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powerpc fixes for 6.7 #5

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- Fix a bug where heavy VAS (accelerator) usage could race with partition
    migration and prevent the migration from completing.
 
  - Update MAINTAINERS to add Aneesh & Naveen.
 
 Thanks to: Haren Myneni
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Merge tag 'powerpc-6.7-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc fixes from Michael Ellerman:

 - Fix a bug where heavy VAS (accelerator) usage could race with
   partition migration and prevent the migration from completing.

 - Update MAINTAINERS to add Aneesh & Naveen.

Thanks to Haren Myneni.

* tag 'powerpc-6.7-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  MAINTAINERS: powerpc: Add Aneesh & Naveen
  powerpc/pseries/vas: Migration suspend waits for no in-progress open windows
This commit is contained in:
Linus Torvalds 2023-12-17 08:50:00 -08:00
commit 5ef3720d91
3 changed files with 48 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
MAINTAINERS
View File

@ -12189,6 +12189,8 @@ LINUX FOR POWERPC (32-BIT AND 64-BIT)
M: Michael Ellerman <mpe@ellerman.id.au>
R: Nicholas Piggin <npiggin@gmail.com>
R: Christophe Leroy <christophe.leroy@csgroup.eu>
R: Aneesh Kumar K.V <aneesh.kumar@kernel.org>
R: Naveen N. Rao <naveen.n.rao@linux.ibm.com>
L: linuxppc-dev@lists.ozlabs.org
S: Supported
W: https://github.com/linuxppc/wiki/wiki

51
arch/powerpc/platforms/pseries/vas.c
View File

@ -385,11 +385,15 @@ static struct vas_window *vas_allocate_window(int vas_id, u64 flags,
* same fault IRQ is not freed by the OS before.
*/
mutex_lock(&vas_pseries_mutex);
if (migration_in_progress)
if (migration_in_progress) {
rc = -EBUSY;
else
} else {
rc = allocate_setup_window(txwin, (u64 *)&domain[0],
cop_feat_caps->win_type);
if (!rc)
caps->nr_open_wins_progress++;
}
mutex_unlock(&vas_pseries_mutex);
if (rc)
goto out;
@ -404,8 +408,17 @@ static struct vas_window *vas_allocate_window(int vas_id, u64 flags,
goto out_free;
txwin->win_type = cop_feat_caps->win_type;
mutex_lock(&vas_pseries_mutex);
/*
* The migration SUSPEND thread sets migration_in_progress and
* closes all open windows from the list. But the window is
* added to the list after open and modify HCALLs. So possible
* that migration_in_progress is set before modify HCALL which
* may cause some windows are still open when the hypervisor
* initiates the migration.
* So checks the migration_in_progress flag again and close all
* open windows.
*
* Possible to lose the acquired credit with DLPAR core
* removal after the window is opened. So if there are any
* closed windows (means with lost credits), do not give new
@ -413,9 +426,11 @@ static struct vas_window *vas_allocate_window(int vas_id, u64 flags,
* after the existing windows are reopened when credits are
* available.
*/
if (!caps->nr_close_wins) {
mutex_lock(&vas_pseries_mutex);
if (!caps->nr_close_wins && !migration_in_progress) {
list_add(&txwin->win_list, &caps->list);
caps->nr_open_windows++;
caps->nr_open_wins_progress--;
mutex_unlock(&vas_pseries_mutex);
vas_user_win_add_mm_context(&txwin->vas_win.task_ref);
return &txwin->vas_win;
@ -433,6 +448,12 @@ out_free:
*/
free_irq_setup(txwin);
h_deallocate_vas_window(txwin->vas_win.winid);
/*
* Hold mutex and reduce nr_open_wins_progress counter.
*/
mutex_lock(&vas_pseries_mutex);
caps->nr_open_wins_progress--;
mutex_unlock(&vas_pseries_mutex);
out:
atomic_dec(&cop_feat_caps->nr_used_credits);
kfree(txwin);
@ -937,14 +958,14 @@ int vas_migration_handler(int action)
struct vas_caps *vcaps;
int i, rc = 0;
pr_info("VAS migration event %d\n", action);
/*
* NX-GZIP is not enabled. Nothing to do for migration.
*/
if (!copypaste_feat)
return rc;
mutex_lock(&vas_pseries_mutex);
if (action == VAS_SUSPEND)
migration_in_progress = true;
else
@ -990,12 +1011,27 @@ int vas_migration_handler(int action)
switch (action) {
case VAS_SUSPEND:
mutex_lock(&vas_pseries_mutex);
rc = reconfig_close_windows(vcaps, vcaps->nr_open_windows,
true);
/*
* Windows are included in the list after successful
* open. So wait for closing these in-progress open
* windows in vas_allocate_window() which will be
* done if the migration_in_progress is set.
*/
while (vcaps->nr_open_wins_progress) {
mutex_unlock(&vas_pseries_mutex);
msleep(10);
mutex_lock(&vas_pseries_mutex);
}
mutex_unlock(&vas_pseries_mutex);
break;
case VAS_RESUME:
mutex_lock(&vas_pseries_mutex);
atomic_set(&caps->nr_total_credits, new_nr_creds);
rc = reconfig_open_windows(vcaps, new_nr_creds, true);
mutex_unlock(&vas_pseries_mutex);
break;
default:
/* should not happen */
@ -1011,8 +1047,9 @@ int vas_migration_handler(int action)
goto out;
}
pr_info("VAS migration event (%d) successful\n", action);
out:
mutex_unlock(&vas_pseries_mutex);
return rc;
}

2
arch/powerpc/platforms/pseries/vas.h
View File

@ -91,6 +91,8 @@ struct vas_cop_feat_caps {
struct vas_caps {
struct vas_cop_feat_caps caps;
struct list_head list; /* List of open windows */
int nr_open_wins_progress; /* Number of open windows in */
/* progress. Used in migration */
int nr_close_wins; /* closed windows in the hypervisor for DLPAR */
int nr_open_windows; /* Number of successful open windows */
u8 feat; /* Feature type */