Re: [RFC PATCH v5 0/5] vfio-pci: Add support for mmapping MSI-X table

From: Alexey Kardashevskiy <aik@ozlabs.ru>
To: linuxppc-dev@lists.ozlabs.org
Cc: David Gibson <david@gibson.dropbear.id.au>,
	kvm-ppc@vger.kernel.org, kvm@vger.kernel.org,
	Yongji Xie <elohimes@gmail.com>,
	Eric Auger <eric.auger@redhat.com>,
	Kyle Mahlkuch <Kyle.Mahlkuch@ibm.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	Jike Song <jike.song@intel.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Joerg Roedel <joro@8bytes.org>,
	Arvind Yadav <arvind.yadav.cs@gmail.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	David Woodhouse <dwmw2@infradead.org>,
	Kirti Wankhede <kwankhede@nvidia.com>,
	Mauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com>,
	Neo Jia <cjia@nvidia.com>, Paul Mackerras <paulus@samba.org>,
	Vlad Tsyrklevich <vlad@tsyrklevich.net>,
	iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH v5 0/5] vfio-pci: Add support for mmapping MSI-X table
Date: Mon, 11 Sep 2017 13:27:46 +1000	[thread overview]
Message-ID: <3c8302eb-0485-809b-6052-a8ceacd119e7@ozlabs.ru> (raw)
In-Reply-To: <79581f70-a4c9-dac9-a671-4de7f55bd86e@ozlabs.ru>

On 29/08/17 12:58, Alexey Kardashevskiy wrote:
> On 21/08/17 12:47, Alexey Kardashevskiy wrote:
>> Folks,
>>
>> Ok, people did talk, exchanged ideas, lovely :) What happens now? Do I
>> repost this or go back to PCI bus flags or something else? Thanks.
> 
> 
> Anyone, any help? How do we proceed with this? Thanks.

Ping, anyone?

Or everybody is just waiting for the kvm forum to discuss it in person? Thanks.

> 
> 
> 
>>
>>
>>
>> On 14/08/17 19:45, Alexey Kardashevskiy wrote:
>>> Folks,
>>>
>>> Is there anything to change besides those compiler errors and David's
>>> comment in 5/5? Or the while patchset is too bad? Thanks.
>>>
>>>
>>>
>>> On 07/08/17 17:25, Alexey Kardashevskiy wrote:
>>>> This is a followup for "[PATCH kernel v4 0/6] vfio-pci: Add support for mmapping MSI-X table"
>>>> http://www.spinics.net/lists/kvm/msg152232.html
>>>>
>>>> This time it is using "caps" in IOMMU groups. The main question is if PCI
>>>> bus flags or IOMMU domains are still better (and which one).
>>>
>>>>
>>>>
>>>>
>>>> Here is some background:
>>>>
>>>> Current vfio-pci implementation disallows to mmap the page
>>>> containing MSI-X table in case that users can write directly
>>>> to MSI-X table and generate an incorrect MSIs.
>>>>
>>>> However, this will cause some performance issue when there
>>>> are some critical device registers in the same page as the
>>>> MSI-X table. We have to handle the mmio access to these
>>>> registers in QEMU emulation rather than in guest.
>>>>
>>>> To solve this issue, this series allows to expose MSI-X table
>>>> to userspace when hardware enables the capability of interrupt
>>>> remapping which can ensure that a given PCI device can only
>>>> shoot the MSIs assigned for it. And we introduce a new bus_flags
>>>> PCI_BUS_FLAGS_MSI_REMAP to test this capability on PCI side
>>>> for different archs.
>>>>
>>>>
>>>> This is based on sha1
>>>> 26c5cebfdb6c "Merge branch 'parisc-4.13-4' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux"
>>>>
>>>> Please comment. Thanks.
>>>>
>>>> Changelog:
>>>>
>>>> v5:
>>>> * redid the whole thing via so-called IOMMU group capabilities
>>>>
>>>> v4:
>>>> * rebased on recent upstream
>>>> * got all 6 patches from v2 (v3 was missing some)
>>>>
>>>>
>>>>
>>>>
>>>> Alexey Kardashevskiy (5):
>>>>   iommu: Add capabilities to a group
>>>>   iommu: Set IOMMU_GROUP_CAP_ISOLATE_MSIX if MSI controller enables IRQ
>>>>     remapping
>>>>   iommu/intel/amd: Set IOMMU_GROUP_CAP_ISOLATE_MSIX if IRQ remapping is
>>>>     enabled
>>>>   powerpc/iommu: Set IOMMU_GROUP_CAP_ISOLATE_MSIX
>>>>   vfio-pci: Allow to expose MSI-X table to userspace when safe
>>>>
>>>>  include/linux/iommu.h            | 20 ++++++++++++++++++++
>>>>  include/linux/vfio.h             |  1 +
>>>>  arch/powerpc/kernel/iommu.c      |  1 +
>>>>  drivers/iommu/amd_iommu.c        |  3 +++
>>>>  drivers/iommu/intel-iommu.c      |  3 +++
>>>>  drivers/iommu/iommu.c            | 35 +++++++++++++++++++++++++++++++++++
>>>>  drivers/vfio/pci/vfio_pci.c      | 20 +++++++++++++++++---
>>>>  drivers/vfio/pci/vfio_pci_rdwr.c |  5 ++++-
>>>>  drivers/vfio/vfio.c              | 15 +++++++++++++++
>>>>  9 files changed, 99 insertions(+), 4 deletions(-)
>>>>
>>>
>>>
>>
>>
> 
> 

-- 
Alexey