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[134.134.136.24]) by mx.google.com with ESMTPS id l71si39570490pgd.314.2019.08.02.13.58.49 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 02 Aug 2019 13:58:49 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of alexander.h.duyck@linux.intel.com designates 134.134.136.24 as permitted sender) client-ip=134.134.136.24; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of alexander.h.duyck@linux.intel.com designates 134.134.136.24 as permitted sender) smtp.mailfrom=alexander.h.duyck@linux.intel.com; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=intel.com X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 02 Aug 2019 13:58:48 -0700 X-IronPort-AV: E=Sophos;i="5.64,339,1559545200"; d="scan'208";a="184691853" Received: from ahduyck-desk1.jf.intel.com ([10.7.198.76]) by orsmga002-auth.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 02 Aug 2019 13:58:48 -0700 Message-ID: Subject: Re: [PATCH v3 QEMU 2/2] virtio-balloon: Provide a interface for unused page reporting From: Alexander Duyck To: Nitesh Narayan Lal , Alexander Duyck , kvm@vger.kernel.org, david@redhat.com, mst@redhat.com, dave.hansen@intel.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org Cc: yang.zhang.wz@gmail.com, pagupta@redhat.com, riel@surriel.com, konrad.wilk@oracle.com, willy@infradead.org, lcapitulino@redhat.com, wei.w.wang@intel.com, aarcange@redhat.com, pbonzini@redhat.com, dan.j.williams@intel.com Date: Fri, 02 Aug 2019 13:58:48 -0700 In-Reply-To: <63bbf480-7d0c-dd5c-08bf-1951039fcd54@redhat.com> References: <20190801222158.22190.96964.stgit@localhost.localdomain> <20190801224320.24744.16673.stgit@localhost.localdomain> <63bbf480-7d0c-dd5c-08bf-1951039fcd54@redhat.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.30.5 (3.30.5-1.fc29) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, 2019-08-02 at 16:40 -0400, Nitesh Narayan Lal wrote: > On 8/1/19 6:43 PM, Alexander Duyck wrote: > > From: Alexander Duyck > > > > Add support for what I am referring to as "unused page reporting". > > Basically the idea is to function very similar to how the balloon works > > in that we basically end up madvising the page as not being used. However > > we don't really need to bother with any deflate type logic since the page > > will be faulted back into the guest when it is read or written to. > > > > This is meant to be a simplification of the existing balloon interface > > to use for providing hints to what memory needs to be freed. I am assuming > > this is safe to do as the deflate logic does not actually appear to do very > > much other than tracking what subpages have been released and which ones > > haven't. > > > > Signed-off-by: Alexander Duyck > > --- > > hw/virtio/virtio-balloon.c | 46 ++++++++++++++++++++++- > > include/hw/virtio/virtio-balloon.h | 2 + > > include/standard-headers/linux/virtio_balloon.h | 1 + > > 3 files changed, 46 insertions(+), 3 deletions(-) > > > > diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c > > index 003b3ebcfdfb..7a30df63bc77 100644 > > --- a/hw/virtio/virtio-balloon.c > > +++ b/hw/virtio/virtio-balloon.c > > @@ -320,6 +320,40 @@ static void balloon_stats_set_poll_interval(Object *obj, Visitor *v, > > balloon_stats_change_timer(s, 0); > > } > > > > +static void virtio_balloon_handle_report(VirtIODevice *vdev, VirtQueue *vq) > > +{ > > + VirtIOBalloon *dev = VIRTIO_BALLOON(vdev); > > + VirtQueueElement *elem; > > + > > + while ((elem = virtqueue_pop(vq, sizeof(VirtQueueElement)))) { > > + unsigned int i; > > + > > + for (i = 0; i < elem->in_num; i++) { > > + void *addr = elem->in_sg[i].iov_base; > > + size_t size = elem->in_sg[i].iov_len; > > + ram_addr_t ram_offset; > > + size_t rb_page_size; > > + RAMBlock *rb; > > + > > + if (qemu_balloon_is_inhibited() || dev->poison_val) > > + continue; > > + > > + rb = qemu_ram_block_from_host(addr, false, &ram_offset); > > + rb_page_size = qemu_ram_pagesize(rb); > > + > > + /* For now we will simply ignore unaligned memory regions */ > > + if ((ram_offset | size) & (rb_page_size - 1)) > > + continue; > > + > > + ram_block_discard_range(rb, ram_offset, size); > > + } > > + > > + virtqueue_push(vq, elem, 0); > > + virtio_notify(vdev, vq); > > + g_free(elem); > > + } > > +} > > + > > static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq) > > { > > VirtIOBalloon *s = VIRTIO_BALLOON(vdev); > > @@ -627,7 +661,8 @@ static size_t virtio_balloon_config_size(VirtIOBalloon *s) > > return sizeof(struct virtio_balloon_config); > > } > > if (virtio_has_feature(features, VIRTIO_BALLOON_F_PAGE_POISON) || > > - virtio_has_feature(features, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) { > > + virtio_has_feature(features, VIRTIO_BALLOON_F_FREE_PAGE_HINT) || > > + virtio_has_feature(features, VIRTIO_BALLOON_F_REPORTING)) { > > return sizeof(struct virtio_balloon_config); > > } > > return offsetof(struct virtio_balloon_config, free_page_report_cmd_id); > > @@ -715,7 +750,8 @@ static uint64_t virtio_balloon_get_features(VirtIODevice *vdev, uint64_t f, > > VirtIOBalloon *dev = VIRTIO_BALLOON(vdev); > > f |= dev->host_features; > > virtio_add_feature(&f, VIRTIO_BALLOON_F_STATS_VQ); > > - if (virtio_has_feature(f, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) { > > + if (virtio_has_feature(f, VIRTIO_BALLOON_F_FREE_PAGE_HINT) || > > + virtio_has_feature(f, VIRTIO_BALLOON_F_REPORTING)) { > > virtio_add_feature(&f, VIRTIO_BALLOON_F_PAGE_POISON); > > } > > > > @@ -805,6 +841,10 @@ static void virtio_balloon_device_realize(DeviceState *dev, Error **errp) > > s->dvq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output); > > s->svq = virtio_add_queue(vdev, 128, virtio_balloon_receive_stats); > > > > + if (virtio_has_feature(s->host_features, VIRTIO_BALLOON_F_REPORTING)) { > > + s->rvq = virtio_add_queue(vdev, 32, virtio_balloon_handle_report); > > + } > > + > This does makes sense. I haven't seen the kernel patch yet, but I am guessing > you will use this max_vq size to define the capacity. Right. It was one of the suggestions I had received for the last patch set. So since I was already using it to limit the capacity I thought I might as well shrink the size of the queue on the hypervisor and save space. > > if (virtio_has_feature(s->host_features, > > VIRTIO_BALLOON_F_FREE_PAGE_HINT)) { > > s->free_page_vq = virtio_add_queue(vdev, VIRTQUEUE_MAX_SIZE, > > @@ -931,6 +971,8 @@ static Property virtio_balloon_properties[] = { > > */ > > DEFINE_PROP_BOOL("qemu-4-0-config-size", VirtIOBalloon, > > qemu_4_0_config_size, false), > > + DEFINE_PROP_BIT("unused-page-reporting", VirtIOBalloon, host_features, > > + VIRTIO_BALLOON_F_REPORTING, true), > > DEFINE_PROP_LINK("iothread", VirtIOBalloon, iothread, TYPE_IOTHREAD, > > IOThread *), > > DEFINE_PROP_END_OF_LIST(), > > diff --git a/include/hw/virtio/virtio-balloon.h b/include/hw/virtio/virtio-balloon.h > > index 7fe78e5c14d7..db5bf7127112 100644 > > --- a/include/hw/virtio/virtio-balloon.h > > +++ b/include/hw/virtio/virtio-balloon.h > > @@ -42,7 +42,7 @@ enum virtio_balloon_free_page_report_status { > > > > typedef struct VirtIOBalloon { > > VirtIODevice parent_obj; > > - VirtQueue *ivq, *dvq, *svq, *free_page_vq; > > + VirtQueue *ivq, *dvq, *svq, *free_page_vq, *rvq; > > uint32_t free_page_report_status; > > uint32_t num_pages; > > uint32_t actual; > > diff --git a/include/standard-headers/linux/virtio_balloon.h b/include/standard-headers/linux/virtio_balloon.h > > index 9375ca2a70de..1c5f6d6f2de6 100644 > > --- a/include/standard-headers/linux/virtio_balloon.h > > +++ b/include/standard-headers/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 */ > > Do we really need this change? or is this something which is picked from the > Linux kernel? > If we do need it, then Cornelia suggested to split off any update to this header > into a separate patch, so that it can be replaced by a proper headers update > when it is merged. I'll keep that in mind. I didn't think of this as an official submission for QEMU as of yet. I have been mostly focused on the kernel side of things for now.