Commit d9213319 authored by Nathan Lynch's avatar Nathan Lynch Committed by Michael Ellerman
Browse files

powerpc/pseries/mobility: extract VASI session polling logic 



The behavior of rtas_ibm_suspend_me_unsafe() is to return -EAGAIN to
the caller until the specified VASI suspend session state makes the
transition from H_VASI_ENABLED to H_VASI_SUSPENDING. In the interest
of separating concerns to prepare for a new implementation of the
join/suspend sequence, extract VASI session polling logic into a
couple of local functions. Waiting for the session state to reach
H_VASI_SUSPENDING before calling rtas_ibm_suspend_me_unsafe() ensures
that we will never get an EAGAIN result necessitating a retry. No
user-visible change in behavior is intended.

Signed-off-by: default avatarNathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201207215200.1785968-12-nathanl@linux.ibm.com
parent c3ae9781

arch/powerpc/platforms/pseries/mobility.c

+64 −5
Original line number Diff line number Diff line
@@ -345,6 +345,66 @@ void post_mobility_fixup(void) 
	return;

}



static int poll_vasi_state(u64 handle, unsigned long *res)

{

	unsigned long retbuf[PLPAR_HCALL_BUFSIZE];

	long hvrc;

	int ret;



	hvrc = plpar_hcall(H_VASI_STATE, retbuf, handle);

	switch (hvrc) {

	case H_SUCCESS:

		ret = 0;

		*res = retbuf[0];

		break;

	case H_PARAMETER:

		ret = -EINVAL;

		break;

	case H_FUNCTION:

		ret = -EOPNOTSUPP;

		break;

	case H_HARDWARE:

	default:

		pr_err("unexpected H_VASI_STATE result %ld\n", hvrc);

		ret = -EIO;

		break;

	}

	return ret;

}



static int wait_for_vasi_session_suspending(u64 handle)

{

	unsigned long state;

	int ret;



	/*

	 * Wait for transition from H_VASI_ENABLED to

	 * H_VASI_SUSPENDING. Treat anything else as an error.

	 */

	while (true) {

		ret = poll_vasi_state(handle, &state);



		if (ret != 0 || state == H_VASI_SUSPENDING) {

			break;

		} else if (state == H_VASI_ENABLED) {

			ssleep(1);

		} else {

			pr_err("unexpected H_VASI_STATE result %lu\n", state);

			ret = -EIO;

			break;

		}

	}



	/*

	 * Proceed even if H_VASI_STATE is unavailable. If H_JOIN or

	 * ibm,suspend-me are also unimplemented, we'll recover then.

	 */

	if (ret == -EOPNOTSUPP)

		ret = 0;



	return ret;

}



static ssize_t migration_store(struct class *class,

			       struct class_attribute *attr, const char *buf,

			       size_t count)
@@ -356,12 +416,11 @@ static ssize_t migration_store(struct class *class, 
	if (rc)

		return rc;



	do {

		rc = rtas_ibm_suspend_me_unsafe(streamid);

		if (rc == -EAGAIN)

			ssleep(1);

	} while (rc == -EAGAIN);

	rc = wait_for_vasi_session_suspending(streamid);

	if (rc)

		return rc;



	rc = rtas_ibm_suspend_me_unsafe(streamid);

	if (rc)

		return rc;