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Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Greg Kroah-Hartman , "linux-hyperv@vger.kernel.org" , "linux-kernel@vger.kernel.org" CC: Long Li Subject: RE: [PATCH] uio_hv_generic: Set event for all channels on the device Thread-Topic: [PATCH] uio_hv_generic: Set event for all channels on the device Thread-Index: AQHbiLEONmJ0LaTVDE27zBJ6w1ZcUrNdEAHw Date: Fri, 28 Feb 2025 19:11:44 +0000 Message-ID: References: <1740617158-15902-1-git-send-email-longli@linuxonhyperv.com> In-Reply-To: <1740617158-15902-1-git-send-email-longli@linuxonhyperv.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-publictraffictype: Email x-ms-traffictypediagnostic: SN6PR02MB4157:EE_|DM8PR02MB7878:EE_ x-ms-office365-filtering-correlation-id: 9e9c400d-cdb3-44a0-aade-08dd582bbda9 x-microsoft-antispam: BCL:0;ARA:14566002|19110799003|461199028|8060799006|8062599003|15080799006|3412199025|440099028|12091999003|41001999003|102099032|56899033; x-microsoft-antispam-message-info: =?us-ascii?Q?/x1jg/0Jnkf0bf0nYNvdlHZiWtV4uk44OWgM4xcJkPbChz7D1oHEwaTJSnEP?= =?us-ascii?Q?CeOIrfiLULcI9/PnbkQ1JyPwNdphCkn4BoHzpIHHet4iIflUmcDn5oPC3HUE?= =?us-ascii?Q?Y+xazQmQcVbIhdEzfb3SVawppbv3cZlv0U2c7bxNOzjpEMjSbUa82j+VWhyn?= =?us-ascii?Q?yr20mSQD9M2UkB8hxTI5QwLCgUG0aWeUNsUA1ORaCwtE1dqhjUROU7bO3h5I?= =?us-ascii?Q?zLRdKLCfn0pMaJHzPIf6Wqi392DDZmVRFhEUdfX2AWXkA9iYzpLyk2Eiacx2?= =?us-ascii?Q?QnqbRrvazejeCzEDQqlgyXUps2LtSfxmyBaZ5sPc2Upfs3VTIRIVUAewix9e?= =?us-ascii?Q?w0IJkJcA6HXBCJoHc5bvrDYB2AcQkO2UyH41vb3lBukChqDOrY1cDczMT3JT?= =?us-ascii?Q?yVvsUCpJ1RT2g9m5AocyG1ISqvx51MokUJDaN035zuek9A1kpd0phRF+Gfud?= =?us-ascii?Q?s0C343KRYRkfyqyNw64b/S/OwP1uSlgihyZqXRA2JtXmetPnSvPwckZRxhvV?= =?us-ascii?Q?fG2fJrRMmmm4ismbvcSyNgbpV0+kVir6p9sbFX6YeiallLFuCFfRBYoWiqZC?= =?us-ascii?Q?/zgEWLh4MkYFHvOxjAIROLThPvGJ/UFY8Qji9r5+yqmOQgzaLWrulDs27yrH?= =?us-ascii?Q?EuT8gSlAC7L+mGsuUscTSU8mnC5boENgWOSdsaflzYebUS09lSxxq7ilhkCC?= =?us-ascii?Q?sytANlI1S+n7y2j4QfSVyM9pse6lxvaxQwL4moJykbplvBTw1kdHrXECzgKj?= =?us-ascii?Q?hXeVXor/SUnX2CEnqSARVlAdU5Hn77J9aqCGCd8ADz4bkbpXnkRP3TQo43sl?= =?us-ascii?Q?bAH6EnygHORZYap2ruu2ilKjT3mfnZKxePs6GkywSQ+3MSXAWWTDBiHjLGkV?= =?us-ascii?Q?ublB0T68I5raa5uY7WLWF8OTix3/J3HB9pRAYkN+XcZ7TOp6kVpUlxg3w4dp?= =?us-ascii?Q?2IAgE/M/R22YXjp9yWGMeZVIKluyBIAf9bVkBoLxXxmiILOY8HKbgGGZDfsV?= =?us-ascii?Q?LxJtz1utJbBhww89PP1CFAJ6BF3OtVAzk30jXizzW8SdXNSquXOmQ7KMETY5?= =?us-ascii?Q?WVlxBFGUFahqQfuwTOZF1WWk+q1iAEic0OF8eEuldB/CK/XiWgY=3D?= x-ms-exchange-antispam-messagedata-chunkcount: 1 x-ms-exchange-antispam-messagedata-0: =?us-ascii?Q?wmd1VI/vngKTBoOMsujRM6TqVBwGl9GaTtVm09YjVvV3zy/4/4roW147ApS/?= =?us-ascii?Q?67cKJCn/4okfVzF70RuEwCb7xt6khoMc4Fag/0z6aeXW8AdA6RHe+H15t3uM?= =?us-ascii?Q?V9Ml0uNBTtdrl3lpJziroNkbKAyj7GnqtSF7SACsdTVNqqJNFfrNPuBkRqtw?= =?us-ascii?Q?QLJoUxSZCuGZnaQF1KpC4jDVldfJlphFyaHRVC5rrR33h7mdu5vPv0mA5aTM?= =?us-ascii?Q?2gmUX4wPclwXGHO6+2bp4T20DKXSxSm0mcoWGlrRzB8azHiwW6Yqd5YPt2cM?= =?us-ascii?Q?Y47FqcuPSbPlQV9x7f59wF1hGDX3RX3drZmhTxpbtTh2KgKSyreyKH9GGMAR?= =?us-ascii?Q?6nILgzGHQynnV+U/28OLB8dYtdLMoSqnPS4VzOjiPNwU2+kMbFTSdt8l3KSb?= =?us-ascii?Q?UWMBQfcBAVhfAuCrXKlEaOsVzl69NKWu3N+xYMQ6Ddo6AN0Bw1yvjiD1yaBQ?= =?us-ascii?Q?hDS6RxcTl7uM6gAfyueZ8L7aKjVWJk6GzK1oi658hLxcMa9fp/Cbnxz/iDnZ?= =?us-ascii?Q?KJ8Kr9yE5Xui2PAAM3gB13Jk9KNvi5TBthIYXBADea9Zbkt6OIgyGAg1z2TE?= =?us-ascii?Q?EWYKAWWgb7660lGAqD3ThhYC6Nit+VK0ExcdUwOcGXhW/Uj1Z0JQODLvz2Ki?= =?us-ascii?Q?Fe8tDFTzi438Q9+MNajiobkfZSOKhelRosAu5Ot24Qi6Gnp4KlgPvdNT+Yvl?= =?us-ascii?Q?6LA0D+IDrxVWRCxrN8ycp+INz9djuWifZhXwi0+zC65tSHTCHjb+4Rikd8Ao?= =?us-ascii?Q?jB6//3aFzUtKVYmNB6SOdexdwnFdzFbNmOZkOYal4dkWkk9TYvUvH+LBP9Sv?= =?us-ascii?Q?1b/RZ+DZMgBGLrhhfWP12rRGvhtqSz2WuW/L+AUzyYAe7CRYViAeXfTEn9ZN?= =?us-ascii?Q?8BfskXqRLqbXuwY0aqHKEeh7idJJRKdcj+PfnjjA4UAbZsjhdBphac5L6Dge?= =?us-ascii?Q?SFrzHyF/3Bpo6S9zFCwypnybByYWesnZshR2Qp5ruDANsTbkTIeWN+07jvcK?= =?us-ascii?Q?DmzfyUsucVfYsrwqeW7WbHkE0oKnUMNXlAUGRFpKh/+04N3A3I7ubBxIhkJf?= =?us-ascii?Q?9ujB6trtYdfTVNApeqcLTB6VjRtH+ofD1le2stcH8UcS/TdHTsUmR45z10h1?= =?us-ascii?Q?TSUBUVHMeE8mQC8ETog36+iNdT6LxZGHRATN+6TQbodA8YW/1m39Cr5vJE7b?= =?us-ascii?Q?AH3gaOfEvHG2QWGCI9qXr/irK+MklBOwPojoaC43b9mRKALj9snWsyDi2Ug?= =?us-ascii?Q?=3D?= Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-OriginatorOrg: outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: SN6PR02MB4157.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-RMS-PersistedConsumerOrg: 00000000-0000-0000-0000-000000000000 X-MS-Exchange-CrossTenant-Network-Message-Id: 9e9c400d-cdb3-44a0-aade-08dd582bbda9 X-MS-Exchange-CrossTenant-originalarrivaltime: 28 Feb 2025 19:11:44.5088 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 84df9e7f-e9f6-40af-b435-aaaaaaaaaaaa X-MS-Exchange-CrossTenant-rms-persistedconsumerorg: 00000000-0000-0000-0000-000000000000 X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM8PR02MB7878 From: longli@linuxonhyperv.com Sent: Wednesday, = February 26, 2025 4:46 PM >=20 > Hyper-V may offer a non latency sensitive device with subchannels without > monitor bit enabled. The decision is entirely on the Hyper-V host not > configurable within guest. >=20 > When a device has subchannels, also signal events for the subchannel > if its monitor bit is disabled. >=20 > Signed-off-by: Long Li > --- > drivers/uio/uio_hv_generic.c | 30 ++++++++++++++++++++++++------ > 1 file changed, 24 insertions(+), 6 deletions(-) >=20 > diff --git a/drivers/uio/uio_hv_generic.c b/drivers/uio/uio_hv_generic.c > index 3976360d0096..8b6df598a728 100644 > --- a/drivers/uio/uio_hv_generic.c > +++ b/drivers/uio/uio_hv_generic.c > @@ -65,6 +65,16 @@ struct hv_uio_private_data { > char send_name[32]; > }; >=20 > +static void set_event(struct vmbus_channel *channel, s32 irq_state) > +{ > + channel->inbound.ring_buffer->interrupt_mask =3D !irq_state; > + if (!channel->offermsg.monitor_allocated && irq_state) { > + /* MB is needed for host to see the interrupt mask first */ > + virt_mb(); > + vmbus_setevent(channel); A minor point, but vmbus_setevent() checks the "monitor_allocated" flag, and if not set, then calls vmbus_set_event(). Since monitor_allocated() is already checked here, couldn't vmbus_set_event() be called directly? The existing code calls vmbus_setevent() so keeping vmbus_setevent() is less of a change, but it is still doing a redundant check. > + } > +} > + > /* > * This is the irqcontrol callback to be registered to uio_info. > * It can be used to disable/enable interrupt from user space processes. > @@ -79,12 +89,13 @@ hv_uio_irqcontrol(struct uio_info *info, s32 irq_stat= e) > { > struct hv_uio_private_data *pdata =3D info->priv; > struct hv_device *dev =3D pdata->device; > + struct vmbus_channel *primary, *sc; >=20 > - dev->channel->inbound.ring_buffer->interrupt_mask =3D !irq_state; > - virt_mb(); > + primary =3D dev->channel; > + set_event(primary, irq_state); >=20 > - if (!dev->channel->offermsg.monitor_allocated && irq_state) > - vmbus_setevent(dev->channel); > + list_for_each_entry(sc, &primary->sc_list, sc_list) > + set_event(sc, irq_state); Walking the sc_list usually requires holding vmbus_connection.channel_mutex= . Is there a reason it's safe to walk the list here without the mutex? >=20 > return 0; > } > @@ -95,12 +106,19 @@ hv_uio_irqcontrol(struct uio_info *info, s32 irq_sta= te) > static void hv_uio_channel_cb(void *context) > { > struct vmbus_channel *chan =3D context; > - struct hv_device *hv_dev =3D chan->device_obj; > - struct hv_uio_private_data *pdata =3D hv_get_drvdata(hv_dev); > + struct hv_device *hv_dev; > + struct hv_uio_private_data *pdata; >=20 > chan->inbound.ring_buffer->interrupt_mask =3D 1; > virt_mb(); >=20 > + /* > + * The callback may come from a subchannel, in which case look > + * for the hv device in the primary channel > + */ > + hv_dev =3D chan->primary_channel ? > + chan->primary_channel->device_obj : chan->device_obj; This certainly looks correct and necessary. But how did this work in the past? Wouldn't DPDK running on a synthetic NIC have gotten callbacks on a subchannel? I'm just trying to understand whether this a bug fix, or if not, what new scenario requires this change. I'm not understanding how this change is related to the commit message. Michael > + pdata =3D hv_get_drvdata(hv_dev); > uio_event_notify(&pdata->info); > } >=20 > -- > 2.34.1 >=20