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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A0E28C433F5 for ; Fri, 27 May 2022 07:31:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229706AbiE0Ha6 (ORCPT ); Fri, 27 May 2022 03:30:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40838 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239463AbiE0Haz (ORCPT ); Fri, 27 May 2022 03:30:55 -0400 Received: from out30-54.freemail.mail.aliyun.com (out30-54.freemail.mail.aliyun.com [115.124.30.54]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 29E81ED734; Fri, 27 May 2022 00:30:53 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R131e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=alimailimapcm10staff010182156082;MF=xuanzhuo@linux.alibaba.com;NM=1;PH=DS;RN=16;SR=0;TI=SMTPD_---0VEW9CNu_1653636650; Received: from localhost(mailfrom:xuanzhuo@linux.alibaba.com fp:SMTPD_---0VEW9CNu_1653636650) by smtp.aliyun-inc.com(127.0.0.1); Fri, 27 May 2022 15:30:51 +0800 Message-ID: <1653636641.556474-3-xuanzhuo@linux.alibaba.com> Subject: Re: [PATCH V6 3/9] virtio: introduce config op to synchronize vring callbacks Date: Fri, 27 May 2022 15:30:41 +0800 From: Xuan Zhuo To: Jason Wang Cc: tglx@linutronix.de, peterz@infradead.org, paulmck@kernel.org, maz@kernel.org, pasic@linux.ibm.com, cohuck@redhat.com, eperezma@redhat.com, lulu@redhat.com, sgarzare@redhat.com, Vineeth Vijayan , Peter Oberparleiter , linux-s390@vger.kernel.org, mst@redhat.com, jasowang@redhat.com, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org References: <20220527060120.20964-1-jasowang@redhat.com> <20220527060120.20964-4-jasowang@redhat.com> In-Reply-To: <20220527060120.20964-4-jasowang@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On Fri, 27 May 2022 14:01:14 +0800, Jason Wang wrote: > This patch introduces new virtio config op to vring > callbacks. Transport specific method is required to make sure the > write before this function is visible to the vring_interrupt() that is > called after the return of this function. For the transport that > doesn't provide synchronize_vqs(), use synchornize_rcu() which > synchronize with IRQ implicitly as a fallback. > > Cc: Thomas Gleixner > Cc: Peter Zijlstra > Cc: "Paul E. McKenney" > Cc: Marc Zyngier > Cc: Halil Pasic > Cc: Cornelia Huck > Cc: Vineeth Vijayan > Cc: Peter Oberparleiter > Cc: linux-s390@vger.kernel.org > Reviewed-by: Cornelia Huck > Signed-off-by: Jason Wang Reviewed-by: Xuan Zhuo > --- > include/linux/virtio_config.h | 25 +++++++++++++++++++++++++ > 1 file changed, 25 insertions(+) > > diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h > index b341dd62aa4d..25be018810a7 100644 > --- a/include/linux/virtio_config.h > +++ b/include/linux/virtio_config.h > @@ -57,6 +57,11 @@ struct virtio_shm_region { > * include a NULL entry for vqs unused by driver > * Returns 0 on success or error status > * @del_vqs: free virtqueues found by find_vqs(). > + * @synchronize_cbs: synchronize with the virtqueue callbacks (optional) > + * The function guarantees that all memory operations on the > + * queue before it are visible to the vring_interrupt() that is > + * called after it. > + * vdev: the virtio_device > * @get_features: get the array of feature bits for this device. > * vdev: the virtio_device > * Returns the first 64 feature bits (all we currently need). > @@ -89,6 +94,7 @@ struct virtio_config_ops { > const char * const names[], const bool *ctx, > struct irq_affinity *desc); > void (*del_vqs)(struct virtio_device *); > + void (*synchronize_cbs)(struct virtio_device *); > u64 (*get_features)(struct virtio_device *vdev); > int (*finalize_features)(struct virtio_device *vdev); > const char *(*bus_name)(struct virtio_device *vdev); > @@ -217,6 +223,25 @@ int virtio_find_vqs_ctx(struct virtio_device *vdev, unsigned nvqs, > desc); > } > > +/** > + * virtio_synchronize_cbs - synchronize with virtqueue callbacks > + * @vdev: the device > + */ > +static inline > +void virtio_synchronize_cbs(struct virtio_device *dev) > +{ > + if (dev->config->synchronize_cbs) { > + dev->config->synchronize_cbs(dev); > + } else { > + /* > + * A best effort fallback to synchronize with > + * interrupts, preemption and softirq disabled > + * regions. See comment above synchronize_rcu(). > + */ > + synchronize_rcu(); > + } > +} > + > /** > * virtio_device_ready - enable vq use in probe function > * @vdev: the device > -- > 2.25.1 >