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From: Thomas Gleixner <tglx@linutronix.de>
To: "Tian\, Kevin" <kevin.tian@intel.com>, Jason Gunthorpe <jgg@nvidia.com>
Cc: "Jiang\, Dave" <dave.jiang@intel.com>,
	Bjorn Helgaas <helgaas@kernel.org>,
	"vkoul\@kernel.org" <vkoul@kernel.org>, "Dey\,
	Megha" <megha.dey@intel.com>, "maz\@kernel.org" <maz@kernel.org>,
	"bhelgaas\@google.com" <bhelgaas@google.com>,
	"alex.williamson\@redhat.com" <alex.williamson@redhat.com>, "Pan\,
	Jacob jun" <jacob.jun.pan@intel.com>, "Raj\,
	Ashok" <ashok.raj@intel.com>, "Liu\, Yi L" <yi.l.liu@intel.com>,
	"Lu\, Baolu" <baolu.lu@intel.com>, "Kumar\,
	Sanjay K" <sanjay.k.kumar@intel.com>, "Luck\,
	Tony" <tony.luck@intel.com>,
	"jing.lin\@intel.com" <jing.lin@intel.com>, "Williams\,
	Dan J" <dan.j.williams@intel.com>,
	"kwankhede\@nvidia.com" <kwankhede@nvidia.com>,
	"eric.auger\@redhat.com" <eric.auger@redhat.com>,
	"parav\@mellanox.com" <parav@mellanox.com>,
	"rafael\@kernel.org" <rafael@kernel.org>,
	"netanelg\@mellanox.com" <netanelg@mellanox.com>,
	"shahafs\@mellanox.com" <shahafs@mellanox.com>,
	"yan.y.zhao\@linux.intel.com" <yan.y.zhao@linux.intel.com>,
	"pbonzini\@redhat.com" <pbonzini@redhat.com>, "Ortiz\,
	Samuel" <samuel.ortiz@intel.com>, "Hossain\,
	Mona" <mona.hossain@intel.com>,
	"dmaengine\@vger.kernel.org" <dmaengine@vger.kernel.org>,
	"linux-kernel\@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-pci\@vger.kernel.org" <linux-pci@vger.kernel.org>,
	"kvm\@vger.kernel.org" <kvm@vger.kernel.org>
Subject: RE: [PATCH v4 06/17] PCI: add SIOV and IMS capability detection
Date: Sat, 07 Nov 2020 01:32:23 +0100	[thread overview]
Message-ID: <871rh6knvs.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <MWHPR11MB1645524BDEDF8899914F32AE8CED0@MWHPR11MB1645.namprd11.prod.outlook.com>

On Fri, Nov 06 2020 at 09:48, Kevin Tian wrote:
>> From: Jason Gunthorpe <jgg@nvidia.com>
>> On Wed, Nov 04, 2020 at 01:34:08PM +0000, Tian, Kevin wrote:
>> The interrupt controller is responsible to create an addr/data pair
>> for an interrupt message. It sets the message format and ensures it
>> routes to the proper CPU interrupt handler. Everything about the
>> addr/data pair is owned by the platform interrupt controller.
>> 
>> Devices do not create interrupts. They only trigger the addr/data pair
>> the platform gives them.
>
> I guess that we may just view it from different angles. On x86 platform,
> a MSI/IMS capable device directly composes interrupt messages, with 
> addr/data pair filled by OS. If there is no IOMMU remapping enabled in 
> the middle, the message just hits the CPU. Your description possibly
> is from software side, e.g. describing the hierarchical IRQ domain
> concept?

No. The device composes nothing. If the interrupt is raised in the
device then the MSI block sends the message which was composed by the OS
and stored in the device's message store. For PCI/MSI that's the MSI or
MSIX table and for IMS that's either on device memory (as IDXD uses) or
some completely different location which Jason described.

This has absolutely nothing to do with the X86 platform. MSI is a
architecture independent mechanism: Send whatever the OS put into the
storage to raise an interrupt in the CPU. The device does neither know
whether that message is going to be intercepted by an interrupt
remapping unit or not.

Stop claiming that any of this has anything to do with x86. It has
absolutely nothing to do with x86 and looking at MSI from an x86
perspective instead of looking at it from the architecture agnostic
technical reality of MSI is the reason why we have this discussion at
all.

We had a similar discussion vs. the way how IMS interrupts have to be
dealt with in terms of irq domains. Can you finally stop looking at
everything as a big x86/intel/platform lump and understand that things
are very well structured and seperated both at the hardware and at the
software level? 

> Do you mind providing the link? There were lots of discussions between
> you and Thomas. I failed to locate the exact mail when searching above
> keywords. 

In this thread: 20200821002424.119492231@linutronix.de and you were on
Cc

Thanks,

        tglx



  parent reply	other threads:[~2020-11-07  0:32 UTC|newest]

Thread overview: 125+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-30 18:50 [PATCH v4 00/17] Add VFIO mediated device support and DEV-MSI support for the idxd driver Dave Jiang
2020-10-30 18:50 ` [PATCH v4 01/17] irqchip: Add IMS (Interrupt Message Store) driver Dave Jiang
2020-10-30 22:01   ` Thomas Gleixner
2020-10-30 18:51 ` [PATCH v4 02/17] iommu/vt-d: Add DEV-MSI support Dave Jiang
2020-10-30 20:31   ` Thomas Gleixner
2020-10-30 20:52     ` Dave Jiang
2020-10-30 18:51 ` [PATCH v4 03/17] dmaengine: idxd: add theory of operation documentation for idxd mdev Dave Jiang
2020-10-30 18:51 ` [PATCH v4 04/17] dmaengine: idxd: add support for readonly config devices Dave Jiang
2020-10-30 18:51 ` [PATCH v4 05/17] dmaengine: idxd: add interrupt handle request support Dave Jiang
2020-10-30 18:51 ` [PATCH v4 06/17] PCI: add SIOV and IMS capability detection Dave Jiang
2020-10-30 19:51   ` Bjorn Helgaas
2020-10-30 21:20     ` Dave Jiang
2020-10-30 21:50       ` Bjorn Helgaas
2020-10-30 22:45       ` Jason Gunthorpe
2020-10-30 22:49         ` Dave Jiang
2020-11-02 13:21           ` Jason Gunthorpe
2020-11-03  2:49             ` Tian, Kevin
2020-11-03 12:43               ` Jason Gunthorpe
2020-11-04  3:41                 ` Tian, Kevin
2020-11-04 12:40                   ` Jason Gunthorpe
2020-11-04 13:34                     ` Tian, Kevin
2020-11-04 13:54                       ` Jason Gunthorpe
2020-11-06  9:48                         ` Tian, Kevin
2020-11-06 13:14                           ` Jason Gunthorpe
2020-11-06 16:48                             ` Raj, Ashok
2020-11-06 17:51                               ` Jason Gunthorpe
2020-11-06 23:47                                 ` Dan Williams
2020-11-07  0:12                                   ` Jason Gunthorpe
2020-11-07  1:42                                     ` Dan Williams
2020-11-08 18:11                                     ` Raj, Ashok
2020-11-08 18:34                                       ` David Woodhouse
2020-11-08 23:25                                         ` Raj, Ashok
2020-11-10 14:19                                           ` Raj, Ashok
2020-11-10 14:41                                             ` David Woodhouse
2020-11-08 23:41                                       ` Jason Gunthorpe
2020-11-09  0:05                                         ` Raj, Ashok
2020-11-08 18:47                                     ` Thomas Gleixner
2020-11-08 19:36                                       ` David Woodhouse
2020-11-08 22:47                                         ` Thomas Gleixner
2020-11-08 23:29                                           ` Jason Gunthorpe
2020-11-11 15:41                                         ` Christoph Hellwig
2020-11-11 16:09                                           ` Raj, Ashok
2020-11-11 22:27                                             ` Thomas Gleixner
2020-11-11 23:03                                               ` Raj, Ashok
2020-11-12  1:13                                                 ` Thomas Gleixner
2020-11-12 13:10                                                 ` Jason Gunthorpe
2020-11-08 23:23                                       ` Jason Gunthorpe
2020-11-08 23:36                                         ` Raj, Ashok
2020-11-09  7:37                                         ` Tian, Kevin
2020-11-09 16:46                                           ` Jason Gunthorpe
2020-11-08 23:58                                       ` Raj, Ashok
2020-11-09  7:59                                         ` Tian, Kevin
2020-11-09 11:21                                         ` Thomas Gleixner
2020-11-09 17:30                                           ` Jason Gunthorpe
2020-11-09 22:40                                             ` Raj, Ashok
2020-11-09 22:42                                             ` Thomas Gleixner
2020-11-10  5:14                                               ` Raj, Ashok
2020-11-10 10:27                                                 ` Thomas Gleixner
2020-11-10 14:13                                                   ` Raj, Ashok
2020-11-10 14:23                                                     ` Jason Gunthorpe
2020-11-11  2:17                                                       ` Tian, Kevin
2020-11-12 13:46                                                         ` Jason Gunthorpe
2020-11-11  7:14                                                     ` Tian, Kevin
2020-11-12 19:32                                                       ` Konrad Rzeszutek Wilk
2020-11-12 22:42                                                         ` Thomas Gleixner
2020-11-13  2:42                                                           ` Tian, Kevin
2020-11-13 12:57                                                             ` Jason Gunthorpe
2020-11-13 13:32                                                             ` Thomas Gleixner
2020-11-13 16:12                                                               ` Luck, Tony
2020-11-13 17:38                                                                 ` Raj, Ashok
2020-11-14 10:34                                                           ` Christoph Hellwig
2020-11-14 21:18                                                             ` Raj, Ashok
2020-11-15 11:26                                                               ` Thomas Gleixner
2020-11-15 19:31                                                                 ` Raj, Ashok
2020-11-15 22:11                                                                   ` Thomas Gleixner
2020-11-16  0:22                                                                     ` Raj, Ashok
2020-11-16  7:31                                                                       ` Tian, Kevin
2020-11-16 15:46                                                                         ` Jason Gunthorpe
2020-11-16 17:56                                                                           ` Thomas Gleixner
2020-11-16 18:02                                                                             ` Jason Gunthorpe
2020-11-16 20:37                                                                               ` Thomas Gleixner
2020-11-16 23:51                                                                               ` Tian, Kevin
2020-11-17  9:21                                                                                 ` Thomas Gleixner
2020-11-16  8:25                                                               ` Christoph Hellwig
2020-11-10 14:19                                                 ` Jason Gunthorpe
2020-11-11  2:35                                                   ` Tian, Kevin
2020-11-08 21:18                             ` Thomas Gleixner
2020-11-08 22:09                               ` David Woodhouse
2020-11-08 22:52                                 ` Thomas Gleixner
2020-11-07  0:32                           ` Thomas Gleixner [this message]
2020-11-09  5:25                             ` Tian, Kevin
2020-10-30 18:51 ` [PATCH v4 07/17] dmaengine: idxd: add IMS support in base driver Dave Jiang
2020-10-30 18:51 ` [PATCH v4 08/17] dmaengine: idxd: add device support functions in prep for mdev Dave Jiang
2020-10-30 18:51 ` [PATCH v4 09/17] dmaengine: idxd: add basic mdev registration and helper functions Dave Jiang
2020-10-30 18:51 ` [PATCH v4 10/17] dmaengine: idxd: add emulation rw routines Dave Jiang
2020-10-30 18:52 ` [PATCH v4 11/17] dmaengine: idxd: prep for virtual device commands Dave Jiang
2020-10-30 18:52 ` [PATCH v4 12/17] dmaengine: idxd: virtual device commands emulation Dave Jiang
2020-10-30 18:52 ` [PATCH v4 13/17] dmaengine: idxd: ims setup for the vdcm Dave Jiang
2020-10-30 21:26   ` Thomas Gleixner
2020-10-30 18:52 ` [PATCH v4 14/17] dmaengine: idxd: add mdev type as a new wq type Dave Jiang
2020-10-30 18:52 ` [PATCH v4 15/17] dmaengine: idxd: add dedicated wq mdev type Dave Jiang
2020-10-30 18:52 ` [PATCH v4 16/17] dmaengine: idxd: add new wq state for mdev Dave Jiang
2020-10-30 18:52 ` [PATCH v4 17/17] dmaengine: idxd: add error notification from host driver to mediated device Dave Jiang
2020-10-30 18:58 ` [PATCH v4 00/17] Add VFIO mediated device support and DEV-MSI support for the idxd driver Jason Gunthorpe
2020-10-30 19:13   ` Dave Jiang
2020-10-30 19:17     ` Jason Gunthorpe
2020-10-30 19:23       ` Raj, Ashok
2020-10-30 19:30         ` Jason Gunthorpe
2020-10-30 20:43           ` Raj, Ashok
2020-10-30 22:54             ` Jason Gunthorpe
2020-10-31  2:50             ` Thomas Gleixner
2020-10-31 23:53               ` Raj, Ashok
2020-11-02 13:20                 ` Jason Gunthorpe
2020-11-02 16:20                   ` Raj, Ashok
2020-11-02 17:19                     ` Jason Gunthorpe
2020-11-02 18:18                       ` Dave Jiang
2020-11-02 18:26                         ` Jason Gunthorpe
2020-11-02 18:38                           ` Dan Williams
2020-11-02 18:51                             ` Jason Gunthorpe
2020-11-02 19:26                               ` Dan Williams
2020-10-30 20:48 ` Thomas Gleixner
2020-10-30 20:59   ` Dave Jiang
2020-10-30 22:10     ` Thomas Gleixner
     [not found] <draft-875z6ekcj5.fsf@nanos.tec.linutronix.de>
2020-11-09 14:08 ` [PATCH v4 06/17] PCI: add SIOV and IMS capability detection Thomas Gleixner
2020-11-09 18:10   ` Raj, Ashok

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