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From: Thomas Gleixner <tglx@linutronix.de>
To: Dave Jiang <dave.jiang@intel.com>, Jason Gunthorpe <jgg@nvidia.com>
Cc: Allen Hubbe <allenbh@gmail.com>,
	linux-s390@vger.kernel.org, Kevin Tian <kevin.tian@intel.com>,
	x86@kernel.org, Ashok Raj <ashok.raj@intel.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Marc Zygnier <maz@kernel.org>, Heiko Carstens <hca@linux.ibm.com>,
	LKML <linux-kernel@vger.kernel.org>,
	iommu@lists.linux-foundation.org,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	Joerg Roedel <jroedel@suse.de>,
	Bjorn Helgaas <helgaas@kernel.org>,
	linux-pci@vger.kernel.org, linux-ntb@googlegroups.com,
	Logan Gunthorpe <logang@deltatee.com>,
	Megha Dey <megha.dey@intel.com>
Subject: Re: [patch 21/32] NTB/msi: Convert to msi_on_each_desc()
Date: Wed, 01 Dec 2021 19:41:05 +0100	[thread overview]
Message-ID: <87pmqg88xq.ffs@tglx> (raw)
In-Reply-To: <8c2262ba-173e-0007-bc4c-94ec54b2847d@intel.com>

Dave,

please trim your replies.

On Wed, Dec 01 2021 at 09:28, Dave Jiang wrote:

> On 12/1/2021 3:16 AM, Thomas Gleixner wrote:
>> Jason,
>>
>> CC+ IOMMU folks
>>
>> On Tue, Nov 30 2021 at 20:17, Jason Gunthorpe wrote:
>>> On Tue, Nov 30, 2021 at 10:23:16PM +0100, Thomas Gleixner wrote:
>>
>> Though I fear there is also a use case for MSI-X and IMS tied to the
>> same device. That network card you are talking about might end up using
>> MSI-X for a control block and then IMS for the actual network queues
>> when it is used as physical function device as a whole, but that's
>> conceptually a different case.
>
> Hi Thomas. This is actually the IDXD usage for a mediated device passed 
> to a guest kernel when we plumb the pass through of IMS to the guest 
> rather than doing previous implementation of having a MSIX vector on 
> guest backed by IMS.

Which makes a lot of sense.

> The control block for the mediated device is emulated and therefore an
> emulated MSIX vector will be surfaced as vector 0. However the queues
> will backed by IMS vectors. So we end up needing MSIX and IMS coexist
> running on the guest kernel for the same device.

Why? What's wrong with using straight MSI-X for all of them?

Thanks,

        tglx
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  reply	other threads:[~2021-12-01 18:41 UTC|newest]

Thread overview: 71+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20211126230957.239391799@linutronix.de>
     [not found] ` <20211126232735.547996838@linutronix.de>
     [not found]   ` <7daba0e2-73a3-4980-c3a5-a71f6b597b22@deltatee.com>
     [not found]     ` <874k7ueldt.ffs@tglx>
     [not found]       ` <6ba084d6-2b26-7c86-4526-8fcd3d921dfd@deltatee.com>
     [not found]         ` <87ilwacwp8.ffs@tglx>
     [not found]           ` <d6f13729-1b83-fa7d-3f0d-98d4e3f7a2aa@deltatee.com>
     [not found]             ` <87v909bf2k.ffs@tglx>
     [not found]               ` <20211130202800.GE4670@nvidia.com>
     [not found]                 ` <87o861banv.ffs@tglx>
     [not found]                   ` <20211201001748.GF4670@nvidia.com>
2021-12-01 10:16                     ` [patch 21/32] NTB/msi: Convert to msi_on_each_desc() Thomas Gleixner
2021-12-01 13:00                       ` Jason Gunthorpe via iommu
2021-12-01 17:35                         ` Thomas Gleixner
2021-12-01 18:14                           ` Jason Gunthorpe via iommu
2021-12-01 18:46                             ` Logan Gunthorpe
2021-12-01 20:21                             ` Thomas Gleixner
2021-12-02  0:01                               ` Thomas Gleixner
2021-12-02 13:55                                 ` Jason Gunthorpe via iommu
2021-12-02 14:23                                   ` Greg Kroah-Hartman
2021-12-02 14:45                                     ` Jason Gunthorpe via iommu
2021-12-02 19:25                                   ` Thomas Gleixner
2021-12-02 20:00                                     ` Jason Gunthorpe via iommu
2021-12-02 22:31                                       ` Thomas Gleixner
2021-12-03  0:37                                         ` Jason Gunthorpe via iommu
2021-12-03 15:07                                           ` Thomas Gleixner
2021-12-03 16:41                                             ` Jason Gunthorpe via iommu
2021-12-04 14:20                                               ` Thomas Gleixner
2021-12-05 14:16                                                 ` Thomas Gleixner
2021-12-06 14:43                                                   ` Jason Gunthorpe via iommu
2021-12-06 15:47                                                     ` Thomas Gleixner
2021-12-06 17:00                                                       ` Jason Gunthorpe via iommu
2021-12-06 20:28                                                         ` Thomas Gleixner
2021-12-06 21:06                                                           ` Jason Gunthorpe via iommu
2021-12-06 22:21                                                             ` Thomas Gleixner
2021-12-06 14:19                                                 ` Jason Gunthorpe via iommu
2021-12-06 15:06                                                   ` Thomas Gleixner
2021-12-09  6:26                                               ` Tian, Kevin
2021-12-09  9:03                                                 ` Thomas Gleixner
2021-12-09 12:17                                                   ` Tian, Kevin
2021-12-09 15:57                                                     ` Thomas Gleixner
2021-12-10  7:37                                                       ` Tian, Kevin
2021-12-09  5:41                                   ` Tian, Kevin
2021-12-09  5:47                                     ` Jason Wang
2021-12-01 16:28                       ` Dave Jiang
2021-12-01 18:41                         ` Thomas Gleixner [this message]
2021-12-01 18:47                           ` Dave Jiang
2021-12-01 20:25                             ` Thomas Gleixner
2021-12-01 21:21                               ` Dave Jiang
2021-12-01 21:44                                 ` Thomas Gleixner
2021-12-01 21:49                                   ` Dave Jiang
2021-12-01 22:03                                     ` Thomas Gleixner
2021-12-01 22:53                                       ` Dave Jiang
2021-12-01 23:57                                         ` Thomas Gleixner
2021-12-09  5:23                                   ` Tian, Kevin
2021-12-09  8:37                                     ` Thomas Gleixner
2021-12-09 12:31                                       ` Tian, Kevin
2021-12-09 16:21                                       ` Jason Gunthorpe via iommu
2021-12-09 20:32                                         ` Thomas Gleixner
2021-12-09 20:58                                           ` Jason Gunthorpe via iommu
2021-12-09 22:09                                             ` Thomas Gleixner
2021-12-10  0:26                                               ` Thomas Gleixner
2021-12-10  7:29                                                 ` Tian, Kevin
2021-12-10 12:13                                                   ` Thomas Gleixner
2021-12-11  8:06                                                     ` Tian, Kevin
2021-12-10 12:39                                                   ` Jason Gunthorpe via iommu
2021-12-10 19:00                                                     ` Thomas Gleixner
2021-12-11  7:44                                                       ` Tian, Kevin
2021-12-11 13:04                                                         ` Thomas Gleixner
2021-12-12  1:56                                                           ` Tian, Kevin
2021-12-12 20:55                                                             ` Thomas Gleixner
2021-12-12 23:37                                                               ` Jason Gunthorpe via iommu
2021-12-13  7:50                                                                 ` Tian, Kevin
2021-12-11  7:52                                                     ` Tian, Kevin
2021-12-12  0:12                                                       ` Thomas Gleixner
2021-12-12  2:14                                                         ` Tian, Kevin
2021-12-12 20:50                                                           ` Thomas Gleixner
2021-12-12 23:42                                                         ` Jason Gunthorpe via iommu
2021-12-10  7:36                                             ` Tian, Kevin
2021-12-10 12:30                                               ` Jason Gunthorpe via iommu
2021-12-12  6:44                                               ` Mika Penttilä
2021-12-12 23:27                                                 ` Jason Gunthorpe via iommu

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