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

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

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__ */

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;

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; }

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; }