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xen/grant-table: remove gnttab_*transfer*() functions
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All grant table operations related to the "transfer" functionality
are unused currently. There have been users in the old days of the
"Xen-o-Linux" kernel, but those didn't make it upstream.

So remove the "transfer" related functions.

Signed-off-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20220311103429.12845-2-jgross@suse.com
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
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jgross1 authored and Boris Ostrovsky committed Mar 16, 2022
1 parent 982e443 commit b0f2126
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Showing 2 changed files with 2 additions and 119 deletions.
113 changes: 2 additions & 111 deletions drivers/xen/grant-table.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -109,7 +109,7 @@ struct gnttab_ops {
void (*unmap_frames)(void);
/*
* Introducing a valid entry into the grant table, granting the frame of
* this grant entry to domain for accessing or transfering. Ref
* this grant entry to domain for accessing. Ref
* parameter is reference of this introduced grant entry, domid is id of
* granted domain, frame is the page frame to be granted, and flags is
* status of the grant entry to be updated.
Expand All @@ -125,14 +125,6 @@ struct gnttab_ops {
* access for this entry and return success(==1).
*/
int (*end_foreign_access_ref)(grant_ref_t ref, int readonly);
/*
* Stop granting a grant entry to domain for transfer. Ref parameter is
* reference of a grant entry whose grant transfer will be stopped. If
* tranfer has not started, just reclaim the grant entry and return
* failure(==0). Otherwise, wait for the transfer to complete and then
* return the frame.
*/
unsigned long (*end_foreign_transfer_ref)(grant_ref_t ref);
/*
* Read the frame number related to a given grant reference.
*/
Expand Down Expand Up @@ -230,10 +222,7 @@ static void put_free_entry(grant_ref_t ref)
* Following applies to gnttab_update_entry_v1 and gnttab_update_entry_v2.
* Introducing a valid entry into the grant table:
* 1. Write ent->domid.
* 2. Write ent->frame:
* GTF_permit_access: Frame to which access is permitted.
* GTF_accept_transfer: Pseudo-phys frame slot being filled by new
* frame, or zero if none.
* 2. Write ent->frame: Frame to which access is permitted.
* 3. Write memory barrier (WMB).
* 4. Write ent->flags, inc. valid type.
*/
Expand Down Expand Up @@ -455,102 +444,6 @@ void gnttab_end_foreign_access(grant_ref_t ref, int readonly,
}
EXPORT_SYMBOL_GPL(gnttab_end_foreign_access);

int gnttab_grant_foreign_transfer(domid_t domid, unsigned long pfn)
{
int ref;

ref = get_free_entries(1);
if (unlikely(ref < 0))
return -ENOSPC;
gnttab_grant_foreign_transfer_ref(ref, domid, pfn);

return ref;
}
EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer);

void gnttab_grant_foreign_transfer_ref(grant_ref_t ref, domid_t domid,
unsigned long pfn)
{
gnttab_interface->update_entry(ref, domid, pfn, GTF_accept_transfer);
}
EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer_ref);

static unsigned long gnttab_end_foreign_transfer_ref_v1(grant_ref_t ref)
{
unsigned long frame;
u16 flags;
u16 *pflags;

pflags = &gnttab_shared.v1[ref].flags;

/*
* If a transfer is not even yet started, try to reclaim the grant
* reference and return failure (== 0).
*/
while (!((flags = *pflags) & GTF_transfer_committed)) {
if (sync_cmpxchg(pflags, flags, 0) == flags)
return 0;
cpu_relax();
}

/* If a transfer is in progress then wait until it is completed. */
while (!(flags & GTF_transfer_completed)) {
flags = *pflags;
cpu_relax();
}

rmb(); /* Read the frame number /after/ reading completion status. */
frame = gnttab_shared.v1[ref].frame;
BUG_ON(frame == 0);

return frame;
}

static unsigned long gnttab_end_foreign_transfer_ref_v2(grant_ref_t ref)
{
unsigned long frame;
u16 flags;
u16 *pflags;

pflags = &gnttab_shared.v2[ref].hdr.flags;

/*
* If a transfer is not even yet started, try to reclaim the grant
* reference and return failure (== 0).
*/
while (!((flags = *pflags) & GTF_transfer_committed)) {
if (sync_cmpxchg(pflags, flags, 0) == flags)
return 0;
cpu_relax();
}

/* If a transfer is in progress then wait until it is completed. */
while (!(flags & GTF_transfer_completed)) {
flags = *pflags;
cpu_relax();
}

rmb(); /* Read the frame number /after/ reading completion status. */
frame = gnttab_shared.v2[ref].full_page.frame;
BUG_ON(frame == 0);

return frame;
}

unsigned long gnttab_end_foreign_transfer_ref(grant_ref_t ref)
{
return gnttab_interface->end_foreign_transfer_ref(ref);
}
EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer_ref);

unsigned long gnttab_end_foreign_transfer(grant_ref_t ref)
{
unsigned long frame = gnttab_end_foreign_transfer_ref(ref);
put_free_entry(ref);
return frame;
}
EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer);

void gnttab_free_grant_reference(grant_ref_t ref)
{
put_free_entry(ref);
Expand Down Expand Up @@ -1423,7 +1316,6 @@ static const struct gnttab_ops gnttab_v1_ops = {
.unmap_frames = gnttab_unmap_frames_v1,
.update_entry = gnttab_update_entry_v1,
.end_foreign_access_ref = gnttab_end_foreign_access_ref_v1,
.end_foreign_transfer_ref = gnttab_end_foreign_transfer_ref_v1,
.read_frame = gnttab_read_frame_v1,
};

Expand All @@ -1435,7 +1327,6 @@ static const struct gnttab_ops gnttab_v2_ops = {
.unmap_frames = gnttab_unmap_frames_v2,
.update_entry = gnttab_update_entry_v2,
.end_foreign_access_ref = gnttab_end_foreign_access_ref_v2,
.end_foreign_transfer_ref = gnttab_end_foreign_transfer_ref_v2,
.read_frame = gnttab_read_frame_v2,
};

Expand Down
8 changes: 0 additions & 8 deletions include/xen/grant_table.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -125,11 +125,6 @@ void gnttab_end_foreign_access(grant_ref_t ref, int readonly,
*/
int gnttab_try_end_foreign_access(grant_ref_t ref);

int gnttab_grant_foreign_transfer(domid_t domid, unsigned long pfn);

unsigned long gnttab_end_foreign_transfer_ref(grant_ref_t ref);
unsigned long gnttab_end_foreign_transfer(grant_ref_t ref);

/*
* operations on reserved batches of grant references
*/
Expand Down Expand Up @@ -162,9 +157,6 @@ static inline void gnttab_page_grant_foreign_access_ref_one(
readonly);
}

void gnttab_grant_foreign_transfer_ref(grant_ref_t, domid_t domid,
unsigned long pfn);

static inline void
gnttab_set_map_op(struct gnttab_map_grant_ref *map, phys_addr_t addr,
uint32_t flags, grant_ref_t ref, domid_t domid)
Expand Down

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