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[79.176.10.77]) by smtp.gmail.com with ESMTPSA id g33sm3860901qtd.12.2019.10.11.05.51.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 11 Oct 2019 05:51:29 -0700 (PDT) Date: Fri, 11 Oct 2019 08:51:24 -0400 From: "Michael S. Tsirkin" To: Mikhail Sennikovsky Subject: Re: [RFC 2/2] virtio-net: use post load hook Message-ID: <20191011083603-mutt-send-email-mst@kernel.org> References: <20191010180412.26236-1-mst@redhat.com> <20191010180412.26236-2-mst@redhat.com> <20191011055111-mutt-send-email-mst@kernel.org> <20191011060342-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 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: Jason Wang , qemu-devel@nongnu.org, stefanha@redhat.com, "Dr. David Alan Gilbert" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, Oct 11, 2019 at 12:34:59PM +0200, Mikhail Sennikovsky wrote: > I still wonder though if this approach is really cleaner than my > original one of having an extra argument in set_features callback, > saying whether the device settings (offloads in case of virtio-net) > need to be reset. > > Mikhail I prefer this approach as I think it's generally a saner way to restore the device state: first the virtio core, then the device specific state. We should consider not invoking set features callback during load at all: its real purpose is to validate the features, the _nocheck variant makes no sense to me. But that's a bigger change. > > Am Fr., 11. Okt. 2019 um 12:30 Uhr schrieb Mikhail Sennikovsky > : > > > > Am Fr., 11. Okt. 2019 um 12:08 Uhr schrieb Michael S. Tsirkin : > > >... > > > And pre save hook can do n->saved_guest_offloads = n->curr_guest_offloads. > > Would you want to have the saved_guest_offloads as part of the saved state? > > The curr_guest_offloads info is already there, so why would you want > > to duplicate that? > > Wouldn't it be better to just do n->saved_guest_offloads = > > n->curr_guest_offloads in virtio_net_post_load_device, > > and then do > > n->curr_guest_offloads = n->saved_guest_offloads; > > if (peer_has_vnet_hdr(n)) { > > virtio_net_apply_guest_offloads(n); > > in the new post load hook (virtio_net_post_load_virtio) exactly like you say? > > > > Mikhail > > > > > > > > > > > On Fri, Oct 11, 2019 at 11:58:38AM +0200, Mikhail Sennikovsky wrote: > > > > Note that the virtio_net_set_features gets also called from the > > > > virtio_pci_common_write when guest does virtio device configuration. > > > > In that case the curr_guest_offloads are still expected to be reset. > > > > > > > > Mikhail > > > > > > > > Am Fr., 11. Okt. 2019 um 11:51 Uhr schrieb Michael S. Tsirkin : > > > > > > > > > > On Fri, Oct 11, 2019 at 11:46:22AM +0200, Mikhail Sennikovsky wrote: > > > > > > Hi Michael, > > > > > > > > > > > > Unfortunately your approach will not work, because the > > > > > > VirtIONet::curr_guest_offloads would still be reset in > > > > > > virtio_net_set_features: > > > > > > -- > > > > > > if (n->has_vnet_hdr) { > > > > > > n->curr_guest_offloads = > > > > > > virtio_net_guest_offloads_by_features(features); > > > > > > > > > > So let's move that part to the new hook too. > > > > > > > > > > > -- > > > > > > ( https://github.com/qemu/qemu/blob/master/hw/net/virtio-net.c#L774 ) > > > > > > > > > > > > I.e. although virtio_net_apply_guest_offloads would now be called > > > > > > after the virtio_net_set_features, by the time it is called the > > > > > > VirtIONet::curr_guest_offloads would be reset to a full list of > > > > > > features. > > > > > > > > > > > > Regards, > > > > > > Mikhail > > > > > > > > > > > > Am Do., 10. Okt. 2019 um 20:04 Uhr schrieb Michael S. Tsirkin : > > > > > > > > > > > > > > Currently offloads disabled by guest via the VIRTIO_NET_CTRL_GUEST_OFFLOADS_SET > > > > > > > command are not preserved on VM migration. > > > > > > > Instead all offloads reported by guest features (via VIRTIO_PCI_GUEST_FEATURES) > > > > > > > get enabled. > > > > > > > What happens is: first the VirtIONet::curr_guest_offloads gets restored > > > > > > > and offloads are getting set correctly: > > > > > > > > > > > > > > #0 qemu_set_offload (nc=0x555556a11400, csum=1, tso4=0, tso6=0, ecn=0, ufo=0) at net/net.c:474 > > > > > > > #1 virtio_net_apply_guest_offloads (n=0x555557701ca0) at hw/net/virtio-net.c:720 > > > > > > > #2 virtio_net_post_load_device (opaque=0x555557701ca0, version_id=11) at hw/net/virtio-net.c:2334 > > > > > > > #3 vmstate_load_state (f=0x5555569dc010, vmsd=0x555556577c80 , opaque=0x555557701ca0, version_id=11) > > > > > > > at migration/vmstate.c:168 > > > > > > > #4 virtio_load (vdev=0x555557701ca0, f=0x5555569dc010, version_id=11) at hw/virtio/virtio.c:2197 > > > > > > > #5 virtio_device_get (f=0x5555569dc010, opaque=0x555557701ca0, size=0, field=0x55555668cd00 <__compound_literal.5>) at hw/virtio/virtio.c:2036 > > > > > > > #6 vmstate_load_state (f=0x5555569dc010, vmsd=0x555556577ce0 , opaque=0x555557701ca0, version_id=11) at migration/vmstate.c:143 > > > > > > > #7 vmstate_load (f=0x5555569dc010, se=0x5555578189e0) at migration/savevm.c:829 > > > > > > > #8 qemu_loadvm_section_start_full (f=0x5555569dc010, mis=0x5555569eee20) at migration/savevm.c:2211 > > > > > > > #9 qemu_loadvm_state_main (f=0x5555569dc010, mis=0x5555569eee20) at migration/savevm.c:2395 > > > > > > > #10 qemu_loadvm_state (f=0x5555569dc010) at migration/savevm.c:2467 > > > > > > > #11 process_incoming_migration_co (opaque=0x0) at migration/migration.c:449 > > > > > > > > > > > > > > However later on the features are getting restored, and offloads get reset to > > > > > > > everything supported by features: > > > > > > > > > > > > > > #0 qemu_set_offload (nc=0x555556a11400, csum=1, tso4=1, tso6=1, ecn=0, ufo=0) at net/net.c:474 > > > > > > > #1 virtio_net_apply_guest_offloads (n=0x555557701ca0) at hw/net/virtio-net.c:720 > > > > > > > #2 virtio_net_set_features (vdev=0x555557701ca0, features=5104441767) at hw/net/virtio-net.c:773 > > > > > > > #3 virtio_set_features_nocheck (vdev=0x555557701ca0, val=5104441767) at hw/virtio/virtio.c:2052 > > > > > > > #4 virtio_load (vdev=0x555557701ca0, f=0x5555569dc010, version_id=11) at hw/virtio/virtio.c:2220 > > > > > > > #5 virtio_device_get (f=0x5555569dc010, opaque=0x555557701ca0, size=0, field=0x55555668cd00 <__compound_literal.5>) at hw/virtio/virtio.c:2036 > > > > > > > #6 vmstate_load_state (f=0x5555569dc010, vmsd=0x555556577ce0 , opaque=0x555557701ca0, version_id=11) at migration/vmstate.c:143 > > > > > > > #7 vmstate_load (f=0x5555569dc010, se=0x5555578189e0) at migration/savevm.c:829 > > > > > > > #8 qemu_loadvm_section_start_full (f=0x5555569dc010, mis=0x5555569eee20) at migration/savevm.c:2211 > > > > > > > #9 qemu_loadvm_state_main (f=0x5555569dc010, mis=0x5555569eee20) at migration/savevm.c:2395 > > > > > > > #10 qemu_loadvm_state (f=0x5555569dc010) at migration/savevm.c:2467 > > > > > > > #11 process_incoming_migration_co (opaque=0x0) at migration/migration.c:449 > > > > > > > > > > > > > > Fix this by pushing out offload initialization to the new post load hook. > > > > > > > > > > > > > > Reported-by: Mikhail Sennikovsky > > > > > > > Signed-off-by: Michael S. Tsirkin > > > > > > > --- > > > > > > > hw/net/virtio-net.c | 14 ++++++++++---- > > > > > > > 1 file changed, 10 insertions(+), 4 deletions(-) > > > > > > > > > > > > > > diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c > > > > > > > index 9f11422337..62fb858e2d 100644 > > > > > > > --- a/hw/net/virtio-net.c > > > > > > > +++ b/hw/net/virtio-net.c > > > > > > > @@ -2333,10 +2333,6 @@ static int virtio_net_post_load_device(void *opaque, int version_id) > > > > > > > n->curr_guest_offloads = virtio_net_supported_guest_offloads(n); > > > > > > > } > > > > > > > > > > > > > > - if (peer_has_vnet_hdr(n)) { > > > > > > > - virtio_net_apply_guest_offloads(n); > > > > > > > - } > > > > > > > - > > > > > > > virtio_net_set_queues(n); > > > > > > > > > > > > > > /* Find the first multicast entry in the saved MAC filter */ > > > > > > > @@ -2370,6 +2366,15 @@ static int virtio_net_post_load_device(void *opaque, int version_id) > > > > > > > return 0; > > > > > > > } > > > > > > > > > > > > > > +static int virtio_net_post_load_virtio(VirtIODevice *vdev) > > > > > > > +{ > > > > > > > + if (peer_has_vnet_hdr(n)) { > > > > > > > + virtio_net_apply_guest_offloads(n); > > > > > > > + } > > > > > > > + > > > > > > > + return 0; > > > > > > > +} > > > > > > > + > > > > > > > /* tx_waiting field of a VirtIONetQueue */ > > > > > > > static const VMStateDescription vmstate_virtio_net_queue_tx_waiting = { > > > > > > > .name = "virtio-net-queue-tx_waiting", > > > > > > > @@ -2912,6 +2917,7 @@ static void virtio_net_class_init(ObjectClass *klass, void *data) > > > > > > > vdc->guest_notifier_mask = virtio_net_guest_notifier_mask; > > > > > > > vdc->guest_notifier_pending = virtio_net_guest_notifier_pending; > > > > > > > vdc->legacy_features |= (0x1 << VIRTIO_NET_F_GSO); > > > > > > > + vdc->post_load = virtio_net_post_load_virtio; > > > > > > > vdc->vmsd = &vmstate_virtio_net_device; > > > > > > > } > > > > > > > > > > > > > > -- > > > > > > > MST > > > > > > >