From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3y1zZt02TPzDsQP for ; Wed, 27 Sep 2017 10:43:33 +1000 (AEST) Received: from pps.filterd (m0098413.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v8R0cYii046375 for ; Tue, 26 Sep 2017 20:43:31 -0400 Received: from e23smtp03.au.ibm.com (e23smtp03.au.ibm.com [202.81.31.145]) by mx0b-001b2d01.pphosted.com with ESMTP id 2d81gk0bcw-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Tue, 26 Sep 2017 20:43:31 -0400 Received: from localhost by e23smtp03.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 27 Sep 2017 10:43:28 +1000 Received: from d23av01.au.ibm.com (d23av01.au.ibm.com [9.190.234.96]) by d23relay08.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v8R0hQIp33816610 for ; Wed, 27 Sep 2017 10:43:26 +1000 Received: from d23av01.au.ibm.com (localhost [127.0.0.1]) by d23av01.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id v8R0hQda026161 for ; Wed, 27 Sep 2017 10:43:26 +1000 From: Andrew Donnellan To: stable@vger.kernel.org Cc: fbarrat@linux.vnet.ibm.com, mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org Subject: [PATCH 4.4] cxl: Fix driver use count Date: Wed, 27 Sep 2017 10:43:17 +1000 Message-Id: <20170927004317.9671-1-andrew.donnellan@au1.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Frederic Barrat commit 197267d0356004a31c4d6b6336598f5dff3301e1 upstream. cxl keeps a driver use count, which is used with the hash memory model on p8 to know when to upgrade local TLBIs to global and to trigger callbacks to manage the MMU for PSL8. If a process opens a context and closes without attaching or fails the attachment, the driver use count is never decremented. As a consequence, TLB invalidations remain global, even if there are no active cxl contexts. We should increment the driver use count when the process is attaching to the cxl adapter, and not on open. It's not needed before the adapter starts using the context and the use count is decremented on the detach path, so it makes more sense. It affects only the user api. The kernel api is already doing The Right Thing. Signed-off-by: Frederic Barrat Cc: stable@vger.kernel.org # v4.2+ Fixes: 7bb5d91a4dda ("cxl: Rework context lifetimes") Acked-by: Andrew Donnellan Signed-off-by: Michael Ellerman [ajd: backport to stable v4.4 tree] Signed-off-by: Andrew Donnellan --- drivers/misc/cxl/api.c | 4 ++++ drivers/misc/cxl/file.c | 8 +++++++- 2 files changed, 11 insertions(+), 1 deletion(-) diff --git a/drivers/misc/cxl/api.c b/drivers/misc/cxl/api.c index ea3eeb7011e1..690eb1a18caf 100644 --- a/drivers/misc/cxl/api.c +++ b/drivers/misc/cxl/api.c @@ -176,6 +176,10 @@ int cxl_start_context(struct cxl_context *ctx, u64 wed, kernel = false; } + /* + * Increment driver use count. Enables global TLBIs for hash + * and callbacks to handle the segment table + */ cxl_ctx_get(); if ((rc = cxl_attach_process(ctx, kernel, wed , 0))) { diff --git a/drivers/misc/cxl/file.c b/drivers/misc/cxl/file.c index 10a02934bfc0..013558f4da4f 100644 --- a/drivers/misc/cxl/file.c +++ b/drivers/misc/cxl/file.c @@ -94,7 +94,6 @@ static int __afu_open(struct inode *inode, struct file *file, bool master) pr_devel("afu_open pe: %i\n", ctx->pe); file->private_data = ctx; - cxl_ctx_get(); /* indicate success */ rc = 0; @@ -205,11 +204,18 @@ static long afu_ioctl_start_work(struct cxl_context *ctx, ctx->pid = get_task_pid(current, PIDTYPE_PID); ctx->glpid = get_task_pid(current->group_leader, PIDTYPE_PID); + /* + * Increment driver use count. Enables global TLBIs for hash + * and callbacks to handle the segment table + */ + cxl_ctx_get(); + trace_cxl_attach(ctx, work.work_element_descriptor, work.num_interrupts, amr); if ((rc = cxl_attach_process(ctx, false, work.work_element_descriptor, amr))) { afu_release_irqs(ctx, ctx); + cxl_ctx_put(); goto out; } -- 2.11.0