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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 D56B8C4709B for ; Thu, 3 Jun 2021 17:07:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CA3A161402 for ; Thu, 3 Jun 2021 17:07:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231154AbhFCRJi (ORCPT ); Thu, 3 Jun 2021 13:09:38 -0400 Received: from mail.kernel.org ([198.145.29.99]:40634 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230507AbhFCRJh (ORCPT ); Thu, 3 Jun 2021 13:09:37 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 80AF3613FA; Thu, 3 Jun 2021 17:07:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1622740072; bh=2lVh5NkMWKcDdgRJf5gWZI/lLSeNE7nfG/pCe+/EixQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HbkEF20BIPr6Ryd9qJghZ0f3Dec18ifwob5g4iFAFmF9eH0Tl9Wc5HW9bg54p1vzT qmfas3RDURlqEA0MW4Oul0aLggqK4I1tNbOpRPuVVlXcm02TiH67rEeBm7uqo9P4a6 HE/8ZrCEp0uZ6JukfVYBG8LdSjQwHHTPjDz+FRFp0YDTfuAKqvAWBznsuFgU6RFzDg b6wlHWts4dEYFI+MZcDjJNSHvyM4jmyz07yx4FaE5N9i+fJOnknQCB6IGVBNNjAz/j wJ8cgB00AfjlzU50p4t4670XXLLsNeGHjQw2L7VGqzGx1CI91ZPMxZhRjo4ZGriRby P4Thr4QIG/LbQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Eric Farman , Matthew Rosato , Cornelia Huck , Sasha Levin , linux-s390@vger.kernel.org, kvm@vger.kernel.org Subject: [PATCH AUTOSEL 5.12 14/43] vfio-ccw: Serialize FSM IDLE state with I/O completion Date: Thu, 3 Jun 2021 13:07:04 -0400 Message-Id: <20210603170734.3168284-14-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210603170734.3168284-1-sashal@kernel.org> References: <20210603170734.3168284-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-s390@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