Re: [PATCH v2 2/3] drm/xen-front: Use Xen common shared buffer implementation

[Oleksandr Andrushchenko <andr2000@gmail.com>]

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On 12/5/18 10:20 AM, Oleksandr Andrushchenko wrote:
> Hello, Daniel!
>
> Could you please ack/nack the patch, so either we can merge the
>
> series or I can address your comments if any
>
> Thank you,
>
> Oleksandr
>
> On 11/30/18 9:42 AM, Oleksandr Andrushchenko wrote:
>> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>>
>> Use page directory based shared buffer implementation
>> now available as common code for Xen frontend drivers.
>>
>> Remove flushing of shared buffer on page flip as this
>> workaround needs a proper fix.
>>
>> Signed-off-by: Oleksandr Andrushchenko 
>> <oleksandr_andrushchenko@epam.com>
>> ---
>>   drivers/gpu/drm/xen/Kconfig               |   1 +
>>   drivers/gpu/drm/xen/Makefile              |   1 -
>>   drivers/gpu/drm/xen/xen_drm_front.c       |  65 ++--
>>   drivers/gpu/drm/xen/xen_drm_front_gem.c   |   1 -
>>   drivers/gpu/drm/xen/xen_drm_front_shbuf.c | 414 ----------------------
>>   drivers/gpu/drm/xen/xen_drm_front_shbuf.h |  64 ----
>>   6 files changed, 26 insertions(+), 520 deletions(-)
>>   delete mode 100644 drivers/gpu/drm/xen/xen_drm_front_shbuf.c
>>   delete mode 100644 drivers/gpu/drm/xen/xen_drm_front_shbuf.h
>>
>> diff --git a/drivers/gpu/drm/xen/Kconfig b/drivers/gpu/drm/xen/Kconfig
>> index 4cca160782ab..f969d486855d 100644
>> --- a/drivers/gpu/drm/xen/Kconfig
>> +++ b/drivers/gpu/drm/xen/Kconfig
>> @@ -12,6 +12,7 @@ config DRM_XEN_FRONTEND
>>       select DRM_KMS_HELPER
>>       select VIDEOMODE_HELPERS
>>       select XEN_XENBUS_FRONTEND
>> +    select XEN_FRONT_PGDIR_SHBUF
>>       help
>>         Choose this option if you want to enable a para-virtualized
>>         frontend DRM/KMS driver for Xen guest OSes.
>> diff --git a/drivers/gpu/drm/xen/Makefile b/drivers/gpu/drm/xen/Makefile
>> index 712afff5ffc3..825905f67faa 100644
>> --- a/drivers/gpu/drm/xen/Makefile
>> +++ b/drivers/gpu/drm/xen/Makefile
>> @@ -4,7 +4,6 @@ drm_xen_front-objs := xen_drm_front.o \
>>                 xen_drm_front_kms.o \
>>                 xen_drm_front_conn.o \
>>                 xen_drm_front_evtchnl.o \
>> -              xen_drm_front_shbuf.o \
>>                 xen_drm_front_cfg.o \
>>                 xen_drm_front_gem.o
>>   diff --git a/drivers/gpu/drm/xen/xen_drm_front.c 
>> b/drivers/gpu/drm/xen/xen_drm_front.c
>> index 6b6d5ab82ec3..4d3d36fc3a5d 100644
>> --- a/drivers/gpu/drm/xen/xen_drm_front.c
>> +++ b/drivers/gpu/drm/xen/xen_drm_front.c
>> @@ -19,6 +19,7 @@
>>   #include <xen/xen.h>
>>   #include <xen/xenbus.h>
>>   +#include <xen/xen-front-pgdir-shbuf.h>
>>   #include <xen/interface/io/displif.h>
>>     #include "xen_drm_front.h"
>> @@ -26,28 +27,20 @@
>>   #include "xen_drm_front_evtchnl.h"
>>   #include "xen_drm_front_gem.h"
>>   #include "xen_drm_front_kms.h"
>> -#include "xen_drm_front_shbuf.h"
>>     struct xen_drm_front_dbuf {
>>       struct list_head list;
>>       u64 dbuf_cookie;
>>       u64 fb_cookie;
>> -    struct xen_drm_front_shbuf *shbuf;
>> +
>> +    struct xen_front_pgdir_shbuf shbuf;
>>   };
>>   -static int dbuf_add_to_list(struct xen_drm_front_info *front_info,
>> -                struct xen_drm_front_shbuf *shbuf, u64 dbuf_cookie)
>> +static void dbuf_add_to_list(struct xen_drm_front_info *front_info,
>> +                 struct xen_drm_front_dbuf *dbuf, u64 dbuf_cookie)
>>   {
>> -    struct xen_drm_front_dbuf *dbuf;
>> -
>> -    dbuf = kzalloc(sizeof(*dbuf), GFP_KERNEL);
>> -    if (!dbuf)
>> -        return -ENOMEM;
>> -
>>       dbuf->dbuf_cookie = dbuf_cookie;
>> -    dbuf->shbuf = shbuf;
>>       list_add(&dbuf->list, &front_info->dbuf_list);
>> -    return 0;
>>   }
>>     static struct xen_drm_front_dbuf *dbuf_get(struct list_head 
>> *dbuf_list,
>> @@ -62,15 +55,6 @@ static struct xen_drm_front_dbuf *dbuf_get(struct 
>> list_head *dbuf_list,
>>       return NULL;
>>   }
>>   -static void dbuf_flush_fb(struct list_head *dbuf_list, u64 fb_cookie)
>> -{
>> -    struct xen_drm_front_dbuf *buf, *q;
>> -
>> -    list_for_each_entry_safe(buf, q, dbuf_list, list)
>> -        if (buf->fb_cookie == fb_cookie)
>> -            xen_drm_front_shbuf_flush(buf->shbuf);
>> -}
>> -
>>   static void dbuf_free(struct list_head *dbuf_list, u64 dbuf_cookie)
>>   {
>>       struct xen_drm_front_dbuf *buf, *q;
>> @@ -78,8 +62,8 @@ static void dbuf_free(struct list_head *dbuf_list, 
>> u64 dbuf_cookie)
>>       list_for_each_entry_safe(buf, q, dbuf_list, list)
>>           if (buf->dbuf_cookie == dbuf_cookie) {
>>               list_del(&buf->list);
>> -            xen_drm_front_shbuf_unmap(buf->shbuf);
>> -            xen_drm_front_shbuf_free(buf->shbuf);
>> +            xen_front_pgdir_shbuf_unmap(&buf->shbuf);
>> +            xen_front_pgdir_shbuf_free(&buf->shbuf);
>>               kfree(buf);
>>               break;
>>           }
>> @@ -91,8 +75,8 @@ static void dbuf_free_all(struct list_head *dbuf_list)
>>         list_for_each_entry_safe(buf, q, dbuf_list, list) {
>>           list_del(&buf->list);
>> -        xen_drm_front_shbuf_unmap(buf->shbuf);
>> -        xen_drm_front_shbuf_free(buf->shbuf);
>> +        xen_front_pgdir_shbuf_unmap(&buf->shbuf);
>> +        xen_front_pgdir_shbuf_free(&buf->shbuf);
>>           kfree(buf);
>>       }
>>   }
>> @@ -171,9 +155,9 @@ int xen_drm_front_dbuf_create(struct 
>> xen_drm_front_info *front_info,
>>                     u32 bpp, u64 size, struct page **pages)
>>   {
>>       struct xen_drm_front_evtchnl *evtchnl;
>> -    struct xen_drm_front_shbuf *shbuf;
>> +    struct xen_drm_front_dbuf *dbuf;
>>       struct xendispl_req *req;
>> -    struct xen_drm_front_shbuf_cfg buf_cfg;
>> +    struct xen_front_pgdir_shbuf_cfg buf_cfg;
>>       unsigned long flags;
>>       int ret;
>>   @@ -181,28 +165,29 @@ int xen_drm_front_dbuf_create(struct 
>> xen_drm_front_info *front_info,
>>       if (unlikely(!evtchnl))
>>           return -EIO;
>>   +    dbuf = kzalloc(sizeof(*dbuf), GFP_KERNEL);
>> +    if (!dbuf)
>> +        return -ENOMEM;
>> +
>> +    dbuf_add_to_list(front_info, dbuf, dbuf_cookie);
>> +
>>       memset(&buf_cfg, 0, sizeof(buf_cfg));
>>       buf_cfg.xb_dev = front_info->xb_dev;
>> +    buf_cfg.num_pages = DIV_ROUND_UP(size, PAGE_SIZE);
>>       buf_cfg.pages = pages;
>> -    buf_cfg.size = size;
>> +    buf_cfg.pgdir = &dbuf->shbuf;
>>       buf_cfg.be_alloc = front_info->cfg.be_alloc;
>>   -    shbuf = xen_drm_front_shbuf_alloc(&buf_cfg);
>> -    if (IS_ERR(shbuf))
>> -        return PTR_ERR(shbuf);
>> -
>> -    ret = dbuf_add_to_list(front_info, shbuf, dbuf_cookie);
>> -    if (ret < 0) {
>> -        xen_drm_front_shbuf_free(shbuf);
>> -        return ret;
>> -    }
>> +    ret = xen_front_pgdir_shbuf_alloc(&buf_cfg);
>> +    if (ret < 0)
>> +        goto fail_shbuf_alloc;
>>         mutex_lock(&evtchnl->u.req.req_io_lock);
>>         spin_lock_irqsave(&front_info->io_lock, flags);
>>       req = be_prepare_req(evtchnl, XENDISPL_OP_DBUF_CREATE);
>>       req->op.dbuf_create.gref_directory =
>> -            xen_drm_front_shbuf_get_dir_start(shbuf);
>> + xen_front_pgdir_shbuf_get_dir_start(&dbuf->shbuf);
>>       req->op.dbuf_create.buffer_sz = size;
>>       req->op.dbuf_create.dbuf_cookie = dbuf_cookie;
>>       req->op.dbuf_create.width = width;
>> @@ -221,7 +206,7 @@ int xen_drm_front_dbuf_create(struct 
>> xen_drm_front_info *front_info,
>>       if (ret < 0)
>>           goto fail;
>>   -    ret = xen_drm_front_shbuf_map(shbuf);
>> +    ret = xen_front_pgdir_shbuf_map(&dbuf->shbuf);
>>       if (ret < 0)
>>           goto fail;
>>   @@ -230,6 +215,7 @@ int xen_drm_front_dbuf_create(struct 
>> xen_drm_front_info *front_info,
>>     fail:
>>       mutex_unlock(&evtchnl->u.req.req_io_lock);
>> +fail_shbuf_alloc:
>>       dbuf_free(&front_info->dbuf_list, dbuf_cookie);
>>       return ret;
>>   }
>> @@ -358,7 +344,6 @@ int xen_drm_front_page_flip(struct 
>> xen_drm_front_info *front_info,
>>       if (unlikely(conn_idx >= front_info->num_evt_pairs))
>>           return -EINVAL;
>>   -    dbuf_flush_fb(&front_info->dbuf_list, fb_cookie);
>>       evtchnl = &front_info->evt_pairs[conn_idx].req;
>>         mutex_lock(&evtchnl->u.req.req_io_lock);
>> diff --git a/drivers/gpu/drm/xen/xen_drm_front_gem.c 
>> b/drivers/gpu/drm/xen/xen_drm_front_gem.c
>> index c85bfe7571cb..53be4c7dc0a4 100644
>> --- a/drivers/gpu/drm/xen/xen_drm_front_gem.c
>> +++ b/drivers/gpu/drm/xen/xen_drm_front_gem.c
>> @@ -22,7 +22,6 @@
>>   #include <xen/balloon.h>
>>     #include "xen_drm_front.h"
>> -#include "xen_drm_front_shbuf.h"
>>     struct xen_gem_object {
>>       struct drm_gem_object base;
>> diff --git a/drivers/gpu/drm/xen/xen_drm_front_shbuf.c 
>> b/drivers/gpu/drm/xen/xen_drm_front_shbuf.c
>> deleted file mode 100644
>> index d333b67cc1a0..000000000000
>> --- a/drivers/gpu/drm/xen/xen_drm_front_shbuf.c
>> +++ /dev/null
>> @@ -1,414 +0,0 @@
>> -// SPDX-License-Identifier: GPL-2.0 OR MIT
>> -
>> -/*
>> - *  Xen para-virtual DRM device
>> - *
>> - * Copyright (C) 2016-2018 EPAM Systems Inc.
>> - *
>> - * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>> - */
>> -
>> -#include <drm/drmP.h>
>> -
>> -#if defined(CONFIG_X86)
>> -#include <drm/drm_cache.h>
>> -#endif
>> -#include <linux/errno.h>
>> -#include <linux/mm.h>
>> -
>> -#include <asm/xen/hypervisor.h>
>> -#include <xen/balloon.h>
>> -#include <xen/xen.h>
>> -#include <xen/xenbus.h>
>> -#include <xen/interface/io/ring.h>
>> -#include <xen/interface/io/displif.h>
>> -
>> -#include "xen_drm_front.h"
>> -#include "xen_drm_front_shbuf.h"
>> -
>> -struct xen_drm_front_shbuf_ops {
>> -    /*
>> -     * Calculate number of grefs required to handle this buffer,
>> -     * e.g. if grefs are required for page directory only or the buffer
>> -     * pages as well.
>> -     */
>> -    void (*calc_num_grefs)(struct xen_drm_front_shbuf *buf);
>> -    /* Fill page directory according to para-virtual display 
>> protocol. */
>> -    void (*fill_page_dir)(struct xen_drm_front_shbuf *buf);
>> -    /* Claim grant references for the pages of the buffer. */
>> -    int (*grant_refs_for_buffer)(struct xen_drm_front_shbuf *buf,
>> -                     grant_ref_t *priv_gref_head, int gref_idx);
>> -    /* Map grant references of the buffer. */
>> -    int (*map)(struct xen_drm_front_shbuf *buf);
>> -    /* Unmap grant references of the buffer. */
>> -    int (*unmap)(struct xen_drm_front_shbuf *buf);
>> -};
>> -
>> -grant_ref_t xen_drm_front_shbuf_get_dir_start(struct 
>> xen_drm_front_shbuf *buf)
>> -{
>> -    if (!buf->grefs)
>> -        return GRANT_INVALID_REF;
>> -
>> -    return buf->grefs[0];
>> -}
>> -
>> -int xen_drm_front_shbuf_map(struct xen_drm_front_shbuf *buf)
>> -{
>> -    if (buf->ops->map)
>> -        return buf->ops->map(buf);
>> -
>> -    /* no need to map own grant references */
>> -    return 0;
>> -}
>> -
>> -int xen_drm_front_shbuf_unmap(struct xen_drm_front_shbuf *buf)
>> -{
>> -    if (buf->ops->unmap)
>> -        return buf->ops->unmap(buf);
>> -
>> -    /* no need to unmap own grant references */
>> -    return 0;
>> -}
>> -
>> -void xen_drm_front_shbuf_flush(struct xen_drm_front_shbuf *buf)
>> -{
>> -#if defined(CONFIG_X86)
>> -    drm_clflush_pages(buf->pages, buf->num_pages);
>> -#endif
>> -}
>> -
>> -void xen_drm_front_shbuf_free(struct xen_drm_front_shbuf *buf)
>> -{
>> -    if (buf->grefs) {
>> -        int i;
>> -
>> -        for (i = 0; i < buf->num_grefs; i++)
>> -            if (buf->grefs[i] != GRANT_INVALID_REF)
>> -                gnttab_end_foreign_access(buf->grefs[i],
>> -                              0, 0UL);
>> -    }
>> -    kfree(buf->grefs);
>> -    kfree(buf->directory);
>> -    kfree(buf);
>> -}
>> -
>> -/*
>> - * number of grefs a page can hold with respect to the
>> - * struct xendispl_page_directory header
>> - */
>> -#define XEN_DRM_NUM_GREFS_PER_PAGE ((PAGE_SIZE - \
>> -        offsetof(struct xendispl_page_directory, gref)) / \
>> -        sizeof(grant_ref_t))
>> -
>> -static int get_num_pages_dir(struct xen_drm_front_shbuf *buf)
>> -{
>> -    /* number of pages the page directory consumes itself */
>> -    return DIV_ROUND_UP(buf->num_pages, XEN_DRM_NUM_GREFS_PER_PAGE);
>> -}
>> -
>> -static void backend_calc_num_grefs(struct xen_drm_front_shbuf *buf)
>> -{
>> -    /* only for pages the page directory consumes itself */
>> -    buf->num_grefs = get_num_pages_dir(buf);
>> -}
>> -
>> -static void guest_calc_num_grefs(struct xen_drm_front_shbuf *buf)
>> -{
>> -    /*
>> -     * number of pages the page directory consumes itself
>> -     * plus grefs for the buffer pages
>> -     */
>> -    buf->num_grefs = get_num_pages_dir(buf) + buf->num_pages;
>> -}
>> -
>> -#define xen_page_to_vaddr(page) \
>> -        ((uintptr_t)pfn_to_kaddr(page_to_xen_pfn(page)))
>> -
>> -static int backend_unmap(struct xen_drm_front_shbuf *buf)
>> -{
>> -    struct gnttab_unmap_grant_ref *unmap_ops;
>> -    int i, ret;
>> -
>> -    if (!buf->pages || !buf->backend_map_handles || !buf->grefs)
>> -        return 0;
>> -
>> -    unmap_ops = kcalloc(buf->num_pages, sizeof(*unmap_ops),
>> -                GFP_KERNEL);
>> -    if (!unmap_ops) {
>> -        DRM_ERROR("Failed to get memory while unmapping\n");
>> -        return -ENOMEM;
>> -    }
>> -
>> -    for (i = 0; i < buf->num_pages; i++) {
>> -        phys_addr_t addr;
>> -
>> -        addr = xen_page_to_vaddr(buf->pages[i]);
>> -        gnttab_set_unmap_op(&unmap_ops[i], addr, GNTMAP_host_map,
>> -                    buf->backend_map_handles[i]);
>> -    }
>> -
>> -    ret = gnttab_unmap_refs(unmap_ops, NULL, buf->pages,
>> -                buf->num_pages);
>> -
>> -    for (i = 0; i < buf->num_pages; i++) {
>> -        if (unlikely(unmap_ops[i].status != GNTST_okay))
>> -            DRM_ERROR("Failed to unmap page %d: %d\n",
>> -                  i, unmap_ops[i].status);
>> -    }
>> -
>> -    if (ret)
>> -        DRM_ERROR("Failed to unmap grant references, ret %d", ret);
>> -
>> -    kfree(unmap_ops);
>> -    kfree(buf->backend_map_handles);
>> -    buf->backend_map_handles = NULL;
>> -    return ret;
>> -}
>> -
>> -static int backend_map(struct xen_drm_front_shbuf *buf)
>> -{
>> -    struct gnttab_map_grant_ref *map_ops = NULL;
>> -    unsigned char *ptr;
>> -    int ret, cur_gref, cur_dir_page, cur_page, grefs_left;
>> -
>> -    map_ops = kcalloc(buf->num_pages, sizeof(*map_ops), GFP_KERNEL);
>> -    if (!map_ops)
>> -        return -ENOMEM;
>> -
>> -    buf->backend_map_handles = kcalloc(buf->num_pages,
>> -                       sizeof(*buf->backend_map_handles),
>> -                       GFP_KERNEL);
>> -    if (!buf->backend_map_handles) {
>> -        kfree(map_ops);
>> -        return -ENOMEM;
>> -    }
>> -
>> -    /*
>> -     * read page directory to get grefs from the backend: for external
>> -     * buffer we only allocate buf->grefs for the page directory,
>> -     * so buf->num_grefs has number of pages in the page directory 
>> itself
>> -     */
>> -    ptr = buf->directory;
>> -    grefs_left = buf->num_pages;
>> -    cur_page = 0;
>> -    for (cur_dir_page = 0; cur_dir_page < buf->num_grefs; 
>> cur_dir_page++) {
>> -        struct xendispl_page_directory *page_dir =
>> -                (struct xendispl_page_directory *)ptr;
>> -        int to_copy = XEN_DRM_NUM_GREFS_PER_PAGE;
>> -
>> -        if (to_copy > grefs_left)
>> -            to_copy = grefs_left;
>> -
>> -        for (cur_gref = 0; cur_gref < to_copy; cur_gref++) {
>> -            phys_addr_t addr;
>> -
>> -            addr = xen_page_to_vaddr(buf->pages[cur_page]);
>> -            gnttab_set_map_op(&map_ops[cur_page], addr,
>> -                      GNTMAP_host_map,
>> -                      page_dir->gref[cur_gref],
>> -                      buf->xb_dev->otherend_id);
>> -            cur_page++;
>> -        }
>> -
>> -        grefs_left -= to_copy;
>> -        ptr += PAGE_SIZE;
>> -    }
>> -    ret = gnttab_map_refs(map_ops, NULL, buf->pages, buf->num_pages);
>> -
>> -    /* save handles even if error, so we can unmap */
>> -    for (cur_page = 0; cur_page < buf->num_pages; cur_page++) {
>> -        buf->backend_map_handles[cur_page] = map_ops[cur_page].handle;
>> -        if (unlikely(map_ops[cur_page].status != GNTST_okay))
>> -            DRM_ERROR("Failed to map page %d: %d\n",
>> -                  cur_page, map_ops[cur_page].status);
>> -    }
>> -
>> -    if (ret) {
>> -        DRM_ERROR("Failed to map grant references, ret %d", ret);
>> -        backend_unmap(buf);
>> -    }
>> -
>> -    kfree(map_ops);
>> -    return ret;
>> -}
>> -
>> -static void backend_fill_page_dir(struct xen_drm_front_shbuf *buf)
>> -{
>> -    struct xendispl_page_directory *page_dir;
>> -    unsigned char *ptr;
>> -    int i, num_pages_dir;
>> -
>> -    ptr = buf->directory;
>> -    num_pages_dir = get_num_pages_dir(buf);
>> -
>> -    /* fill only grefs for the page directory itself */
>> -    for (i = 0; i < num_pages_dir - 1; i++) {
>> -        page_dir = (struct xendispl_page_directory *)ptr;
>> -
>> -        page_dir->gref_dir_next_page = buf->grefs[i + 1];
>> -        ptr += PAGE_SIZE;
>> -    }
>> -    /* last page must say there is no more pages */
>> -    page_dir = (struct xendispl_page_directory *)ptr;
>> -    page_dir->gref_dir_next_page = GRANT_INVALID_REF;
>> -}
>> -
>> -static void guest_fill_page_dir(struct xen_drm_front_shbuf *buf)
>> -{
>> -    unsigned char *ptr;
>> -    int cur_gref, grefs_left, to_copy, i, num_pages_dir;
>> -
>> -    ptr = buf->directory;
>> -    num_pages_dir = get_num_pages_dir(buf);
>> -
>> -    /*
>> -     * while copying, skip grefs at start, they are for pages
>> -     * granted for the page directory itself
>> -     */
>> -    cur_gref = num_pages_dir;
>> -    grefs_left = buf->num_pages;
>> -    for (i = 0; i < num_pages_dir; i++) {
>> -        struct xendispl_page_directory *page_dir =
>> -                (struct xendispl_page_directory *)ptr;
>> -
>> -        if (grefs_left <= XEN_DRM_NUM_GREFS_PER_PAGE) {
>> -            to_copy = grefs_left;
>> -            page_dir->gref_dir_next_page = GRANT_INVALID_REF;
>> -        } else {
>> -            to_copy = XEN_DRM_NUM_GREFS_PER_PAGE;
>> -            page_dir->gref_dir_next_page = buf->grefs[i + 1];
>> -        }
>> -        memcpy(&page_dir->gref, &buf->grefs[cur_gref],
>> -               to_copy * sizeof(grant_ref_t));
>> -        ptr += PAGE_SIZE;
>> -        grefs_left -= to_copy;
>> -        cur_gref += to_copy;
>> -    }
>> -}
>> -
>> -static int guest_grant_refs_for_buffer(struct xen_drm_front_shbuf *buf,
>> -                       grant_ref_t *priv_gref_head,
>> -                       int gref_idx)
>> -{
>> -    int i, cur_ref, otherend_id;
>> -
>> -    otherend_id = buf->xb_dev->otherend_id;
>> -    for (i = 0; i < buf->num_pages; i++) {
>> -        cur_ref = gnttab_claim_grant_reference(priv_gref_head);
>> -        if (cur_ref < 0)
>> -            return cur_ref;
>> -
>> -        gnttab_grant_foreign_access_ref(cur_ref, otherend_id,
>> -                        xen_page_to_gfn(buf->pages[i]),
>> -                        0);
>> -        buf->grefs[gref_idx++] = cur_ref;
>> -    }
>> -    return 0;
>> -}
>> -
>> -static int grant_references(struct xen_drm_front_shbuf *buf)
>> -{
>> -    grant_ref_t priv_gref_head;
>> -    int ret, i, j, cur_ref;
>> -    int otherend_id, num_pages_dir;
>> -
>> -    ret = gnttab_alloc_grant_references(buf->num_grefs, 
>> &priv_gref_head);
>> -    if (ret < 0) {
>> -        DRM_ERROR("Cannot allocate grant references\n");
>> -        return ret;
>> -    }
>> -
>> -    otherend_id = buf->xb_dev->otherend_id;
>> -    j = 0;
>> -    num_pages_dir = get_num_pages_dir(buf);
>> -    for (i = 0; i < num_pages_dir; i++) {
>> -        unsigned long frame;
>> -
>> -        cur_ref = gnttab_claim_grant_reference(&priv_gref_head);
>> -        if (cur_ref < 0)
>> -            return cur_ref;
>> -
>> -        frame = xen_page_to_gfn(virt_to_page(buf->directory +
>> -                    PAGE_SIZE * i));
>> -        gnttab_grant_foreign_access_ref(cur_ref, otherend_id, frame, 
>> 0);
>> -        buf->grefs[j++] = cur_ref;
>> -    }
>> -
>> -    if (buf->ops->grant_refs_for_buffer) {
>> -        ret = buf->ops->grant_refs_for_buffer(buf, &priv_gref_head, j);
>> -        if (ret)
>> -            return ret;
>> -    }
>> -
>> -    gnttab_free_grant_references(priv_gref_head);
>> -    return 0;
>> -}
>> -
>> -static int alloc_storage(struct xen_drm_front_shbuf *buf)
>> -{
>> -    buf->grefs = kcalloc(buf->num_grefs, sizeof(*buf->grefs), 
>> GFP_KERNEL);
>> -    if (!buf->grefs)
>> -        return -ENOMEM;
>> -
>> -    buf->directory = kcalloc(get_num_pages_dir(buf), PAGE_SIZE, 
>> GFP_KERNEL);
>> -    if (!buf->directory)
>> -        return -ENOMEM;
>> -
>> -    return 0;
>> -}
>> -
>> -/*
>> - * For be allocated buffers we don't need grant_refs_for_buffer as 
>> those
>> - * grant references are allocated at backend side
>> - */
>> -static const struct xen_drm_front_shbuf_ops backend_ops = {
>> -    .calc_num_grefs = backend_calc_num_grefs,
>> -    .fill_page_dir = backend_fill_page_dir,
>> -    .map = backend_map,
>> -    .unmap = backend_unmap
>> -};
>> -
>> -/* For locally granted references we do not need to map/unmap the 
>> references */
>> -static const struct xen_drm_front_shbuf_ops local_ops = {
>> -    .calc_num_grefs = guest_calc_num_grefs,
>> -    .fill_page_dir = guest_fill_page_dir,
>> -    .grant_refs_for_buffer = guest_grant_refs_for_buffer,
>> -};
>> -
>> -struct xen_drm_front_shbuf *
>> -xen_drm_front_shbuf_alloc(struct xen_drm_front_shbuf_cfg *cfg)
>> -{
>> -    struct xen_drm_front_shbuf *buf;
>> -    int ret;
>> -
>> -    buf = kzalloc(sizeof(*buf), GFP_KERNEL);
>> -    if (!buf)
>> -        return ERR_PTR(-ENOMEM);
>> -
>> -    if (cfg->be_alloc)
>> -        buf->ops = &backend_ops;
>> -    else
>> -        buf->ops = &local_ops;
>> -
>> -    buf->xb_dev = cfg->xb_dev;
>> -    buf->num_pages = DIV_ROUND_UP(cfg->size, PAGE_SIZE);
>> -    buf->pages = cfg->pages;
>> -
>> -    buf->ops->calc_num_grefs(buf);
>> -
>> -    ret = alloc_storage(buf);
>> -    if (ret)
>> -        goto fail;
>> -
>> -    ret = grant_references(buf);
>> -    if (ret)
>> -        goto fail;
>> -
>> -    buf->ops->fill_page_dir(buf);
>> -
>> -    return buf;
>> -
>> -fail:
>> -    xen_drm_front_shbuf_free(buf);
>> -    return ERR_PTR(ret);
>> -}
>> diff --git a/drivers/gpu/drm/xen/xen_drm_front_shbuf.h 
>> b/drivers/gpu/drm/xen/xen_drm_front_shbuf.h
>> deleted file mode 100644
>> index 7545c692539e..000000000000
>> --- a/drivers/gpu/drm/xen/xen_drm_front_shbuf.h
>> +++ /dev/null
>> @@ -1,64 +0,0 @@
>> -/* SPDX-License-Identifier: GPL-2.0 OR MIT */
>> -
>> -/*
>> - *  Xen para-virtual DRM device
>> - *
>> - * Copyright (C) 2016-2018 EPAM Systems Inc.
>> - *
>> - * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>> - */
>> -
>> -#ifndef __XEN_DRM_FRONT_SHBUF_H_
>> -#define __XEN_DRM_FRONT_SHBUF_H_
>> -
>> -#include <linux/kernel.h>
>> -#include <linux/scatterlist.h>
>> -
>> -#include <xen/grant_table.h>
>> -
>> -struct xen_drm_front_shbuf {
>> -    /*
>> -     * number of references granted for the backend use:
>> -     *  - for allocated/imported dma-buf's this holds number of grant
>> -     *    references for the page directory and pages of the buffer
>> -     *  - for the buffer provided by the backend this holds number of
>> -     *    grant references for the page directory as grant 
>> references for
>> -     *    the buffer will be provided by the backend
>> -     */
>> -    int num_grefs;
>> -    grant_ref_t *grefs;
>> -    unsigned char *directory;
>> -
>> -    int num_pages;
>> -    struct page **pages;
>> -
>> -    struct xenbus_device *xb_dev;
>> -
>> -    /* these are the ops used internally depending on be_alloc mode */
>> -    const struct xen_drm_front_shbuf_ops *ops;
>> -
>> -    /* Xen map handles for the buffer allocated by the backend */
>> -    grant_handle_t *backend_map_handles;
>> -};
>> -
>> -struct xen_drm_front_shbuf_cfg {
>> -    struct xenbus_device *xb_dev;
>> -    size_t size;
>> -    struct page **pages;
>> -    bool be_alloc;
>> -};
>> -
>> -struct xen_drm_front_shbuf *
>> -xen_drm_front_shbuf_alloc(struct xen_drm_front_shbuf_cfg *cfg);
>> -
>> -grant_ref_t xen_drm_front_shbuf_get_dir_start(struct 
>> xen_drm_front_shbuf *buf);
>> -
>> -int xen_drm_front_shbuf_map(struct xen_drm_front_shbuf *buf);
>> -
>> -int xen_drm_front_shbuf_unmap(struct xen_drm_front_shbuf *buf);
>> -
>> -void xen_drm_front_shbuf_flush(struct xen_drm_front_shbuf *buf);
>> -
>> -void xen_drm_front_shbuf_free(struct xen_drm_front_shbuf *buf);
>> -
>> -#endif /* __XEN_DRM_FRONT_SHBUF_H_ */

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