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Mon, 18 May 2020 15:28:56 +0000 (UTC) Subject: Re: [PATCH v1 1/3] virtio-balloon: fix free page hinting without an iothread To: Alexander Duyck References: <20200518083704.52646-1-david@redhat.com> <20200518083704.52646-2-david@redhat.com> 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: <63874c2d-82ee-ed79-d108-aed90f6ee484@redhat.com> Date: Mon, 18 May 2020 17:28:55 +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: 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: 8bit 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 = 2020/05/17 22:52:27 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action 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: Alexander Bulekov , Wei Wang , =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , qemu-devel@nongnu.org, "Michael S . Tsirkin" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 18.05.20 17:01, Alexander Duyck wrote: > On Mon, May 18, 2020 at 1:37 AM David Hildenbrand wrote: >> >> In case we don't have an iothread, we mark the feature as abscent but >> still add the queue. 'free_page_bh' remains set to NULL. >> >> qemu-system-i386 \ >> -M microvm \ >> -nographic \ >> -device virtio-balloon-device,free-page-hint=true \ >> -nographic \ >> -display none \ >> -monitor none \ >> -serial none \ >> -qtest stdio >> >> Doing a "write 0xc0000e30 0x24 >> 0x030000000300000003000000030000000300000003000000030000000300000003000000" >> >> We will trigger a SEGFAULT. Let's move the check and bail out. >> >> While at it, move the static initializations to instance_initialize(). >> >> Fixes: c13c4153f76d ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT") >> Reported-by: Alexander Bulekov >> Cc: Wei Wang >> Cc: Michael S. Tsirkin >> Cc: Philippe Mathieu-Daudé >> Cc: Alexander Duyck >> Signed-off-by: David Hildenbrand >> --- >> hw/virtio/virtio-balloon.c | 35 ++++++++++++++++++----------------- >> 1 file changed, 18 insertions(+), 17 deletions(-) >> >> diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c >> index 065cd450f1..dc3b1067ab 100644 >> --- a/hw/virtio/virtio-balloon.c >> +++ b/hw/virtio/virtio-balloon.c >> @@ -789,6 +789,13 @@ static void virtio_balloon_device_realize(DeviceState *dev, Error **errp) >> return; >> } >> >> + if (virtio_has_feature(s->host_features, >> + VIRTIO_BALLOON_F_FREE_PAGE_HINT) && !s->iothread) { >> + error_setg(errp, "'free-page-hint' requires 'iothread' to be set"); >> + virtio_cleanup(vdev); >> + return; >> + } >> + >> s->ivq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output); >> s->dvq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output); >> s->svq = virtio_add_queue(vdev, 128, virtio_balloon_receive_stats); >> @@ -797,24 +804,11 @@ static void virtio_balloon_device_realize(DeviceState *dev, Error **errp) >> VIRTIO_BALLOON_F_FREE_PAGE_HINT)) { >> s->free_page_vq = virtio_add_queue(vdev, VIRTQUEUE_MAX_SIZE, >> virtio_balloon_handle_free_page_vq); >> - s->free_page_report_status = FREE_PAGE_REPORT_S_STOP; >> - s->free_page_report_cmd_id = >> - VIRTIO_BALLOON_FREE_PAGE_REPORT_CMD_ID_MIN; >> - s->free_page_report_notify.notify = >> - virtio_balloon_free_page_report_notify; >> precopy_add_notifier(&s->free_page_report_notify); >> - if (s->iothread) { >> - object_ref(OBJECT(s->iothread)); >> - s->free_page_bh = aio_bh_new(iothread_get_aio_context(s->iothread), >> - virtio_ballloon_get_free_page_hints, s); >> - qemu_mutex_init(&s->free_page_lock); >> - qemu_cond_init(&s->free_page_cond); >> - s->block_iothread = false; >> - } else { >> - /* Simply disable this feature if the iothread wasn't created. */ >> - s->host_features &= ~(1 << VIRTIO_BALLOON_F_FREE_PAGE_HINT); >> - virtio_error(vdev, "iothread is missing"); >> - } >> + >> + object_ref(OBJECT(s->iothread)); >> + s->free_page_bh = aio_bh_new(iothread_get_aio_context(s->iothread), >> + virtio_ballloon_get_free_page_hints, s); >> } >> reset_stats(s); >> } >> @@ -892,6 +886,13 @@ static void virtio_balloon_instance_init(Object *obj) >> { >> VirtIOBalloon *s = VIRTIO_BALLOON(obj); >> >> + qemu_mutex_init(&s->free_page_lock); >> + qemu_cond_init(&s->free_page_cond); >> + s->free_page_report_status = FREE_PAGE_REPORT_S_STOP; >> + s->free_page_report_cmd_id = VIRTIO_BALLOON_FREE_PAGE_REPORT_CMD_ID_MIN; >> + s->free_page_report_notify.notify = virtio_balloon_free_page_report_notify; >> + s->block_iothread = false; >> + >> object_property_add(obj, "guest-stats", "guest statistics", >> balloon_stats_get_all, NULL, NULL, s); >> > > So the one nit I have is that I am not sure you need to bother with > initializing block_iothread since it should already be initialized to > false/0 shouldn't it? Otherwise this all looks good to me. Yes, and as "FREE_PAGE_REPORT_S_STOP = 0", that's implicitly set as well. Both can go IMHO. > > Reviewed-by: Alexander Duyck > Thanks! -- Thanks, David / dhildenb