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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,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 EF2F1C433FF for ; Thu, 8 Aug 2019 12:06:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CB9EB208C3 for ; Thu, 8 Aug 2019 12:06:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731274AbfHHMGx (ORCPT ); Thu, 8 Aug 2019 08:06:53 -0400 Received: from out30-131.freemail.mail.aliyun.com ([115.124.30.131]:55261 "EHLO out30-131.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726156AbfHHMGw (ORCPT ); Thu, 8 Aug 2019 08:06:52 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R961e4;CH=green;DM=||false|;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04394;MF=luoben@linux.alibaba.com;NM=1;PH=DS;RN=5;SR=0;TI=SMTPD_---0TYy50iH_1565266002; Received: from localhost(mailfrom:luoben@linux.alibaba.com fp:SMTPD_---0TYy50iH_1565266002) by smtp.aliyun-inc.com(127.0.0.1); Thu, 08 Aug 2019 20:06:50 +0800 From: Ben Luo To: tglx@linutronix.de, alex.williamson@redhat.com, linux-kernel@vger.kernel.org Cc: tao.ma@linux.alibaba.com, gerry@linux.alibaba.com Subject: [PATCH 2/2] vfio_pci: make use of update_irq_devid and optimize irq ops Date: Thu, 8 Aug 2019 20:07:32 +0800 Message-Id: <461a0d843c8ac4c31de61d08f4940884742f77b5.1565263723.git.luoben@linux.alibaba.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When userspace (e.g. qemu) triggers a switch between KVM irqfd and userspace eventfd, only dev_id of irq action (i.e. the "trigger" in this patch's context) will be changed, but a free-then-request-irq action is taken in current code. And, irq affinity setting in VM will also trigger a free-then-request-irq action, which actully changes nothing, but only fires a producer re-registration to update irte in case that posted-interrupt is in use. This patch makes use of update_irq_devid() and optimize both cases above, which reduces the risk of losing interrupt and also cuts some overhead. Signed-off-by: Ben Luo Reviewed-by: Liu Jiang --- drivers/vfio/pci/vfio_pci_intrs.c | 100 +++++++++++++++++++++++--------------- 1 file changed, 62 insertions(+), 38 deletions(-) diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c index 3fa3f72..1323dc8 100644 --- a/drivers/vfio/pci/vfio_pci_intrs.c +++ b/drivers/vfio/pci/vfio_pci_intrs.c @@ -285,69 +285,93 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_device *vdev, int vector, int fd, bool msix) { struct pci_dev *pdev = vdev->pdev; - struct eventfd_ctx *trigger; + struct eventfd_ctx *trigger = NULL; int irq, ret; if (vector < 0 || vector >= vdev->num_ctx) return -EINVAL; + if (fd >= 0) { + trigger = eventfd_ctx_fdget(fd); + if (IS_ERR(trigger)) + return PTR_ERR(trigger); + } + irq = pci_irq_vector(pdev, vector); if (vdev->ctx[vector].trigger) { - free_irq(irq, vdev->ctx[vector].trigger); - irq_bypass_unregister_producer(&vdev->ctx[vector].producer); - kfree(vdev->ctx[vector].name); - eventfd_ctx_put(vdev->ctx[vector].trigger); - vdev->ctx[vector].trigger = NULL; + if (vdev->ctx[vector].trigger != trigger) { + if (trigger) { + ret = update_irq_devid(irq, + vdev->ctx[vector].trigger, trigger); + if (unlikely(ret)) { + dev_info(&pdev->dev, + "update_irq_devid %d (token %p) fails: %d\n", + irq, vdev->ctx[vector].trigger, ret); + eventfd_ctx_put(trigger); + return ret; + } + irq_bypass_unregister_producer(&vdev->ctx[vector].producer); + eventfd_ctx_put(vdev->ctx[vector].trigger); + vdev->ctx[vector].producer.token = trigger; + vdev->ctx[vector].trigger = trigger; + } else { + free_irq(irq, vdev->ctx[vector].trigger); + irq_bypass_unregister_producer(&vdev->ctx[vector].producer); + kfree(vdev->ctx[vector].name); + eventfd_ctx_put(vdev->ctx[vector].trigger); + vdev->ctx[vector].trigger = NULL; + } + } else + irq_bypass_unregister_producer(&vdev->ctx[vector].producer); } if (fd < 0) return 0; - vdev->ctx[vector].name = kasprintf(GFP_KERNEL, "vfio-msi%s[%d](%s)", - msix ? "x" : "", vector, - pci_name(pdev)); - if (!vdev->ctx[vector].name) - return -ENOMEM; + if (vdev->ctx[vector].trigger == NULL) { + vdev->ctx[vector].name = kasprintf(GFP_KERNEL, "vfio-msi%s[%d](%s)", + msix ? "x" : "", vector, + pci_name(pdev)); + if (!vdev->ctx[vector].name) { + eventfd_ctx_put(trigger); + return -ENOMEM; + } - trigger = eventfd_ctx_fdget(fd); - if (IS_ERR(trigger)) { - kfree(vdev->ctx[vector].name); - return PTR_ERR(trigger); - } + /* + * The MSIx vector table resides in device memory which may be cleared + * via backdoor resets. We don't allow direct access to the vector + * table so even if a userspace driver attempts to save/restore around + * such a reset it would be unsuccessful. To avoid this, restore the + * cached value of the message prior to enabling. + */ + if (msix) { + struct msi_msg msg; - /* - * The MSIx vector table resides in device memory which may be cleared - * via backdoor resets. We don't allow direct access to the vector - * table so even if a userspace driver attempts to save/restore around - * such a reset it would be unsuccessful. To avoid this, restore the - * cached value of the message prior to enabling. - */ - if (msix) { - struct msi_msg msg; + get_cached_msi_msg(irq, &msg); + pci_write_msi_msg(irq, &msg); + } - get_cached_msi_msg(irq, &msg); - pci_write_msi_msg(irq, &msg); - } + ret = request_irq(irq, vfio_msihandler, 0, + vdev->ctx[vector].name, trigger); + if (ret) { + kfree(vdev->ctx[vector].name); + eventfd_ctx_put(trigger); + return ret; + } - ret = request_irq(irq, vfio_msihandler, 0, - vdev->ctx[vector].name, trigger); - if (ret) { - kfree(vdev->ctx[vector].name); - eventfd_ctx_put(trigger); - return ret; + vdev->ctx[vector].producer.token = trigger; + vdev->ctx[vector].producer.irq = irq; + vdev->ctx[vector].trigger = trigger; } - vdev->ctx[vector].producer.token = trigger; - vdev->ctx[vector].producer.irq = irq; + /* always update irte for posted mode */ ret = irq_bypass_register_producer(&vdev->ctx[vector].producer); if (unlikely(ret)) dev_info(&pdev->dev, "irq bypass producer (token %p) registration fails: %d\n", vdev->ctx[vector].producer.token, ret); - vdev->ctx[vector].trigger = trigger; - return 0; } -- 1.8.3.1