ibmvnic: Do partial reset on login failure

Perform a partial reset before sending a login request if any of the
following are true:
 1. If a previous request times out. This can be dangerous because the
 	VIOS could still receive the old login request at any point after
 	the timeout. Therefore, it is best to re-register the CRQ's  and
 	sub-CRQ's before retrying.
 2. If the previous request returns an error that is not described in
 	PAPR. PAPR provides procedures if the login returns with partial
 	success or aborted return codes (section L.5.1) but other values
	do not have a defined procedure. Previously, these conditions
	just returned error from the login function rather than trying
	to resolve the issue.
 	This can cause further issues since most callers of the login
 	function are not prepared to handle an error when logging in. This
 	improper cleanup can lead to the device being permanently DOWN'd.
 	For example, if the VIOS believes that the device is already logged
 	in then it will return INVALID_STATE (-7). If we never re-register
 	CRQ's then it will always think that the device is already logged
 	in. This leaves the device inoperable.

The partial reset involves freeing the sub-CRQs, freeing the CRQ then
registering and initializing a new CRQ and sub-CRQs. This essentially
restarts all communication with VIOS to allow for a fresh login attempt
that will be unhindered by any previous failed attempts.

Fixes: dff515a3e71d ("ibmvnic: Harden device login requests")
Signed-off-by: Nick Child <nnac123@linux.ibm.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20230809221038.51296-4-nnac123@linux.ibm.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

0 files changed, 0 insertions, 0 deletions