xen: dma-buf support for grant device

From: Oleksandr Andrushchenko <[email protected]>

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 <[email protected]>

From: Oleksandr Andrushchenko <[email protected]>

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 <[email protected]>

From: Oleksandr Andrushchenko <[email protected]>

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 <[email protected]>

From: Oleksandr Andrushchenko <[email protected]>

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 <[email protected]>

From: Oleksandr Andrushchenko <[email protected]>

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 <[email protected]>

---
  drivers/xen/grant-table.c | 54 +++++++++++++++++++++++++--------------
  include/xen/grant_table.h |  3 +++
  2 files changed, 38 insertions(+), 19 deletions(-)

drivers/xen/grant-table.c +35 -19

index ba36ff3e4903..dbb48a89e987 100644
@@ -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);

include/xen/grant_table.h +0 -0

index 2e37741f6b8d..de03f2542bb7 100644

From: Oleksandr Andrushchenko <[email protected]>

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 <[email protected]>

---
  drivers/xen/grant-table.c | 54 +++++++++++++++++++++++++--------------
  include/xen/grant_table.h |  3 +++
  2 files changed, 38 insertions(+), 19 deletions(-)

drivers/xen/grant-table.c +35 -19

index ba36ff3e4903..dbb48a89e987 100644
@@ -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);

include/xen/grant_table.h +0 -0

index 2e37741f6b8d..de03f2542bb7 100644

From: Oleksandr Andrushchenko <[email protected]>

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 <[email protected]>

From: Oleksandr Andrushchenko <[email protected]>

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 <[email protected]>

include/xen/mem-reservation.h new file +21 -0

new file mode 100644
index 000000000000..a727d65a1e61
@@ -0,0 +1,65 @@
+/* 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/kernel.h>
+#include <linux/slab.h>
+
+#include <asm/xen/hypercall.h>
+#include <asm/tlb.h>
+

Quoted 27 lines · Oleksandr Andrushchenko

include/xen/mem-reservation.h new file +21 -0

new file mode 100644
index 000000000000..a727d65a1e61
@@ -0,0 +1,65 @@
+/* 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/kernel.h>
+#include <linux/slab.h>
+
+#include <asm/xen/hypercall.h>
+#include <asm/tlb.h>
+

include/xen/mem-reservation.h line 31

Quoted 10 lines

include/xen/mem-reservation.h new file +10 -0

+#include <xen/interface/memory.h>
+#include <xen/page.h>
+
+#ifdef CONFIG_XEN_SCRUB_PAGES
+void xenmem_reservation_scrub_page(struct page *page);
+#else
+static inline void xenmem_reservation_scrub_page(struct page *page)
+{
+}
+#endif

Given that this is a wrapper around a single call I'd prefer

inline void xenmem_reservation_scrub_page(struct page *page) {
#ifdef CONFIG_XEN_SCRUB_PAGES
    clear_highpage(page);
#endif
}

-boris

Quoted 27 lines · Oleksandr Andrushchenko

include/xen/mem-reservation.h new file +21 -0

new file mode 100644
index 000000000000..a727d65a1e61
@@ -0,0 +1,65 @@
+/* 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/kernel.h>
+#include <linux/slab.h>
+
+#include <asm/xen/hypercall.h>
+#include <asm/tlb.h>
+

include/xen/mem-reservation.h line 31

Quoted 10 lines

include/xen/mem-reservation.h new file +10 -0

+#include <xen/interface/memory.h>
+#include <xen/page.h>
+
+#ifdef CONFIG_XEN_SCRUB_PAGES
+void xenmem_reservation_scrub_page(struct page *page);
+#else
+static inline void xenmem_reservation_scrub_page(struct page *page)
+{
+}
+#endif

Given that this is a wrapper around a single call I'd prefer

inline void xenmem_reservation_scrub_page(struct page *page) {
#ifdef CONFIG_XEN_SCRUB_PAGES
    clear_highpage(page);
#endif
}

-boris

Quoted 27 lines · Oleksandr Andrushchenko

include/xen/mem-reservation.h new file +21 -0

new file mode 100644
index 000000000000..a727d65a1e61
@@ -0,0 +1,65 @@
+/* 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/kernel.h>
+#include <linux/slab.h>
+
+#include <asm/xen/hypercall.h>
+#include <asm/tlb.h>
+

include/xen/mem-reservation.h line 31

Quoted 10 lines

include/xen/mem-reservation.h new file +10 -0

+#include <xen/interface/memory.h>
+#include <xen/page.h>
+
+#ifdef CONFIG_XEN_SCRUB_PAGES
+void xenmem_reservation_scrub_page(struct page *page);
+#else
+static inline void xenmem_reservation_scrub_page(struct page *page)
+{
+}
+#endif

Given that this is a wrapper around a single call I'd prefer

inline void xenmem_reservation_scrub_page(struct page *page) {
#ifdef CONFIG_XEN_SCRUB_PAGES
    clear_highpage(page);
#endif
}

-boris

Quoted 42 lines · Boris Ostrovsky

Quoted 28 lines · Oleksandr Andrushchenko

include/xen/mem-reservation.h new file +21 -0

new file mode 100644
index 000000000000..a727d65a1e61
@@ -0,0 +1,65 @@
+/* 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/kernel.h>
+#include <linux/slab.h>
+
+#include <asm/xen/hypercall.h>
+#include <asm/tlb.h>
+

include/xen/mem-reservation.h line 31

Quoted 10 lines

include/xen/mem-reservation.h new file +10 -0

+#include <xen/interface/memory.h>
+#include <xen/page.h>
+
+#ifdef CONFIG_XEN_SCRUB_PAGES
+void xenmem_reservation_scrub_page(struct page *page);
+#else
+static inline void xenmem_reservation_scrub_page(struct page *page)
+{
+}
+#endif

Given that this is a wrapper around a single call I'd prefer

Quoted 6 lines

inline void xenmem_reservation_scrub_page(struct page *page) {
#ifdef CONFIG_XEN_SCRUB_PAGES clear_highpage(page);
#endif
}

Unfortunately this can't be done because of EXPORT_SYMBOL_GPL(xenmem_reservation_scrub_page); which is obviously cannot be used for static inline functions.

So, I'll keep it as is.

Quoted 5 lines

-boris

Thank you,
Oleksandr

Quoted 42 lines · Boris Ostrovsky

Quoted 28 lines · Oleksandr Andrushchenko

include/xen/mem-reservation.h new file +21 -0

new file mode 100644
index 000000000000..a727d65a1e61
@@ -0,0 +1,65 @@
+/* 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/kernel.h>
+#include <linux/slab.h>
+
+#include <asm/xen/hypercall.h>
+#include <asm/tlb.h>
+

include/xen/mem-reservation.h line 31

Quoted 10 lines

include/xen/mem-reservation.h new file +10 -0

+#include <xen/interface/memory.h>
+#include <xen/page.h>
+
+#ifdef CONFIG_XEN_SCRUB_PAGES
+void xenmem_reservation_scrub_page(struct page *page);
+#else
+static inline void xenmem_reservation_scrub_page(struct page *page)
+{
+}
+#endif

Given that this is a wrapper around a single call I'd prefer

Quoted 6 lines

inline void xenmem_reservation_scrub_page(struct page *page) {
#ifdef CONFIG_XEN_SCRUB_PAGES clear_highpage(page);
#endif
}

Unfortunately this can't be done because of EXPORT_SYMBOL_GPL(xenmem_reservation_scrub_page); which is obviously cannot be used for static inline functions.

So, I'll keep it as is.

Quoted 5 lines

-boris

Thank you,
Oleksandr

Quoted 48 lines · Oleksandr Andrushchenko

Quoted 47 lines · Boris Ostrovsky

Quoted 28 lines · Oleksandr Andrushchenko

include/xen/mem-reservation.h new file +21 -0

new file mode 100644
index 000000000000..a727d65a1e61
@@ -0,0 +1,65 @@
+/* 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/kernel.h>
+#include <linux/slab.h>
+
+#include <asm/xen/hypercall.h>
+#include <asm/tlb.h>
+

include/xen/mem-reservation.h line 31

Quoted 10 lines

include/xen/mem-reservation.h new file +10 -0

+#include <xen/interface/memory.h>
+#include <xen/page.h>
+
+#ifdef CONFIG_XEN_SCRUB_PAGES
+void xenmem_reservation_scrub_page(struct page *page);
+#else
+static inline void xenmem_reservation_scrub_page(struct page *page)
+{
+}
+#endif

Given that this is a wrapper around a single call I'd prefer

inline void xenmem_reservation_scrub_page(struct page *page) {
#ifdef CONFIG_XEN_SCRUB_PAGES
     clear_highpage(page);
#endif
}

Quoted 3 lines

Unfortunately this can't be done because of EXPORT_SYMBOL_GPL(xenmem_reservation_scrub_page); which is obviously cannot be used for static inline functions.

Why do you need to export it? It's an inline defined in the header file. Just like clear_highpage().

-boris

Quoted 7 lines

So, I'll keep it as is.

Quoted 4 lines

-boris

Thank you,
Oleksandr

Quoted 48 lines · Oleksandr Andrushchenko

Quoted 47 lines · Boris Ostrovsky

Quoted 28 lines · Oleksandr Andrushchenko

include/xen/mem-reservation.h new file +21 -0

new file mode 100644
index 000000000000..a727d65a1e61
@@ -0,0 +1,65 @@
+/* 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/kernel.h>
+#include <linux/slab.h>
+
+#include <asm/xen/hypercall.h>
+#include <asm/tlb.h>
+

include/xen/mem-reservation.h line 31

Quoted 10 lines

include/xen/mem-reservation.h new file +10 -0

+#include <xen/interface/memory.h>
+#include <xen/page.h>
+
+#ifdef CONFIG_XEN_SCRUB_PAGES
+void xenmem_reservation_scrub_page(struct page *page);
+#else
+static inline void xenmem_reservation_scrub_page(struct page *page)
+{
+}
+#endif

Given that this is a wrapper around a single call I'd prefer

inline void xenmem_reservation_scrub_page(struct page *page) {
#ifdef CONFIG_XEN_SCRUB_PAGES
     clear_highpage(page);
#endif
}

Quoted 3 lines

Unfortunately this can't be done because of EXPORT_SYMBOL_GPL(xenmem_reservation_scrub_page); which is obviously cannot be used for static inline functions.

Why do you need to export it? It's an inline defined in the header file. Just like clear_highpage().

-boris

Quoted 7 lines

So, I'll keep it as is.

Quoted 4 lines

-boris

Thank you,
Oleksandr

Quoted 27 lines · Oleksandr Andrushchenko

include/xen/mem-reservation.h new file +21 -0

new file mode 100644
index 000000000000..a727d65a1e61
@@ -0,0 +1,65 @@
+/* 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/kernel.h>
+#include <linux/slab.h>
+
+#include <asm/xen/hypercall.h>
+#include <asm/tlb.h>
+

include/xen/mem-reservation.h line 31

Quoted 10 lines

include/xen/mem-reservation.h new file +10 -0

+#include <xen/interface/memory.h>
+#include <xen/page.h>
+
+#ifdef CONFIG_XEN_SCRUB_PAGES
+void xenmem_reservation_scrub_page(struct page *page);
+#else
+static inline void xenmem_reservation_scrub_page(struct page *page)
+{
+}
+#endif

Given that this is a wrapper around a single call I'd prefer

inline void xenmem_reservation_scrub_page(struct page *page) {
#ifdef CONFIG_XEN_SCRUB_PAGES
    clear_highpage(page);
#endif
}

-boris

include/xen/mem-reservation.h new file +21 -0

new file mode 100644
index 000000000000..a727d65a1e61
@@ -0,0 +1,65 @@
+/* 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/kernel.h>
+#include <linux/slab.h>
+
+#include <asm/xen/hypercall.h>
+#include <asm/tlb.h>
+

From: Oleksandr Andrushchenko <[email protected]>

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 terms that proper memory reservation is made ({increase|decrease}_reservation and VA mappings 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 <[email protected]>

---
 drivers/xen/Kconfig       |  13 +++++
 drivers/xen/grant-table.c | 109 ++++++++++++++++++++++++++++++++++++++
 include/xen/grant_table.h |  18 +++++++
 3 files changed, 140 insertions(+)

drivers/xen/Kconfig +13 -0

index e5d0c28372ea..39536ddfbce4 100644
@@ -161,6 +161,19 @@ 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 terms that proper memory reservation is made
+	  ({increase|decrease}_reservation and VA mappings 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

drivers/xen/grant-table.c +58 -0

index dbb48a89e987..5658e58d9cc6 100644
@@ -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>
 

@@ -811,6 +815,73 @@ int gnttab_alloc_pages(int nr_pages, struct page **pages)
 }
 EXPORT_SYMBOL_GPL(gnttab_alloc_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_err("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_err("Failed to decrease reservation for DMA buffer\n");
+		ret = -EFAULT;
+		goto fail_free_dma;
+	}
+
+	ret = gnttab_pages_set_private(args->nr_pages, args->pages);
+	if (ret < 0)
+		goto fail_clear_private;
+
+	return 0;
+
+fail_clear_private:
+	gnttab_pages_clear_private(args->nr_pages, args->pages);
+fail_free_dma:
+	xenmem_reservation_increase(args->nr_pages, args->frames);

drivers/xen/grant-table.c +37 -0

+/**
+ * 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_err("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

include/xen/grant_table.h +11 -0

index de03f2542bb7..9bc5bc07d4d3 100644
@@ -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;

From: Oleksandr Andrushchenko <[email protected]>

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 terms that proper memory reservation is made ({increase|decrease}_reservation and VA mappings 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 <[email protected]>

---
 drivers/xen/Kconfig       |  13 +++++
 drivers/xen/grant-table.c | 109 ++++++++++++++++++++++++++++++++++++++
 include/xen/grant_table.h |  18 +++++++
 3 files changed, 140 insertions(+)

drivers/xen/Kconfig +13 -0

index e5d0c28372ea..39536ddfbce4 100644
@@ -161,6 +161,19 @@ 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 terms that proper memory reservation is made
+	  ({increase|decrease}_reservation and VA mappings 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

drivers/xen/grant-table.c +58 -0

index dbb48a89e987..5658e58d9cc6 100644
@@ -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>
 

@@ -811,6 +815,73 @@ int gnttab_alloc_pages(int nr_pages, struct page **pages)
 }
 EXPORT_SYMBOL_GPL(gnttab_alloc_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_err("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_err("Failed to decrease reservation for DMA buffer\n");
+		ret = -EFAULT;
+		goto fail_free_dma;
+	}
+
+	ret = gnttab_pages_set_private(args->nr_pages, args->pages);
+	if (ret < 0)
+		goto fail_clear_private;
+
+	return 0;
+
+fail_clear_private:
+	gnttab_pages_clear_private(args->nr_pages, args->pages);
+fail_free_dma:
+	xenmem_reservation_increase(args->nr_pages, args->frames);

drivers/xen/grant-table.c +37 -0

+/**
+ * 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_err("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

include/xen/grant_table.h +18 -0

index de03f2542bb7..9bc5bc07d4d3 100644
@@ -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);
 

Quoted 127 lines · Oleksandr Andrushchenko

From: Oleksandr Andrushchenko <[email protected]>

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 terms that proper memory reservation is made ({increase|decrease}_reservation and VA mappings 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 <[email protected]>

---
  drivers/xen/Kconfig       |  13 +++++
  drivers/xen/grant-table.c | 109 ++++++++++++++++++++++++++++++++++++++
  include/xen/grant_table.h |  18 +++++++
  3 files changed, 140 insertions(+)

drivers/xen/Kconfig +13 -0

index e5d0c28372ea..39536ddfbce4 100644
@@ -161,6 +161,19 @@ 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 terms that proper memory reservation is made
+	  ({increase|decrease}_reservation and VA mappings 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

drivers/xen/grant-table.c +62 -0

index dbb48a89e987..5658e58d9cc6 100644
@@ -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>
 

@@ -811,6 +815,73 @@ int gnttab_alloc_pages(int nr_pages, struct page **pages)
  }
  EXPORT_SYMBOL_GPL(gnttab_alloc_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_err("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_err("Failed to decrease reservation for DMA buffer\n");
+		ret = -EFAULT;
+		goto fail_free_dma;
+	}
+
+	ret = gnttab_pages_set_private(args->nr_pages, args->pages);
+	if (ret < 0)
+		goto fail_clear_private;
+
+	return 0;
+
+fail_clear_private:
+	gnttab_pages_clear_private(args->nr_pages, args->pages);
+fail_free_dma:
+	xenmem_reservation_increase(args->nr_pages, args->frames);
+	xenmem_reservation_va_mapping_update(args->nr_pages, args->pages,
+					     args->frames);
+	if (args->coherent)
+		dma_free_coherent(args->dev, size,

drivers/xen/grant-table.c int gnttab_alloc_pages(int nr_pages, struct page **pages) · line 881

Quoted 6 lines

drivers/xen/grant-table.c +6 -0

+				  args->vaddr, args->dev_bus_addr);
+	else
+		dma_free_wc(args->dev, size,
+			    args->vaddr, args->dev_bus_addr);
+	return ret;
+}

Would it be possible to call gnttab_dma_free_pages() here?

Quoted 11 lines

drivers/xen/grant-table.c +3 -0

+EXPORT_SYMBOL_GPL(gnttab_dma_alloc_pages);
+#endif
+
  void gnttab_pages_clear_private(int nr_pages, struct page **pages)
  {
  	int i;

@@ -838,6 +909,44 @@ void gnttab_free_pages(int nr_pages, struct page **pages)
  }
  EXPORT_SYMBOL_GPL(gnttab_free_pages);
 

drivers/xen/grant-table.c void gnttab_free_pages(int nr_pages, struct page **pages) · line 912

Quoted 1 line

drivers/xen/grant-table.c +1 -0

+#ifdef CONFIG_XEN_GRANT_DMA_ALLOC

I'd move this after (or before) gnttab_dma_alloc_page() to keep both inside a single ifdef block.

-boris

Quoted 61 lines

drivers/xen/grant-table.c +37 -0

+/**
+ * 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_err("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

include/xen/grant_table.h +13 -0

index de03f2542bb7..9bc5bc07d4d3 100644
@@ -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;
+};

include/xen/grant_table.h void gnttab_free_auto_xlat_frames(void); · line 221

Quoted 8 lines

include/xen/grant_table.h +5 -0

+
+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);
 

Quoted 127 lines · Oleksandr Andrushchenko

From: Oleksandr Andrushchenko <[email protected]>

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 terms that proper memory reservation is made ({increase|decrease}_reservation and VA mappings 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 <[email protected]>

---
  drivers/xen/Kconfig       |  13 +++++
  drivers/xen/grant-table.c | 109 ++++++++++++++++++++++++++++++++++++++
  include/xen/grant_table.h |  18 +++++++
  3 files changed, 140 insertions(+)

drivers/xen/Kconfig +13 -0

index e5d0c28372ea..39536ddfbce4 100644
@@ -161,6 +161,19 @@ 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 terms that proper memory reservation is made
+	  ({increase|decrease}_reservation and VA mappings 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

drivers/xen/grant-table.c +62 -0

index dbb48a89e987..5658e58d9cc6 100644
@@ -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>
 

@@ -811,6 +815,73 @@ int gnttab_alloc_pages(int nr_pages, struct page **pages)
  }
  EXPORT_SYMBOL_GPL(gnttab_alloc_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_err("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_err("Failed to decrease reservation for DMA buffer\n");
+		ret = -EFAULT;
+		goto fail_free_dma;
+	}
+
+	ret = gnttab_pages_set_private(args->nr_pages, args->pages);
+	if (ret < 0)
+		goto fail_clear_private;
+
+	return 0;
+
+fail_clear_private:
+	gnttab_pages_clear_private(args->nr_pages, args->pages);
+fail_free_dma:
+	xenmem_reservation_increase(args->nr_pages, args->frames);
+	xenmem_reservation_va_mapping_update(args->nr_pages, args->pages,
+					     args->frames);
+	if (args->coherent)
+		dma_free_coherent(args->dev, size,

drivers/xen/grant-table.c int gnttab_alloc_pages(int nr_pages, struct page **pages) · line 881

Quoted 6 lines

drivers/xen/grant-table.c +6 -0

+				  args->vaddr, args->dev_bus_addr);
+	else
+		dma_free_wc(args->dev, size,
+			    args->vaddr, args->dev_bus_addr);
+	return ret;
+}

Would it be possible to call gnttab_dma_free_pages() here?

Quoted 11 lines

drivers/xen/grant-table.c +3 -0

+EXPORT_SYMBOL_GPL(gnttab_dma_alloc_pages);
+#endif
+
  void gnttab_pages_clear_private(int nr_pages, struct page **pages)
  {
  	int i;

@@ -838,6 +909,44 @@ void gnttab_free_pages(int nr_pages, struct page **pages)
  }
  EXPORT_SYMBOL_GPL(gnttab_free_pages);
 

drivers/xen/grant-table.c void gnttab_free_pages(int nr_pages, struct page **pages) · line 912

Quoted 1 line

drivers/xen/grant-table.c +1 -0

+#ifdef CONFIG_XEN_GRANT_DMA_ALLOC

I'd move this after (or before) gnttab_dma_alloc_page() to keep both inside a single ifdef block.

-boris

Quoted 61 lines

drivers/xen/grant-table.c +37 -0

+/**
+ * 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_err("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

include/xen/grant_table.h +13 -0

index de03f2542bb7..9bc5bc07d4d3 100644
@@ -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;
+};

include/xen/grant_table.h void gnttab_free_auto_xlat_frames(void); · line 221

Quoted 8 lines

include/xen/grant_table.h +5 -0

+
+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);
 

From: Oleksandr Andrushchenko <[email protected]>

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 <[email protected]>

---
 drivers/xen/gntdev.c      | 99 ++++++++++++++++++++++++++++++++++++++-
 include/uapi/xen/gntdev.h | 15 ++++++
 2 files changed, 112 insertions(+), 2 deletions(-)

drivers/xen/gntdev.c +11 -0

index bd56653b9bbc..9813fc440c70 100644
@@ -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
+	/*

drivers/xen/gntdev.c +15 -0

+	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;

drivers/xen/gntdev.c +33 -1

 	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;
 

drivers/xen/gntdev.c +15 -1

+			map->unmap_ops[i].dev_bus_addr = __pfn_to_phys(mfn);
+		}
+#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 call 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;
 

include/uapi/xen/gntdev.h +6 -0

index 6d1163456c03..4b9d498a31d4 100644
@@ -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.
+ */
+
+/*

From: Oleksandr Andrushchenko <[email protected]>

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 <[email protected]>

---
 drivers/xen/gntdev.c      | 99 ++++++++++++++++++++++++++++++++++++++-
 include/uapi/xen/gntdev.h | 15 ++++++
 2 files changed, 112 insertions(+), 2 deletions(-)

drivers/xen/gntdev.c +11 -0

index bd56653b9bbc..9813fc440c70 100644
@@ -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
+	/*

drivers/xen/gntdev.c +15 -0

+	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;

drivers/xen/gntdev.c +33 -1

 	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;
 

drivers/xen/gntdev.c +15 -1

+			map->unmap_ops[i].dev_bus_addr = __pfn_to_phys(mfn);
+		}
+#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 call 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;
 

include/uapi/xen/gntdev.h +15 -0

index 6d1163456c03..4b9d498a31d4 100644
@@ -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__ */

Quoted 46 lines · Oleksandr Andrushchenko

From: Oleksandr Andrushchenko <[email protected]>

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 <[email protected]>

---
  drivers/xen/gntdev.c      | 99 ++++++++++++++++++++++++++++++++++++++-
  include/uapi/xen/gntdev.h | 15 ++++++
  2 files changed, 112 insertions(+), 2 deletions(-)

drivers/xen/gntdev.c +11 -0

index bd56653b9bbc..9813fc440c70 100644
@@ -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
+	/*

drivers/xen/gntdev.c struct grant_map { · line 119

Quoted 10 lines

drivers/xen/gntdev.c +10 -0

+	 * 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;
+	/* This is required for gnttab_dma_{alloc|free}_pages. */

How about

/* Needed to avoid allocation in gnttab_dma_free_pages(). */

Quoted 26 lines

drivers/xen/gntdev.c +15 -0

+	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;

drivers/xen/gntdev.c static void gntdev_free_map(struct grant_map *map) · line 169

Quoted 10 lines

drivers/xen/gntdev.c +8 -0

+
+		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

Can this be done under if (map->dma_vaddr) ?

In other words, is it
possible for dma_vaddr to be NULL and still have unallocated frames pointer?

Quoted 52 lines

drivers/xen/gntdev.c +33 -1

  	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;
 

drivers/xen/gntdev.c static int map_grant_pages(struct grant_map *map) · line 408

Quoted 9 lines

drivers/xen/gntdev.c +5 -0

@@ -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 mfn;
+
+			mfn = __pfn_to_mfn(page_to_pfn(map->pages[i]));

Not pfn_to_mfn()?

-boris

Quoted 54 lines

drivers/xen/gntdev.c +15 -1

+			map->unmap_ops[i].dev_bus_addr = __pfn_to_phys(mfn);
+		}
+#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 call 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;
 

include/uapi/xen/gntdev.h +13 -0

index 6d1163456c03..4b9d498a31d4 100644
@@ -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.
+ */

include/uapi/xen/gntdev.h struct ioctl_gntdev_grant_copy { · line 218

Quoted 3 lines

include/uapi/xen/gntdev.h +2 -0

+#define GNTDEV_DMA_FLAG_COHERENT	(1 << 1)
+
  #endif /* __LINUX_PUBLIC_GNTDEV_H__ */

_______________________________________________
Xen-devel mailing list
[email protected]
https://lists.xenproject.org/mailman/listinfo/xen-devel

Quoted 27 lines · Boris Ostrovsky

On 06/01/2018 07:41 AM, Oleksandr Andrushchenko wrote:

drivers/xen/gntdev.c +0 -0

@@ -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;

drivers/xen/gntdev.c +12 -0

+
+        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);

drivers/xen/gntdev.c +4 -0

+
+#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
+    kfree(map->frames);
+#endif

Quoted 5 lines

Can this be done under if (map->dma_vaddr) ?

  In other words, is it
possible for dma_vaddr to be NULL and still have unallocated frames pointer?

It is possible to have vaddr == NULL and frames != NULL as we allocate frames outside of gnttab_dma_alloc_pages which may fail. Calling kfree on NULL pointer is safe,

so
I see no reason to change this code.

Quoted 56 lines

Quoted 56 lines

      kfree(map->pages);
      kfree(map->grants);
      kfree(map->map_ops);

drivers/xen/gntdev.c +0 -0

@@ -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;

drivers/xen/gntdev.c +0 -0

@@ -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;

drivers/xen/gntdev.c +29 -0

+
+    /*
+     * 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)

Quoted 8 lines

drivers/xen/gntdev.c static int map_grant_pages(struct grant_map *map) · line 408

Quoted 6 lines

              map->kunmap_ops[i].handle = map->kmap_ops[i].handle;

drivers/xen/gntdev.c +5 -0

+#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
+        else if (map->dma_vaddr) {
+            unsigned long mfn;
+
+            mfn = __pfn_to_mfn(page_to_pfn(map->pages[i]));

Not pfn_to_mfn()?

I'd love to, but pfn_to_mfn is only defined for x86, not ARM: [1] and [2] Thus,

drivers/xen/gntdev.c:408:10: error: implicit declaration of function ‘pfn_to_mfn’ [-Werror=implicit-function-declaration]
    mfn = pfn_to_mfn(page_to_pfn(map->pages[i]));

So, I'll keep __pfn_to_mfn

Quoted 27 lines · Boris Ostrovsky

On 06/01/2018 07:41 AM, Oleksandr Andrushchenko wrote:

drivers/xen/gntdev.c +0 -0

@@ -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;

drivers/xen/gntdev.c +12 -0

+
+        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);

drivers/xen/gntdev.c +4 -0

+
+#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
+    kfree(map->frames);
+#endif

Quoted 5 lines

Can this be done under if (map->dma_vaddr) ?

  In other words, is it
possible for dma_vaddr to be NULL and still have unallocated frames pointer?

It is possible to have vaddr == NULL and frames != NULL as we allocate frames outside of gnttab_dma_alloc_pages which may fail. Calling kfree on NULL pointer is safe,

so
I see no reason to change this code.

Quoted 56 lines

Quoted 56 lines

      kfree(map->pages);
      kfree(map->grants);
      kfree(map->map_ops);

drivers/xen/gntdev.c +0 -0

@@ -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;

drivers/xen/gntdev.c +0 -0

@@ -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;

drivers/xen/gntdev.c +29 -0

+
+    /*
+     * 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)

Quoted 8 lines

drivers/xen/gntdev.c static int map_grant_pages(struct grant_map *map) · line 408

Quoted 6 lines

              map->kunmap_ops[i].handle = map->kmap_ops[i].handle;

drivers/xen/gntdev.c +5 -0

+#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
+        else if (map->dma_vaddr) {
+            unsigned long mfn;
+
+            mfn = __pfn_to_mfn(page_to_pfn(map->pages[i]));

Not pfn_to_mfn()?

I'd love to, but pfn_to_mfn is only defined for x86, not ARM: [1] and [2] Thus,

drivers/xen/gntdev.c:408:10: error: implicit declaration of function ‘pfn_to_mfn’ [-Werror=implicit-function-declaration]
    mfn = pfn_to_mfn(page_to_pfn(map->pages[i]));

So, I'll keep __pfn_to_mfn