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 <[email protected]>
---
drivers/xen/grant-table.c | 113 +-------------------------------------
include/xen/grant_table.h | 8 ---
2 files changed, 2 insertions(+), 119 deletions(-)
diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index 5c83d41766c8..8963af8ec764 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -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.
@@ -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.
*/
@@ -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.
*/
@@ -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);
@@ -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,
};
@@ -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,
};
diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h
index c9fea9389ebe..9f9b1a297f0d 100644
--- a/include/xen/grant_table.h
+++ b/include/xen/grant_table.h
@@ -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
*/
@@ -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)
--
2.34.1
On 15.03.22 00:37, Boris Ostrovsky wrote:
>
> On 3/11/22 5:34 AM, Juergen Gross wrote:
>> 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.
>
>
> Do we need to assert somewhere that transfer flags are not set?
This would be an orthogonal change, right? My patch is just removing
never called functions.
In any case I believe checking those flags is the job of the hypervisor.
If an operation is illegal due to a transfer flag being set, it needs to
be rejected at hypervisor level.
Juergen
On 3/11/22 5:34 AM, Juergen Gross wrote:
> 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.
Do we need to assert somewhere that transfer flags are not set?
-boris
On 3/11/22 5:34 AM, Juergen Gross wrote:
> 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 <[email protected]>
Applied to for-linus-5.18 (both patches)
On 3/15/22 2:10 AM, Juergen Gross wrote:
> On 15.03.22 00:37, Boris Ostrovsky wrote:
>>
>> On 3/11/22 5:34 AM, Juergen Gross wrote:
>>> 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.
>>
>>
>> Do we need to assert somewhere that transfer flags are not set?
>
> This would be an orthogonal change, right? My patch is just removing
> never called functions.
>
I was thinking of having this done as part of code removal (maybe as a separate patch).
> In any case I believe checking those flags is the job of the hypervisor.
> If an operation is illegal due to a transfer flag being set, it needs to
> be rejected at hypervisor level.
True.
Reviewed-by: Boris Ostrovsky <[email protected]>