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From: "Dey, Megha" <megha.dey@linux.intel.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Dave Jiang <dave.jiang@intel.com>,
	vkoul@kernel.org, maz@kernel.org, bhelgaas@google.com,
	rafael@kernel.org, gregkh@linuxfoundation.org,
	tglx@linutronix.de, hpa@zytor.com, alex.williamson@redhat.com,
	jacob.jun.pan@intel.com, ashok.raj@intel.com, yi.l.liu@intel.com,
	baolu.lu@intel.com, kevin.tian@intel.com,
	sanjay.k.kumar@intel.com, tony.luck@intel.com,
	jing.lin@intel.com, dan.j.williams@intel.com,
	kwankhede@nvidia.com, eric.auger@redhat.com, parav@mellanox.com,
	dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org,
	x86@kernel.org, linux-pci@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: [PATCH RFC 04/15] drivers/base: Add support for a new IMS irq domain
Date: Sun, 3 May 2020 17:25:28 -0700	[thread overview]
Message-ID: <8ff2aace-0697-b8ef-de68-1bcc49d6727f@linux.intel.com> (raw)
In-Reply-To: <20200503224659.GU26002@ziepe.ca>



On 5/3/2020 3:46 PM, Jason Gunthorpe wrote:
> On Sun, May 03, 2020 at 03:40:44PM -0700, Dey, Megha wrote:
>> On 5/3/2020 3:25 PM, Jason Gunthorpe wrote:
>>> On Fri, May 01, 2020 at 03:30:02PM -0700, Dey, Megha wrote:
>>>> Hi Jason,
>>>>
>>>> On 4/23/2020 1:11 PM, Jason Gunthorpe wrote:
>>>>> On Tue, Apr 21, 2020 at 04:34:11PM -0700, Dave Jiang wrote:
>>>>>> diff --git a/drivers/base/ims-msi.c b/drivers/base/ims-msi.c
>>>>>> new file mode 100644
>>>>>> index 000000000000..738f6d153155
>>>>>> +++ b/drivers/base/ims-msi.c
>>>>>> @@ -0,0 +1,100 @@
>>>>>> +// SPDX-License-Identifier: GPL-2.0-only
>>>>>> +/*
>>>>>> + * Support for Device Specific IMS interrupts.
>>>>>> + *
>>>>>> + * Copyright © 2019 Intel Corporation.
>>>>>> + *
>>>>>> + * Author: Megha Dey <megha.dey@intel.com>
>>>>>> + */
>>>>>> +
>>>>>> +#include <linux/dmar.h>
>>>>>> +#include <linux/irq.h>
>>>>>> +#include <linux/mdev.h>
>>>>>> +#include <linux/pci.h>
>>>>>> +
>>>>>> +/*
>>>>>> + * Determine if a dev is mdev or not. Return NULL if not mdev device.
>>>>>> + * Return mdev's parent dev if success.
>>>>>> + */
>>>>>> +static inline struct device *mdev_to_parent(struct device *dev)
>>>>>> +{
>>>>>> +	struct device *ret = NULL;
>>>>>> +	struct device *(*fn)(struct device *dev);
>>>>>> +	struct bus_type *bus = symbol_get(mdev_bus_type);
>>>>>> +
>>>>>> +	if (bus && dev->bus == bus) {
>>>>>> +		fn = symbol_get(mdev_dev_to_parent_dev);
>>>>>> +		ret = fn(dev);
>>>>>> +		symbol_put(mdev_dev_to_parent_dev);
>>>>>> +		symbol_put(mdev_bus_type);
>>>>>
>>>>> No, things like this are not OK in the drivers/base
>>>>>
>>>>> Whatever this is doing needs to be properly architected in some
>>>>> generic way.
>>>>
>>>> Basically what I am trying to do here is to determine if the device is an
>>>> mdev device or not.
>>>
>>> Why? mdev devices are virtual they don't have HW elements.
>>
>> Hmm yeah exactly, since they are virtual, they do not have an associated IRQ
>> domain right? So they use the irq domain of the parent device..
>>
>>>
>>> The caller should use the concrete pci_device to allocate
>>> platform_msi? What is preventing this?
>>
>> hmmm do you mean to say all platform-msi adhere to the rules of a PCI
>> device?
> 
> I mean where a platform-msi can work should be defined by the arch,
> and probably is related to things like having an irq_domain attached
> 
> So, like pci, drivers must only try to do platfor_msi stuff on
> particular devices. eg on pci_device and platform_device types.
> 
> Even so it may not even work, but I can't think of any reason why it
> should be made to work on a virtual device like mdev.
> 
>> The use case if when we have a device assigned to a guest and we
>> want to allocate IMS(platform-msi) interrupts for that
>> guest-assigned device. Currently, this is abstracted through a mdev
>> interface.
> 
> And the mdev has the pci_device internally, so it should simply pass
> that pci_device to the platform_msi machinery.

hmm i am not sure I follow this. mdev has a pci_device internally? which 
struct are you referring to here?

mdev is merely a micropartitioned PCI device right, which no real PCI 
resource backing. I am not how else we can find the IRQ domain 
associated with an mdev..

> 
> This is no different from something like pci_iomap() which must be
> used with the pci_device.
> 
> Jason
> 

  reply	other threads:[~2020-05-04  0:25 UTC|newest]

Thread overview: 89+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-21 23:33 [PATCH RFC 00/15] Add VFIO mediated device support and IMS support for the idxd driver Dave Jiang
2020-04-21 23:33 ` [PATCH RFC 01/15] drivers/base: Introduce platform_msi_ops Dave Jiang
2020-04-26  7:01   ` Greg KH
2020-04-27 21:38     ` Dave Jiang
2020-04-28  7:34       ` Greg KH
2020-04-21 23:33 ` [PATCH RFC 02/15] drivers/base: Introduce a new platform-msi list Dave Jiang
2020-04-25 21:13   ` Thomas Gleixner
2020-05-04  0:08     ` Dey, Megha
2020-04-21 23:34 ` [PATCH RFC 03/15] drivers/base: Allocate/free platform-msi interrupts by group Dave Jiang
2020-04-25 21:23   ` Thomas Gleixner
2020-05-04  0:08     ` Dey, Megha
2020-04-21 23:34 ` [PATCH RFC 04/15] drivers/base: Add support for a new IMS irq domain Dave Jiang
2020-04-23 20:11   ` Jason Gunthorpe
2020-05-01 22:30     ` Dey, Megha
2020-05-03 22:25       ` Jason Gunthorpe
2020-05-03 22:40         ` Dey, Megha
2020-05-03 22:46           ` Jason Gunthorpe
2020-05-04  0:25             ` Dey, Megha [this message]
2020-05-04 12:14               ` Jason Gunthorpe
2020-05-06 10:27                 ` Tian, Kevin
2020-04-25 21:38   ` Thomas Gleixner
2020-05-04  0:11     ` Dey, Megha
2020-04-21 23:34 ` [PATCH RFC 05/15] ims-msi: Add mask/unmask routines Dave Jiang
2020-04-25 21:49   ` Thomas Gleixner
2020-05-04  0:16     ` Dey, Megha
2020-04-21 23:34 ` [PATCH RFC 06/15] ims-msi: Enable IMS interrupts Dave Jiang
2020-04-25 22:13   ` Thomas Gleixner
2020-05-04  0:17     ` Dey, Megha
2020-04-21 23:34 ` [PATCH RFC 07/15] Documentation: Interrupt Message store Dave Jiang
2020-04-23 20:04   ` Jason Gunthorpe
2020-05-01 22:32     ` Dey, Megha
2020-05-03 22:28       ` Jason Gunthorpe
2020-05-03 22:41         ` Dey, Megha
2020-04-21 23:34 ` [PATCH RFC 08/15] vfio/mdev: Add a member for iommu domain in mdev_device Dave Jiang
2020-04-21 23:34 ` [PATCH RFC 09/15] vfio/type1: Save domain when attach domain to mdev Dave Jiang
2020-04-21 23:34 ` [PATCH RFC 10/15] dmaengine: idxd: add config support for readonly devices Dave Jiang
2020-04-21 23:34 ` [PATCH RFC 11/15] dmaengine: idxd: add IMS support in base driver Dave Jiang
2020-04-21 23:35 ` [PATCH RFC 12/15] dmaengine: idxd: add device support functions in prep for mdev Dave Jiang
2020-04-21 23:35 ` [PATCH RFC 13/15] dmaengine: idxd: add support for VFIO mediated device Dave Jiang
2020-04-21 23:35 ` [PATCH RFC 14/15] dmaengine: idxd: add error notification from host driver to " Dave Jiang
2020-04-21 23:35 ` [PATCH RFC 15/15] dmaengine: idxd: add ABI documentation for mediated device support Dave Jiang
2020-04-21 23:54 ` [PATCH RFC 00/15] Add VFIO mediated device support and IMS support for the idxd driver Jason Gunthorpe
2020-04-22  0:53   ` Tian, Kevin
2020-04-22 11:50     ` Jason Gunthorpe
2020-04-22 21:14       ` Raj, Ashok
2020-04-23 19:12         ` Jason Gunthorpe
2020-04-24  3:27           ` Tian, Kevin
2020-04-24 12:44             ` Jason Gunthorpe
2020-04-24 16:25               ` Tian, Kevin
2020-04-24 18:12                 ` Jason Gunthorpe
2020-04-26  5:18                   ` Tian, Kevin
2020-04-26 19:13                     ` Jason Gunthorpe
2020-04-27  3:43                       ` Alex Williamson
2020-04-27 11:58                         ` Jason Gunthorpe
2020-04-27 13:19                           ` Alex Williamson
2020-04-27 13:22                             ` Jason Gunthorpe
2020-04-27 14:18                               ` Alex Williamson
2020-04-27 14:25                                 ` Jason Gunthorpe
2020-04-27 15:41                                   ` Alex Williamson
2020-04-27 16:16                                     ` Jason Gunthorpe
2020-04-27 16:25                                       ` Dave Jiang
2020-04-27 21:56                                         ` Jason Gunthorpe
2020-04-29  9:42                               ` Tian, Kevin
2020-05-08 20:47                                 ` Raj, Ashok
2020-05-08 23:16                                   ` Jason Gunthorpe
2020-05-08 23:52                                     ` Dave Jiang
2020-05-09  0:09                                     ` Raj, Ashok
2020-05-09 12:21                                       ` Jason Gunthorpe
2020-05-13  2:29                                         ` Jason Wang
2020-05-13  8:30                                         ` Tian, Kevin
2020-05-13 12:40                                           ` Jason Gunthorpe
2020-04-27 12:13                       ` Tian, Kevin
2020-04-27 12:55                         ` Jason Gunthorpe
2020-04-22 21:24   ` Dan Williams
2020-04-23 19:17     ` Dan Williams
2020-04-23 19:49       ` Jason Gunthorpe
2020-05-01 22:31         ` Dey, Megha
2020-05-03 22:21           ` Jason Gunthorpe
2020-05-03 22:32             ` Dey, Megha
2020-04-23 19:18     ` Jason Gunthorpe
2020-05-01 22:31       ` Dey, Megha
2020-05-03 22:22         ` Jason Gunthorpe
2020-05-03 22:31           ` Dey, Megha
2020-05-03 22:36             ` Jason Gunthorpe
2020-05-04  0:20               ` Dey, Megha
2020-04-22 23:04   ` Dey, Megha
2020-04-23 19:44     ` Jason Gunthorpe
2020-05-01 22:32       ` Dey, Megha
2020-04-24  6:31   ` Jason Wang

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