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Tsirkin" To: Stefan Hajnoczi Cc: qemu-devel@nongnu.org, Peter Maydell , Hawkins Jiawei , Jason Wang Subject: Re: [PULL 08/83] vdpa: Restore hash calculation state Message-ID: <20231019140406-mutt-send-email-mst@kernel.org> References: <1908cfd6e1748d94680e468b9df6321087b8fcf2.1697644299.git.mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Received-SPF: pass client-ip=170.10.133.124; envelope-from=mst@redhat.com; helo=us-smtp-delivery-124.mimecast.com 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, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Thu, Oct 19, 2023 at 09:32:28AM -0700, Stefan Hajnoczi wrote: > On Wed, 18 Oct 2023 at 08:56, Michael S. Tsirkin wrote: > > > > From: Hawkins Jiawei > > > > This patch introduces vhost_vdpa_net_load_rss() to restore > > the hash calculation state at device's startup. > > > > Note that vhost_vdpa_net_load_rss() has `do_rss` argument, > > which allows future code to reuse this function to restore > > the receive-side scaling state when the VIRTIO_NET_F_RSS > > feature is enabled in SVQ. Currently, vhost_vdpa_net_load_rss() > > could only be invoked when `do_rss` is set to false. > > > > Signed-off-by: Hawkins Jiawei > > Message-Id: > > Reviewed-by: Michael S. Tsirkin > > Signed-off-by: Michael S. Tsirkin > > --- > > net/vhost-vdpa.c | 91 ++++++++++++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 91 insertions(+) > > > > diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c > > index 4b7c3b81b8..40d0bcbc0b 100644 > > --- a/net/vhost-vdpa.c > > +++ b/net/vhost-vdpa.c > > @@ -817,6 +817,88 @@ static int vhost_vdpa_net_load_mac(VhostVDPAState *s, const VirtIONet *n, > > return 0; > > } > > > > +static int vhost_vdpa_net_load_rss(VhostVDPAState *s, const VirtIONet *n, > > + struct iovec *out_cursor, > > + struct iovec *in_cursor, bool do_rss) > > +{ > > + struct virtio_net_rss_config cfg; > > + ssize_t r; > > + g_autofree uint16_t *table = NULL; > > + > > + /* > > + * According to VirtIO standard, "Initially the device has all hash > > + * types disabled and reports only VIRTIO_NET_HASH_REPORT_NONE.". > > + * > > + * Therefore, there is no need to send this CVQ command if the > > + * driver disable the all hash types, which aligns with > > + * the device's defaults. > > + * > > + * Note that the device's defaults can mismatch the driver's > > + * configuration only at live migration. > > + */ > > + if (!n->rss_data.enabled || > > + n->rss_data.hash_types == VIRTIO_NET_HASH_REPORT_NONE) { > > + return 0; > > + } > > + > > + cfg.hash_types = cpu_to_le32(n->rss_data.hash_types); > > + > > + /* > > + * According to VirtIO standard, "Field reserved MUST contain zeroes. > > + * It is defined to make the structure to match the layout of > > + * virtio_net_rss_config structure, defined in 5.1.6.5.7.". > > + * > > + * Therefore, we need to zero the fields in struct virtio_net_rss_config, > > + * which corresponds the `reserved` field in > > + * struct virtio_net_hash_config. > > + */ > > + memset(&cfg.indirection_table_mask, 0, > > + sizeof_field(struct virtio_net_hash_config, reserved)); > > Please take a look at the following CI failure: > > In file included from /usr/include/string.h:495, > from /home/gitlab-runner/builds/-LCfcJ2T/0/qemu-project/qemu/include/qemu/osdep.h:116, > from ../net/vhost-vdpa.c:12: > In function ‘memset’, > inlined from ‘vhost_vdpa_net_load_rss’ at ../net/vhost-vdpa.c:874:9: > /usr/include/s390x-linux-gnu/bits/string_fortified.h:71:10: error: > ‘__builtin_memset’ offset [7, 12] from the object at ‘cfg’ is out of > the bounds of referenced subobject ‘indirection_table_mask’ with type > ‘short unsigned int’ at offset 4 [-Werror=array-bounds] > 71 | return __builtin___memset_chk (__dest, __ch, __len, __bos0 (__dest)); > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > cc1: all warnings being treated as errors > > https://gitlab.com/qemu-project/qemu/-/jobs/5329820077 Hmm yes - the trick it's trying to implement is this: struct virtio_net_rss_config { uint32_t hash_types; uint16_t indirection_table_mask; uint16_t unclassified_queue; uint16_t indirection_table[1/* + indirection_table_mask */]; uint16_t max_tx_vq; uint8_t hash_key_length; uint8_t hash_key_data[/* hash_key_length */]; }; ... struct virtio_net_hash_config { uint32_t hash_types; /* for compatibility with virtio_net_rss_config */ uint16_t reserved[4]; uint8_t hash_key_length; uint8_t hash_key_data[/* hash_key_length */]; }; as you see layout matches. Using a union is probably the right way to address this. Dropped for now, thanks! > > + > > + table = g_malloc_n(n->rss_data.indirections_len, > > + sizeof(n->rss_data.indirections_table[0])); > > + for (int i = 0; i < n->rss_data.indirections_len; ++i) { > > + table[i] = cpu_to_le16(n->rss_data.indirections_table[i]); > > + } > > + > > + /* > > + * Consider that virtio_net_handle_rss() currently does not restore the > > + * hash key length parsed from the CVQ command sent from the guest into > > + * n->rss_data and uses the maximum key length in other code, so we also > > + * employthe the maxium key length here. > > + */ > > + cfg.hash_key_length = sizeof(n->rss_data.key); > > + > > + const struct iovec data[] = { > > + { > > + .iov_base = &cfg, > > + .iov_len = offsetof(struct virtio_net_rss_config, > > + indirection_table), > > + }, { > > + .iov_base = table, > > + .iov_len = n->rss_data.indirections_len * > > + sizeof(n->rss_data.indirections_table[0]), > > + }, { > > + .iov_base = &cfg.max_tx_vq, > > + .iov_len = offsetof(struct virtio_net_rss_config, hash_key_data) - > > + offsetof(struct virtio_net_rss_config, max_tx_vq), > > + }, { > > + .iov_base = (void *)n->rss_data.key, > > + .iov_len = sizeof(n->rss_data.key), > > + } > > + }; > > + > > + r = vhost_vdpa_net_load_cmd(s, out_cursor, in_cursor, > > + VIRTIO_NET_CTRL_MQ, > > + VIRTIO_NET_CTRL_MQ_HASH_CONFIG, > > + data, ARRAY_SIZE(data)); > > + if (unlikely(r < 0)) { > > + return r; > > + } > > + > > + return 0; > > +} > > + > > static int vhost_vdpa_net_load_mq(VhostVDPAState *s, > > const VirtIONet *n, > > struct iovec *out_cursor, > > @@ -842,6 +924,15 @@ static int vhost_vdpa_net_load_mq(VhostVDPAState *s, > > return r; > > } > > > > + if (!virtio_vdev_has_feature(&n->parent_obj, VIRTIO_NET_F_HASH_REPORT)) { > > + return 0; > > + } > > + > > + r = vhost_vdpa_net_load_rss(s, n, out_cursor, in_cursor, false); > > + if (unlikely(r < 0)) { > > + return r; > > + } > > + > > return 0; > > } > > > > -- > > MST > > > >