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Mon, 27 Apr 2020 08:21:06 +0000 (UTC) Received: from [10.36.114.127] (ovpn-114-127.ams2.redhat.com [10.36.114.127]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2D6235D715; Mon, 27 Apr 2020 08:21:01 +0000 (UTC) Subject: Re: [PATCH v22 QEMU 5/5] virtio-balloon: Provide an interface for free page reporting To: Alexander Duyck , mst@redhat.com References: <20200424164239.10723.58352.stgit@localhost.localdomain> <20200424165034.10723.77728.stgit@localhost.localdomain> From: David Hildenbrand Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= mQINBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABtCREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT6JAlgEEwEIAEICGwMFCQlmAYAGCwkIBwMCBhUI AgkKCwQWAgMBAh4BAheAFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl3pImkCGQEACgkQTd4Q 9wD/g1o+VA//SFvIHUAvul05u6wKv/pIR6aICPdpF9EIgEU448g+7FfDgQwcEny1pbEzAmiw zAXIQ9H0NZh96lcq+yDLtONnXk/bEYWHHUA014A1wqcYNRY8RvY1+eVHb0uu0KYQoXkzvu+s Dncuguk470XPnscL27hs8PgOP6QjG4jt75K2LfZ0eAqTOUCZTJxA8A7E9+XTYuU0hs7QVrWJ jQdFxQbRMrYz7uP8KmTK9/Cnvqehgl4EzyRaZppshruKMeyheBgvgJd5On1wWq4ZUV5PFM4x II3QbD3EJfWbaJMR55jI9dMFa+vK7MFz3rhWOkEx/QR959lfdRSTXdxs8V3zDvChcmRVGN8U Vo93d1YNtWnA9w6oCW1dnDZ4kgQZZSBIjp6iHcA08apzh7DPi08jL7M9UQByeYGr8KuR4i6e RZI6xhlZerUScVzn35ONwOC91VdYiQgjemiVLq1WDDZ3B7DIzUZ4RQTOaIWdtXBWb8zWakt/ ztGhsx0e39Gvt3391O1PgcA7ilhvqrBPemJrlb9xSPPRbaNAW39P8ws/UJnzSJqnHMVxbRZC Am4add/SM+OCP0w3xYss1jy9T+XdZa0lhUvJfLy7tNcjVG/sxkBXOaSC24MFPuwnoC9WvCVQ ZBxouph3kqc4Dt5X1EeXVLeba+466P1fe1rC8MbcwDkoUo65Ag0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAGJAiUEGAECAA8FAlXLn5ECGwwFCQlmAYAACgkQTd4Q 9wD/g1qA6w/+M+ggFv+JdVsz5+ZIc6MSyGUozASX+bmIuPeIecc9UsFRatc91LuJCKMkD9Uv GOcWSeFpLrSGRQ1Z7EMzFVU//qVs6uzhsNk0RYMyS0B6oloW3FpyQ+zOVylFWQCzoyyf227y GW8HnXunJSC+4PtlL2AY4yZjAVAPLK2l6mhgClVXTQ/S7cBoTQKP+jvVJOoYkpnFxWE9pn4t H5QIFk7Ip8TKr5k3fXVWk4lnUi9MTF/5L/mWqdyIO1s7cjharQCstfWCzWrVeVctpVoDfJWp 4LwTuQ5yEM2KcPeElLg5fR7WB2zH97oI6/Ko2DlovmfQqXh9xWozQt0iGy5tWzh6I0JrlcxJ ileZWLccC4XKD1037Hy2FLAjzfoWgwBLA6ULu0exOOdIa58H4PsXtkFPrUF980EEibUp0zFz GotRVekFAceUaRvAj7dh76cToeZkfsjAvBVb4COXuhgX6N4pofgNkW2AtgYu1nUsPAo+NftU CxrhjHtLn4QEBpkbErnXQyMjHpIatlYGutVMS91XTQXYydCh5crMPs7hYVsvnmGHIaB9ZMfB njnuI31KBiLUks+paRkHQlFcgS2N3gkRBzH7xSZ+t7Re3jvXdXEzKBbQ+dC3lpJB0wPnyMcX FOTT3aZT7IgePkt5iC/BKBk3hqKteTnJFeVIT7EC+a6YUFg= Organization: Red Hat GmbH Message-ID: Date: Mon, 27 Apr 2020 10:21:01 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200424165034.10723.77728.stgit@localhost.localdomain> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=207.211.31.81; envelope-from=david@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/04/26 23:33:12 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.81 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: virtio-dev@lists.oasis-open.org, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 24.04.20 18:50, Alexander Duyck wrote: > From: Alexander Duyck > > Add support for free page reporting. 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 provides a new way of letting the guest proactively report free > pages to the hypervisor, so the hypervisor can reuse them. In contrast to > inflate/deflate that is triggered via the hypervisor explicitly. > > Signed-off-by: Alexander Duyck > --- > hw/virtio/virtio-balloon.c | 67 ++++++++++++++++++++++++++++++++++++ > include/hw/virtio/virtio-balloon.h | 2 + > 2 files changed, 68 insertions(+), 1 deletion(-) > > diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c > index c1c76ec09c95..2ce56c6c0794 100644 > --- a/hw/virtio/virtio-balloon.c > +++ b/hw/virtio/virtio-balloon.c > @@ -321,6 +321,67 @@ 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; > + > + /* > + * When we discard the page it has the effect of removing the page > + * from the hypervisor itself and causing it to be zeroed when it > + * is returned to us. So we must not discard the page if it is > + * accessible by another device or process, or if the guest is > + * expecting it to retain a non-zero value. > + */ > + if (qemu_balloon_is_inhibited() || dev->poison_val) { > + goto skip_element; > + } > + > + 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; > + RAMBlock *rb; > + > + /* > + * There is no need to check the memory section to see if > + * it is ram/readonly/romd like there is for handle_output > + * below. If the region is not meant to be written to then > + * address_space_map will have allocated a bounce buffer > + * and it will be freed in address_space_unmap and trigger > + * and unassigned_mem_write before failing to copy over the > + * buffer. If more than one bad descriptor is provided it > + * will return NULL after the first bounce buffer and fail > + * to map any resources. > + */ > + rb = qemu_ram_block_from_host(addr, false, &ram_offset); > + if (!rb) { > + trace_virtio_balloon_bad_addr(elem->in_addr[i]); > + continue; > + } > + > + /* > + * For now we will simply ignore unaligned memory regions, or > + * regions that overrun the end of the RAMBlock. > + */ > + if (!QEMU_IS_ALIGNED(ram_offset | size, qemu_ram_pagesize(rb)) || > + (ram_offset + size) > qemu_ram_get_used_length(rb)) { > + continue; > + } > + > + ram_block_discard_range(rb, ram_offset, size); > + } > + > +skip_element: > + 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); > @@ -818,6 +879,10 @@ 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); > + } > + > if (virtio_has_feature(s->host_features, > VIRTIO_BALLOON_F_FREE_PAGE_HINT)) { > s->free_page_vq = virtio_add_queue(vdev, VIRTQUEUE_MAX_SIZE, > @@ -945,6 +1010,8 @@ static Property virtio_balloon_properties[] = { > VIRTIO_BALLOON_F_FREE_PAGE_HINT, false), > DEFINE_PROP_BIT("page-poison", VirtIOBalloon, host_features, > VIRTIO_BALLOON_F_PAGE_POISON, true), > + DEFINE_PROP_BIT("free-page-reporting", VirtIOBalloon, host_features, > + VIRTIO_BALLOON_F_REPORTING, false), > /* QEMU 4.0 accidentally changed the config size even when free-page-hint > * is disabled, resulting in QEMU 3.1 migration incompatibility. This > * property retains this quirk for QEMU 4.1 machine types. > diff --git a/include/hw/virtio/virtio-balloon.h b/include/hw/virtio/virtio-balloon.h > index 3ca2a78e1aca..ac4013d51010 100644 > --- a/include/hw/virtio/virtio-balloon.h > +++ b/include/hw/virtio/virtio-balloon.h > @@ -42,7 +42,7 @@ enum virtio_balloon_free_page_hint_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_hint_status; > uint32_t num_pages; > uint32_t actual; > Acked-by: David Hildenbrand -- Thanks, David / dhildenb