From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BF197C2B9F4 for ; Mon, 14 Jun 2021 11:21:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 978A9610A0 for ; Mon, 14 Jun 2021 11:21:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235814AbhFNLX1 (ORCPT ); Mon, 14 Jun 2021 07:23:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:42526 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235617AbhFNLK5 (ORCPT ); Mon, 14 Jun 2021 07:10:57 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8E7F36193F; Mon, 14 Jun 2021 10:47:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1623667634; bh=2lVh5NkMWKcDdgRJf5gWZI/lLSeNE7nfG/pCe+/EixQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=eCgr7AtJs9Z5ng2WTC9lPk0Vhxy6fotBJQqPLBAgSk9rzSJtFzHCQwktOsnmyb4Mm q3/EUtjgRzp8eozbKPHVxAP/UzUSGUInFzGEUvgvv5V7GhWoNdHOLXK6cPOCZZOWtU IyiC3yATucpIPKl0rHrWLPf4wVCR0aHV2Qp2Ils8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Farman , Matthew Rosato , Cornelia Huck , Sasha Levin Subject: [PATCH 5.12 015/173] vfio-ccw: Serialize FSM IDLE state with I/O completion Date: Mon, 14 Jun 2021 12:25:47 +0200 Message-Id: <20210614102658.654374785@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210614102658.137943264@linuxfoundation.org> References: <20210614102658.137943264@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Eric Farman [ Upstream commit 2af7a834a435460d546f0cf0a8b8e4d259f1d910 ] Today, the stacked call to vfio_ccw_sch_io_todo() does three things: 1) Update a solicited IRB with CP information, and release the CP if the interrupt was the end of a START operation. 2) Copy the IRB data into the io_region, under the protection of the io_mutex 3) Reset the vfio-ccw FSM state to IDLE to acknowledge that vfio-ccw can accept more work. The trouble is that step 3 is (A) invoked for both solicited and unsolicited interrupts, and (B) sitting after the mutex for step 2. This second piece becomes a problem if it processes an interrupt for a CLEAR SUBCHANNEL while another thread initiates a START, thus allowing the CP and FSM states to get out of sync. That is: CPU 1 CPU 2 fsm_do_clear() fsm_irq() fsm_io_request() vfio_ccw_sch_io_todo() fsm_io_helper() Since the FSM state and CP should be kept in sync, let's make a note when the CP is released, and rely on that as an indication that the FSM should also be reset at the end of this routine and open up the device for more work. Signed-off-by: Eric Farman Acked-by: Matthew Rosato Reviewed-by: Cornelia Huck Message-Id: <20210511195631.3995081-4-farman@linux.ibm.com> Signed-off-by: Cornelia Huck Signed-off-by: Sasha Levin --- drivers/s390/cio/vfio_ccw_drv.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c index 8c625b530035..9b61e9b131ad 100644 --- a/drivers/s390/cio/vfio_ccw_drv.c +++ b/drivers/s390/cio/vfio_ccw_drv.c @@ -86,6 +86,7 @@ static void vfio_ccw_sch_io_todo(struct work_struct *work) struct vfio_ccw_private *private; struct irb *irb; bool is_final; + bool cp_is_finished = false; private = container_of(work, struct vfio_ccw_private, io_work); irb = &private->irb; @@ -94,14 +95,21 @@ static void vfio_ccw_sch_io_todo(struct work_struct *work) (SCSW_ACTL_DEVACT | SCSW_ACTL_SCHACT)); if (scsw_is_solicited(&irb->scsw)) { cp_update_scsw(&private->cp, &irb->scsw); - if (is_final && private->state == VFIO_CCW_STATE_CP_PENDING) + if (is_final && private->state == VFIO_CCW_STATE_CP_PENDING) { cp_free(&private->cp); + cp_is_finished = true; + } } mutex_lock(&private->io_mutex); memcpy(private->io_region->irb_area, irb, sizeof(*irb)); mutex_unlock(&private->io_mutex); - if (private->mdev && is_final) + /* + * Reset to IDLE only if processing of a channel program + * has finished. Do not overwrite a possible processing + * state if the final interrupt was for HSCH or CSCH. + */ + if (private->mdev && cp_is_finished) private->state = VFIO_CCW_STATE_IDLE; if (private->io_trigger) -- 2.30.2