nr_pages, struct page **pages)
+int gnttab_pages_set_private(int nr_pages, struct page **pages)
 {
 	int i;
-	int ret;
-
-	ret = alloc_xenballooned_pages(nr_pages, pages);
-	if (ret < 0)
-		return ret;
 
 	for (i = 0; i < nr_pages; i++) {
 #if BITS_PER_LONG < 64
 		struct xen_page_foreign *foreign;
 
 		foreign = kzalloc(sizeof(*foreign), GFP_KERNEL);
-		if (!foreign) {
-			gnttab_free_pages(nr_pages, pages);
+		if (!foreign)
 			return -ENOMEM;
-		}
+
 		set_page_private(pages[i], (unsigned long)foreign);
 #endif
 		SetPagePrivate(pages[i]);
@@ -799,14 +788,30 @@ int gnttab_alloc_pages(int nr_pages, struct page **pages)
 
 	return 0;
 }
-EXPORT_SYMBOL_GPL(gnttab_alloc_pages);
+EXPORT_SYMBOL_GPL(gnttab_pages_set_private);
 
 /**
- * gnttab_free_pages - free pages allocated by gnttab_alloc_pages()
- * @nr_pages; number of pages to free
- * @pages: the pages
+ * gnttab_alloc_pages - alloc pages suitable for grant mapping into
+ * @nr_pages: number of pages to alloc
+ * @pages: returns the pages
  */
-void gnttab_free_pages(int nr_pages, struct page **pages)
+int gnttab_alloc_pages(int nr_pages, struct page **pages)
+{
+	int ret;
+
+	ret = alloc_xenballooned_pages(nr_pages, pages);
+	if (ret < 0)
+		return ret;
+
+	ret = gnttab_pages_set_private(nr_pages, pages);
+	if (ret < 0)
+		gnttab_free_pages(nr_pages, pages);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(gnttab_alloc_pages);
+
+void gnttab_pages_clear_private(int nr_pages, struct page **pages)
 {
 	int i;
 
@@ -818,6 +823,17 @@ void gnttab_free_pages(int nr_pages, struct page **pages)
 			ClearPagePrivate(pages[i]);
 		}
 	}
+}
+EXPORT_SYMBOL_GPL(gnttab_pages_clear_private);
+
+/**
+ * gnttab_free_pages - free pages allocated by gnttab_alloc_pages()
+ * @nr_pages; number of pages to free
+ * @pages: the pages
+ */
+void gnttab_free_pages(int nr_pages, struct page **pages)
+{
+	gnttab_pages_clear_private(nr_pages, pages);
 	free_xenballooned_pages(nr_pages, pages);
 }
 EXPORT_SYMBOL_GPL(gnttab_free_pages);
diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h
index 2e37741f6b8d..de03f2542bb7 100644
--- a/include/xen/grant_table.h
+++ b/include/xen/grant_table.h
@@ -198,6 +198,9 @@ void gnttab_free_auto_xlat_frames(void);
 int gnttab_alloc_pages(int nr_pages, struct page **pages);
 void gnttab_free_pages(int nr_pages, struct page **pages);
 
+int gnttab_pages_set_private(int nr_pages, struct page **pages);
+void gnttab_pages_clear_private(int nr_pages, struct page **pages);
+
 int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
 		    struct gnttab_map_grant_ref *kmap_ops,
 		    struct page **pages, unsigned int count);
-- 
2.17.1

[PATCH v4 3/9] xen/balloon: Share common memory reservation routines

[Oleksandr Andrushchenko]

From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

Memory {increase|decrease}_reservation and VA mappings update/reset
code used in balloon driver can be made common, so other drivers can
also re-use the same functionality without open-coding.
Create a dedicated file for the shared code and export corresponding
symbols for other kernel modules.

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
---
 drivers/xen/Makefile          |   1 +
 drivers/xen/balloon.c         |  75 ++-------------------
 drivers/xen/mem-reservation.c | 118 ++++++++++++++++++++++++++++++++++
 include/xen/mem-reservation.h |  59 +++++++++++++++++
 4 files changed, 184 insertions(+), 69 deletions(-)
 create mode 100644 drivers/xen/mem-reservation.c
 create mode 100644 include/xen/mem-reservation.h

diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index 451e833f5931..3c87b0c3aca6 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -2,6 +2,7 @@
 obj-$(CONFIG_HOTPLUG_CPU)		+= cpu_hotplug.o
 obj-$(CONFIG_X86)			+= fallback.o
 obj-y	+= grant-table.o features.o balloon.o manage.o preempt.o time.o
+obj-y	+= mem-reservation.o
 obj-y	+= events/
 obj-y	+= xenbus/
 
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 065f0b607373..e12bb256036f 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -71,6 +71,7 @@
 #include <xen/balloon.h>
 #include <xen/features.h>
 #include <xen/page.h>
+#include <xen/mem-reservation.h>
 
 static int xen_hotplug_unpopulated;
 
@@ -157,13 +158,6 @@ static DECLARE_DELAYED_WORK(balloon_worker, balloon_process);
 #define GFP_BALLOON \
 	(GFP_HIGHUSER | __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC)
 
-static void scrub_page(struct page *page)
-{
-#ifdef CONFIG_XEN_SCRUB_PAGES
-	clear_highpage(page);
-#endif
-}
-
 /* balloon_append: add the given page to the balloon. */
 static void __balloon_append(struct page *page)
 {
@@ -463,11 +457,6 @@ static enum bp_state increase_reservation(unsigned long nr_pages)
 	int rc;
 	unsigned long i;
 	struct page   *page;
-	struct xen_memory_reservation reservation = {
-		.address_bits = 0,
-		.extent_order = EXTENT_ORDER,
-		.domid        = DOMID_SELF
-	};
 
 	if (nr_pages > ARRAY_SIZE(frame_list))
 		nr_pages = ARRAY_SIZE(frame_list);
@@ -479,16 +468,11 @@ static enum bp_state increase_reservation(unsigned long nr_pages)
 			break;
 		}
 
-		/* XENMEM_populate_physmap requires a PFN based on Xen
-		 * granularity.
-		 */
 		frame_list[i] = page_to_xen_pfn(page);
 		page = balloon_next_page(page);
 	}
 
-	set_xen_guest_handle(reservation.extent_start, frame_list);
-	reservation.nr_extents = nr_pages;
-	rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
+	rc = xenmem_reservation_increase(nr_pages, frame_list);
 	if (rc <= 0)
 		return BP_EAGAIN;
 
@@ -496,29 +480,7 @@ static enum bp_state increase_reservation(unsigned long nr_pages)
 		page = balloon_retrieve(false);
 		BUG_ON(page == NULL);
 
-#ifdef CONFIG_XEN_HAVE_PVMMU
-		/*
-		 * We don't support PV MMU when Linux and Xen is using
-		 * different page granularity.
-		 */
-		BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
-
-		if (!xen_feature(XENFEAT_auto_translated_physmap)) {
-			unsigned long pfn = page_to_pfn(page);
-
-			set_phys_to_machine(pfn, frame_list[i]);
-
-			/* Link back into the page tables if not highmem. */
-			if (!PageHighMem(page)) {
-				int ret;
-				ret = HYPERVISOR_update_va_mapping(
-						(unsigned long)__va(pfn << PAGE_SHIFT),
-						mfn_pte(frame_list[i], PAGE_KERNEL),
-						0);
-				BUG_ON(ret);
-			}
-		}
-#endif
+		xenmem_reservation_va_mapping_update(1, &page, &frame_list[i]);
 
 		/* Relinquish the page back to the allocator. */
 		free_reserved_page(page);
@@ -535,11 +497,6 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
 	unsigned long i;
 	struct page *page, *tmp;
 	int ret;
-	struct xen_memory_reservation reservation = {
-		.address_bits = 0,
-		.extent_order = EXTENT_ORDER,
-		.domid        = DOMID_SELF
-	};
 	LIST_HEAD(pages);
 
 	if (nr_pages > ARRAY_SIZE(frame_list))
@@ -553,7 +510,7 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
 			break;
 		}
 		adjust_managed_page_count(page, -1);
-		scrub_page(page);
+		xenmem_reservation_scrub_page(page);
 		list_add(&page->lru, &pages);
 	}
 
@@ -572,28 +529,10 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
 	 */
 	i = 0;
 	list_for_each_entry_safe(page, tmp, &pages, lru) {
-		/* XENMEM_decrease_reservation requires a GFN */
 		frame_list[i++] = xen_page_to_gfn(page);
 
-#ifdef CONFIG_XEN_HAVE_PVMMU
-		/*
-		 * We don't support PV MMU when Linux and Xen is using
-		 * different page granularity.
-		 */
-		BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
-
-		if (!xen_feature(XENFEAT_auto_translated_physmap)) {
-			unsigned long pfn = page_to_pfn(page);
+		xenmem_reservation_va_mapping_reset(1, &page);
 
-			if (!PageHighMem(page)) {
-				ret = HYPERVISOR_update_va_mapping(
-						(unsigned long)__va(pfn << PAGE_SHIFT),
-						__pte_ma(0), 0);
-				BUG_ON(ret);
-			}
-			__set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
-		}
-#endif
 		list_del(&page->lru);
 
 		balloon_append(page);
@@ -601,9 +540,7 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
 
 	flush_tlb_all();
 
-	set_xen_guest_handle(reservation.extent_start, frame_list);
-	reservation.nr_extents   = nr_pages;
-	ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation);
+	ret = xenmem_reservation_decrease(nr_pages, frame_list);
 	BUG_ON(ret != nr_pages);
 
 	balloon_stats.current_pages -= nr_pages;
diff --git a/drivers/xen/mem-reservation.c b/drivers/xen/mem-reservation.c
new file mode 100644
index 000000000000..084799c6180e
--- /dev/null
+++ b/drivers/xen/mem-reservation.c
@@ -0,0 +1,118 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/******************************************************************************
+ * Xen memory reservation utilities.
+ *
+ * Copyright (c) 2003, B Dragovic
+ * Copyright (c) 2003-2004, M Williamson, K Fraser
+ * Copyright (c) 2005 Dan M. Smith, IBM Corporation
+ * Copyright (c) 2010 Daniel Kiper
+ * Copyright (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
+ */
+
+#include <asm/xen/hypercall.h>
+
+#include <xen/interface/memory.h>
+#include <xen/mem-reservation.h>
+
+/*
+ * Use one extent per PAGE_SIZE to avoid to break down the page into
+ * multiple frame.
+ */
+#define EXTENT_ORDER (fls(XEN_PFN_PER_PAGE) - 1)
+
+#ifdef CONFIG_XEN_HAVE_PVMMU
+void __xenmem_reservation_va_mapping_update(unsigned long count,
+					    struct page **pages,
+					    xen_pfn_t *frames)
+{
+	int i;
+
+	for (i = 0; i < count; i++) {
+		struct page *page = pages[i];
+		unsigned long pfn = page_to_pfn(page);
+
+		BUG_ON(!page);
+
+		/*
+		 * We don't support PV MMU when Linux and Xen is using
+		 * different page granularity.
+		 */
+		BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
+
+		set_phys_to_machine(pfn, frames[i]);
+
+		/* Link back into the page tables if not highmem. */
+		if (!PageHighMem(page)) {
+			int ret;
+
+			ret = HYPERVISOR_update_va_mapping(
+					(unsigned long)__va(pfn << PAGE_SHIFT),
+					mfn_pte(frames[i], PAGE_KERNEL),
+					0);
+			BUG_ON(ret);
+		}
+	}
+}
+EXPORT_SYMBOL_GPL(__xenmem_reservation_va_mapping_update);
+
+void __xenmem_reservation_va_mapping_reset(unsigned long count,
+					   struct page **pages)
+{
+	int i;
+
+	for (i = 0; i < count; i++) {
+		struct page *page = pages[i];
+		unsigned long pfn = page_to_pfn(page);
+
+		/*
+		 * We don't support PV MMU when Linux and Xen are using
+		 * different page granularity.
+		 */
+		BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
+
+		if (!PageHighMem(page)) {
+			int ret;
+
+			ret = HYPERVISOR_update_va_mapping(
+					(unsigned long)__va(pfn << PAGE_SHIFT),
+					__pte_ma(0), 0);
+			BUG_ON(ret);
+		}
+		__set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
+	}
+}
+EXPORT_SYMBOL_GPL(__xenmem_reservation_va_mapping_reset);
+#endif /* CONFIG_XEN_HAVE_PVMMU */
+
+/* @frames is an array of PFNs */
+int xenmem_reservation_increase(int count, xen_pfn_t *frames)
+{
+	struct xen_memory_reservation reservation = {
+		.address_bits = 0,
+		.extent_order = EXTENT_ORDER,
+		.domid        = DOMID_SELF
+	};
+
+	/* XENMEM_populate_physmap requires a PFN based on Xen granularity. */
+	set_xen_guest_handle(reservation.extent_start, frames);
+	reservation.nr_extents = count;
+	return HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
+}
+EXPORT_SYMBOL_GPL(xenmem_reservation_increase);
+
+/* @frames is an array of GFNs */
+int xenmem_reservation_decrease(int count, xen_pfn_t *frames)
+{
+	struct xen_memory_reservation reservation = {
+		.address_bits = 0,
+		.extent_order = EXTENT_ORDER,
+		.domid        = DOMID_SELF
+	};
+
+	/* XENMEM_decrease_reservation requires a GFN */
+	set_xen_guest_handle(reservation.extent_start, frames);
+	reservation.nr_extents = count;
+	return HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation);
+}
+EXPORT_SYMBOL_GPL(xenmem_reservation_decrease);
diff --git a/include/xen/mem-reservation.h b/include/xen/mem-reservation.h
new file mode 100644
index 000000000000..80b52b4945e9
--- /dev/null
+++ b/include/xen/mem-reservation.h
@@ -0,0 +1,59 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * Xen memory reservation utilities.
+ *
+ * Copyright (c) 2003, B Dragovic
+ * Copyright (c) 2003-2004, M Williamson, K Fraser
+ * Copyright (c) 2005 Dan M. Smith, IBM Corporation
+ * Copyright (c) 2010 Daniel Kiper
+ * Copyright (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
+ */
+
+#ifndef _XENMEM_RESERVATION_H
+#define _XENMEM_RESERVATION_H
+
+#include <linux/highmem.h>
+
+#include <xen/page.h>
+
+static inline void xenmem_reservation_scrub_page(struct page *page)
+{
+#ifdef CONFIG_XEN_SCRUB_PAGES
+	clear_highpage(page);
+#endif
+}
+
+#ifdef CONFIG_XEN_HAVE_PVMMU
+void __xenmem_reservation_va_mapping_update(unsigned long count,
+					    struct page **pages,
+					    xen_pfn_t *frames);
+
+void __xenmem_reservation_va_mapping_reset(unsigned long count,
+					   struct page **pages);
+#endif
+
+static inline void xenmem_reservation_va_mapping_update(unsigned long count,
+							struct page **pages,
+							xen_pfn_t *frames)
+{
+#ifdef CONFIG_XEN_HAVE_PVMMU
+	if (!xen_feature(XENFEAT_auto_translated_physmap))
+		__xenmem_reservation_va_mapping_update(count, pages, frames);
+#endif
+}
+
+static inline void xenmem_reservation_va_mapping_reset(unsigned long count,
+						       struct page **pages)
+{
+#ifdef CONFIG_XEN_HAVE_PVMMU
+	if (!xen_feature(XENFEAT_auto_translated_physmap))
+		__xenmem_reservation_va_mapping_reset(count, pages);
+#endif
+}
+
+int xenmem_reservation_increase(int count, xen_pfn_t *frames);
+
+int xenmem_reservation_decrease(int count, xen_pfn_t *frames);
+
+#endif
-- 
2.17.1

[PATCH v4 4/9] xen/grant-table: Allow allocating buffers suitable for DMA

[Oleksandr Andrushchenko]

From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

Extend grant table module API to allow allocating buffers that can
be used for DMA operations and mapping foreign grant references
on top of those.
The resulting buffer is similar to the one allocated by the balloon
driver in that proper memory reservation is made by
({increase|decrease}_reservation and VA mappings are updated if
needed).
This is useful for sharing foreign buffers with HW drivers which
cannot work with scattered buffers provided by the balloon driver,
but require DMAable memory instead.

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
---
 drivers/xen/Kconfig       | 14 ++++++
 drivers/xen/grant-table.c | 97 +++++++++++++++++++++++++++++++++++++++
 include/xen/grant_table.h | 18 ++++++++
 3 files changed, 129 insertions(+)

diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index e5d0c28372ea..75e5c40f80a5 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -161,6 +161,20 @@ config XEN_GRANT_DEV_ALLOC
 	  to other domains. This can be used to implement frontend drivers
 	  or as part of an inter-domain shared memory channel.
 
+config XEN_GRANT_DMA_ALLOC
+	bool "Allow allocating DMA capable buffers with grant reference module"
+	depends on XEN && HAS_DMA
+	help
+	  Extends grant table module API to allow allocating DMA capable
+	  buffers and mapping foreign grant references on top of it.
+	  The resulting buffer is similar to one allocated by the balloon
+	  driver in that proper memory reservation is made by
+	  ({increase|decrease}_reservation and VA mappings are updated if
+	  needed).
+	  This is useful for sharing foreign buffers with HW drivers which
+	  cannot work with scattered buffers provided by the balloon driver,
+	  but require DMAable memory instead.
+
 config SWIOTLB_XEN
 	def_bool y
 	select SWIOTLB
diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index dbb48a89e987..26ed498b5e6d 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -45,6 +45,9 @@
 #include <linux/workqueue.h>
 #include <linux/ratelimit.h>
 #include <linux/moduleparam.h>
+#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
+#include <linux/dma-mapping.h>
+#endif
 
 #include <xen/xen.h>
 #include <xen/interface/xen.h>
@@ -57,6 +60,7 @@
 #ifdef CONFIG_X86
 #include <asm/xen/cpuid.h>
 #endif
+#include <xen/mem-reservation.h>
 #include <asm/xen/hypercall.h>
 #include <asm/xen/interface.h>
 
@@ -838,6 +842,99 @@ void gnttab_free_pages(int nr_pages, struct page **pages)
 }
 EXPORT_SYMBOL_GPL(gnttab_free_pages);
 
+#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
+/**
+ * gnttab_dma_alloc_pages - alloc DMAable pages suitable for grant mapping into
+ * @args: arguments to the function
+ */
+int gnttab_dma_alloc_pages(struct gnttab_dma_alloc_args *args)
+{
+	unsigned long pfn, start_pfn;
+	size_t size;
+	int i, ret;
+
+	size = args->nr_pages << PAGE_SHIFT;
+	if (args->coherent)
+		args->vaddr = dma_alloc_coherent(args->dev, size,
+						 &args->dev_bus_addr,
+						 GFP_KERNEL | __GFP_NOWARN);
+	else
+		args->vaddr = dma_alloc_wc(args->dev, size,
+					   &args->dev_bus_addr,
+					   GFP_KERNEL | __GFP_NOWARN);
+	if (!args->vaddr) {
+		pr_debug("Failed to allocate DMA buffer of size %zu\n", size);
+		return -ENOMEM;
+	}
+
+	start_pfn = __phys_to_pfn(args->dev_bus_addr);
+	for (pfn = start_pfn, i = 0; pfn < start_pfn + args->nr_pages;
+			pfn++, i++) {
+		struct page *page = pfn_to_page(pfn);
+
+		args->pages[i] = page;
+		args->frames[i] = xen_page_to_gfn(page);
+		xenmem_reservation_scrub_page(page);
+	}
+
+	xenmem_reservation_va_mapping_reset(args->nr_pages, args->pages);
+
+	ret = xenmem_reservation_decrease(args->nr_pages, args->frames);
+	if (ret != args->nr_pages) {
+		pr_debug("Failed to decrease reservation for DMA buffer\n");
+		ret = -EFAULT;
+		goto fail;
+	}
+
+	ret = gnttab_pages_set_private(args->nr_pages, args->pages);
+	if (ret < 0)
+		goto fail;
+
+	return 0;
+
+fail:
+	gnttab_dma_free_pages(args);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(gnttab_dma_alloc_pages);
+
+/**
+ * gnttab_dma_free_pages - free DMAable pages
+ * @args: arguments to the function
+ */
+int gnttab_dma_free_pages(struct gnttab_dma_alloc_args *args)
+{
+	size_t size;
+	int i, ret;
+
+	gnttab_pages_clear_private(args->nr_pages, args->pages);
+
+	for (i = 0; i < args->nr_pages; i++)
+		args->frames[i] = page_to_xen_pfn(args->pages[i]);
+
+	ret = xenmem_reservation_increase(args->nr_pages, args->frames);
+	if (ret != args->nr_pages) {
+		pr_debug("Failed to decrease reservation for DMA buffer\n");
+		ret = -EFAULT;
+	} else {
+		ret = 0;
+	}
+
+	xenmem_reservation_va_mapping_update(args->nr_pages, args->pages,
+					     args->frames);
+
+	size = args->nr_pages << PAGE_SHIFT;
+	if (args->coherent)
+		dma_free_coherent(args->dev, size,
+				  args->vaddr, args->dev_bus_addr);
+	else
+		dma_free_wc(args->dev, size,
+			    args->vaddr, args->dev_bus_addr);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(gnttab_dma_free_pages);
+#endif
+
 /* Handling of paged out grant targets (GNTST_eagain) */
 #define MAX_DELAY 256
 static inline void
diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h
index de03f2542bb7..9bc5bc07d4d3 100644
--- a/include/xen/grant_table.h
+++ b/include/xen/grant_table.h
@@ -198,6 +198,24 @@ void gnttab_free_auto_xlat_frames(void);
 int gnttab_alloc_pages(int nr_pages, struct page **pages);
 void gnttab_free_pages(int nr_pages, struct page **pages);
 
+#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
+struct gnttab_dma_alloc_args {
+	/* Device for which DMA memory will be/was allocated. */
+	struct device *dev;
+	/* If set then DMA buffer is coherent and write-combine otherwise. */
+	bool coherent;
+
+	int nr_pages;
+	struct page **pages;
+	xen_pfn_t *frames;
+	void *vaddr;
+	dma_addr_t dev_bus_addr;
+};
+
+int gnttab_dma_alloc_pages(struct gnttab_dma_alloc_args *args);
+int gnttab_dma_free_pages(struct gnttab_dma_alloc_args *args);
+#endif
+
 int gnttab_pages_set_private(int nr_pages, struct page **pages);
 void gnttab_pages_clear_private(int nr_pages, struct page **pages);
 
-- 
2.17.1

[PATCH v4 5/9] xen/gntdev: Allow mappings for DMA buffers

[Oleksandr Andrushchenko]

From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

Allow mappings for DMA backed  buffers if grant table module
supports such: this extends grant device to not only map buffers
made of balloon pages, but also from buffers allocated with
dma_alloc_xxx.

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
---
 drivers/xen/gntdev.c      | 99 ++++++++++++++++++++++++++++++++++++++-
 include/uapi/xen/gntdev.h | 15 ++++++
 2 files changed, 112 insertions(+), 2 deletions(-)

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index bd56653b9bbc..0ec670d1d4e7 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -37,6 +37,9 @@
 #include <linux/slab.h>
 #include <linux/highmem.h>
 #include <linux/refcount.h>
+#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
+#include <linux/of_device.h>
+#endif
 
 #include <xen/xen.h>
 #include <xen/grant_table.h>
@@ -72,6 +75,11 @@ struct gntdev_priv {
 	struct mutex lock;
 	struct mm_struct *mm;
 	struct mmu_notifier mn;
+
+#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
+	/* Device for which DMA memory is allocated. */
+	struct device *dma_dev;
+#endif
 };
 
 struct unmap_notify {
@@ -96,10 +104,27 @@ struct grant_map {
 	struct gnttab_unmap_grant_ref *kunmap_ops;
 	struct page **pages;
 	unsigned long pages_vm_start;
+
+#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
+	/*
+	 * If dmabuf_vaddr is not NULL then this mapping is backed by DMA
+	 * capable memory.
+	 */
+
+	struct device *dma_dev;
+	/* Flags used to create this DMA buffer: GNTDEV_DMA_FLAG_XXX. */
+	int dma_flags;
+	void *dma_vaddr;
+	dma_addr_t dma_bus_addr;
+	/* Needed to avoid allocation in gnttab_dma_free_pages(). */
+	xen_pfn_t *frames;
+#endif
 };
 
 static int unmap_grant_pages(struct grant_map *map, int offset, int pages);
 
+static struct miscdevice gntdev_miscdev;
+
 /* ------------------------------------------------------------------ */
 
 static void gntdev_print_maps(struct gntdev_priv *priv,
@@ -121,8 +146,27 @@ static void gntdev_free_map(struct grant_map *map)
 	if (map == NULL)
 		return;
 
+#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
+	if (map->dma_vaddr) {
+		struct gnttab_dma_alloc_args args;
+
+		args.dev = map->dma_dev;
+		args.coherent = !!(map->dma_flags & GNTDEV_DMA_FLAG_COHERENT);
+		args.nr_pages = map->count;
+		args.pages = map->pages;
+		args.frames = map->frames;
+		args.vaddr = map->dma_vaddr;
+		args.dev_bus_addr = map->dma_bus_addr;
+
+		gnttab_dma_free_pages(&args);
+	} else
+#endif
 	if (map->pages)
 		gnttab_free_pages(map->count, map->pages);
+
+#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
+	kfree(map->frames);
+#endif
 	kfree(map->pages);
 	kfree(map->grants);
 	kfree(map->map_ops);
@@ -132,7 +176,8 @@ static void gntdev_free_map(struct grant_map *map)
 	kfree(map);
 }
 
-static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count)
+static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count,
+					  int dma_flags)
 {
 	struct grant_map *add;
 	int i;
@@ -155,6 +200,37 @@ static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count)
 	    NULL == add->pages)
 		goto err;
 
+#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
+	add->dma_flags = dma_flags;
+
+	/*
+	 * Check if this mapping is requested to be backed
+	 * by a DMA buffer.
+	 */
+	if (dma_flags & (GNTDEV_DMA_FLAG_WC | GNTDEV_DMA_FLAG_COHERENT)) {
+		struct gnttab_dma_alloc_args args;
+
+		add->frames = kcalloc(count, sizeof(add->frames[0]),
+				      GFP_KERNEL);
+		if (!add->frames)
+			goto err;
+
+		/* Remember the device, so we can free DMA memory. */
+		add->dma_dev = priv->dma_dev;
+
+		args.dev = priv->dma_dev;
+		args.coherent = !!(dma_flags & GNTDEV_DMA_FLAG_COHERENT);
+		args.nr_pages = count;
+		args.pages = add->pages;
+		args.frames = add->frames;
+
+		if (gnttab_dma_alloc_pages(&args))
+			goto err;
+
+		add->dma_vaddr = args.vaddr;
+		add->dma_bus_addr = args.dev_bus_addr;
+	} else
+#endif
 	if (gnttab_alloc_pages(count, add->pages))
 		goto err;
 
@@ -325,6 +401,14 @@ static int map_grant_pages(struct grant_map *map)
 		map->unmap_ops[i].handle = map->map_ops[i].handle;
 		if (use_ptemod)
 			map->kunmap_ops[i].handle = map->kmap_ops[i].handle;
+#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
+		else if (map->dma_vaddr) {
+			unsigned long bfn;
+
+			bfn = pfn_to_bfn(page_to_pfn(map->pages[i]));
+			map->unmap_ops[i].dev_bus_addr = __pfn_to_phys(bfn);
+		}
+#endif
 	}
 	return err;
 }
@@ -548,6 +632,17 @@ static int gntdev_open(struct inode *inode, struct file *flip)
 	}
 
 	flip->private_data = priv;
+#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
+	priv->dma_dev = gntdev_miscdev.this_device;
+
+	/*
+	 * The device is not spawn from a device tree, so arch_setup_dma_ops
+	 * is not called, thus leaving the device with dummy DMA ops.
+	 * Fix this by calling of_dma_configure() with a NULL node to set
+	 * default DMA ops.
+	 */
+	of_dma_configure(priv->dma_dev, NULL);
+#endif
 	pr_debug("priv %p\n", priv);
 
 	return 0;
@@ -589,7 +684,7 @@ static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv,
 		return -EINVAL;
 
 	err = -ENOMEM;
-	map = gntdev_alloc_map(priv, op.count);
+	map = gntdev_alloc_map(priv, op.count, 0 /* This is not a dma-buf. */);
 	if (!map)
 		return err;
 
diff --git a/include/uapi/xen/gntdev.h b/include/uapi/xen/gntdev.h
index 6d1163456c03..4b9d498a31d4 100644
--- a/include/uapi/xen/gntdev.h
+++ b/include/uapi/xen/gntdev.h
@@ -200,4 +200,19 @@ struct ioctl_gntdev_grant_copy {
 /* Send an interrupt on the indicated event channel */
 #define UNMAP_NOTIFY_SEND_EVENT 0x2
 
+/*
+ * 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)
+
 #endif /* __LINUX_PUBLIC_GNTDEV_H__ */
-- 
2.17.1

[PATCH v4 6/9] xen/gntdev: Make private routines/structures accessible

[Oleksandr Andrushchenko]

From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

This is in preparation for adding support of DMA buffer
functionality: make map/unmap related code and structures, used
privately by gntdev, ready for dma-buf extension, which will re-use
these. Rename corresponding structures as those become non-private
to gntdev now.

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
---
 drivers/xen/gntdev-common.h |  88 +++++++++++++++++++++++
 drivers/xen/gntdev.c        | 134 ++++++++++++------------------------
 2 files changed, 131 insertions(+), 91 deletions(-)
 create mode 100644 drivers/xen/gntdev-common.h

diff --git a/drivers/xen/gntdev-common.h b/drivers/xen/gntdev-common.h
new file mode 100644
index 000000000000..2346c198f72e
--- /dev/null
+++ b/drivers/xen/gntdev-common.h
@@ -0,0 +1,88 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * Common functionality of grant device.
+ *
+ * Copyright (c) 2006-2007, D G Murray.
+ *           (c) 2009 Gerd Hoffmann <kraxel@redhat.com>
+ *           (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
+ */
+
+#ifndef _GNTDEV_COMMON_H
+#define _GNTDEV_COMMON_H
+
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/mmu_notifier.h>
+#include <linux/types.h>
+
+struct gntdev_priv {
+	/* Maps with visible offsets in the file descriptor. */
+	struct list_head maps;
+	/*
+	 * Maps that are not visible; will be freed on munmap.
+	 * Only populated if populate_freeable_maps == 1
+	 */
+	struct list_head freeable_maps;
+	/* lock protects maps and freeable_maps. */
+	struct mutex lock;
+	struct mm_struct *mm;
+	struct mmu_notifier mn;
+
+#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
+	/* Device for which DMA memory is allocated. */
+	struct device *dma_dev;
+#endif
+};
+
+struct gntdev_unmap_notify {
+	int flags;
+	/* Address relative to the start of the gntdev_grant_map. */
+	int addr;
+	int event;
+};
+
+struct gntdev_grant_map {
+	struct list_head next;
+	struct vm_area_struct *vma;
+	int index;
+	int count;
+	int flags;
+	refcount_t users;
+	struct gntdev_unmap_notify notify;
+	struct ioctl_gntdev_grant_ref *grants;
+	struct gnttab_map_grant_ref   *map_ops;
+	struct gnttab_unmap_grant_ref *unmap_ops;
+	struct gnttab_map_grant_ref   *kmap_ops;
+	struct gnttab_unmap_grant_ref *kunmap_ops;
+	struct page **pages;
+	unsigned long pages_vm_start;
+
+#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
+	/*
+	 * If dmabuf_vaddr is not NULL then this mapping is backed by DMA
+	 * capable memory.
+	 */
+
+	struct device *dma_dev;
+	/* Flags used to create this DMA buffer: GNTDEV_DMA_FLAG_XXX. */
+	int dma_flags;
+	void *dma_vaddr;
+	dma_addr_t dma_bus_addr;
+	/* Needed to avoid allocation in gnttab_dma_free_pages(). */
+	xen_pfn_t *frames;
+#endif
+};
+
+struct gntdev_grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count,
+					  int dma_flags);
+
+void gntdev_add_map(struct gntdev_priv *priv, struct gntdev_grant_map *add);
+
+void gntdev_put_map(struct gntdev_priv *priv, struct gntdev_grant_map *map);
+
+bool gntdev_account_mapped_pages(int count);
+
+int gntdev_map_grant_pages(struct gntdev_grant_map *map);
+
+#endif
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 0ec670d1d4e7..3385fc4ed386 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -6,6 +6,7 @@
  *
  * Copyright (c) 2006-2007, D G Murray.
  *           (c) 2009 Gerd Hoffmann <kraxel@redhat.com>
+ *           (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ -26,10 +27,6 @@
 #include <linux/init.h>
 #include <linux/miscdevice.h>
 #include <linux/fs.h>
-#include <linux/mm.h>
-#include <linux/mman.h>
-#include <linux/mmu_notifier.h>
-#include <linux/types.h>
 #include <linux/uaccess.h>
 #include <linux/sched.h>
 #include <linux/sched/mm.h>
@@ -50,6 +47,8 @@
 #include <asm/xen/hypervisor.h>
 #include <asm/xen/hypercall.h>
 
+#include "gntdev-common.h"
+
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Derek G. Murray <Derek.Murray@cl.cam.ac.uk>, "
 	      "Gerd Hoffmann <kraxel@redhat.com>");
@@ -65,73 +64,23 @@ static atomic_t pages_mapped = ATOMIC_INIT(0);
 static int use_ptemod;
 #define populate_freeable_maps use_ptemod
 
-struct gntdev_priv {
-	/* maps with visible offsets in the file descriptor */
-	struct list_head maps;
-	/* maps that are not visible; will be freed on munmap.
-	 * Only populated if populate_freeable_maps == 1 */
-	struct list_head freeable_maps;
-	/* lock protects maps and freeable_maps */
-	struct mutex lock;
-	struct mm_struct *mm;
-	struct mmu_notifier mn;
-
-#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
-	/* Device for which DMA memory is allocated. */
-	struct device *dma_dev;
-#endif
-};
-
-struct unmap_notify {
-	int flags;
-	/* Address relative to the start of the grant_map */
-	int addr;
-	int event;
-};
-
-struct grant_map {
-	struct list_head next;
-	struct vm_area_struct *vma;
-	int index;
-	int count;
-	int flags;
-	refcount_t users;
-	struct unmap_notify notify;
-	struct ioctl_gntdev_grant_ref *grants;
-	struct gnttab_map_grant_ref   *map_ops;
-	struct gnttab_unmap_grant_ref *unmap_ops;
-	struct gnttab_map_grant_ref   *kmap_ops;
-	struct gnttab_unmap_grant_ref *kunmap_ops;
-	struct page **pages;
-	unsigned long pages_vm_start;
-
-#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
-	/*
-	 * If dmabuf_vaddr is not NULL then this mapping is backed by DMA
-	 * capable memory.
-	 */
-
-	struct device *dma_dev;
-	/* Flags used to create this DMA buffer: GNTDEV_DMA_FLAG_XXX. */
-	int dma_flags;
-	void *dma_vaddr;
-	dma_addr_t dma_bus_addr;
-	/* Needed to avoid allocation in gnttab_dma_free_pages(). */
-	xen_pfn_t *frames;
-#endif
-};
-
-static int unmap_grant_pages(struct grant_map *map, int offset, int pages);
+static int unmap_grant_pages(struct gntdev_grant_map *map,
+			     int offset, int pages);
 
 static struct miscdevice gntdev_miscdev;
 
 /* ------------------------------------------------------------------ */
 
+bool gntdev_account_mapped_pages(int count)
+{
+	return atomic_add_return(count, &pages_mapped) > limit;
+}
+
 static void gntdev_print_maps(struct gntdev_priv *priv,
 			      char *text, int text_index)
 {
 #ifdef DEBUG
-	struct grant_map *map;
+	struct gntdev_grant_map *map;
 
 	pr_debug("%s: maps list (priv %p)\n", __func__, priv);
 	list_for_each_entry(map, &priv->maps, next)
@@ -141,7 +90,7 @@ static void gntdev_print_maps(struct gntdev_priv *priv,
 #endif
 }
 
-static void gntdev_free_map(struct grant_map *map)
+static void gntdev_free_map(struct gntdev_grant_map *map)
 {
 	if (map == NULL)
 		return;
@@ -176,13 +125,13 @@ static void gntdev_free_map(struct grant_map *map)
 	kfree(map);
 }
 
-static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count,
+struct gntdev_grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count,
 					  int dma_flags)
 {
-	struct grant_map *add;
+	struct gntdev_grant_map *add;
 	int i;
 
-	add = kzalloc(sizeof(struct grant_map), GFP_KERNEL);
+	add = kzalloc(sizeof(*add), GFP_KERNEL);
 	if (NULL == add)
 		return NULL;
 
@@ -252,9 +201,9 @@ static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count,
 	return NULL;
 }
 
-static void gntdev_add_map(struct gntdev_priv *priv, struct grant_map *add)
+void gntdev_add_map(struct gntdev_priv *priv, struct gntdev_grant_map *add)
 {
-	struct grant_map *map;
+	struct gntdev_grant_map *map;
 
 	list_for_each_entry(map, &priv->maps, next) {
 		if (add->index + add->count < map->index) {
@@ -269,10 +218,10 @@ static void gntdev_add_map(struct gntdev_priv *priv, struct grant_map *add)
 	gntdev_print_maps(priv, "[new]", add->index);
 }
 
-static struct grant_map *gntdev_find_map_index(struct gntdev_priv *priv,
-		int index, int count)
+static struct gntdev_grant_map *gntdev_find_map_index(struct gntdev_priv *priv,
+						      int index, int count)
 {
-	struct grant_map *map;
+	struct gntdev_grant_map *map;
 
 	list_for_each_entry(map, &priv->maps, next) {
 		if (map->index != index)
@@ -284,7 +233,7 @@ static struct grant_map *gntdev_find_map_index(struct gntdev_priv *priv,
 	return NULL;
 }
 
-static void gntdev_put_map(struct gntdev_priv *priv, struct grant_map *map)
+void gntdev_put_map(struct gntdev_priv *priv, struct gntdev_grant_map *map)
 {
 	if (!map)
 		return;
@@ -315,7 +264,7 @@ static void gntdev_put_map(struct gntdev_priv *priv, struct grant_map *map)
 static int find_grant_ptes(pte_t *pte, pgtable_t token,
 		unsigned long addr, void *data)
 {
-	struct grant_map *map = data;
+	struct gntdev_grant_map *map = data;
 	unsigned int pgnr = (addr - map->vma->vm_start) >> PAGE_SHIFT;
 	int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte;
 	u64 pte_maddr;
@@ -348,7 +297,7 @@ static int set_grant_ptes_as_special(pte_t *pte, pgtable_t token,
 }
 #endif
 
-static int map_grant_pages(struct grant_map *map)
+int gntdev_map_grant_pages(struct gntdev_grant_map *map)
 {
 	int i, err = 0;
 
@@ -413,7 +362,8 @@ static int map_grant_pages(struct grant_map *map)
 	return err;
 }
 
-static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)
+static int __unmap_grant_pages(struct gntdev_grant_map *map, int offset,
+			       int pages)
 {
 	int i, err = 0;
 	struct gntab_unmap_queue_data unmap_data;
@@ -448,7 +398,8 @@ static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)
 	return err;
 }
 
-static int unmap_grant_pages(struct grant_map *map, int offset, int pages)
+static int unmap_grant_pages(struct gntdev_grant_map *map, int offset,
+			     int pages)
 {
 	int range, err = 0;
 
@@ -480,7 +431,7 @@ static int unmap_grant_pages(struct grant_map *map, int offset, int pages)
 
 static void gntdev_vma_open(struct vm_area_struct *vma)
 {
-	struct grant_map *map = vma->vm_private_data;
+	struct gntdev_grant_map *map = vma->vm_private_data;
 
 	pr_debug("gntdev_vma_open %p\n", vma);
 	refcount_inc(&map->users);
@@ -488,7 +439,7 @@ static void gntdev_vma_open(struct vm_area_struct *vma)
 
 static void gntdev_vma_close(struct vm_area_struct *vma)
 {
-	struct grant_map *map = vma->vm_private_data;
+	struct gntdev_grant_map *map = vma->vm_private_data;
 	struct file *file = vma->vm_file;
 	struct gntdev_priv *priv = file->private_data;
 
@@ -512,7 +463,7 @@ static void gntdev_vma_close(struct vm_area_struct *vma)
 static struct page *gntdev_vma_find_special_page(struct vm_area_struct *vma,
 						 unsigned long addr)
 {
-	struct grant_map *map = vma->vm_private_data;
+	struct gntdev_grant_map *map = vma->vm_private_data;
 
 	return map->pages[(addr - map->pages_vm_start) >> PAGE_SHIFT];
 }
@@ -525,7 +476,7 @@ static const struct vm_operations_struct gntdev_vmops = {
 
 /* ------------------------------------------------------------------ */
 
-static void unmap_if_in_range(struct grant_map *map,
+static void unmap_if_in_range(struct gntdev_grant_map *map,
 			      unsigned long start, unsigned long end)
 {
 	unsigned long mstart, mend;
@@ -554,7 +505,7 @@ static void mn_invl_range_start(struct mmu_notifier *mn,
 				unsigned long start, unsigned long end)
 {
 	struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
-	struct grant_map *map;
+	struct gntdev_grant_map *map;
 
 	mutex_lock(&priv->lock);
 	list_for_each_entry(map, &priv->maps, next) {
@@ -570,7 +521,7 @@ static void mn_release(struct mmu_notifier *mn,
 		       struct mm_struct *mm)
 {
 	struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
-	struct grant_map *map;
+	struct gntdev_grant_map *map;
 	int err;
 
 	mutex_lock(&priv->lock);
@@ -651,13 +602,14 @@ static int gntdev_open(struct inode *inode, struct file *flip)
 static int gntdev_release(struct inode *inode, struct file *flip)
 {
 	struct gntdev_priv *priv = flip->private_data;
-	struct grant_map *map;
+	struct gntdev_grant_map *map;
 
 	pr_debug("priv %p\n", priv);
 
 	mutex_lock(&priv->lock);
 	while (!list_empty(&priv->maps)) {
-		map = list_entry(priv->maps.next, struct grant_map, next);
+		map = list_entry(priv->maps.next,
+				 struct gntdev_grant_map, next);
 		list_del(&map->next);
 		gntdev_put_map(NULL /* already removed */, map);
 	}
@@ -674,7 +626,7 @@ static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv,
 				       struct ioctl_gntdev_map_grant_ref __user *u)
 {
 	struct ioctl_gntdev_map_grant_ref op;
-	struct grant_map *map;
+	struct gntdev_grant_map *map;
 	int err;
 
 	if (copy_from_user(&op, u, sizeof(op)) != 0)
@@ -688,7 +640,7 @@ static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv,
 	if (!map)
 		return err;
 
-	if (unlikely(atomic_add_return(op.count, &pages_mapped) > limit)) {
+	if (unlikely(gntdev_account_mapped_pages(op.count))) {
 		pr_debug("can't map: over limit\n");
 		gntdev_put_map(NULL, map);
 		return err;
@@ -715,7 +667,7 @@ static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv,
 					 struct ioctl_gntdev_unmap_grant_ref __user *u)
 {
 	struct ioctl_gntdev_unmap_grant_ref op;
-	struct grant_map *map;
+	struct gntdev_grant_map *map;
 	int err = -ENOENT;
 
 	if (copy_from_user(&op, u, sizeof(op)) != 0)
@@ -741,7 +693,7 @@ static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv,
 {
 	struct ioctl_gntdev_get_offset_for_vaddr op;
 	struct vm_area_struct *vma;
-	struct grant_map *map;
+	struct gntdev_grant_map *map;
 	int rv = -EINVAL;
 
 	if (copy_from_user(&op, u, sizeof(op)) != 0)
@@ -772,7 +724,7 @@ static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv,
 static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u)
 {
 	struct ioctl_gntdev_unmap_notify op;
-	struct grant_map *map;
+	struct gntdev_grant_map *map;
 	int rc;
 	int out_flags;
 	unsigned int out_event;
@@ -1070,7 +1022,7 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
 	struct gntdev_priv *priv = flip->private_data;
 	int index = vma->vm_pgoff;
 	int count = vma_pages(vma);
-	struct grant_map *map;
+	struct gntdev_grant_map *map;
 	int i, err = -EINVAL;
 
 	if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED))
@@ -1127,7 +1079,7 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
 		}
 	}
 
-	err = map_grant_pages(map);
+	err = gntdev_map_grant_pages(map);
 	if (err)
 		goto out_put_map;
 
-- 
2.17.1

[PATCH v4 7/9] xen/gntdev: Add initial support for dma-buf UAPI

[Oleksandr Andrushchenko]

From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

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>
---
 drivers/xen/Kconfig         |  10 ++
 drivers/xen/Makefile        |   1 +
 drivers/xen/gntdev-common.h |   6 ++
 drivers/xen/gntdev-dmabuf.c | 177 ++++++++++++++++++++++++++++++++++++
 drivers/xen/gntdev-dmabuf.h |  33 +++++++
 drivers/xen/gntdev.c        |  31 +++++++
 include/uapi/xen/gntdev.h   |  91 ++++++++++++++++++
 7 files changed, 349 insertions(+)
 create mode 100644 drivers/xen/gntdev-dmabuf.c
 create mode 100644 drivers/xen/gntdev-dmabuf.h

diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index 75e5c40f80a5..b459edfacff3 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -152,6 +152,16 @@ config XEN_GNTDEV
 	help
 	  Allows userspace processes to use grants.
 
+config XEN_GNTDEV_DMABUF
+	bool "Add support for dma-buf grant access device driver extension"
+	depends on XEN_GNTDEV && XEN_GRANT_DMA_ALLOC && DMA_SHARED_BUFFER
+	help
+	  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.
+
 config XEN_GRANT_DEV_ALLOC
 	tristate "User-space grant reference allocator driver"
 	depends on XEN
diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index 3c87b0c3aca6..33afb7b2b227 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -41,5 +41,6 @@ obj-$(CONFIG_XEN_PVCALLS_BACKEND)	+= pvcalls-back.o
 obj-$(CONFIG_XEN_PVCALLS_FRONTEND)	+= pvcalls-front.o
 xen-evtchn-y				:= evtchn.o
 xen-gntdev-y				:= gntdev.o
+xen-gntdev-$(CONFIG_XEN_GNTDEV_DMABUF)	+= gntdev-dmabuf.o
 xen-gntalloc-y				:= gntalloc.o
 xen-privcmd-y				:= privcmd.o
diff --git a/drivers/xen/gntdev-common.h b/drivers/xen/gntdev-common.h
index 2346c198f72e..2f8b949c3eeb 100644
--- a/drivers/xen/gntdev-common.h
+++ b/drivers/xen/gntdev-common.h
@@ -16,6 +16,8 @@
 #include <linux/mmu_notifier.h>
 #include <linux/types.h>
 
+struct gntdev_dmabuf_priv;
+
 struct gntdev_priv {
 	/* Maps with visible offsets in the file descriptor. */
 	struct list_head maps;
@@ -33,6 +35,10 @@ struct gntdev_priv {
 	/* Device for which DMA memory is allocated. */
 	struct device *dma_dev;
 #endif
+
+#ifdef CONFIG_XEN_GNTDEV_DMABUF
+	struct gntdev_dmabuf_priv *dmabuf_priv;
+#endif
 };
 
 struct gntdev_unmap_notify {
diff --git a/drivers/xen/gntdev-dmabuf.c b/drivers/xen/gntdev-dmabuf.c
new file mode 100644
index 000000000000..af782c0a8a19
--- /dev/null
+++ b/drivers/xen/gntdev-dmabuf.c
@@ -0,0 +1,177 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Xen dma-buf functionality for gntdev.
+ *
+ * Copyright (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
+ */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/uaccess.h>
+
+#include <xen/xen.h>
+#include <xen/grant_table.h>
+
+#include "gntdev-common.h"
+#include "gntdev-dmabuf.h"
+
+struct gntdev_dmabuf_priv {
+	/* List of exported DMA buffers. */
+	struct list_head exp_list;
+	/* List of wait objects. */
+	struct list_head exp_wait_list;
+	/* This is the lock which protects dma_buf_xxx lists. */
+	struct mutex lock;
+};
+
+/* DMA buffer export support. */
+
+/* Implementation of wait for exported DMA buffer to be released. */
+
+static int dmabuf_exp_wait_released(struct gntdev_dmabuf_priv *priv, int fd,
+				    int wait_to_ms)
+{
+	return -EINVAL;
+}
+
+static int dmabuf_exp_from_refs(struct gntdev_priv *priv, int flags,
+				int count, u32 domid, u32 *refs, u32 *fd)
+{
+	*fd = -1;
+	return -EINVAL;
+}
+
+/* DMA buffer import support. */
+
+static struct gntdev_dmabuf *
+dmabuf_imp_to_refs(struct gntdev_dmabuf_priv *priv, struct device *dev,
+		   int fd, int count, int domid)
+{
+	return ERR_PTR(-ENOMEM);
+}
+
+static u32 *dmabuf_imp_get_refs(struct gntdev_dmabuf *gntdev_dmabuf)
+{
+	return NULL;
+}
+
+static int dmabuf_imp_release(struct gntdev_dmabuf_priv *priv, u32 fd)
+{
+	return -EINVAL;
+}
+
+/* DMA buffer IOCTL support. */
+
+long gntdev_ioctl_dmabuf_exp_from_refs(struct gntdev_priv *priv, int use_ptemod,
+				       struct ioctl_gntdev_dmabuf_exp_from_refs __user *u)
+{
+	struct ioctl_gntdev_dmabuf_exp_from_refs op;
+	u32 *refs;
+	long ret;
+
+	if (use_ptemod) {
+		pr_debug("Cannot provide dma-buf: use_ptemode %d\n",
+			 use_ptemod);
+		return -EINVAL;
+	}
+
+	if (copy_from_user(&op, u, sizeof(op)) != 0)
+		return -EFAULT;
+
+	if (unlikely(op.count <= 0))
+		return -EINVAL;
+
+	refs = kcalloc(op.count, sizeof(*refs), GFP_KERNEL);
+	if (!refs)
+		return -ENOMEM;
+
+	if (copy_from_user(refs, u->refs, sizeof(*refs) * op.count) != 0) {
+		ret = -EFAULT;
+		goto out;
+	}
+
+	ret = dmabuf_exp_from_refs(priv, op.flags, op.count,
+				   op.domid, refs, &op.fd);
+	if (ret)
+		goto out;
+
+	if (copy_to_user(u, &op, sizeof(op)) != 0)
+		ret = -EFAULT;
+
+out:
+	kfree(refs);
+	return ret;
+}
+
+long gntdev_ioctl_dmabuf_exp_wait_released(struct gntdev_priv *priv,
+					   struct ioctl_gntdev_dmabuf_exp_wait_released __user *u)
+{
+	struct ioctl_gntdev_dmabuf_exp_wait_released op;
+
+	if (copy_from_user(&op, u, sizeof(op)) != 0)
+		return -EFAULT;
+
+	return dmabuf_exp_wait_released(priv->dmabuf_priv, op.fd,
+					op.wait_to_ms);
+}
+
+long gntdev_ioctl_dmabuf_imp_to_refs(struct gntdev_priv *priv,
+				     struct ioctl_gntdev_dmabuf_imp_to_refs __user *u)
+{
+	struct ioctl_gntdev_dmabuf_imp_to_refs op;
+	struct gntdev_dmabuf *gntdev_dmabuf;
+	long ret;
+
+	if (copy_from_user(&op, u, sizeof(op)) != 0)
+		return -EFAULT;
+
+	if (unlikely(op.count <= 0))
+		return -EINVAL;
+
+	gntdev_dmabuf = dmabuf_imp_to_refs(priv->dmabuf_priv,
+					   priv->dma_dev, op.fd,
+					   op.count, op.domid);
+	if (IS_ERR(gntdev_dmabuf))
+		return PTR_ERR(gntdev_dmabuf);
+
+	if (copy_to_user(u->refs, dmabuf_imp_get_refs(gntdev_dmabuf),
+			 sizeof(*u->refs) * op.count) != 0) {
+		ret = -EFAULT;
+		goto out_release;
+	}
+	return 0;
+
+out_release:
+	dmabuf_imp_release(priv->dmabuf_priv, op.fd);
+	return ret;
+}
+
+long gntdev_ioctl_dmabuf_imp_release(struct gntdev_priv *priv,
+				     struct ioctl_gntdev_dmabuf_imp_release __user *u)
+{
+	struct ioctl_gntdev_dmabuf_imp_release op;
+
+	if (copy_from_user(&op, u, sizeof(op)) != 0)
+		return -EFAULT;
+
+	return dmabuf_imp_release(priv->dmabuf_priv, op.fd);
+}
+
+struct gntdev_dmabuf_priv *gntdev_dmabuf_init(void)
+{
+	struct gntdev_dmabuf_priv *priv;
+
+	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return ERR_PTR(-ENOMEM);
+
+	return priv;
+}
+
+void gntdev_dmabuf_fini(struct gntdev_dmabuf_priv *priv)
+{
+	kfree(priv);
+}
diff --git a/drivers/xen/gntdev-dmabuf.h b/drivers/xen/gntdev-dmabuf.h
new file mode 100644
index 000000000000..7220a53d0fc5
--- /dev/null
+++ b/drivers/xen/gntdev-dmabuf.h
@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * Xen dma-buf functionality for gntdev.
+ *
+ * Copyright (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
+ */
+
+#ifndef _GNTDEV_DMABUF_H
+#define _GNTDEV_DMABUF_H
+
+#include <xen/gntdev.h>
+
+struct gntdev_dmabuf_priv;
+struct gntdev_priv;
+
+struct gntdev_dmabuf_priv *gntdev_dmabuf_init(void);
+
+void gntdev_dmabuf_fini(struct gntdev_dmabuf_priv *priv);
+
+long gntdev_ioctl_dmabuf_exp_from_refs(struct gntdev_priv *priv, int use_ptemod,
+				       struct ioctl_gntdev_dmabuf_exp_from_refs __user *u);
+
+long gntdev_ioctl_dmabuf_exp_wait_released(struct gntdev_priv *priv,
+					   struct ioctl_gntdev_dmabuf_exp_wait_released __user *u);
+
+long gntdev_ioctl_dmabuf_imp_to_refs(struct gntdev_priv *priv,
+				     struct ioctl_gntdev_dmabuf_imp_to_refs __user *u);
+
+long gntdev_ioctl_dmabuf_imp_release(struct gntdev_priv *priv,
+				     struct ioctl_gntdev_dmabuf_imp_release __user *u);
+
+#endif
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 3385fc4ed386..b0365b022a40 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -48,6 +48,9 @@
 #include <asm/xen/hypercall.h>
 
 #include "gntdev-common.h"
+#ifdef CONFIG_XEN_GNTDEV_DMABUF
+#include "gntdev-dmabuf.h"
+#endif
 
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Derek G. Murray <Derek.Murray@cl.cam.ac.uk>, "
@@ -566,6 +569,15 @@ static int gntdev_open(struct inode *inode, struct file *flip)
 	INIT_LIST_HEAD(&priv->freeable_maps);
 	mutex_init(&priv->lock);
 
+#ifdef CONFIG_XEN_GNTDEV_DMABUF
+	priv->dmabuf_priv = gntdev_dmabuf_init();
+	if (IS_ERR(priv->dmabuf_priv)) {
+		ret = PTR_ERR(priv->dmabuf_priv);
+		kfree(priv);
+		return ret;
+	}
+#endif
+
 	if (use_ptemod) {
 		priv->mm = get_task_mm(current);
 		if (!priv->mm) {
@@ -616,8 +628,13 @@ static int gntdev_release(struct inode *inode, struct file *flip)
 	WARN_ON(!list_empty(&priv->freeable_maps));
 	mutex_unlock(&priv->lock);
 
+#ifdef CONFIG_XEN_GNTDEV_DMABUF
+	gntdev_dmabuf_fini(priv->dmabuf_priv);
+#endif
+
 	if (use_ptemod)
 		mmu_notifier_unregister(&priv->mn, priv->mm);
+
 	kfree(priv);
 	return 0;
 }
@@ -1009,6 +1026,20 @@ static long gntdev_ioctl(struct file *flip,
 	case IOCTL_GNTDEV_GRANT_COPY:
 		return gntdev_ioctl_grant_copy(priv, ptr);
 
+#ifdef CONFIG_XEN_GNTDEV_DMABUF
+	case IOCTL_GNTDEV_DMABUF_EXP_FROM_REFS:
+		return gntdev_ioctl_dmabuf_exp_from_refs(priv, use_ptemod, ptr);
+
+	case IOCTL_GNTDEV_DMABUF_EXP_WAIT_RELEASED:
+		return gntdev_ioctl_dmabuf_exp_wait_released(priv, ptr);
+
+	case IOCTL_GNTDEV_DMABUF_IMP_TO_REFS:
+		return gntdev_ioctl_dmabuf_imp_to_refs(priv, ptr);
+
+	case IOCTL_GNTDEV_DMABUF_IMP_RELEASE:
+		return gntdev_ioctl_dmabuf_imp_release(priv, ptr);
+#endif
+
 	default:
 		pr_debug("priv %p, unknown cmd %x\n", priv, cmd);
 		return -ENOIOCTLCMD;
diff --git a/include/uapi/xen/gntdev.h b/include/uapi/xen/gntdev.h
index 4b9d498a31d4..fe4423e518c6 100644
--- a/include/uapi/xen/gntdev.h
+++ b/include/uapi/xen/gntdev.h
@@ -5,6 +5,7 @@
  * 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
@@ -215,4 +216,94 @@ struct ioctl_gntdev_grant_copy {
  */
 #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] 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_DMA_FLAG_XXX. */
+	__u32 flags;
+	/* Number of grant references in @refs array. */
+	__u32 count;
+	/* OUT parameters. */
+	/* File descriptor of the dma-buf. */
+	__u32 fd;
+	/* The domain ID of the grant references to be mapped. */
+	__u32 domid;
+	/* Variable IN parameter. */
+	/* Array of grant references of size @count. */
+	__u32 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 within @wait_to_ms milliseconds the buffer is not released
+ * then -ETIMEDOUT error is returned.
+ * If the buffer with the 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 */
+	__u32 fd;
+	__u32 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. */
+	__u32 fd;
+	/* Number of grant references in @refs array. */
+	__u32 count;
+	/* The domain ID for which references to be granted. */
+	__u32 domid;
+	/* Reserved - must be zero. */
+	__u32 reserved;
+	/* OUT parameters. */
+	/* Array of grant references of size @count. */
+	__u32 refs[1];
+};
+
+/*
+ * This will close all references to the imported buffer with file descriptor
+ * @fd, 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 */
+	__u32 fd;
+	__u32 reserved;
+};
+
 #endif /* __LINUX_PUBLIC_GNTDEV_H__ */
-- 
2.17.1

[PATCH v4 8/9] xen/gntdev: Implement dma-buf export functionality

[Oleksandr Andrushchenko]

From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

1. Create a dma-buf from grant references provided by the foreign
   domain. By default dma-buf is backed by system memory pages, but
   by providing GNTDEV_DMA_FLAG_XXX flags it can also be created
   as a DMA write-combine/coherent buffer, e.g. allocated with
   corresponding dma_alloc_xxx API.
   Export the resulting buffer as a new dma-buf.

2. Implement waiting for the dma-buf to be released: block until the
   dma-buf with the file descriptor provided is released.
   If within the time-out provided the buffer is not released then
   -ETIMEDOUT error is returned. If the buffer with the file descriptor
   does not exist or has already been released, then -ENOENT is
   returned. For valid file descriptors this must not be treated as
   error.

3. Make gntdev's common code and structures available to dma-buf.

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
---
 drivers/xen/gntdev-dmabuf.c | 470 +++++++++++++++++++++++++++++++++++-
 1 file changed, 467 insertions(+), 3 deletions(-)

diff --git a/drivers/xen/gntdev-dmabuf.c b/drivers/xen/gntdev-dmabuf.c
index af782c0a8a19..07a98aa52cab 100644
--- a/drivers/xen/gntdev-dmabuf.c
+++ b/drivers/xen/gntdev-dmabuf.c
@@ -3,11 +3,14 @@
 /*
  * Xen dma-buf functionality for gntdev.
  *
+ * DMA buffer implementation is based on drivers/gpu/drm/drm_prime.c.
+ *
  * Copyright (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
  */
 
 #include <linux/kernel.h>
 #include <linux/errno.h>
+#include <linux/dma-buf.h>
 #include <linux/slab.h>
 #include <linux/types.h>
 #include <linux/uaccess.h>
@@ -18,6 +21,39 @@
 #include "gntdev-common.h"
 #include "gntdev-dmabuf.h"
 
+struct gntdev_dmabuf {
+	struct gntdev_dmabuf_priv *priv;
+	struct dma_buf *dmabuf;
+	struct list_head next;
+	int fd;
+
+	union {
+		struct {
+			/* Exported buffers are reference counted. */
+			struct kref refcount;
+
+			struct gntdev_priv *priv;
+			struct gntdev_grant_map *map;
+		} exp;
+	} u;
+
+	/* Number of pages this buffer has. */
+	int nr_pages;
+	/* Pages of this buffer. */
+	struct page **pages;
+};
+
+struct gntdev_dmabuf_wait_obj {
+	struct list_head next;
+	struct gntdev_dmabuf *gntdev_dmabuf;
+	struct completion completion;
+};
+
+struct gntdev_dmabuf_attachment {
+	struct sg_table *sgt;
+	enum dma_data_direction dir;
+};
+
 struct gntdev_dmabuf_priv {
 	/* List of exported DMA buffers. */
 	struct list_head exp_list;
@@ -31,17 +67,441 @@ struct gntdev_dmabuf_priv {
 
 /* Implementation of wait for exported DMA buffer to be released. */
 
+static void dmabuf_exp_release(struct kref *kref);
+
+static struct gntdev_dmabuf_wait_obj *
+dmabuf_exp_wait_obj_new(struct gntdev_dmabuf_priv *priv,
+			struct gntdev_dmabuf *gntdev_dmabuf)
+{
+	struct gntdev_dmabuf_wait_obj *obj;
+
+	obj = kzalloc(sizeof(*obj), GFP_KERNEL);
+	if (!obj)
+		return ERR_PTR(-ENOMEM);
+
+	init_completion(&obj->completion);
+	obj->gntdev_dmabuf = gntdev_dmabuf;
+
+	mutex_lock(&priv->lock);
+	list_add(&obj->next, &priv->exp_wait_list);
+	/* Put our reference and wait for gntdev_dmabuf's release to fire. */
+	kref_put(&gntdev_dmabuf->u.exp.refcount, dmabuf_exp_release);
+	mutex_unlock(&priv->lock);
+	return obj;
+}
+
+static void dmabuf_exp_wait_obj_free(struct gntdev_dmabuf_priv *priv,
+				     struct gntdev_dmabuf_wait_obj *obj)
+{
+	mutex_lock(&priv->lock);
+	list_del(&obj->next);
+	mutex_unlock(&priv->lock);
+	kfree(obj);
+}
+
+static int dmabuf_exp_wait_obj_wait(struct gntdev_dmabuf_wait_obj *obj,
+				    u32 wait_to_ms)
+{
+	if (wait_for_completion_timeout(&obj->completion,
+			msecs_to_jiffies(wait_to_ms)) <= 0)
+		return -ETIMEDOUT;
+
+	return 0;
+}
+
+static void dmabuf_exp_wait_obj_signal(struct gntdev_dmabuf_priv *priv,
+				       struct gntdev_dmabuf *gntdev_dmabuf)
+{
+	struct gntdev_dmabuf_wait_obj *obj;
+
+	list_for_each_entry(obj, &priv->exp_wait_list, next)
+		if (obj->gntdev_dmabuf == gntdev_dmabuf) {
+			pr_debug("Found gntdev_dmabuf in the wait list, wake\n");
+			complete_all(&obj->completion);
+			break;
+		}
+}
+
+static struct gntdev_dmabuf *
+dmabuf_exp_wait_obj_get_dmabuf(struct gntdev_dmabuf_priv *priv, int fd)
+{
+	struct gntdev_dmabuf *gntdev_dmabuf, *ret = ERR_PTR(-ENOENT);
+
+	mutex_lock(&priv->lock);
+	list_for_each_entry(gntdev_dmabuf, &priv->exp_list, next)
+		if (gntdev_dmabuf->fd == fd) {
+			pr_debug("Found gntdev_dmabuf in the wait list\n");
+			kref_get(&gntdev_dmabuf->u.exp.refcount);
+			ret = gntdev_dmabuf;
+			break;
+		}
+	mutex_unlock(&priv->lock);
+	return ret;
+}
+
 static int dmabuf_exp_wait_released(struct gntdev_dmabuf_priv *priv, int fd,
 				    int wait_to_ms)
 {
-	return -EINVAL;
+	struct gntdev_dmabuf *gntdev_dmabuf;
+	struct gntdev_dmabuf_wait_obj *obj;
+	int ret;
+
+	pr_debug("Will wait for dma-buf with fd %d\n", fd);
+	/*
+	 * Try to find the DMA buffer: if not found means that
+	 * either the buffer has already been released or file descriptor
+	 * provided is wrong.
+	 */
+	gntdev_dmabuf = dmabuf_exp_wait_obj_get_dmabuf(priv, fd);
+	if (IS_ERR(gntdev_dmabuf))
+		return PTR_ERR(gntdev_dmabuf);
+
+	/*
+	 * gntdev_dmabuf still exists and is reference count locked by us now,
+	 * so prepare to wait: allocate wait object and add it to the wait list,
+	 * so we can find it on release.
+	 */
+	obj = dmabuf_exp_wait_obj_new(priv, gntdev_dmabuf);
+	if (IS_ERR(obj))
+		return PTR_ERR(obj);
+
+	ret = dmabuf_exp_wait_obj_wait(obj, wait_to_ms);
+	dmabuf_exp_wait_obj_free(priv, obj);
+	return ret;
+}
+
+/* DMA buffer export support. */
+
+static struct sg_table *
+dmabuf_pages_to_sgt(struct page **pages, unsigned int nr_pages)
+{
+	struct sg_table *sgt;
+	int ret;
+
+	sgt = kmalloc(sizeof(*sgt), GFP_KERNEL);
+	if (!sgt) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	ret = sg_alloc_table_from_pages(sgt, pages, nr_pages, 0,
+					nr_pages << PAGE_SHIFT,
+					GFP_KERNEL);
+	if (ret)
+		goto out;
+
+	return sgt;
+
+out:
+	kfree(sgt);
+	return ERR_PTR(ret);
+}
+
+static int dmabuf_exp_ops_attach(struct dma_buf *dma_buf,
+				 struct device *target_dev,
+				 struct dma_buf_attachment *attach)
+{
+	struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach;
+
+	gntdev_dmabuf_attach = kzalloc(sizeof(*gntdev_dmabuf_attach),
+				       GFP_KERNEL);
+	if (!gntdev_dmabuf_attach)
+		return -ENOMEM;
+
+	gntdev_dmabuf_attach->dir = DMA_NONE;
+	attach->priv = gntdev_dmabuf_attach;
+	return 0;
+}
+
+static void dmabuf_exp_ops_detach(struct dma_buf *dma_buf,
+				  struct dma_buf_attachment *attach)
+{
+	struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach = attach->priv;
+
+	if (gntdev_dmabuf_attach) {
+		struct sg_table *sgt = gntdev_dmabuf_attach->sgt;
+
+		if (sgt) {
+			if (gntdev_dmabuf_attach->dir != DMA_NONE)
+				dma_unmap_sg_attrs(attach->dev, sgt->sgl,
+						   sgt->nents,
+						   gntdev_dmabuf_attach->dir,
+						   DMA_ATTR_SKIP_CPU_SYNC);
+			sg_free_table(sgt);
+		}
+
+		kfree(sgt);
+		kfree(gntdev_dmabuf_attach);
+		attach->priv = NULL;
+	}
+}
+
+static struct sg_table *
+dmabuf_exp_ops_map_dma_buf(struct dma_buf_attachment *attach,
+			   enum dma_data_direction dir)
+{
+	struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach = attach->priv;
+	struct gntdev_dmabuf *gntdev_dmabuf = attach->dmabuf->priv;
+	struct sg_table *sgt;
+
+	pr_debug("Mapping %d pages for dev %p\n", gntdev_dmabuf->nr_pages,
+		 attach->dev);
+
+	if (dir == DMA_NONE || !gntdev_dmabuf_attach)
+		return ERR_PTR(-EINVAL);
+
+	/* Return the cached mapping when possible. */
+	if (gntdev_dmabuf_attach->dir == dir)
+		return gntdev_dmabuf_attach->sgt;
+
+	/*
+	 * Two mappings with different directions for the same attachment are
+	 * not allowed.
+	 */
+	if (gntdev_dmabuf_attach->dir != DMA_NONE)
+		return ERR_PTR(-EBUSY);
+
+	sgt = dmabuf_pages_to_sgt(gntdev_dmabuf->pages,
+				  gntdev_dmabuf->nr_pages);
+	if (!IS_ERR(sgt)) {
+		if (!dma_map_sg_attrs(attach->dev, sgt->sgl, sgt->nents, dir,
+				      DMA_ATTR_SKIP_CPU_SYNC)) {
+			sg_free_table(sgt);
+			kfree(sgt);
+			sgt = ERR_PTR(-ENOMEM);
+		} else {
+			gntdev_dmabuf_attach->sgt = sgt;
+			gntdev_dmabuf_attach->dir = dir;
+		}
+	}
+	if (IS_ERR(sgt))
+		pr_debug("Failed to map sg table for dev %p\n", attach->dev);
+	return sgt;
+}
+
+static void dmabuf_exp_ops_unmap_dma_buf(struct dma_buf_attachment *attach,
+					 struct sg_table *sgt,
+					 enum dma_data_direction dir)
+{
+	/* Not implemented. The unmap is done at dmabuf_exp_ops_detach(). */
+}
+
+static void dmabuf_exp_release(struct kref *kref)
+{
+	struct gntdev_dmabuf *gntdev_dmabuf =
+		container_of(kref, struct gntdev_dmabuf, u.exp.refcount);
+
+	dmabuf_exp_wait_obj_signal(gntdev_dmabuf->priv, gntdev_dmabuf);
+	list_del(&gntdev_dmabuf->next);
+	kfree(gntdev_dmabuf);
+}
+
+static void dmabuf_exp_remove_map(struct gntdev_priv *priv,
+				  struct gntdev_grant_map *map)
+{
+	mutex_lock(&priv->lock);
+	list_del(&map->next);
+	gntdev_put_map(NULL /* already removed */, map);
+	mutex_unlock(&priv->lock);
+}
+
+static void dmabuf_exp_ops_release(struct dma_buf *dma_buf)
+{
+	struct gntdev_dmabuf *gntdev_dmabuf = dma_buf->priv;
+	struct gntdev_dmabuf_priv *priv = gntdev_dmabuf->priv;
+
+	dmabuf_exp_remove_map(gntdev_dmabuf->u.exp.priv,
+			      gntdev_dmabuf->u.exp.map);
+	mutex_lock(&priv->lock);
+	kref_put(&gntdev_dmabuf->u.exp.refcount, dmabuf_exp_release);
+	mutex_unlock(&priv->lock);
+}
+
+static void *dmabuf_exp_ops_kmap_atomic(struct dma_buf *dma_buf,
+					unsigned long page_num)
+{
+	/* Not implemented. */
+	return NULL;
+}
+
+static void dmabuf_exp_ops_kunmap_atomic(struct dma_buf *dma_buf,
+					 unsigned long page_num, void *addr)
+{
+	/* Not implemented. */
+}
+
+static void *dmabuf_exp_ops_kmap(struct dma_buf *dma_buf,
+				 unsigned long page_num)
+{
+	/* Not implemented. */
+	return NULL;
+}
+
+static void dmabuf_exp_ops_kunmap(struct dma_buf *dma_buf,
+				  unsigned long page_num, void *addr)
+{
+	/* Not implemented. */
+}
+
+static int dmabuf_exp_ops_mmap(struct dma_buf *dma_buf,
+			       struct vm_area_struct *vma)
+{
+	/* Not implemented. */
+	return 0;
+}
+
+static const struct dma_buf_ops dmabuf_exp_ops =  {
+	.attach = dmabuf_exp_ops_attach,
+	.detach = dmabuf_exp_ops_detach,
+	.map_dma_buf = dmabuf_exp_ops_map_dma_buf,
+	.unmap_dma_buf = dmabuf_exp_ops_unmap_dma_buf,
+	.release = dmabuf_exp_ops_release,
+	.map = dmabuf_exp_ops_kmap,
+	.map_atomic = dmabuf_exp_ops_kmap_atomic,
+	.unmap = dmabuf_exp_ops_kunmap,
+	.unmap_atomic = dmabuf_exp_ops_kunmap_atomic,
+	.mmap = dmabuf_exp_ops_mmap,
+};
+
+struct gntdev_dmabuf_export_args {
+	struct gntdev_priv *priv;
+	struct gntdev_grant_map *map;
+	struct gntdev_dmabuf_priv *dmabuf_priv;
+	struct device *dev;
+	int count;
+	struct page **pages;
+	u32 fd;
+};
+
+static int dmabuf_exp_from_pages(struct gntdev_dmabuf_export_args *args)
+{
+	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
+	struct gntdev_dmabuf *gntdev_dmabuf;
+	int ret;
+
+	gntdev_dmabuf = kzalloc(sizeof(*gntdev_dmabuf), GFP_KERNEL);
+	if (!gntdev_dmabuf)
+		return -ENOMEM;
+
+	kref_init(&gntdev_dmabuf->u.exp.refcount);
+
+	gntdev_dmabuf->priv = args->dmabuf_priv;
+	gntdev_dmabuf->nr_pages = args->count;
+	gntdev_dmabuf->pages = args->pages;
+	gntdev_dmabuf->u.exp.priv = args->priv;
+	gntdev_dmabuf->u.exp.map = args->map;
+
+	exp_info.exp_name = KBUILD_MODNAME;
+	if (args->dev->driver && args->dev->driver->owner)
+		exp_info.owner = args->dev->driver->owner;
+	else
+		exp_info.owner = THIS_MODULE;
+	exp_info.ops = &dmabuf_exp_ops;
+	exp_info.size = args->count << PAGE_SHIFT;
+	exp_info.flags = O_RDWR;
+	exp_info.priv = gntdev_dmabuf;
+
+	gntdev_dmabuf->dmabuf = dma_buf_export(&exp_info);
+	if (IS_ERR(gntdev_dmabuf->dmabuf)) {
+		ret = PTR_ERR(gntdev_dmabuf->dmabuf);
+		gntdev_dmabuf->dmabuf = NULL;
+		goto fail;
+	}
+
+	ret = dma_buf_fd(gntdev_dmabuf->dmabuf, O_CLOEXEC);
+	if (ret < 0)
+		goto fail;
+
+	gntdev_dmabuf->fd = ret;
+	args->fd = ret;
+
+	pr_debug("Exporting DMA buffer with fd %d\n", ret);
+
+	mutex_lock(&args->dmabuf_priv->lock);
+	list_add(&gntdev_dmabuf->next, &args->dmabuf_priv->exp_list);
+	mutex_unlock(&args->dmabuf_priv->lock);
+	return 0;
+
+fail:
+	if (gntdev_dmabuf->dmabuf)
+		dma_buf_put(gntdev_dmabuf->dmabuf);
+	kfree(gntdev_dmabuf);
+	return ret;
+}
+
+static struct gntdev_grant_map *
+dmabuf_exp_alloc_backing_storage(struct gntdev_priv *priv, int dmabuf_flags,
+				 int count)
+{
+	struct gntdev_grant_map *map;
+
+	if (unlikely(count <= 0))
+		return ERR_PTR(-EINVAL);
+
+	if ((dmabuf_flags & GNTDEV_DMA_FLAG_WC) &&
+	    (dmabuf_flags & GNTDEV_DMA_FLAG_COHERENT)) {
+		pr_debug("Wrong dma-buf flags: 0x%x\n", dmabuf_flags);
+		return ERR_PTR(-EINVAL);
+	}
+
+	map = gntdev_alloc_map(priv, count, dmabuf_flags);
+	if (!map)
+		return ERR_PTR(-ENOMEM);
+
+	if (unlikely(gntdev_account_mapped_pages(count))) {
+		pr_debug("can't map %d pages: over limit\n", count);
+		gntdev_put_map(NULL, map);
+		return ERR_PTR(-ENOMEM);
+	}
+	return map;
 }
 
 static int dmabuf_exp_from_refs(struct gntdev_priv *priv, int flags,
 				int count, u32 domid, u32 *refs, u32 *fd)
 {
-	*fd = -1;
-	return -EINVAL;
+	struct gntdev_grant_map *map;
+	struct gntdev_dmabuf_export_args args;
+	int i, ret;
+
+	map = dmabuf_exp_alloc_backing_storage(priv, flags, count);
+	if (IS_ERR(map))
+		return PTR_ERR(map);
+
+	for (i = 0; i < count; i++) {
+		map->grants[i].domid = domid;
+		map->grants[i].ref = refs[i];
+	}
+
+	mutex_lock(&priv->lock);
+	gntdev_add_map(priv, map);
+	mutex_unlock(&priv->lock);
+
+	map->flags |= GNTMAP_host_map;
+#if defined(CONFIG_X86)
+	map->flags |= GNTMAP_device_map;
+#endif
+
+	ret = gntdev_map_grant_pages(map);
+	if (ret < 0)
+		goto out;
+
+	args.priv = priv;
+	args.map = map;
+	args.dev = priv->dma_dev;
+	args.dmabuf_priv = priv->dmabuf_priv;
+	args.count = map->count;
+	args.pages = map->pages;
+
+	ret = dmabuf_exp_from_pages(&args);
+	if (ret < 0)
+		goto out;
+
+	*fd = args.fd;
+	return 0;
+
+out:
+	dmabuf_exp_remove_map(priv, map);
+	return ret;
 }
 
 /* DMA buffer import support. */
@@ -168,6 +628,10 @@ struct gntdev_dmabuf_priv *gntdev_dmabuf_init(void)
 	if (!priv)
 		return ERR_PTR(-ENOMEM);
 
+	mutex_init(&priv->lock);
+	INIT_LIST_HEAD(&priv->exp_list);
+	INIT_LIST_HEAD(&priv->exp_wait_list);
+
 	return priv;
 }
 
-- 
2.17.1

[PATCH v4 9/9] xen/gntdev: Implement dma-buf import functionality

[Oleksandr Andrushchenko]

From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

1. Import a dma-buf with the file descriptor provided and export
   granted references to the pages of that dma-buf into the array
   of grant references.

2. Add API to 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.

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
---
 drivers/xen/gntdev-dmabuf.c | 239 +++++++++++++++++++++++++++++++++++-
 1 file changed, 234 insertions(+), 5 deletions(-)

diff --git a/drivers/xen/gntdev-dmabuf.c b/drivers/xen/gntdev-dmabuf.c
index 07a98aa52cab..de1f32026203 100644
--- a/drivers/xen/gntdev-dmabuf.c
+++ b/drivers/xen/gntdev-dmabuf.c
@@ -21,6 +21,15 @@
 #include "gntdev-common.h"
 #include "gntdev-dmabuf.h"
 
+#ifndef GRANT_INVALID_REF
+/*
+ * Note on usage of grant reference 0 as invalid grant reference:
+ * grant reference 0 is valid, but never exposed to a driver,
+ * because of the fact it is already in use/reserved by the PV console.
+ */
+#define GRANT_INVALID_REF	0
+#endif
+
 struct gntdev_dmabuf {
 	struct gntdev_dmabuf_priv *priv;
 	struct dma_buf *dmabuf;
@@ -35,6 +44,14 @@ struct gntdev_dmabuf {
 			struct gntdev_priv *priv;
 			struct gntdev_grant_map *map;
 		} exp;
+		struct {
+			/* Granted references of the imported buffer. */
+			grant_ref_t *refs;
+			/* Scatter-gather table of the imported buffer. */
+			struct sg_table *sgt;
+			/* dma-buf attachment of the imported buffer. */
+			struct dma_buf_attachment *attach;
+		} imp;
 	} u;
 
 	/* Number of pages this buffer has. */
@@ -59,6 +76,8 @@ struct gntdev_dmabuf_priv {
 	struct list_head exp_list;
 	/* List of wait objects. */
 	struct list_head exp_wait_list;
+	/* List of imported DMA buffers. */
+	struct list_head imp_list;
 	/* This is the lock which protects dma_buf_xxx lists. */
 	struct mutex lock;
 };
@@ -506,21 +525,230 @@ static int dmabuf_exp_from_refs(struct gntdev_priv *priv, int flags,
 
 /* DMA buffer import support. */
 
+static int
+dmabuf_imp_grant_foreign_access(struct page **pages, u32 *refs,
+				int count, int domid)
+{
+	grant_ref_t priv_gref_head;
+	int i, ret;
+
+	ret = gnttab_alloc_grant_references(count, &priv_gref_head);
+	if (ret < 0) {
+		pr_debug("Cannot allocate grant references, ret %d\n", ret);
+		return ret;
+	}
+
+	for (i = 0; i < count; i++) {
+		int cur_ref;
+
+		cur_ref = gnttab_claim_grant_reference(&priv_gref_head);
+		if (cur_ref < 0) {
+			ret = cur_ref;
+			pr_debug("Cannot claim grant reference, ret %d\n", ret);
+			goto out;
+		}
+
+		gnttab_grant_foreign_access_ref(cur_ref, domid,
+						xen_page_to_gfn(pages[i]), 0);
+		refs[i] = cur_ref;
+	}
+
+	return 0;
+
+out:
+	gnttab_free_grant_references(priv_gref_head);
+	return ret;
+}
+
+static void dmabuf_imp_end_foreign_access(u32 *refs, int count)
+{
+	int i;
+
+	for (i = 0; i < count; i++)
+		if (refs[i] != GRANT_INVALID_REF)
+			gnttab_end_foreign_access(refs[i], 0, 0UL);
+}
+
+static void dmabuf_imp_free_storage(struct gntdev_dmabuf *gntdev_dmabuf)
+{
+	kfree(gntdev_dmabuf->pages);
+	kfree(gntdev_dmabuf->u.imp.refs);
+	kfree(gntdev_dmabuf);
+}
+
+static struct gntdev_dmabuf *dmabuf_imp_alloc_storage(int count)
+{
+	struct gntdev_dmabuf *gntdev_dmabuf;
+	int i;
+
+	gntdev_dmabuf = kzalloc(sizeof(*gntdev_dmabuf), GFP_KERNEL);
+	if (!gntdev_dmabuf)
+		goto fail;
+
+	gntdev_dmabuf->u.imp.refs = kcalloc(count,
+					    sizeof(gntdev_dmabuf->u.imp.refs[0]),
+					    GFP_KERNEL);
+	if (!gntdev_dmabuf->u.imp.refs)
+		goto fail;
+
+	gntdev_dmabuf->pages = kcalloc(count,
+				       sizeof(gntdev_dmabuf->pages[0]),
+				       GFP_KERNEL);
+	if (!gntdev_dmabuf->pages)
+		goto fail;
+
+	gntdev_dmabuf->nr_pages = count;
+
+	for (i = 0; i < count; i++)
+		gntdev_dmabuf->u.imp.refs[i] = GRANT_INVALID_REF;
+
+	return gntdev_dmabuf;
+
+fail:
+	dmabuf_imp_free_storage(gntdev_dmabuf);
+	return ERR_PTR(-ENOMEM);
+}
+
 static struct gntdev_dmabuf *
 dmabuf_imp_to_refs(struct gntdev_dmabuf_priv *priv, struct device *dev,
 		   int fd, int count, int domid)
 {
-	return ERR_PTR(-ENOMEM);
+	struct gntdev_dmabuf *gntdev_dmabuf, *ret;
+	struct dma_buf *dma_buf;
+	struct dma_buf_attachment *attach;
+	struct sg_table *sgt;
+	struct sg_page_iter sg_iter;
+	int i;
+
+	dma_buf = dma_buf_get(fd);
+	if (IS_ERR(dma_buf))
+		return ERR_CAST(dma_buf);
+
+	gntdev_dmabuf = dmabuf_imp_alloc_storage(count);
+	if (IS_ERR(gntdev_dmabuf)) {
+		ret = gntdev_dmabuf;
+		goto fail_put;
+	}
+
+	gntdev_dmabuf->priv = priv;
+	gntdev_dmabuf->fd = fd;
+
+	attach = dma_buf_attach(dma_buf, dev);
+	if (IS_ERR(attach)) {
+		ret = ERR_CAST(attach);
+		goto fail_free_obj;
+	}
+
+	gntdev_dmabuf->u.imp.attach = attach;
+
+	sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
+	if (IS_ERR(sgt)) {
+		ret = ERR_CAST(sgt);
+		goto fail_detach;
+	}
+
+	/* Check number of pages that imported buffer has. */
+	if (attach->dmabuf->size != gntdev_dmabuf->nr_pages << PAGE_SHIFT) {
+		ret = ERR_PTR(-EINVAL);
+		pr_debug("DMA buffer has %zu pages, user-space expects %d\n",
+			 attach->dmabuf->size, gntdev_dmabuf->nr_pages);
+		goto fail_unmap;
+	}
+
+	gntdev_dmabuf->u.imp.sgt = sgt;
+
+	/* Now convert sgt to array of pages and check for page validity. */
+	i = 0;
+	for_each_sg_page(sgt->sgl, &sg_iter, sgt->nents, 0) {
+		struct page *page = sg_page_iter_page(&sg_iter);
+		/*
+		 * Check if page is valid: this can happen if we are given
+		 * a page from VRAM or other resources which are not backed
+		 * by a struct page.
+		 */
+		if (!pfn_valid(page_to_pfn(page))) {
+			ret = ERR_PTR(-EINVAL);
+			goto fail_unmap;
+		}
+
+		gntdev_dmabuf->pages[i++] = page;
+	}
+
+	ret = ERR_PTR(dmabuf_imp_grant_foreign_access(gntdev_dmabuf->pages,
+						      gntdev_dmabuf->u.imp.refs,
+						      count, domid));
+	if (IS_ERR(ret))
+		goto fail_end_access;
+
+	pr_debug("Imported DMA buffer with fd %d\n", fd);
+
+	mutex_lock(&priv->lock);
+	list_add(&gntdev_dmabuf->next, &priv->imp_list);
+	mutex_unlock(&priv->lock);
+
+	return gntdev_dmabuf;
+
+fail_end_access:
+	dmabuf_imp_end_foreign_access(gntdev_dmabuf->u.imp.refs, count);
+fail_unmap:
+	dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL);
+fail_detach:
+	dma_buf_detach(dma_buf, attach);
+fail_free_obj:
+	dmabuf_imp_free_storage(gntdev_dmabuf);
+fail_put:
+	dma_buf_put(dma_buf);
+	return ret;
 }
 
-static u32 *dmabuf_imp_get_refs(struct gntdev_dmabuf *gntdev_dmabuf)
+/*
+ * Find the hyper dma-buf by its file descriptor and remove
+ * it from the buffer's list.
+ */
+static struct gntdev_dmabuf *
+dmabuf_imp_find_unlink(struct gntdev_dmabuf_priv *priv, int fd)
 {
-	return NULL;
+	struct gntdev_dmabuf *q, *gntdev_dmabuf, *ret = ERR_PTR(-ENOENT);
+
+	mutex_lock(&priv->lock);
+	list_for_each_entry_safe(gntdev_dmabuf, q, &priv->imp_list, next) {
+		if (gntdev_dmabuf->fd == fd) {
+			pr_debug("Found gntdev_dmabuf in the import list\n");
+			ret = gntdev_dmabuf;
+			list_del(&gntdev_dmabuf->next);
+			break;
+		}
+	}
+	mutex_unlock(&priv->lock);
+	return ret;
 }
 
 static int dmabuf_imp_release(struct gntdev_dmabuf_priv *priv, u32 fd)
 {
-	return -EINVAL;
+	struct gntdev_dmabuf *gntdev_dmabuf;
+	struct dma_buf_attachment *attach;
+	struct dma_buf *dma_buf;
+
+	gntdev_dmabuf = dmabuf_imp_find_unlink(priv, fd);
+	if (IS_ERR(gntdev_dmabuf))
+		return PTR_ERR(gntdev_dmabuf);
+
+	pr_debug("Releasing DMA buffer with fd %d\n", fd);
+
+	dmabuf_imp_end_foreign_access(gntdev_dmabuf->u.imp.refs,
+				      gntdev_dmabuf->nr_pages);
+
+	attach = gntdev_dmabuf->u.imp.attach;
+
+	if (gntdev_dmabuf->u.imp.sgt)
+		dma_buf_unmap_attachment(attach, gntdev_dmabuf->u.imp.sgt,
+					 DMA_BIDIRECTIONAL);
+	dma_buf = attach->dmabuf;
+	dma_buf_detach(attach->dmabuf, attach);
+	dma_buf_put(dma_buf);
+
+	dmabuf_imp_free_storage(gntdev_dmabuf);
+	return 0;
 }
 
 /* DMA buffer IOCTL support. */
@@ -597,7 +825,7 @@ long gntdev_ioctl_dmabuf_imp_to_refs(struct gntdev_priv *priv,
 	if (IS_ERR(gntdev_dmabuf))
 		return PTR_ERR(gntdev_dmabuf);
 
-	if (copy_to_user(u->refs, dmabuf_imp_get_refs(gntdev_dmabuf),
+	if (copy_to_user(u->refs, gntdev_dmabuf->u.imp.refs,
 			 sizeof(*u->refs) * op.count) != 0) {
 		ret = -EFAULT;
 		goto out_release;
@@ -631,6 +859,7 @@ struct gntdev_dmabuf_priv *gntdev_dmabuf_init(void)
 	mutex_init(&priv->lock);
 	INIT_LIST_HEAD(&priv->exp_list);
 	INIT_LIST_HEAD(&priv->exp_wait_list);
+	INIT_LIST_HEAD(&priv->imp_list);
 
 	return priv;
 }
-- 
2.17.1

Re: [PATCH v4 5/9] xen/gntdev: Allow mappings for DMA buffers

[Oleksandr Andrushchenko]

[-- Attachment #1: Type: text/plain, Size: 6853 bytes --]

Please note, that this will need a change (attached) while
applying to the mainline kernel because of API changes [1].

Unfortunately, current Xen tip kernel tree is v4.17-rc5 based,
so I cannot make the change in this patch now.

[1] 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3d6ce86ee79465e1b1b6e287f8ea26b553fc768e

On 06/15/2018 09:27 AM, Oleksandr Andrushchenko wrote:
> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>
> Allow mappings for DMA backed  buffers if grant table module
> supports such: this extends grant device to not only map buffers
> made of balloon pages, but also from buffers allocated with
> dma_alloc_xxx.
>
> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> ---
>   drivers/xen/gntdev.c      | 99 ++++++++++++++++++++++++++++++++++++++-
>   include/uapi/xen/gntdev.h | 15 ++++++
>   2 files changed, 112 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
> index bd56653b9bbc..0ec670d1d4e7 100644
> --- a/drivers/xen/gntdev.c
> +++ b/drivers/xen/gntdev.c
> @@ -37,6 +37,9 @@
>   #include <linux/slab.h>
>   #include <linux/highmem.h>
>   #include <linux/refcount.h>
> +#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
> +#include <linux/of_device.h>
> +#endif
>   
>   #include <xen/xen.h>
>   #include <xen/grant_table.h>
> @@ -72,6 +75,11 @@ struct gntdev_priv {
>   	struct mutex lock;
>   	struct mm_struct *mm;
>   	struct mmu_notifier mn;
> +
> +#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
> +	/* Device for which DMA memory is allocated. */
> +	struct device *dma_dev;
> +#endif
>   };
>   
>   struct unmap_notify {
> @@ -96,10 +104,27 @@ struct grant_map {
>   	struct gnttab_unmap_grant_ref *kunmap_ops;
>   	struct page **pages;
>   	unsigned long pages_vm_start;
> +
> +#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
> +	/*
> +	 * If dmabuf_vaddr is not NULL then this mapping is backed by DMA
> +	 * capable memory.
> +	 */
> +
> +	struct device *dma_dev;
> +	/* Flags used to create this DMA buffer: GNTDEV_DMA_FLAG_XXX. */
> +	int dma_flags;
> +	void *dma_vaddr;
> +	dma_addr_t dma_bus_addr;
> +	/* Needed to avoid allocation in gnttab_dma_free_pages(). */
> +	xen_pfn_t *frames;
> +#endif
>   };
>   
>   static int unmap_grant_pages(struct grant_map *map, int offset, int pages);
>   
> +static struct miscdevice gntdev_miscdev;
> +
>   /* ------------------------------------------------------------------ */
>   
>   static void gntdev_print_maps(struct gntdev_priv *priv,
> @@ -121,8 +146,27 @@ static void gntdev_free_map(struct grant_map *map)
>   	if (map == NULL)
>   		return;
>   
> +#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
> +	if (map->dma_vaddr) {
> +		struct gnttab_dma_alloc_args args;
> +
> +		args.dev = map->dma_dev;
> +		args.coherent = !!(map->dma_flags & GNTDEV_DMA_FLAG_COHERENT);
> +		args.nr_pages = map->count;
> +		args.pages = map->pages;
> +		args.frames = map->frames;
> +		args.vaddr = map->dma_vaddr;
> +		args.dev_bus_addr = map->dma_bus_addr;
> +
> +		gnttab_dma_free_pages(&args);
> +	} else
> +#endif
>   	if (map->pages)
>   		gnttab_free_pages(map->count, map->pages);
> +
> +#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
> +	kfree(map->frames);
> +#endif
>   	kfree(map->pages);
>   	kfree(map->grants);
>   	kfree(map->map_ops);
> @@ -132,7 +176,8 @@ static void gntdev_free_map(struct grant_map *map)
>   	kfree(map);
>   }
>   
> -static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count)
> +static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count,
> +					  int dma_flags)
>   {
>   	struct grant_map *add;
>   	int i;
> @@ -155,6 +200,37 @@ static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count)
>   	    NULL == add->pages)
>   		goto err;
>   
> +#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
> +	add->dma_flags = dma_flags;
> +
> +	/*
> +	 * Check if this mapping is requested to be backed
> +	 * by a DMA buffer.
> +	 */
> +	if (dma_flags & (GNTDEV_DMA_FLAG_WC | GNTDEV_DMA_FLAG_COHERENT)) {
> +		struct gnttab_dma_alloc_args args;
> +
> +		add->frames = kcalloc(count, sizeof(add->frames[0]),
> +				      GFP_KERNEL);
> +		if (!add->frames)
> +			goto err;
> +
> +		/* Remember the device, so we can free DMA memory. */
> +		add->dma_dev = priv->dma_dev;
> +
> +		args.dev = priv->dma_dev;
> +		args.coherent = !!(dma_flags & GNTDEV_DMA_FLAG_COHERENT);
> +		args.nr_pages = count;
> +		args.pages = add->pages;
> +		args.frames = add->frames;
> +
> +		if (gnttab_dma_alloc_pages(&args))
> +			goto err;
> +
> +		add->dma_vaddr = args.vaddr;
> +		add->dma_bus_addr = args.dev_bus_addr;
> +	} else
> +#endif
>   	if (gnttab_alloc_pages(count, add->pages))
>   		goto err;
>   
> @@ -325,6 +401,14 @@ static int map_grant_pages(struct grant_map *map)
>   		map->unmap_ops[i].handle = map->map_ops[i].handle;
>   		if (use_ptemod)
>   			map->kunmap_ops[i].handle = map->kmap_ops[i].handle;
> +#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
> +		else if (map->dma_vaddr) {
> +			unsigned long bfn;
> +
> +			bfn = pfn_to_bfn(page_to_pfn(map->pages[i]));
> +			map->unmap_ops[i].dev_bus_addr = __pfn_to_phys(bfn);
> +		}
> +#endif
>   	}
>   	return err;
>   }
> @@ -548,6 +632,17 @@ static int gntdev_open(struct inode *inode, struct file *flip)
>   	}
>   
>   	flip->private_data = priv;
> +#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
> +	priv->dma_dev = gntdev_miscdev.this_device;
> +
> +	/*
> +	 * The device is not spawn from a device tree, so arch_setup_dma_ops
> +	 * is not called, thus leaving the device with dummy DMA ops.
> +	 * Fix this by calling of_dma_configure() with a NULL node to set
> +	 * default DMA ops.
> +	 */
> +	of_dma_configure(priv->dma_dev, NULL);
> +#endif
>   	pr_debug("priv %p\n", priv);
>   
>   	return 0;
> @@ -589,7 +684,7 @@ static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv,
>   		return -EINVAL;
>   
>   	err = -ENOMEM;
> -	map = gntdev_alloc_map(priv, op.count);
> +	map = gntdev_alloc_map(priv, op.count, 0 /* This is not a dma-buf. */);
>   	if (!map)
>   		return err;
>   
> diff --git a/include/uapi/xen/gntdev.h b/include/uapi/xen/gntdev.h
> index 6d1163456c03..4b9d498a31d4 100644
> --- a/include/uapi/xen/gntdev.h
> +++ b/include/uapi/xen/gntdev.h
> @@ -200,4 +200,19 @@ struct ioctl_gntdev_grant_copy {
>   /* Send an interrupt on the indicated event channel */
>   #define UNMAP_NOTIFY_SEND_EVENT 0x2
>   
> +/*
> + * 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)
> +
>   #endif /* __LINUX_PUBLIC_GNTDEV_H__ */


[-- Attachment #2: 0001-xen-gntdev-fix-of_dma_configure-API-change.patch --]
[-- Type: text/x-patch, Size: 862 bytes --]

From bd96819f5c3fd94b878698ec8c1579c7115ff293 Mon Sep 17 00:00:00 2001
From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Date: Fri, 15 Jun 2018 08:55:57 +0300
Subject: [PATCH] xen/gntdev: fix of_dma_configure API change

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
---
 drivers/xen/gntdev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 46cee32c2a37..fd680a8c8ece 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -604,7 +604,7 @@ static int gntdev_open(struct inode *inode, struct file *flip)
 	 * Fix this by calling of_dma_configure() with a NULL node to set
 	 * default DMA ops.
 	 */
-	of_dma_configure(priv->dma_dev, NULL);
+	of_dma_configure(priv->dma_dev, NULL, true);
 #endif
 	pr_debug("priv %p\n", priv);
 
-- 
2.17.1

Re: [PATCH v4 5/9] xen/gntdev: Allow mappings for DMA buffers

[Juergen Gross]

On 15/06/18 08:32, Oleksandr Andrushchenko wrote:
> Please note, that this will need a change (attached) while
> applying to the mainline kernel because of API changes [1].
> 
> Unfortunately, current Xen tip kernel tree is v4.17-rc5 based,
> so I cannot make the change in this patch now.

I don't see any chance this series could go into 4.18, as the merge
window is just closing. So please post the patch based on current
Linux master of torvalds/linux.git


Juergen

Re: [PATCH v4 5/9] xen/gntdev: Allow mappings for DMA buffers

[Oleksandr Andrushchenko]

On 06/15/2018 09:46 AM, Juergen Gross wrote:
> On 15/06/18 08:32, Oleksandr Andrushchenko wrote:
>> Please note, that this will need a change (attached) while
>> applying to the mainline kernel because of API changes [1].
>>
>> Unfortunately, current Xen tip kernel tree is v4.17-rc5 based,
>> so I cannot make the change in this patch now.
> I don't see any chance this series could go into 4.18, as the merge
> window is just closing. So please post the patch based on current
> Linux master of torvalds/linux.git
Ok, I'll wait for any comments/r-b's and then rebase to
torvalds/linux.git and push v5?
BTW, is there any plan to rebase Xen tip kernel?
>
> Juergen

Re: [PATCH v4 3/9] xen/balloon: Share common memory reservation routines

[Boris Ostrovsky]

On 06/15/2018 02:27 AM, Oleksandr Andrushchenko wrote:
> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>
> Memory {increase|decrease}_reservation and VA mappings update/reset
> code used in balloon driver can be made common, so other drivers can
> also re-use the same functionality without open-coding.
> Create a dedicated file for the shared code and export corresponding
> symbols for other kernel modules.
>
> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>

Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

Re: [PATCH v4 7/9] xen/gntdev: Add initial support for dma-buf UAPI

[Boris Ostrovsky]

On 06/15/2018 02:27 AM, Oleksandr Andrushchenko wrote:
> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>
> 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>

Re: [PATCH v4 8/9] xen/gntdev: Implement dma-buf export functionality

[Boris Ostrovsky]

On 06/15/2018 02:27 AM, Oleksandr Andrushchenko wrote:
> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>
> 1. Create a dma-buf from grant references provided by the foreign
>    domain. By default dma-buf is backed by system memory pages, but
>    by providing GNTDEV_DMA_FLAG_XXX flags it can also be created
>    as a DMA write-combine/coherent buffer, e.g. allocated with
>    corresponding dma_alloc_xxx API.
>    Export the resulting buffer as a new dma-buf.
>
> 2. Implement waiting for the dma-buf to be released: block until the
>    dma-buf with the file descriptor provided is released.
>    If within the time-out provided the buffer is not released then
>    -ETIMEDOUT error is returned. If the buffer with the file descriptor
>    does not exist or has already been released, then -ENOENT is
>    returned. For valid file descriptors this must not be treated as
>    error.
>
> 3. Make gntdev's common code and structures available to dma-buf.
>
> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>


Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

Re: [PATCH v4 9/9] xen/gntdev: Implement dma-buf import functionality

[Boris Ostrovsky]

On 06/15/2018 02:27 AM, Oleksandr Andrushchenko wrote:
> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>
> 1. Import a dma-buf with the file descriptor provided and export
>    granted references to the pages of that dma-buf into the array
>    of grant references.
>
> 2. Add API to 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.
>
> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>


Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

Re: [PATCH v4 5/9] xen/gntdev: Allow mappings for DMA buffers

[Boris Ostrovsky]

On 06/15/2018 02:50 AM, Oleksandr Andrushchenko wrote:
> On 06/15/2018 09:46 AM, Juergen Gross wrote:
>> On 15/06/18 08:32, Oleksandr Andrushchenko wrote:
>>> Please note, that this will need a change (attached) while
>>> applying to the mainline kernel because of API changes [1].
>>>
>>> Unfortunately, current Xen tip kernel tree is v4.17-rc5 based,
>>> so I cannot make the change in this patch now.
>> I don't see any chance this series could go into 4.18, as the merge
>> window is just closing. So please post the patch based on current
>> Linux master of torvalds/linux.git
> Ok, I'll wait for any comments/r-b's and then rebase to
> torvalds/linux.git and push v5?

As I mentioned earlier, I would very much like at least a review of the
new interfaces by someone more knowledgeable than me.


> BTW, is there any plan to rebase Xen tip kernel?


It is typically rebased to rc5 or r6, at which point patches for the
next merge window are applied.

-borsi

Re: [PATCH v4 0/9] xen: dma-buf support for grant device

[Oleksandr Andrushchenko]

Boris, Juergen!

Thank you so much for your comments and time spent on this
series. Appreciate that very much!

Thank you,
Oleksandr

On 06/15/2018 09:27 AM, Oleksandr Andrushchenko wrote:
> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>
> This work is in response to my previous attempt to introduce Xen/DRM
> zero-copy driver [1] to enable Linux dma-buf API [2] for Xen based
> frontends/backends. There is also an existing hyper_dmabuf approach
> available [3] which, if reworked to utilize the proposed solution,
> can greatly benefit as well.
>
> RFC for this series was published and discussed [9], comments addressed.
>
> The original rationale behind this work was to enable zero-copying
> use-cases while working with Xen para-virtual display driver [4]:
> when using Xen PV DRM frontend driver then on backend side one will
> need to do copying of display buffers' contents (filled by the
> frontend's user-space) into buffers allocated at the backend side.
> Taking into account the size of display buffers and frames per
> second it may result in unneeded huge data bus occupation and
> performance loss.
>
> The helper driver [4] allows implementing zero-copying use-cases
> when using Xen para-virtualized frontend display driver by implementing
> a DRM/KMS helper driver running on backend's side.
> It utilizes PRIME buffers API (implemented on top of Linux dma-buf)
> to share frontend's buffers with physical device drivers on
> backend's side:
>
>   - a dumb buffer created on backend's side can be shared
>     with the Xen PV frontend driver, so it directly writes
>     into backend's domain memory (into the buffer exported from
>     DRM/KMS driver of a physical display device)
>   - a dumb buffer allocated by the frontend can be imported
>     into physical device DRM/KMS driver, thus allowing to
>     achieve no copying as well
>
> Finally, it was discussed and decided ([1], [5]) that it is worth
> implementing such use-cases via extension of the existing Xen gntdev
> driver instead of introducing new DRM specific driver.
> Please note, that the support of dma-buf is Linux only,
> as dma-buf is a Linux only thing.
>
> Now to the proposed solution. The changes  to the existing Xen drivers
> in the Linux kernel fall into 2 categories:
> 1. DMA-able memory buffer allocation and increasing/decreasing memory
>     reservation of the pages of such a buffer.
>     This is required if we are about to share dma-buf with the hardware
>     that does require those to be allocated with dma_alloc_xxx API.
>     (It is still possible to allocate a dma-buf from any system memory,
>     e.g. system pages).
> 2. Extension of the gntdev driver to enable it to import/export dma-buf’s.
>
> The first six patches are in preparation for Xen dma-buf support,
> but I consider those usable regardless of the dma-buf use-case,
> e.g. other frontend/backend kernel modules may also benefit from these
> for better code reuse:
>      0001-xen-grant-table-Export-gnttab_-alloc-free-_pages-as-.patch
>      0002-xen-grant-table-Make-set-clear-page-private-code-sha.patch
>      0003-xen-balloon-Share-common-memory-reservation-routines.patch
>      0004-xen-grant-table-Allow-allocating-buffers-suitable-fo.patch
>      0005-xen-gntdev-Allow-mappings-for-DMA-buffers.patch
>      0006-xen-gntdev-Make-private-routines-structures-accessib.patch
>
> The next three patches are Xen implementation of dma-buf as part of
> the grant device:
>      0007-xen-gntdev-Add-initial-support-for-dma-buf-UAPI.patch
>      0008-xen-gntdev-Implement-dma-buf-export-functionality.patch
>      0009-xen-gntdev-Implement-dma-buf-import-functionality.patch
>
> The corresponding libxengnttab changes are available at [6].
>
> All the above was tested with display backend [7] and its accompanying
> helper library [8] on Renesas ARM64 based board.
> Basic balloon tests on x86.
>
> *To all the communities*: I would like to ask you to review the proposed
> solution and give feedback on it, so I can improve and send final
> patches for review (this is still work in progress, but enough to start
> discussing the implementation).
>
> Thank you in advance,
> Oleksandr Andrushchenko
>
> [1] https://lists.freedesktop.org/archives/dri-devel/2018-April/173163.html
> [2] https://elixir.bootlin.com/linux/v4.17-rc5/source/Documentation/driver-api/dma-buf.rst
> [3] https://lists.xenproject.org/archives/html/xen-devel/2018-02/msg01202.html
> [4] https://cgit.freedesktop.org/drm/drm-misc/tree/drivers/gpu/drm/xen
> [5] https://patchwork.kernel.org/patch/10279681/
> [6] https://github.com/andr2000/xen/tree/xen_dma_buf_v1
> [7] https://github.com/andr2000/displ_be/tree/xen_dma_buf_v1
> [8] https://github.com/andr2000/libxenbe/tree/xen_dma_buf_v1
> [9] https://lkml.org/lkml/2018/5/17/215
>
> Changes since v3:
> *****************
> - added r-b tags
> - minor fixes
> - removed gntdev_remove_map as it can be coded directly now
> - moved IOCTL code to gntdev-dmabuf.c
> - removed usless wait list walks and changed some walks to use
>    normal version of list iterators instead of safe ones as
>    we run under a lock anyways
> - cleaned up comments, descriptions, pr_debug messages
>
> Changes since v2:
> *****************
> - fixed missed break in dmabuf_exp_wait_obj_signal
> - re-worked debug and error messages, be less verbose
> - removed patch for making gntdev functions available to other drivers
> - removed WARN_ON's in dma-buf code
> - moved all dma-buf related code into gntdev-dmabuf
> - introduced gntdev-common.h with common structures and function prototypes
> - added additional checks for number of grants in IOCTLs
> - gnttab patch cleanup
> - made xenmem_reservation_scrub_page defined in the header as inline
> - fixed __pfn_to_mfn use to pfn_to_bfn
> - no changes to patches 1-2
>
> Changes since v1:
> *****************
> - Define GNTDEV_DMA_FLAG_XXX starting from bit 0
> - Rename mem_reservation.h to mem-reservation.h
> - Remove usless comments
> - Change licenses from GPLv2 OR MIT to GPLv2 only
> - Make xenmem_reservation_va_mapping_{update|clear} inline
> - Change EXPORT_SYMBOL to EXPORT_SYMBOL_GPL for new functions
> - Make gnttab_dma_{alloc|free}_pages to request frames array
>    be allocated outside
> - Fixe gnttab_dma_alloc_pages fail path (added xenmem_reservation_increase)
> - Move most of dma-buf from gntdev.c to gntdev-dmabuf.c
> - Add required dependencies to Kconfig
> - Rework "#ifdef CONFIG_XEN_XXX" for if/else
> - Export gnttab_{alloc|free}_pages as GPL symbols (patch 1)
>
> Oleksandr Andrushchenko (9):
>    xen/grant-table: Export gnttab_{alloc|free}_pages as GPL
>    xen/grant-table: Make set/clear page private code shared
>    xen/balloon: Share common memory reservation routines
>    xen/grant-table: Allow allocating buffers suitable for DMA
>    xen/gntdev: Allow mappings for DMA buffers
>    xen/gntdev: Make private routines/structures accessible
>    xen/gntdev: Add initial support for dma-buf UAPI
>    xen/gntdev: Implement dma-buf export functionality
>    xen/gntdev: Implement dma-buf import functionality
>
>   drivers/xen/Kconfig           |  24 +
>   drivers/xen/Makefile          |   2 +
>   drivers/xen/balloon.c         |  75 +--
>   drivers/xen/gntdev-common.h   |  94 ++++
>   drivers/xen/gntdev-dmabuf.c   | 870 ++++++++++++++++++++++++++++++++++
>   drivers/xen/gntdev-dmabuf.h   |  33 ++
>   drivers/xen/gntdev.c          | 220 ++++++---
>   drivers/xen/grant-table.c     | 153 +++++-
>   drivers/xen/mem-reservation.c | 118 +++++
>   include/uapi/xen/gntdev.h     | 106 +++++
>   include/xen/grant_table.h     |  21 +
>   include/xen/mem-reservation.h |  59 +++
>   12 files changed, 1615 insertions(+), 160 deletions(-)
>   create mode 100644 drivers/xen/gntdev-common.h
>   create mode 100644 drivers/xen/gntdev-dmabuf.c
>   create mode 100644 drivers/xen/gntdev-dmabuf.h
>   create mode 100644 drivers/xen/mem-reservation.c
>   create mode 100644 include/xen/mem-reservation.h
>

Re: [PATCH v4 5/9] xen/gntdev: Allow mappings for DMA buffers

[Oleksandr Andrushchenko]

On 06/16/2018 12:07 AM, Boris Ostrovsky wrote:
> On 06/15/2018 02:50 AM, Oleksandr Andrushchenko wrote:
>> On 06/15/2018 09:46 AM, Juergen Gross wrote:
>>> On 15/06/18 08:32, Oleksandr Andrushchenko wrote:
>>>> Please note, that this will need a change (attached) while
>>>> applying to the mainline kernel because of API changes [1].
>>>>
>>>> Unfortunately, current Xen tip kernel tree is v4.17-rc5 based,
>>>> so I cannot make the change in this patch now.
>>> I don't see any chance this series could go into 4.18, as the merge
>>> window is just closing. So please post the patch based on current
>>> Linux master of torvalds/linux.git
>> Ok, I'll wait for any comments/r-b's and then rebase to
>> torvalds/linux.git and push v5?
> As I mentioned earlier, I would very much like at least a review of the
> new interfaces by someone more knowledgeable than me.
I am adding "DMA BUFFER SHARING FRAMEWORK" maintainer to the list.
Sumit, could please help reviewing this? The whole work here
is to add dma-buf to Xen's grant device driver.

Intel could probably also say couple of words as they also
might re-use this work.
>
>> BTW, is there any plan to rebase Xen tip kernel?
>
> It is typically rebased to rc5 or r6, at which point patches for the
> next merge window are applied.
>
> -borsi

Re: [PATCH v4 8/9] xen/gntdev: Implement dma-buf export functionality

[Oleksandr Andrushchenko]

+
> +static const struct dma_buf_ops dmabuf_exp_ops =  {
> +	.attach = dmabuf_exp_ops_attach,
> +	.detach = dmabuf_exp_ops_detach,
> +	.map_dma_buf = dmabuf_exp_ops_map_dma_buf,
> +	.unmap_dma_buf = dmabuf_exp_ops_unmap_dma_buf,
> +	.release = dmabuf_exp_ops_release,
> +	.map = dmabuf_exp_ops_kmap,
> +	.map_atomic = dmabuf_exp_ops_kmap_atomic,
> +	.unmap = dmabuf_exp_ops_kunmap,
> +	.unmap_atomic = dmabuf_exp_ops_kunmap_atomic,
> +	.mmap = dmabuf_exp_ops_mmap,
> +};
> +
>
Due to upcoming API change [1] the atomic ops need to be removed before
merging into the mainline

[1] 
https://cgit.freedesktop.org/drm/drm-misc/commit/include/linux/dma-buf.h?id=f664a52695429b68afb4e130a0f69cd5fd1fec86

Re: [PATCH v4 0/9] xen: dma-buf support for grant device

[Oleksandr Andrushchenko]

Hello, Boris, Juergen!

Do you think I can re-base the series (which already has
all required R-b's from Xen community) onto the latest kernel
with API changes to patches 5 (of_dma_configure) and 8
(dma-buf atomic ops) and we can merge it to the Xen's kernel tree?

It seems like no other reviews or objections are there so this
seems reasonable to me now.

Thank you,
Oleksandr

On 06/15/2018 09:27 AM, Oleksandr Andrushchenko wrote:
> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>
> This work is in response to my previous attempt to introduce Xen/DRM
> zero-copy driver [1] to enable Linux dma-buf API [2] for Xen based
> frontends/backends. There is also an existing hyper_dmabuf approach
> available [3] which, if reworked to utilize the proposed solution,
> can greatly benefit as well.
>
> RFC for this series was published and discussed [9], comments addressed.
>
> The original rationale behind this work was to enable zero-copying
> use-cases while working with Xen para-virtual display driver [4]:
> when using Xen PV DRM frontend driver then on backend side one will
> need to do copying of display buffers' contents (filled by the
> frontend's user-space) into buffers allocated at the backend side.
> Taking into account the size of display buffers and frames per
> second it may result in unneeded huge data bus occupation and
> performance loss.
>
> The helper driver [4] allows implementing zero-copying use-cases
> when using Xen para-virtualized frontend display driver by implementing
> a DRM/KMS helper driver running on backend's side.
> It utilizes PRIME buffers API (implemented on top of Linux dma-buf)
> to share frontend's buffers with physical device drivers on
> backend's side:
>
>   - a dumb buffer created on backend's side can be shared
>     with the Xen PV frontend driver, so it directly writes
>     into backend's domain memory (into the buffer exported from
>     DRM/KMS driver of a physical display device)
>   - a dumb buffer allocated by the frontend can be imported
>     into physical device DRM/KMS driver, thus allowing to
>     achieve no copying as well
>
> Finally, it was discussed and decided ([1], [5]) that it is worth
> implementing such use-cases via extension of the existing Xen gntdev
> driver instead of introducing new DRM specific driver.
> Please note, that the support of dma-buf is Linux only,
> as dma-buf is a Linux only thing.
>
> Now to the proposed solution. The changes  to the existing Xen drivers
> in the Linux kernel fall into 2 categories:
> 1. DMA-able memory buffer allocation and increasing/decreasing memory
>     reservation of the pages of such a buffer.
>     This is required if we are about to share dma-buf with the hardware
>     that does require those to be allocated with dma_alloc_xxx API.
>     (It is still possible to allocate a dma-buf from any system memory,
>     e.g. system pages).
> 2. Extension of the gntdev driver to enable it to import/export dma-buf’s.
>
> The first six patches are in preparation for Xen dma-buf support,
> but I consider those usable regardless of the dma-buf use-case,
> e.g. other frontend/backend kernel modules may also benefit from these
> for better code reuse:
>      0001-xen-grant-table-Export-gnttab_-alloc-free-_pages-as-.patch
>      0002-xen-grant-table-Make-set-clear-page-private-code-sha.patch
>      0003-xen-balloon-Share-common-memory-reservation-routines.patch
>      0004-xen-grant-table-Allow-allocating-buffers-suitable-fo.patch
>      0005-xen-gntdev-Allow-mappings-for-DMA-buffers.patch
>      0006-xen-gntdev-Make-private-routines-structures-accessib.patch
>
> The next three patches are Xen implementation of dma-buf as part of
> the grant device:
>      0007-xen-gntdev-Add-initial-support-for-dma-buf-UAPI.patch
>      0008-xen-gntdev-Implement-dma-buf-export-functionality.patch
>      0009-xen-gntdev-Implement-dma-buf-import-functionality.patch
>
> The corresponding libxengnttab changes are available at [6].
>
> All the above was tested with display backend [7] and its accompanying
> helper library [8] on Renesas ARM64 based board.
> Basic balloon tests on x86.
>
> *To all the communities*: I would like to ask you to review the proposed
> solution and give feedback on it, so I can improve and send final
> patches for review (this is still work in progress, but enough to start
> discussing the implementation).
>
> Thank you in advance,
> Oleksandr Andrushchenko
>
> [1] https://lists.freedesktop.org/archives/dri-devel/2018-April/173163.html
> [2] https://elixir.bootlin.com/linux/v4.17-rc5/source/Documentation/driver-api/dma-buf.rst
> [3] https://lists.xenproject.org/archives/html/xen-devel/2018-02/msg01202.html
> [4] https://cgit.freedesktop.org/drm/drm-misc/tree/drivers/gpu/drm/xen
> [5] https://patchwork.kernel.org/patch/10279681/
> [6] https://github.com/andr2000/xen/tree/xen_dma_buf_v1
> [7] https://github.com/andr2000/displ_be/tree/xen_dma_buf_v1
> [8] https://github.com/andr2000/libxenbe/tree/xen_dma_buf_v1
> [9] https://lkml.org/lkml/2018/5/17/215
>
> Changes since v3:
> *****************
> - added r-b tags
> - minor fixes
> - removed gntdev_remove_map as it can be coded directly now
> - moved IOCTL code to gntdev-dmabuf.c
> - removed usless wait list walks and changed some walks to use
>    normal version of list iterators instead of safe ones as
>    we run under a lock anyways
> - cleaned up comments, descriptions, pr_debug messages
>
> Changes since v2:
> *****************
> - fixed missed break in dmabuf_exp_wait_obj_signal
> - re-worked debug and error messages, be less verbose
> - removed patch for making gntdev functions available to other drivers
> - removed WARN_ON's in dma-buf code
> - moved all dma-buf related code into gntdev-dmabuf
> - introduced gntdev-common.h with common structures and function prototypes
> - added additional checks for number of grants in IOCTLs
> - gnttab patch cleanup
> - made xenmem_reservation_scrub_page defined in the header as inline
> - fixed __pfn_to_mfn use to pfn_to_bfn
> - no changes to patches 1-2
>
> Changes since v1:
> *****************
> - Define GNTDEV_DMA_FLAG_XXX starting from bit 0
> - Rename mem_reservation.h to mem-reservation.h
> - Remove usless comments
> - Change licenses from GPLv2 OR MIT to GPLv2 only
> - Make xenmem_reservation_va_mapping_{update|clear} inline
> - Change EXPORT_SYMBOL to EXPORT_SYMBOL_GPL for new functions
> - Make gnttab_dma_{alloc|free}_pages to request frames array
>    be allocated outside
> - Fixe gnttab_dma_alloc_pages fail path (added xenmem_reservation_increase)
> - Move most of dma-buf from gntdev.c to gntdev-dmabuf.c
> - Add required dependencies to Kconfig
> - Rework "#ifdef CONFIG_XEN_XXX" for if/else
> - Export gnttab_{alloc|free}_pages as GPL symbols (patch 1)
>
> Oleksandr Andrushchenko (9):
>    xen/grant-table: Export gnttab_{alloc|free}_pages as GPL
>    xen/grant-table: Make set/clear page private code shared
>    xen/balloon: Share common memory reservation routines
>    xen/grant-table: Allow allocating buffers suitable for DMA
>    xen/gntdev: Allow mappings for DMA buffers
>    xen/gntdev: Make private routines/structures accessible
>    xen/gntdev: Add initial support for dma-buf UAPI
>    xen/gntdev: Implement dma-buf export functionality
>    xen/gntdev: Implement dma-buf import functionality
>
>   drivers/xen/Kconfig           |  24 +
>   drivers/xen/Makefile          |   2 +
>   drivers/xen/balloon.c         |  75 +--
>   drivers/xen/gntdev-common.h   |  94 ++++
>   drivers/xen/gntdev-dmabuf.c   | 870 ++++++++++++++++++++++++++++++++++
>   drivers/xen/gntdev-dmabuf.h   |  33 ++
>   drivers/xen/gntdev.c          | 220 ++++++---
>   drivers/xen/grant-table.c     | 153 +++++-
>   drivers/xen/mem-reservation.c | 118 +++++
>   include/uapi/xen/gntdev.h     | 106 +++++
>   include/xen/grant_table.h     |  21 +
>   include/xen/mem-reservation.h |  59 +++
>   12 files changed, 1615 insertions(+), 160 deletions(-)
>   create mode 100644 drivers/xen/gntdev-common.h
>   create mode 100644 drivers/xen/gntdev-dmabuf.c
>   create mode 100644 drivers/xen/gntdev-dmabuf.h
>   create mode 100644 drivers/xen/mem-reservation.c
>   create mode 100644 include/xen/mem-reservation.h
>

Re: [PATCH v4 0/9] xen: dma-buf support for grant device

[Juergen Gross]

On 02/07/18 09:10, Oleksandr Andrushchenko wrote:
> Hello, Boris, Juergen!
> 
> Do you think I can re-base the series (which already has
> all required R-b's from Xen community) onto the latest kernel
> with API changes to patches 5 (of_dma_configure) and 8
> (dma-buf atomic ops) and we can merge it to the Xen's kernel tree?

Rebase: yes.

Merging to the Xen kernel tree: only after setting up the
for-linus-4.19 branch, which will be done by Boris later this
month.


Juergen

Re: [PATCH v4 0/9] xen: dma-buf support for grant device

[Oleksandr Andrushchenko]

On 07/02/2018 11:20 AM, Juergen Gross wrote:
> On 02/07/18 09:10, Oleksandr Andrushchenko wrote:
>> Hello, Boris, Juergen!
>>
>> Do you think I can re-base the series (which already has
>> all required R-b's from Xen community) onto the latest kernel
>> with API changes to patches 5 (of_dma_configure) and 8
>> (dma-buf atomic ops) and we can merge it to the Xen's kernel tree?
> Rebase: yes.
>
> Merging to the Xen kernel tree: only after setting up the
> for-linus-4.19 branch, which will be done by Boris later this
> month.
Then I'll probably have to wait until for-linus-4.19 branch
Boris, do you have any dates in mind for that?
>
> Juergen
Thank you,
Oleksandr

Re: [PATCH v4 0/9] xen: dma-buf support for grant device

[Boris Ostrovsky]

On 07/02/2018 09:12 AM, Oleksandr Andrushchenko wrote:
> On 07/02/2018 11:20 AM, Juergen Gross wrote:
>> On 02/07/18 09:10, Oleksandr Andrushchenko wrote:
>>> Hello, Boris, Juergen!
>>>
>>> Do you think I can re-base the series (which already has
>>> all required R-b's from Xen community) onto the latest kernel
>>> with API changes to patches 5 (of_dma_configure) and 8
>>> (dma-buf atomic ops) and we can merge it to the Xen's kernel tree?
>> Rebase: yes.
>>
>> Merging to the Xen kernel tree: only after setting up the
>> for-linus-4.19 branch, which will be done by Boris later this
>> month.
> Then I'll probably have to wait until for-linus-4.19 branch
> Boris, do you have any dates in mind for that?


Usually after rc5, so I suspect sometime next week.


-boris