From: Dave Jiang <dave.jiang@intel.com>
To: Jason Gunthorpe <jgg@mellanox.com>
Cc: vkoul@kernel.org, megha.dey@intel.com, 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, dave.hansen@intel.com,
netanelg@mellanox.com, shahafs@mellanox.com,
yan.y.zhao@linux.intel.com, pbonzini@redhat.com,
samuel.ortiz@intel.com, mona.hossain@intel.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 v2 00/18] Add VFIO mediated device support and DEV-MSI support for the idxd driver
Date: Tue, 21 Jul 2020 11:00:16 -0700 [thread overview]
Message-ID: <d0ab496e-8eb1-3365-8b2c-533cf95d6556@intel.com> (raw)
In-Reply-To: <20200721164527.GD2021248@mellanox.com>
On 7/21/2020 9:45 AM, Jason Gunthorpe wrote:
> On Tue, Jul 21, 2020 at 09:02:15AM -0700, Dave Jiang wrote:
>> v2:
>> IMS (now dev-msi):
>> With recommendations from Jason/Thomas/Dan on making IMS more generic:
>> Pass a non-pci generic device(struct device) for IMS management instead of mdev
>> Remove all references to mdev and symbol_get/put
>> Remove all references to IMS in common code and replace with dev-msi
>> remove dynamic allocation of platform-msi interrupts: no groups,no new msi list or list helpers
>> Create a generic dev-msi domain with and without interrupt remapping enabled.
>> Introduce dev_msi_domain_alloc_irqs and dev_msi_domain_free_irqs apis
>
> I didn't dig into the details of irq handling to really check this,
> but the big picture of this is much more in line with what I would
> expect for this kind of ability.
>
>> Link to previous discussions with Jason:
>> https://lore.kernel.org/lkml/57296ad1-20fe-caf2-b83f-46d823ca0b5f@intel.com/
>> The emulation part that can be moved to user space is very small due to the majority of the
>> emulations being control bits and need to reside in the kernel. We can revisit the necessity of
>> moving the small emulation part to userspace and required architectural changes at a later time.
>
> The point here is that you already have a user space interface for
> these queues that already has kernel support to twiddle the control
> bits. Generally I'd expect extending that existing kernel code to do
> the small bit more needed for mapping the queue through to PCI
> emulation to be smaller than the 2kloc of new code here to put all the
> emulation and support framework in the kernel, and exposes a lower
> attack surface of kernel code to the guest.
>
>> The kernel can specify the requirements for these callback functions
>> (e.g., the driver is not expected to block, or not expected to take
>> a lock in the callback function).
>
> I didn't notice any of this in the patch series? What is the calling
> context for the platform_msi_ops ? I think I already mentioned that
> ideally we'd need blocking/sleeping. The big selling point is that IMS
> allows this data to move off-chip, which means accessing it is no
> longer just an atomic write to some on-chip memory.
>
> These details should be documented in the comment on top of
> platform_msi_ops
>
> I'm actually a little confused how idxd_ims_irq_mask() manages this -
> I thought IRQ masking should be synchronous, shouldn't there at least be a
> flushing read to ensure that new MSI's are stopped and any in flight
> are flushed to the APIC?
You are right Jason. It's missing a flushing read.
>
> Jason
>
next prev parent reply other threads:[~2020-07-21 18:00 UTC|newest]
Thread overview: 97+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-21 16:02 [PATCH RFC v2 00/18] Add VFIO mediated device support and DEV-MSI support for the idxd driver Dave Jiang
2020-07-21 16:02 ` [PATCH RFC v2 01/18] platform-msi: Introduce platform_msi_ops Dave Jiang
2020-07-21 16:02 ` [PATCH RFC v2 02/18] irq/dev-msi: Add support for a new DEV_MSI irq domain Dave Jiang
2020-07-21 16:13 ` Jason Gunthorpe
2020-07-22 16:50 ` Dey, Megha
2020-07-22 18:52 ` Marc Zyngier
2020-07-22 19:59 ` Jason Gunthorpe
2020-07-23 8:51 ` Marc Zyngier
2020-07-24 0:16 ` Jason Gunthorpe
2020-07-24 0:36 ` Thomas Gleixner
2020-08-05 19:18 ` Dey, Megha
2020-08-05 22:15 ` Jason Gunthorpe
2020-08-05 22:36 ` Dey, Megha
2020-08-05 22:53 ` Jason Gunthorpe
2020-08-06 0:13 ` Dey, Megha
2020-08-06 0:19 ` Jason Gunthorpe
2020-08-06 0:32 ` Dey, Megha
2020-08-06 0:46 ` Jason Gunthorpe
2020-08-06 17:10 ` Thomas Gleixner
2020-08-06 17:58 ` Dey, Megha
2020-08-06 20:21 ` Thomas Gleixner
2020-08-06 22:27 ` Dey, Megha
2020-08-07 8:48 ` Thomas Gleixner
2020-08-07 12:06 ` Jason Gunthorpe
2020-08-07 12:38 ` gregkh
2020-08-07 13:34 ` Jason Gunthorpe
2020-08-07 16:47 ` Thomas Gleixner
2020-08-07 17:54 ` Dey, Megha
2020-08-07 18:39 ` Jason Gunthorpe
2020-08-07 20:31 ` Dey, Megha
2020-08-08 19:47 ` Thomas Gleixner
2020-08-10 21:46 ` Thomas Gleixner
2020-08-11 9:53 ` Thomas Gleixner
2020-08-11 18:46 ` Dey, Megha
2020-08-11 21:25 ` Thomas Gleixner
2020-08-11 18:39 ` Dey, Megha
2020-08-11 22:39 ` Thomas Gleixner
2020-08-07 15:22 ` Thomas Gleixner
2020-08-05 18:55 ` Dey, Megha
2020-07-21 16:02 ` [PATCH RFC v2 03/18] irq/dev-msi: Create IR-DEV-MSI " Dave Jiang
2020-07-21 16:21 ` Jason Gunthorpe
2020-07-22 17:03 ` Dey, Megha
2020-07-22 17:33 ` Jason Gunthorpe
2020-07-22 20:44 ` Thomas Gleixner
2020-08-05 19:02 ` Dey, Megha
2020-07-21 16:02 ` [PATCH RFC v2 04/18] irq/dev-msi: Introduce APIs to allocate/free dev-msi interrupts Dave Jiang
2020-07-21 16:25 ` Jason Gunthorpe
2020-07-22 17:05 ` Dey, Megha
2020-07-22 17:35 ` Jason Gunthorpe
2020-08-05 20:19 ` Dey, Megha
2020-07-21 16:02 ` [PATCH RFC v2 05/18] dmaengine: idxd: add support for readonly config devices Dave Jiang
2020-07-21 16:02 ` [PATCH RFC v2 06/18] dmaengine: idxd: add interrupt handle request support Dave Jiang
2020-07-21 16:03 ` [PATCH RFC v2 07/18] dmaengine: idxd: add DEV-MSI support in base driver Dave Jiang
2020-07-21 16:03 ` [PATCH RFC v2 08/18] dmaengine: idxd: add device support functions in prep for mdev Dave Jiang
2020-07-21 16:03 ` [PATCH RFC v2 09/18] dmaengine: idxd: add basic mdev registration and helper functions Dave Jiang
2020-07-21 16:03 ` [PATCH RFC v2 10/18] dmaengine: idxd: add emulation rw routines Dave Jiang
2020-07-21 16:03 ` [PATCH RFC v2 11/18] dmaengine: idxd: prep for virtual device commands Dave Jiang
2020-07-21 16:03 ` [PATCH RFC v2 12/18] dmaengine: idxd: virtual device commands emulation Dave Jiang
2020-07-21 16:03 ` [PATCH RFC v2 13/18] dmaengine: idxd: ims setup for the vdcm Dave Jiang
2020-07-21 16:03 ` [PATCH RFC v2 14/18] dmaengine: idxd: add mdev type as a new wq type Dave Jiang
2020-07-21 16:03 ` [PATCH RFC v2 15/18] dmaengine: idxd: add dedicated wq mdev type Dave Jiang
2020-07-21 16:04 ` [PATCH RFC v2 16/18] dmaengine: idxd: add new wq state for mdev Dave Jiang
2020-07-21 16:04 ` [PATCH RFC v2 17/18] dmaengine: idxd: add error notification from host driver to mediated device Dave Jiang
2020-07-21 16:04 ` [PATCH RFC v2 18/18] dmaengine: idxd: add ABI documentation for mediated device support Dave Jiang
2020-07-21 16:28 ` [PATCH RFC v2 00/18] Add VFIO mediated device support and DEV-MSI support for the idxd driver Greg KH
2020-07-21 17:17 ` Dave Jiang
2020-07-21 21:35 ` Dan Williams
2020-07-21 16:45 ` Jason Gunthorpe
2020-07-21 18:00 ` Dave Jiang [this message]
2020-07-22 17:31 ` Dey, Megha
2020-07-22 18:16 ` Jason Gunthorpe
2020-07-21 23:54 ` Tian, Kevin
2020-07-24 0:19 ` Jason Gunthorpe
2020-08-06 1:22 ` Alex Williamson
2020-08-07 12:19 ` Jason Gunthorpe
2020-08-10 7:32 ` Tian, Kevin
2020-08-11 17:00 ` Alex Williamson
2020-08-12 1:58 ` Tian, Kevin
2020-08-12 2:36 ` Alex Williamson
2020-08-12 3:35 ` Tian, Kevin
2020-08-12 3:28 ` Jason Wang
2020-08-12 4:05 ` Tian, Kevin
2020-08-13 4:33 ` Jason Wang
2020-08-13 5:26 ` Tian, Kevin
2020-08-13 6:01 ` Jason Wang
2020-08-14 13:23 ` Jason Gunthorpe
2020-08-17 2:24 ` Tian, Kevin
2020-08-14 13:35 ` Jason Gunthorpe
2020-08-17 2:12 ` Tian, Kevin
2020-08-18 0:43 ` Jason Gunthorpe
2020-08-18 1:09 ` Tian, Kevin
2020-08-18 11:50 ` Jason Gunthorpe
2020-08-18 16:27 ` Paolo Bonzini
2020-08-18 16:49 ` Jason Gunthorpe
2020-08-18 17:05 ` Paolo Bonzini
2020-08-18 17:18 ` Jason Gunthorpe
2020-08-19 7:29 ` Tian, Kevin
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