From patchwork Thu Dec 5 16:22:55 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Duyck X-Patchwork-Id: 11275175 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id C3DD813A4 for ; Thu, 5 Dec 2019 16:23:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8E1E824249 for ; Thu, 5 Dec 2019 16:23:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="PrOr9R/h" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730036AbfLEQXB (ORCPT ); Thu, 5 Dec 2019 11:23:01 -0500 Received: from mail-qk1-f194.google.com ([209.85.222.194]:38975 "EHLO mail-qk1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729974AbfLEQXB (ORCPT ); Thu, 5 Dec 2019 11:23:01 -0500 Received: by mail-qk1-f194.google.com with SMTP id d124so3817859qke.6; Thu, 05 Dec 2019 08:22:59 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:from:to:cc:date:message-id:in-reply-to:references :user-agent:mime-version:content-transfer-encoding; bh=8Aoj/PY2IXR7any+Pb7AqLJjXMolEw+Ty6s/twdBS14=; b=PrOr9R/h9WZuJdYt0N5n3zRbHNV0zrXnV2lyzu9RMtmdVjdBenQLY2iwoEeNcletCV ZXL6SzVqNJLxEmNqyJ/rN9m8Tn1O2sQa7X8A3eyPUqdcJykRfmrgOU5ogfZNwilHZCPN bKBZ+j5xiHN5p1uCO46aGGmMl7MWHkJZpLUy4gxKSLOAbnog3orXmUnt304Y3/ngboQF dCC4sxZGkRDpDAXkxBRUNZEjxOBRwORnS4YU3TlE8Dxq1uFR/kwLRJfy/FepPDQFH2pV fx7+RWLIteMysxYPpIXknoxcgh60KJMGLrYpPXqDVUCqGGV+BbtlAL45JWMGZwCkl/td JbEQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:from:to:cc:date:message-id:in-reply-to :references:user-agent:mime-version:content-transfer-encoding; bh=8Aoj/PY2IXR7any+Pb7AqLJjXMolEw+Ty6s/twdBS14=; b=A5W/gwFzVyiI6IjQyusTuviQXUkcLW7i+W40IgO+7GC6FdTu+s7CEGs+HZJlkZOdR4 0MXlBF1GcgHQi5eHQ9Q7RtBqUB+6f5hEImR2Ee6pSxNIkCCu3/hVNGSQDBNl5mpJRcyV JPdc4sLNWR09OvNJWrbx5p7RObv9WM7jWa5famfpZoBP/heojFH4LIR2oyw+dej0EbpE X2/4wcz/EMkMFaGnBGj9PgWHxUhawnxUaucMHpx9k2DUZLiuUwxan7MzIBUNzfI6oNnJ CQmfCemZ2/7GNd6iGTj5e10Kc+Sgn4/wtbu+1hyWUhmRM3Gvm3CXM50FniG7+MQfqJPS OEzQ== X-Gm-Message-State: APjAAAUZ3OZaeG82+YJh8J/pOZSxXUdjYZU/Wl8HxVDHSG7c5IpJhIVq JW9kv9ts7KZ5tld306mY2KQ= X-Google-Smtp-Source: APXvYqwE3Qd2KSXqS7pnp5CJ6Kss9GDS+wqPaj4PJ1oi9DvLHaBexwKSCA3bbI4FpDdVYtskiv5aSg== X-Received: by 2002:ae9:dec5:: with SMTP id s188mr2360934qkf.99.1575562979142; Thu, 05 Dec 2019 08:22:59 -0800 (PST) Received: from localhost.localdomain ([2001:470:b:9c3:9e5c:8eff:fe4f:f2d0]) by smtp.gmail.com with ESMTPSA id q35sm5481907qta.19.2019.12.05.08.22.56 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 05 Dec 2019 08:22:58 -0800 (PST) Subject: [PATCH v15 6/7] virtio-balloon: Add support for providing free page reports to host From: Alexander Duyck To: kvm@vger.kernel.org, mst@redhat.com, linux-kernel@vger.kernel.org, willy@infradead.org, mhocko@kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, mgorman@techsingularity.net, vbabka@suse.cz Cc: yang.zhang.wz@gmail.com, nitesh@redhat.com, konrad.wilk@oracle.com, david@redhat.com, pagupta@redhat.com, riel@surriel.com, lcapitulino@redhat.com, dave.hansen@intel.com, wei.w.wang@intel.com, aarcange@redhat.com, pbonzini@redhat.com, dan.j.williams@intel.com, alexander.h.duyck@linux.intel.com, osalvador@suse.de Date: Thu, 05 Dec 2019 08:22:55 -0800 Message-ID: <20191205162255.19548.63866.stgit@localhost.localdomain> In-Reply-To: <20191205161928.19548.41654.stgit@localhost.localdomain> References: <20191205161928.19548.41654.stgit@localhost.localdomain> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: Alexander Duyck Add support for the page reporting feature provided by virtio-balloon. Reporting differs from the regular balloon functionality in that is is much less durable than a standard memory balloon. Instead of creating a list of pages that cannot be accessed the pages are only inaccessible while they are being indicated to the virtio interface. Once the interface has acknowledged them they are placed back into their respective free lists and are once again accessible by the guest system. Unlike a standard balloon we don't inflate and deflate the pages. Instead we perform the reporting, and once the reporting is completed it is assumed that the page has been dropped from the guest and will be faulted back in the next time the page is accessed. For this reason when I had originally introduced the patch set I referred to this behavior as a "bubble" instead of a "balloon" since the duration is short lived, and when the page is touched the "bubble" is popped and the page is faulted back in. Signed-off-by: Alexander Duyck Acked-by: Michael S. Tsirkin Reviewed-by: David Hildenbrand --- drivers/virtio/Kconfig | 1 + drivers/virtio/virtio_balloon.c | 64 +++++++++++++++++++++++++++++++++++ include/uapi/linux/virtio_balloon.h | 1 + 3 files changed, 66 insertions(+) diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig index 078615cf2afc..4b2dd8259ff5 100644 --- a/drivers/virtio/Kconfig +++ b/drivers/virtio/Kconfig @@ -58,6 +58,7 @@ config VIRTIO_BALLOON tristate "Virtio balloon driver" depends on VIRTIO select MEMORY_BALLOON + select PAGE_REPORTING ---help--- This driver supports increasing and decreasing the amount of memory within a KVM guest. diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index 252591bc7e01..ecd54edba968 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -19,6 +19,7 @@ #include #include #include +#include /* * Balloon device works in 4K page units. So each page is pointed to by @@ -47,6 +48,7 @@ enum virtio_balloon_vq { VIRTIO_BALLOON_VQ_DEFLATE, VIRTIO_BALLOON_VQ_STATS, VIRTIO_BALLOON_VQ_FREE_PAGE, + VIRTIO_BALLOON_VQ_REPORTING, VIRTIO_BALLOON_VQ_MAX }; @@ -114,6 +116,10 @@ struct virtio_balloon { /* To register a shrinker to shrink memory upon memory pressure */ struct shrinker shrinker; + + /* Free page reporting device */ + struct virtqueue *reporting_vq; + struct page_reporting_dev_info pr_dev_info; }; static struct virtio_device_id id_table[] = { @@ -153,6 +159,33 @@ static void tell_host(struct virtio_balloon *vb, struct virtqueue *vq) } +int virtballoon_free_page_report(struct page_reporting_dev_info *pr_dev_info, + struct scatterlist *sg, unsigned int nents) +{ + struct virtio_balloon *vb = + container_of(pr_dev_info, struct virtio_balloon, pr_dev_info); + struct virtqueue *vq = vb->reporting_vq; + unsigned int unused, err; + + /* We should always be able to add these buffers to an empty queue. */ + err = virtqueue_add_inbuf(vq, sg, nents, vb, GFP_NOWAIT | __GFP_NOWARN); + + /* + * In the extremely unlikely case that something has occurred and we + * are able to trigger an error we will simply display a warning + * and exit without actually processing the pages. + */ + if (WARN_ON_ONCE(err)) + return err; + + virtqueue_kick(vq); + + /* When host has read buffer, this completes via balloon_ack */ + wait_event(vb->acked, virtqueue_get_buf(vq, &unused)); + + return 0; +} + static void set_page_pfns(struct virtio_balloon *vb, __virtio32 pfns[], struct page *page) { @@ -477,6 +510,7 @@ static int init_vqs(struct virtio_balloon *vb) names[VIRTIO_BALLOON_VQ_DEFLATE] = "deflate"; names[VIRTIO_BALLOON_VQ_STATS] = NULL; names[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL; + names[VIRTIO_BALLOON_VQ_REPORTING] = NULL; if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { names[VIRTIO_BALLOON_VQ_STATS] = "stats"; @@ -488,6 +522,11 @@ static int init_vqs(struct virtio_balloon *vb) callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL; } + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING)) { + names[VIRTIO_BALLOON_VQ_REPORTING] = "reporting_vq"; + callbacks[VIRTIO_BALLOON_VQ_REPORTING] = balloon_ack; + } + err = vb->vdev->config->find_vqs(vb->vdev, VIRTIO_BALLOON_VQ_MAX, vqs, callbacks, names, NULL, NULL); if (err) @@ -520,6 +559,9 @@ static int init_vqs(struct virtio_balloon *vb) if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) vb->free_page_vq = vqs[VIRTIO_BALLOON_VQ_FREE_PAGE]; + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING)) + vb->reporting_vq = vqs[VIRTIO_BALLOON_VQ_REPORTING]; + return 0; } @@ -939,12 +981,31 @@ static int virtballoon_probe(struct virtio_device *vdev) if (err) goto out_del_balloon_wq; } + + vb->pr_dev_info.report = virtballoon_free_page_report; + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING)) { + unsigned int capacity; + + capacity = virtqueue_get_vring_size(vb->reporting_vq); + if (capacity < PAGE_REPORTING_CAPACITY) { + err = -ENOSPC; + goto out_unregister_shrinker; + } + + err = page_reporting_register(&vb->pr_dev_info); + if (err) + goto out_unregister_shrinker; + } + virtio_device_ready(vdev); if (towards_target(vb)) virtballoon_changed(vdev); return 0; +out_unregister_shrinker: + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) + virtio_balloon_unregister_shrinker(vb); out_del_balloon_wq: if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) destroy_workqueue(vb->balloon_wq); @@ -973,6 +1034,8 @@ static void virtballoon_remove(struct virtio_device *vdev) { struct virtio_balloon *vb = vdev->priv; + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING)) + page_reporting_unregister(&vb->pr_dev_info); if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) virtio_balloon_unregister_shrinker(vb); spin_lock_irq(&vb->stop_update_lock); @@ -1045,6 +1108,7 @@ static int virtballoon_validate(struct virtio_device *vdev) VIRTIO_BALLOON_F_DEFLATE_ON_OOM, VIRTIO_BALLOON_F_FREE_PAGE_HINT, VIRTIO_BALLOON_F_PAGE_POISON, + VIRTIO_BALLOON_F_REPORTING, }; static struct virtio_driver virtio_balloon_driver = { diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h index a1966cd7b677..19974392d324 100644 --- a/include/uapi/linux/virtio_balloon.h +++ b/include/uapi/linux/virtio_balloon.h @@ -36,6 +36,7 @@ #define VIRTIO_BALLOON_F_DEFLATE_ON_OOM 2 /* Deflate balloon on OOM */ #define VIRTIO_BALLOON_F_FREE_PAGE_HINT 3 /* VQ to report free pages */ #define VIRTIO_BALLOON_F_PAGE_POISON 4 /* Guest is using page poisoning */ +#define VIRTIO_BALLOON_F_REPORTING 5 /* Page reporting virtqueue */ /* Size of a PFN in the balloon interface. */ #define VIRTIO_BALLOON_PFN_SHIFT 12